Optical characteristic measurement method, optical characteristic measurement program, and subjective optometry device

Abstract

An optical characteristic measurement method for an eye to be examined, the method comprising, on two-dimensional orthogonal coordinates (110) in which, among astigmatic components of an ocular refraction value, components having astigmatic axis angles of α degrees and α + 90 degrees are defined as an X axis (J0) and components having astigmatic axis angles of α + 45 degrees and α + 135 degrees are defined as a Y axis (J45): a step for determining a first vector (151) representing an astigmatic component of a first correction value; a step for acquiring a first answer direction (152) in a state corrected by the first correction value; a step for determining a first region (153) extending from an end point (150) of the first vector (151) in the first answer direction (152); a step for determining a second vector (161) representing an astigmatic component of a second correction value different from the first correction value; a step for acquiring a second answer direction (162) in a state corrected by the second correction value; a step for determining a second region (163) extending from an end point (160) of the second vector (161) in the second answer direction (162); and a candidate correction value determination step for determining a candidate correction value (172) on the basis of an intersection position (170) of the first region (153) and the second region (163).

Description

Optical Characteristic Measurement Method, Optical Characteristic Measurement Program, and Subjective Refractometer

[0001] The present disclosure relates to an optical characteristic measurement method, an optical characteristic measurement program, and a subjective refractometer for subjectively measuring optical characteristics of an eye to be examined including astigmatic characteristics.

[0002] For example, it is known to measure astigmatic characteristics (e.g., cylindrical power, astigmatic axis angle, etc.) of an eye to be examined by performing a cross-cylinder examination using a point-cloud target on the subject eye with a subjective refractometer that measures optical characteristics of the subject eye. (See Patent Document 1)

[0003] Furthermore, as a method for subjectively measuring astigmatic characteristics of an eye to be examined, a radiation test using a radiation astigmatism chart is known.

[0004] Japanese Unexamined Patent Publication No. 2022-89677

[0005] For example, in a cross-cylinder examination using a point-cloud target, the procedure of asking the subject whether there is a difference in visual perception before and after reversing the cross-cylinder lens while changing the cylindrical power or the astigmatic axis angle is repeated. For this reason, for both the examiner and the subject, the number of operations or questions and answers is large, which takes time and effort. In addition, in the radiation test, although it is easy to estimate the astigmatic axis angle, it may be difficult to measure the astigmatic power. When measuring astigmatic characteristics by radiation examination, it takes time and effort for the examiner and the subject, for example, repeating questions and answers asking the subject about their visual perception while adjusting the power of a cylindrical lens in a trial frame or the like, or using the test in combination with other astigmatism examination targets.

[0006] In view of the above-mentioned prior art, it is a technical object of the present disclosure to provide an optical characteristic measurement method, an optical characteristic measurement program, and a subjective refractometer that smoothly measure astigmatic characteristics of an eye to be examined.

[0007] To solve the above problems, this disclosure is characterized by having the following configuration. (1) An optical property measurement method according to a first aspect of this disclosure is an optical property measurement method for subjectively measuring the optical properties of an eye, including astigmatism, and comprises: a first vector determination step of determining a first vector representing the astigmatism component corresponding to a first correction value for the eye, on a two-dimensional Cartesian coordinate system where, when an arbitrary angle is α, the components of the astigmatism component in the refractive value have astigmatism axis angles of α degrees and α+90 degrees as the X axis, and the components have astigmatism axis angles of α+45 degrees and α+135 degrees as the Y axis; a first response direction acquisition step of obtaining a first response direction, which is the direction of the first response given by the subject, with the light beam of the astigmatism test target presented to the eye corrected by the first correction value; and a first vector extending in the first response direction with the endpoint of the first vector as the base point. The method is characterized by including: a first region determination step of determining a region on the two-dimensional Cartesian coordinate system; a second vector determination step of determining a second vector on the two-dimensional Cartesian coordinate system that represents an astigmatism component corresponding to a second correction value different from the first correction value; a second response direction acquisition step of acquiring the second response direction, which is the direction of the second response given by the subject, with the light beam of the astigmatism test target presented to the eye being examined corrected by the second correction value; a second region determination step of determining a second region extending in the second response direction with the endpoint of the second vector as the base point on the two-dimensional Cartesian coordinate system; and a candidate correction value determination step of determining a candidate correction value to be applied to the eye being examined based on the intersection position of the first region and the second region.(2) An optical properties measurement program according to a second aspect of the present disclosure is an optical properties measurement program executed in an information processing device for subjectively measuring the optical properties of an eye, including astigmatism, wherein the information processing device comprises at least a control unit, and the optical properties measurement program is executed by the control unit to determine a first vector determination step of determining a first vector representing the astigmatism component corresponding to a first correction value for the eye, on a two-dimensional Cartesian coordinate system where, with an arbitrary angle α, the components of the astigmatism component in the refractive value have astigmatism axis angles of α degrees and α+90 degrees as the X axis, and the components have astigmatism axis angles of α+45 degrees and α+135 degrees as the Y axis; and a first response direction acquisition step of acquiring a first response direction, which is the direction of the first response given by the subject, with the light beam of the astigmatism test target presented to the eye corrected by the first correction value. The information processing device is made to execute the following steps: a first region determination step of determining a first region extending in the first response direction with the endpoint of the first vector as the base point on the two-dimensional Cartesian coordinate system; a second vector determination step of determining a second vector representing an astigmatism component corresponding to a second correction value different from the first correction value on the two-dimensional Cartesian coordinate system; a second response direction acquisition step of acquiring the second response direction, which is the direction of the second response given by the subject, with the light beam of the astigmatism test target presented to the subject's eye corrected by the second correction value; a second region determination step of determining a second region extending in the second response direction with the endpoint of the second vector as the base point on the two-dimensional Cartesian coordinate system; and a candidate correction value determination step of determining a candidate correction value to be applied to the subject's eye based on the intersection position of the first region and the second region.(3) A subjective ophthalmoscopic device according to a third aspect of the present disclosure is a subjective ophthalmoscopic device for subjectively measuring the optical properties of an eye, including astigmatism characteristics, comprising: a correction means for changing the optical properties of a target light beam presented to the eye; and a control unit, wherein the control unit determines a first vector representing the astigmatism component corresponding to a first correction value for the eye, on a two-dimensional Cartesian coordinate system where, with an arbitrary angle α, the components of the astigmatism component in the refractive value with astigmatism axis angles of α degrees and α+90 degrees are the X-axis, and the components with astigmatism axis angles of α+45 degrees and α+135 degrees are the Y-axis, and the control unit determines a first vector representing the astigmatism component corresponding to a first correction value for the eye; a first response direction acquisition step for acquiring a first response direction, which is the direction of a first response given by the subject, while the light beam of the astigmatism test target presented to the eye is corrected by the correction means with the first correction value; and the first vector The method is characterized by performing: a first region determination step of determining a first region extending in the first response direction with respect to the endpoint on the two-dimensional Cartesian coordinate system; a second vector determination step of determining a second vector representing an astigmatism component corresponding to a second correction value different from the first correction value on the two-dimensional Cartesian coordinate system; a second response direction acquisition step of acquiring the second response direction, which is the direction of the second response given by the subject, with the light beam of the astigmatism test target presented to the subject's eye corrected by the second correction value by the correction means; a second region determination step of determining a second region extending in the second response direction with respect to the endpoint of the second vector on the two-dimensional Cartesian coordinate system; and a candidate correction value determination step of determining a candidate correction value to be applied to the subject's eye based on the intersection position of the first region and the second region.

[0008] This is an external perspective view of a subjective optometry device supported in a standby position. This is an external perspective view of a subjective optometry device indicated at the measurement position. This is a schematic side view of the projection optical system during distance vision testing. This is a schematic side view of the projection optical system during near vision testing. This is a schematic front view of the refractive power measurement unit. This is an example of a schematic diagram of the control system of a subjective optometry device. This is an example of a flowchart showing the control process of the optical properties measurement method in the first embodiment (using the angular difference between the reference direction and the response direction). This is an example of a diagram of the two-dimensional orthogonal coordinates used in the optical properties measurement method of this embodiment. This is an example of a radiation astigmatism table. This is an example of a condition map for determining the corrected value of a change target based on the angular difference between the reference direction and the response direction. This is an example of a condition map for determining the corrected value of a change target based on the angular difference between the reference direction and the response direction. This is an example of a diagram of the two-dimensional orthogonal coordinates used when determining the corrected value of a change target based on the angular difference between the reference direction and the response direction. This is an example of a flowchart showing the control process of the optical properties measurement method in the second embodiment. This is an example of a diagram of the two-dimensional orthogonal coordinates used when determining candidate corrected values. This is an example of a diagram of the two-dimensional orthogonal coordinates used when determining the second corrected value. This is an example of a flowchart showing the control process for measuring optical properties in a transformation example. This is an example of a two-dimensional Cartesian coordinate diagram to explain a method for determining target correction values ​​based on the concept of vector synthesis.

[0009] <Overview> The following describes one typical embodiment. The items classified in < > below can be used independently or in relation to each other.

[0010] <First Embodiment> The optical properties measurement method of the present disclosure is a method for subjectively measuring the optical properties of an eye, including astigmatism. The optical properties measurement method of the present disclosure includes a step of acquiring the response direction and a step of determining the target correction value. In the step of acquiring the response direction, the response direction answered by the subject is acquired when the light beam of the astigmatism test target presented to the eye is corrected to a reference correction value. In the step of determining the target correction value, the target correction value, which is the next astigmatism correction value, is determined according to the angle difference between the reference direction, which is the direction of the astigmatism axis angle corrected at the reference correction value, and the response direction.

[0011] According to the above configuration, by obtaining two elements—the direction of the astigmatism axis angle corrected at the reference correction value (reference direction) and the direction of the response given by the subject based on their vision when the light beam of the astigmatism test target was corrected at the reference correction value—the target correction value, which is the next astigmatism correction value, can be determined. The target correction value obtained here is not necessarily the true value of the astigmatism characteristics of the eye being examined, but by determining the target correction value according to the angle difference between the direction of the corrected astigmatism axis angle and the response direction, the target correction value tends to approach the true value more easily. Therefore, it becomes easier to reach an appropriate astigmatism correction value efficiently. In other words, by utilizing the residual astigmatism that resulted in the corrected eye, it becomes easier to reach an appropriate astigmatism correction value efficiently, and consequently, it becomes easier to measure the astigmatism characteristics of the eye being examined more smoothly.

[0012] The optical properties measurement method may further include a reference vector determination step. In the reference vector determination step, with an arbitrary angle α, a reference vector is determined that represents the astigmatic component corresponding to the reference corrected value for the eye under examination on a two-dimensional Cartesian coordinate system where the components of the astigmatic component in the refractive value with astigmatic axis angles of α degrees and α+90 degrees are the X-axis, and the components with astigmatic axis angles of α+45 degrees and α+135 degrees are the Y-axis. In the target corrected value determination step, the direction of the reference vector on the two-dimensional Cartesian coordinate system is taken as the reference direction, and the target corrected value is determined according to the angle difference between the reference direction and the response direction. The arbitrary angle α degrees may be any angle between 0 degrees and less than 180 degrees. In this specification, the technology of this disclosure is described with an arbitrary angle α degrees set to 0 degrees.

[0013] By using the two-dimensional Cartesian coordinate system described above, the coordinate system location where the true value of the astigmatism characteristic of the eye being examined is most likely to exist can be accurately predicted based on the reference correction value and the response direction. Therefore, by using the direction of the reference vector and the response direction on the two-dimensional Cartesian coordinate system, the target correction value can be accurately determined.

[0014] However, the target correction value may be determined based on the angular difference between the reference direction and the response direction without setting a reference vector on the above two-dimensional Cartesian coordinate system. For example, a procedure for determining the target correction value (in this disclosure, a procedure that determines how much to change one or both of the cylindrical power and astigmatism axis angle in the reference correction value to determine the target correction value) may be pre-associated by a program or table for each angular difference between the reference direction and the response direction. In the target correction value determination step, the target correction value may be automatically determined according to a procedure pre-associated with the calculated angular difference. Even in this case, the appropriate target correction value can be efficiently determined by utilizing residual astigmatism. Furthermore, when associating the target correction value determination procedure for each angular difference between the reference direction and the response direction (for example, when constructing a program or table), it is possible to appropriately associate the target correction value determination procedure with each angular difference by using the above two-dimensional Cartesian coordinate system shown in double angles.

[0015] Multiple angle ranges may be set within the range of 0 to 180 degrees that the angle difference between the reference direction and the response direction can take. A procedure for determining the target correction value in the target correction value determination step may be pre-associated with each of the multiple angle ranges. In the target correction value determination step, the target correction value may be determined according to a determination procedure pre-associated with the angle range to which the calculated angle difference belongs among the multiple angle ranges.

[0016] In this case, the target correction value can be easily and appropriately set simply by determining which of the multiple angle ranges the calculated angle difference belongs to. Furthermore, when associating the procedure for determining the target correction value with each of the multiple angle ranges, the above-mentioned two-dimensional orthogonal coordinate system, expressed in double-angle form, may be used. In this case, the coordinate system's position where the true value of the astigmatism characteristic of the eye under examination is most likely to exist is appropriately identified, and then the procedure for determining the target correction value is associated with each of the multiple angle ranges.

[0017] In the target correction value determination step, if the angle difference between the reference direction and the response direction is 45 degrees or 135 degrees (including cases where the angle difference is 45 + 90 × n (where n is an integer) degrees), the target correction value may be determined by changing the astigmatism axis angle of the reference correction value. Expressed using the two-dimensional Cartesian coordinates described above, in the target correction value determination step, if the angle difference between the direction of the reference vector and the response direction is represented as perpendicular in the two-dimensional Cartesian coordinates, the target correction value may be determined by changing the astigmatism axis angle of the reference correction value.

[0018] According to the above configuration, when the angle difference between the reference direction and the response direction is 45 degrees or 135 degrees, the amount of correction for the cylindrical power of the reference correction value is appropriate, but the amount of correction for the astigmatism axis angle of the reference correction value is incorrect. To explain this on a double-angle two-dimensional Cartesian coordinate system, when the angle difference between the direction of the reference vector and the response direction is represented as perpendicular in a double-angle two-dimensional Cartesian coordinate system (in other words, when the angle difference between the reference vector and the response direction is 45 degrees or 135 degrees), it becomes clear on the two-dimensional Cartesian coordinate system that the amount of correction for the cylindrical power of the reference correction value is appropriate, but the amount of correction for the astigmatism axis angle of the reference correction value is incorrect. Therefore, when determining the target correction value, only the astigmatism axis angle needs to be changed from the cylindrical power and astigmatism axis angle in the reference correction value, making it possible to determine the target correction value more efficiently. Consequently, astigmatism characteristics can be measured more smoothly.

[0019] Furthermore, the statement that "the angle difference between the direction of the reference vector and the direction of the answer is represented perpendicularly on a double-angle two-dimensional Cartesian coordinate system" means that, on a double-angle two-dimensional Cartesian coordinate system, the angle difference between the direction of the reference vector and the direction of the answer is visually 90 degrees or 270 degrees, where one full rotation is 360 degrees. In other words, when the angle difference between the direction of the reference vector and the direction of the answer is represented perpendicularly on a two-dimensional Cartesian coordinate system, the angle difference between the reference vector and the direction of the answer is 45 degrees or 135 degrees.

[0020] In the target correction value determination step, if the angle difference between the reference direction and the response direction is 0 degrees or 90 degrees (including cases where the angle difference is 90 × n (where n is an integer) degrees), the target correction value may be determined by changing the cylindrical degree of the reference correction value. Expressed using the two-dimensional Cartesian coordinates described above, in the target correction value determination step, if the direction of the reference vector and the response direction are represented as parallel in the two-dimensional Cartesian coordinates, the target correction value may be determined by changing the cylindrical degree.

[0021] According to the above configuration, when the angle difference between the reference direction and the response direction is 0 degrees or 90 degrees, the amount of correction for the astigmatism axis angle of the reference correction value is appropriate, but the amount of correction for the cylindrical power of the reference correction value is incorrect. To explain this on a double-angle two-dimensional Cartesian coordinate system, when the direction of the reference vector and the response direction are represented as parallel in the two-dimensional Cartesian coordinate system (in other words, when the angle difference between the reference vector and the response direction is 0 degrees or 90 degrees, and the angle difference is represented as 0 degrees or 180 degrees in the double-angle two-dimensional orthogonal coordinate system), it is clearly understood on the two-dimensional Cartesian coordinate system that the amount of correction for the astigmatism axis angle of the reference correction value is appropriate, but the amount of correction for the cylindrical power of the reference correction value is incorrect. Therefore, when determining the target correction value, only the cylindrical power among the cylindrical power and astigmatism axis angle in the reference correction value needs to be changed, making it possible to determine the target correction value more efficiently. Consequently, astigmatism characteristics can be measured more smoothly.

[0022] Furthermore, "the direction of the reference vector and the response direction are represented parallel to each other on a two-dimensional Cartesian coordinate system" means that, on a two-dimensional Cartesian coordinate system represented by double angles, the angular difference between the direction of the reference vector and the response direction is visually 0 degrees or 180 degrees, with one full rotation being 360 degrees. In other words, when the angular difference between the direction of the reference vector and the response direction are represented parallel to each other on a two-dimensional Cartesian coordinate system, the angular difference between the reference vector and the response direction is 0 degrees or 90 degrees.

[0023] If the angle difference between the reference direction and the response direction falls within a first angular range including 45 degrees, or a second angular range including 135 degrees, the target correction value may be determined by changing the astigmatism axis angle of the reference correction value (only the astigmatism axis angle in the embodiments described below). If the angle difference between the reference direction and the response direction falls within a third angular range including 0 degrees, or a fourth angular range including 90 degrees, the target correction value may be determined by changing the cylindrical power of the reference correction value (only the cylindrical power in the embodiments described below).

[0024] Expressed using the two-dimensional Cartesian coordinates described above, in the target correction value determination step, if the angle difference between the direction of the reference vector and the response direction on the two-dimensional Cartesian coordinates is within a first angular range including 45 degrees, or within a second angular range including 135 degrees, the target correction value may be determined by changing the astigmatism axis angle of the reference correction value (only the astigmatism axis angle in the embodiments described below). If the angle difference between the direction of the reference vector and the response direction on the two-dimensional Cartesian coordinates is within a third angular range including 0 degrees, or within a fourth angular range including 90 degrees, the target correction value may be determined by changing the cylindrical degree of the reference correction value (only the cylindrical degree in the embodiments described below).

[0025] According to the above configuration, the procedure for determining whether to change the cylindrical power or astigmatism axis angle of the reference correction value to determine the target correction value, based on the angular difference between the reference direction and the response direction (whether it is close to 45 degrees or 135 degrees, or close to 0 degrees or 90 degrees), can be easily and appropriately determined without requiring the examiner's experience or skill level.

[0026] The first angle range is set to a range greater than 0 degrees and less than 90 degrees, and may include 45 degrees. For example, the first angle range may be 45 degrees ± A degrees (A < 45 degrees) (however, 45 degrees does not have to be the median value within the first angle range). The second angle range is set to a range greater than 90 degrees and less than 180 degrees, and may include 135 degrees. For example, the second angle range may be 135 degrees ± B degrees (B < 45 degrees) (however, 135 degrees does not have to be the median value within the second angle range). The third angle range is set to a range greater than 135 degrees and less than or equal to 180 degrees (synonymous with 0 degrees), and within a range of 0 degrees or more and less than 45 degrees, and may include 0 degrees (180 degrees). For example, the third angle range may be 0 degrees ± C degrees (where C < 45 degrees, and if 0 degrees ± C degrees is negative, it is equivalent to the angle obtained by adding 180 degrees to the value of 0 degrees ± C degrees) (however, 0 degrees does not have to be the median value within the third angle range). The fourth angle range is set to a range greater than 45 degrees and less than 135 degrees, and may include 90 degrees. For example, the fourth angle range may be 90 degrees ± D degrees (D < 45 degrees) (however, 90 degrees does not have to be the median value within the fourth angle range).

[0027] In the target correction value determination step, if the angle difference between the reference direction and the response direction is within an intermediate angle range set between the first and third angle ranges, the first and fourth angle ranges, the second and third angle ranges, and the second and fourth angle ranges, the target correction value may be determined by changing both the astigmatism axis angle and the cylindrical power of the reference correction value. Expressed using the two-dimensional Cartesian coordinates described above, in the target correction value determination step, if the angle difference between the direction of the reference vector and the response direction on the two-dimensional Cartesian coordinates is within an intermediate angle range set between the first and third angle ranges, the first and fourth angle ranges, the second and third angle ranges, and the second and fourth angle ranges, the target correction value may be determined by changing both the astigmatism axis angle and the cylindrical power of the reference correction value.

[0028] According to the above configuration, when the angle difference between the reference direction and the response direction is within the intermediate angle range, changing both the astigmatic axis angle and the cylindrical power of the reference correction value makes it easier to bring the target correction value closer to the true value. Explaining this on a double-angle two-dimensional Cartesian coordinate system, it becomes clear on the two-dimensional Cartesian coordinate system that when the angle difference between the direction of the reference vector and the response direction is within the intermediate angle range, changing both the astigmatic axis angle and the cylindrical power of the reference correction value brings the target correction value closer to the true value. Therefore, when determining the target correction value, whether it is appropriate to change both the astigmatic axis angle and the cylindrical power of the reference correction value can be appropriately determined by the angle difference between the reference direction and the response direction. Thus, the target correction value can be determined more efficiently.

[0029] However, it is also possible to set only the first to fourth angle ranges without setting an intermediate angle range. Even in this case, it is appropriate to determine whether it is appropriate to change the astigmatism axis angle or the cylindrical power of the reference correction value based on the angle difference between the reference direction and the response direction.

[0030] In the step of determining the target correction value, if the target correction value is to be determined by changing the astigmatism axis angle of the reference correction value, the amount of change in the astigmatism axis angle may be adjusted according to the magnitude of the cylindrical power corrected in the reference correction value. Furthermore, using a reference vector, the magnitude of the cylindrical power corrected in the reference correction value can also be expressed as the distance between the origin and the endpoint of the reference vector on a two-dimensional Cartesian coordinate system (i.e., the magnitude of the reference vector).

[0031] Regardless of the magnitude of the cylindrical power corrected in the reference correction value, when the astigmatism axis angle of the reference correction value is changed by the same amount, the degree of impact on the vision of the eye being examined changes according to the magnitude of the cylindrical power in the original reference correction value. The following explanation uses double-angle two-dimensional Cartesian coordinates. In the double-angle two-dimensional Cartesian coordinates mentioned above, even if the same amount of change equivalent to the astigmatism axis angle is added to the reference vector, the effect on the displacement distance of the reference vector's endpoint in the two-dimensional Cartesian coordinates differs depending on whether the endpoint of the reference vector is close to the origin or far from the origin. For example, when adding a change equivalent to 3 degrees of astigmatism axis angle to a reference vector whose endpoint is close to the origin, compared to adding a change equivalent to 3 degrees of astigmatism axis angle to a reference vector whose endpoint is far from the origin, the displacement distance of the reference vector's endpoint is greater when the change equivalent to 3 degrees of astigmatism axis angle is added to the reference vector whose endpoint is far from the origin (i.e., the influence and effect on the amount of change is greater).

[0032] Given this background, if the cylindrical power that was originally corrected in the standard corrected value was small, adding only a small change in the astigmatism axis angle to the standard corrected value may not produce a difference that the subject can perceive.

[0033] As described above, by adjusting the amount of change in the astigmatism axis angle of the reference correction value according to the magnitude of the cylindrical power corrected in the reference correction value, an appropriate target correction value can be efficiently determined.

[0034] Another embodiment of the optical property measurement method of this disclosure includes a step of acquiring the response direction and a step of determining the target correction value. In the step of acquiring the response direction, the response direction answered by the subject is acquired when the light beam of the astigmatism test target presented to the eye of the subject is corrected to a reference correction value. In the step of determining the target correction value, a composite correction value is determined as the target correction value, which is the next astigmatism correction value, by combining the reference correction value with an additional correction value in which the astigmatism axis angle matches the response direction.

[0035] According to an alternative optical properties measurement method, a target correction value, which is the next astigmatism correction value, can be determined by obtaining two elements: a reference correction value and the direction of response given by the subject based on their visual perception when the light beam of the astigmatism test target is corrected with the reference correction value. The target correction value obtained here is not necessarily the true value of the astigmatism characteristics of the eye being examined, but by combining an additional correction value, where the astigmatism axis angle matches the response direction, with the reference correction value, the target correction value becomes closer to the true value. Therefore, it becomes easier to efficiently reach an appropriate astigmatism correction value. Consequently, it becomes easier to measure the astigmatism characteristics of the eye being examined more smoothly. In other words, by utilizing the residual astigmatism that results in the corrected eye, it becomes easier to efficiently reach an appropriate astigmatism correction value, and consequently, it becomes easier to measure the astigmatism characteristics of the eye being examined more smoothly.

[0036] In this disclosure, instead of using both an optical component for correcting the reference correction value and an optical component for correcting the additional correction value in the subjective examination, a composite correction value is calculated by combining the reference correction value and the additional correction value, and an optical component that corrects the calculated composite correction value is used in the subjective examination. Therefore, the subjective examination can be performed smoothly without the need to use many optical components in combination.

[0037] Another embodiment of the optical properties measurement method may further include a reference vector determination step and a response vector determination step. In the reference vector determination step, with an arbitrary angle α, a reference vector is determined that represents the astigmatic component corresponding to the reference correction value for the eye under examination on a two-dimensional Cartesian coordinate system where the astigmatic axis angles of α degrees and α+90 degrees are the X-axis and the astigmatic axis angles of α+45 degrees and α+135 degrees are the Y-axis. In the response vector determination step, a response vector whose angle coincides with the response direction is determined on a two-dimensional Cartesian coordinate system. In this case, in the target correction value determination step, the target correction value may be determined on a two-dimensional Cartesian coordinate system based on the coordinates of the endpoint of the composite vector obtained by combining the reference vector and the response vector.

[0038] According to the above configuration, the composite vector corresponds to the combined astigmatism correction value when a cylindrical lens with a predetermined cylindrical correction amount is superimposed on the reference correction value in the response direction (for example, the direction of the residual astigmatism axis angle). Therefore, by determining the composite vector, the target correction value can be appropriately calculated. In other words, the amount of correction for both the cylindrical power and the astigmatism axis angle can be calculated at once, making it easier to measure astigmatism characteristics more smoothly.

[0039] The step of obtaining the response direction may also involve presenting the astigmatism test target to the subject's eye as a radial astigmatism chart and obtaining the response direction from the subject.

[0040] According to the above configuration, when obtaining the direction of response using a radial astigmatism chart, for example, by obtaining the subject's response to the question of which direction of lines on the radial astigmatism chart appears darker, while the luminous flux of the radial astigmatism chart presented to the subject's eye is corrected to predetermined correction values ​​(e.g., reference correction value and target correction value), the direction of response can be obtained more easily (compared to, for example, the cross-cylinder method using point cloud targets). In this way, the operation and question-and-answer session for obtaining the direction of response (e.g., residual astigmatism axis angle) are simplified, and time and effort can be reduced.

[0041] <Second Embodiment> The optical properties measurement method of the present disclosure is a method for subjectively measuring the optical properties of an eye, including astigmatism characteristics. The optical properties measurement method of the present disclosure includes a first vector determination step, a first response direction acquisition step, a first region determination step, a second vector determination step, a second response direction acquisition step, a second region determination step, and a candidate correction value determination step. The first vector determination step determines a first vector representing the astigmatism component corresponding to a first correction value for the eye under examination on a two-dimensional Cartesian coordinate system. When an arbitrary angle is α, in the two-dimensional Cartesian coordinate system, the components of the astigmatism component in the refractive value with astigmatism axis angles of α degrees and α+90 degrees are set as the X axis, and the components with astigmatism axis angles of α+45 degrees and α+135 degrees are set as the Y axis. The first response direction acquisition step acquires the first response direction, which is the direction of the first response given by the subject, with the light beam of the astigmatism test target presented to the eye under examination corrected by the first correction value. The first region determination step determines a first region extending in the first response direction, starting from the endpoint of the first vector, on a two-dimensional Cartesian coordinate system. The second vector determination step determines a second vector in a two-dimensional Cartesian coordinate system that represents the astigmatism component corresponding to a second correction value different from the first correction value. The second response direction acquisition step acquires the second response direction, which is the direction of the second response given by the subject, with the light beam of the astigmatism test target presented to the eye corrected by the second correction value. The second region determination step determines a second region extending in the second response direction, starting from the endpoint of the second vector, on a two-dimensional Cartesian coordinate system. The candidate correction value determination step determines a candidate correction value to be applied to the eye, based on the intersection position of the first region and the second region. The arbitrary angle α degree may be any angle between 0 degrees and 180 degrees. In this specification, the technology of this disclosure is described with the arbitrary angle α degree set to 0 degrees.

[0042] When the answer direction of the subject is acquired in a state where the light flux of the astigmatism examination visual target is corrected to a predetermined value, on two-dimensional orthogonal coordinates, the true value of the astigmatic characteristic of the subject's eye is highly likely to exist on or near a region starting from the end point of the vector of the correction value and extending in the acquired answer direction. Accordingly, subjective examinations (a first examination and a second examination) using an astigmatism examination visual target are performed at least twice, and the true value of the astigmatic characteristic of the subject's eye exists with higher accuracy on or near the intersection position between a first region determined according to a first correction value and a first answer direction in the first examination, and a second region determined according to a second correction value and a second answer direction in the second examination. Therefore, by determining a candidate correction value based on the intersection position, an appropriate astigmatism correction value can be reached efficiently. That is, by intentionally causing residual astigmatism (in at least the second examination) and using the residual astigmatism, an appropriate astigmatism correction value can be obtained efficiently.

[0043] The first region indicates a region estimated to contain or be in the vicinity of the true value of the astigmatic characteristic of the subject's eye based on the first correction value and the first answer direction. The second region indicates a region estimated to contain or be in the vicinity of the true value of the astigmatic characteristic of the subject's eye based on the second correction value and the second answer direction. The intersection position of the first region and the second region is a position where two different regions each estimated to contain or be in the vicinity of the true value of the astigmatic characteristic of the subject's eye overlap, and it is estimated that the true value of the astigmatic characteristic of the subject's eye exists at or near this intersection position. The candidate correction value is determined based on such intersection position.

[0044] At least the second correction value may be determined according to an instruction input by an examiner.

[0045] According to the above configuration, the examiner can manually input and determine a value judged appropriate based on the examiner's own experience, knowledge or optometry policy as the second correction value, thereby efficiently reaching an appropriate astigmatism correction value.

[0046] The optical characteristic measurement method of the present disclosure may further include a first region displaying step and a coordinate information receiving step. In the first region displaying step, two-dimensional orthogonal coordinates including the first region are displayed on a display unit. The coordinate information receiving step receives an input of an instruction to specify coordinate information corresponding to a second correction value on the two-dimensional orthogonal coordinates in a state where the two-dimensional orthogonal coordinates are displayed on the display unit. In this case, in the second vector determining step, the second vector may be determined based on the second correction value corresponding to the coordinate information specified in the coordinate information receiving step.

[0047] According to the above configuration, an examiner can determine the second correction value while considering the positional relationship of the first region on the two-dimensional orthogonal coordinates displayed on the display unit. For example, the examiner can determine the second correction value after grasping the first region displayed on the two-dimensional orthogonal coordinates such that the first region and the second region are likely to intersect perpendicularly as much as possible visually in the two-dimensional orthogonal coordinates (when one revolution is regarded as 360 degrees). In this case, an appropriate astigmatism correction value is more likely to be determined efficiently and appropriately.

[0048] The optical characteristic measurement method of the present disclosure may further include an automatic determining step. In the automatic determining step, at least the second correction value is automatically determined by a value calculated by an arithmetic device based on a predetermined condition.

[0049] When the second correction value is automatically determined, the examiner does not need to hesitate about what value the second correction value should be. Therefore, a subjective examination of an eye to be examined is likely to be performed smoothly.

[0050] In the automatic determining step, in the two-dimensional orthogonal coordinates, the second correction value corresponding to coordinates of a position that passes through a position separated by a distance equal to or greater than a threshold from an end point of the first vector on a half-line extending from the end point of the first vector in a first answer direction, and is located on a perpendicular line visually orthogonal to the half-line (when one revolution is regarded as 360 degrees), and is separated by a distance equal to or greater than a threshold from an intersection of the half-line and the perpendicular line may be determined.

[0051] When a second corrected value is obtained using the above configuration, the second region formed based on the second corrected value and the second response direction is more likely to intersect with the first region at an angle that is visually closer to perpendicular, thus forming a more accurate intersection. As a result, the number of correctable values ​​included in the intersection (i.e., corrected values ​​that can be reproduced by a subjective optometry device) can be appropriately narrowed down, and candidate corrected values ​​can be determined more favorably.

[0052] The first response acquisition step and the second response acquisition step may be performed by presenting the astigmatism test target as a radial astigmatism chart to the subject's eye and obtaining the first response direction or the second response direction from the subject.

[0053] According to the above configuration, when obtaining the response direction (e.g., first response direction and second response direction) using a radiometric astigmatism chart, the response direction can be obtained more easily (compared to, for example, the cross-cylinder method using point cloud targets) by obtaining the subject's response to the question of which direction of lines on the radiometric astigmatism chart appears darker, while the luminous beam of the radiometric astigmatism chart presented to the subject's eye is corrected to a predetermined correction value (e.g., first correction value or second correction value, etc.). This simplifies the operation and question-and-answer process for obtaining the response direction (e.g., residual astigmatism axis angle), reducing time and effort.

[0054] Furthermore, it is also possible to implement a combination of the technology of the first embodiment and the technology of the second embodiment.

[0055] Furthermore, the technologies of the first and second embodiments can also be implemented using a subjective optometry device. For example, a subjective optometry device is a device for subjectively measuring the optical properties of an eye, including astigmatism characteristics, and comprises a correction means for changing the optical properties of a target light beam presented to the eye, a target presentation unit for emitting the target light beam toward the eye, and a control unit. For example, the correction means may correct the light beam of the astigmatism test target presented to the eye according to various correction values ​​(e.g., reference correction value, target correction value, first correction value, second correction value, and candidate correction value, etc.). For example, the target presentation unit may present the astigmatism test target to the eye by emitting the target light beam toward the eye. For example, the control unit may perform the following: the technology of the first embodiment and the various steps in the second embodiment (for example, the step of acquiring the answer direction, the step of determining the target correction value, the step of determining the first vector, the step of acquiring the first answer direction, the step of determining the first area, the step of determining the second vector, the step of acquiring the second answer direction, the step of determining the second area, and the step of determining the candidate correction value, etc.), as well as control of the target presentation unit or the correction means.

[0056] <Examples> Hereinafter, a first and second embodiment of the optical property measurement method of the present disclosure will be described with reference to the drawings. Both the first and second embodiments will be described using as an example the case in which the optical property measurement method of the present disclosure is executed by the control unit of a subjective ophthalmoscopic device. However, the optical property measurement method of the present disclosure does not necessarily have to be executed in a subjective ophthalmoscopic device. For example, the optical property measurement method of the present disclosure may be executed by an information processing device (e.g., a PC, smartphone, or tablet terminal) equipped with an optical property measurement method program that implements the optical property measurement method of the present disclosure. Alternatively, the optical property measurement method of the present disclosure may be executed using, for example, paper on which a two-dimensional Cartesian coordinate system is illustrated, as described later.

[0057] <Subjective Ophthalmic Examination Device> The subjective ophthalmic examination device used in the description of the first and second embodiments (hereinafter sometimes abbreviated as "the subjective ophthalmic examination device of this embodiment" or simply "the subjective ophthalmic examination device") is a device for subjectively measuring the optical characteristics of the eye under examination. For example, the optical characteristics of the eye under examination may be refractive power (for example, at least one of spherical power, cylindrical power, astigmatism axis angle, etc.), binocular vision function (for example, at least one of prism amount, stereopsis function, etc.), contrast sensitivity, etc.

[0058] In this embodiment, the subjective eye examination device is given as an example of a configuration that includes the target presentation means and correction means described later, but is not limited to this. The subjective eye examination device may also have a configuration that includes at least a control unit and a correction means. For example, it may have only a correction means, or it may have a target presentation means and a correction means as a system.

[0059] The subjective optometry device of this embodiment may include a target presentation means. The target presentation means presents a target to the eye under examination. For example, the target presentation means may be a display (e.g., display 31). Alternatively, for example, the target presentation means may be a light source and a target board. Alternatively, for example, the target presentation means may be a light source and a DMD (Digital Micromirror Device).

[0060] For example, the target light beam from the target presentation means may be guided toward the eye under examination via a light projection optical system (e.g., light projection optical system 30). For example, the light projection optical system may have at least one optical element for guiding the target light beam emitted from the target presentation means. As an example, it may have at least one of a lens, a mirror, etc.

[0061] The subjective optometry device of this embodiment may include a corrective means. For example, the corrective means may be configured to change the optical properties of the target light beam. For example, the optical properties of the target light beam may be at least one of the following: spherical power, cylindrical power, astigmatism axis angle, etc. For example, the corrective means may include a corrective optical system as part of the configuration of the corrective means. For example, the corrective optical system is placed in the optical path of the projection optical system and changes the optical properties of the target light beam.

[0062] For example, the corrective optical system may be configured to change the optical properties of the target beam. For instance, the corrective optical system may change the spherical power of the target beam by optically changing the presentation distance of the target to the eye under examination. Alternatively, the corrective optical system may change at least one of the spherical power, cylindrical power, astigmatism axis angle, etc., of the target beam by controlling an optical element. As an example, the optical element may be at least one of a spherical lens, cylindrical lens, cross-cylinder lens, rotary prism, wavefront modulation element, variable focus lens, etc. Of course, it may also be an optical element different from these. Furthermore, the corrective optical system may be a combination of a configuration that changes the presentation distance of the target and a configuration that controls an optical element.

[0063] For example, the corrective optical system may be an ocular refractive power measurement unit (e.g., ocular refractive power measurement unit 40) that places optical elements in front of the eye under examination. For example, the ocular refractive power measurement unit may have a variable focus lens and be configured to change the refractive power of the variable focus lens. Alternatively, for example, the ocular refractive power measurement unit may have a lens disk on which a plurality of optical elements are arranged on the same circumference, and a driving means (e.g., a motor) for rotating the lens disk, and be configured to electrically switch the optical elements by driving the driving means. Of course, the ocular refractive power measurement unit may also have a configuration that includes a variable focus lens, a lens disk, and a driving means.

[0064] Furthermore, for example, the corrective optical system may be configured such that an optical element is placed between a target presentation means and an optical member for guiding the target light beam emitted from the target presentation means, and the optical characteristics of the target light beam are changed by controlling the optical element. In other words, the corrective optical system may be configured as a phantom lens refractometer (phantom corrective optical system).

[0065] Furthermore, for example, the parameters of the corrective means may be parameters set to change the optical properties of the target light beam by the corrective means. For example, the parameters of the corrective means may be the amount of change in the optical properties of the target light beam by the corrective means. Alternatively, for example, the parameters of the corrective means may be parameters relating to the amount of change in the optical properties of the target light beam based on the subjective measurement results of the eye being examined. For example, these amounts of change in the target light beam may be the amount of change in the refractive power of the target light beam (at least one of spherical refractive power, cylindrical refractive power, and astigmatism axis angle). In other words, it may be the amount of correction for correcting the eye being examined (at least one of spherical correction amount, cylindrical correction amount, and astigmatism axis correction amount).

[0066] <First Embodiment> The optical properties measurement method of the first embodiment will be described with reference to Figures 1A, 1B to 9.

[0067] First, the general configuration of the subjective optometry device 100 will be described with reference to Figures 1A, 1B to 4. Note that the general configuration of the subjective optometry device 100 described below is also common to the subjective optometry device (subjective optometry device 100) used in the description of the second embodiment later.

[0068] Figures 1A and 1B are external perspective views of the subjective optometry device 100. Figure 1A shows the refractive power measurement unit 40 supported in the standby position. Figure 1B shows the refractive power measurement unit 40 supported in the measurement position. For example, the subjective optometry device 100 includes a housing 1, a display window 2, a speaker 3, a holding unit 4, an examiner controller 10, an refractive power measurement unit 40, etc.

[0069] The housing 1 has a light projection optical system 30 inside. The presentation window 2 transmits the target light beam from the light projection optical system 30. The target light beam is projected onto the eye E being examined via the presentation window 2. If the refractive power measurement unit 40 is placed between the eye E being examined and the presentation window 2 (see Figure 1B), the target light beam is projected onto the eye E being examined via the presentation window 2 and the examination window 43 described later. In this way, the examination target is presented to the eye E being examined. The speaker 3 outputs voice guidance, etc.

[0070] The holding unit 4 holds the eye refractive power measuring unit 40. For example, the holding unit 4 moves the eye refractive power measuring unit 40 connected to the arm by moving the arm driven by a drive unit (motor, etc.) not shown. This switches the eye refractive power measuring unit 40 between the standby position and the measurement position.

[0071] The examiner controller 10 is used by the examiner to operate the subjective ophthalmoscopic examination device 100. The examiner controller 10 includes a switch unit 11, a monitor 12, etc. The switch unit 11 receives signals for various settings (for example, moving the ocular refractive power measurement unit 40, etc.). The monitor 12 displays various information (for example, the measurement result of the eye being examined E, etc.). The monitor 12 may also function as a touch panel that also serves as the switch unit 11. Signals from the examiner controller 10 are output to the control unit 60 via wired or wireless communication.

[0072] Figures 2A and 2B are schematic diagrams of the light projection optical system 30 viewed from the side. Figure 2A shows the optical arrangement during distance vision testing. Figure 2B shows the optical arrangement during near vision testing. The light projection optical system 30 projects a target light beam toward the eye E under examination. For example, the light projection optical system 30 includes a display 31, a planar mirror 32, a concave mirror 33, a distance / near switching unit 34, etc.

[0073] The display 31 displays a visual target (e.g., a fixation target, a test target, etc.). The visual target is presented to the eye E when the light beam emitted from the display 31 forms an image on the fundus of the eye E being examined. For example, the display 31 may be an LCD (Liquid Crystal Display), an organic EL (Electro Luminescence), a plasma display, etc.

[0074] The planar mirror 32 reflects the target light beam from the display 31 and guides it to the concave mirror 33. The planar mirror 32 also reflects the target light beam from the display 31 and guides it to the eye E under examination. For example, the planar mirror 32 is positioned so that the distance from the eye E to the display 31 (presentation distance) is optically 40 cm during near vision testing of the eye E under examination. It is also possible to use reflective materials such as prisms, beam splitters, or half mirrors instead of the planar mirror 32.

[0075] The concave mirror 33 reflects the target light beam from the display 31 and guides it to the planar mirror 32. For example, the concave mirror 33 is positioned so that the distance from the eye E to the display 31 (presentation distance) is optically 5 m during distance vision testing of the eye E. It is also possible to use reflective materials such as aspherical mirrors or free-form mirrors instead of the concave mirror 33. Furthermore, it is also possible to use lenses or the like instead of the concave mirror 33.

[0076] The distance / near switching unit 34 switches the arrangement of the display 31 between distance vision testing and near vision testing of the eye being examined E. For example, the distance / near switching unit 34 moves the display 31 held in the holder by moving the holder through the drive of a drive unit (motor, etc.) not shown. This switches the distance vision arrangement and near vision arrangement of the display 31.

[0077] For example, during a distance vision test of the eye E under examination, the display screen of the display 31 is directed towards the back of the housing 1 (see Figure 2A). The target light beam from the display 31 enters the planar mirror 32 passing through the optical axis L1 and is reflected by the planar mirror 32 in the direction of the optical axis L2. It also enters the concave mirror 33 passing through the optical axis L2 and is reflected by the concave mirror 33 in the direction of the optical axis L3. Furthermore, it enters the planar mirror 32 passing through the optical axis L3 and is reflected by the planar mirror 32 in the direction of the optical axis L4. As a result, the target light beam, which has passed through each optical component inside the housing 1 and is emitted to the outside of the housing 1, is projected onto the eye E under examination.

[0078] For example, during a near vision test of the eye under examination E, the display screen of the display 31 is directed towards the top surface of the housing 1 (see Figure 2B). The target light beam from the display 31 enters the plane mirror 32 passing through the optical axis L3 and is reflected by the plane mirror 32 in the direction of the optical axis L4. As a result, the target light beam, which has passed through each optical component inside the housing 1 and been emitted to the outside of the housing 1, is projected onto the eye under examination E.

[0079] Figure 3 is a schematic diagram of the eye refractive power measurement unit 40 viewed from the front. The eye refractive power measurement unit 40 subjectively measures the refractive power of the eye E being examined. The eye refractive power measurement unit 40 is also used as a corrective optical system. The corrective optical system is placed in the optical path of the light projection optical system 30 and changes the optical properties of the target light beam. For example, the eye refractive power measurement unit 40 includes a forehead rest 41, a lens unit 42, an examination window 43, a moving unit 44, etc.

[0080] The forehead rest 41 fixes the eye E to a predetermined examination position by pressing it against the subject's head, and maintains a constant distance from the eye E to the examination window 43. The lens unit 42 has a pair of left and right lens units 42L and 42R. The lens unit 42 has an examination window 43 (left examination window 43L and right examination window 43R).

[0081] The moving unit 44 adjusts the distance between the left lens unit 42L and the right lens unit 42R, and the convergence angle (inward angle) between the left lens unit 42L and the right lens unit 42R. For example, the moving unit 44 adjusts the distance between the left lens unit 42L and the right lens unit 42R by driving the drive unit 45 (left drive unit 45L and right drive unit 45R). Also, for example, the moving unit 44 adjusts the convergence angle between the left lens unit 42L and the right lens unit 42R by driving the drive unit 46. For detailed configuration of the moving unit 44, please refer to, for example, Japanese Patent Application Publication No. 2004-329345.

[0082] The lens unit 42 includes a lens disc 50 inside. The lens disc 50 has a pair of left and right lens discs: a left lens disc 50L and a right lens disc 50R. The lens disc 50 is rotated by the drive unit 51 (left drive unit 51L and right drive unit 51R). The lens disc 50 also has an aperture (or an 0D lens) and a plurality of optical elements 52 (left optical element 52L and right optical element 52R) arranged on the same circumference. These optical elements are rotated by the drive unit 53 (left drive unit 53L and right drive unit 53R). This allows the desired optical element 52 to be switched and positioned in the inspection window 43 at the desired angle.

[0083] The lens disc 50 consists of one lens disc or multiple lens discs. For example, a spherical lens disc, a cylindrical lens disc, an auxiliary lens disc, etc., may be provided. For example, a spherical lens disc may have multiple spherical lenses with different spherical powers (spherical refractive powers). For example, a cylindrical lens disc may have multiple cylindrical lenses with different cylindrical powers (cylindrical refractive powers). For example, an auxiliary lens disc may have a shielding plate, a polarizing filter, a red filter / green filter, a dispersion prism, a Maddox lens, a rotary prism, a cross cylinder lens, an auto cross cylinder lens, an alignment lens, etc. A drive unit 51 and a drive unit 53 may be provided for each lens disc.

[0084] The refractive power measurement unit 40 only needs to be capable of changing the optical properties of the target light beam. For example, it may be configured to control an optical element, as in this embodiment. Alternatively, it may be configured to control a wavefront modulation element, for example.

[0085] <Control Unit> Figure 4 is a schematic diagram of the control system of the subjective eye examination device 100. For example, the control unit 60 includes a CPU (processor), RAM, ROM, etc. The CPU controls the operation of each part of the subjective eye examination device 100. Various types of information are temporarily stored in the RAM. Various programs executed by the CPU are stored in the ROM. Note that the control unit 60 may be composed of multiple control units (i.e., multiple processors).

[0086] The control unit 60 is connected to a speaker 3, a display 31, an examiner controller 10, a non-volatile memory 70 (hereinafter referred to as memory 70), etc. The control unit 60 is also connected to the drive unit of the holding unit 4, the drive unit of the near / far switching unit 34, the drive unit of the refractive power measurement unit 40 (drive units 45, 46, 51, 53), etc.

[0087] Memory 70 is a non-transient storage medium that can retain its contents even when the power supply is interrupted. For example, memory 70 can be a hard disk drive, flash ROM, USB memory, etc.

[0088] In this disclosure, the term "processor" refers to one or more hardware processors configured to execute program code contained in a program (i.e., one or more instructions of a program). In other words, a "processor" is a hardware device capable of performing one or more programmed operations. For example, a "processor" may be a general-purpose or application-specific processor and may be at least one of a CPU, microprocessor, GPU, and DFP (Data Flow Processor).

[0089] In this disclosure, the term “memory” refers to one or more hardware memories that are non-transitional tangible recording media configured to record at least one of computer program code and data in a manner accessible by a processor. “Memory” can be implemented by memory technologies such as SRAM, SDRAM, non-volatile / flash type memory, or other types of memory. The computer program code constituting the program is recorded in memory and executed by the processor to enable various functions of the optometry device 100.

[0090] In this disclosure, the term “circuit” refers to one or more logic circuits as hardware, configured to enable the optometry device 1 to perform functions. In other words, “circuit” refers to one or more non-programmable devices. For example, “circuit” could be a custom IC designed to be non-programmable for a specific application.

[0091] In this disclosure, at least one of a circuit and a processor having memory storing computer program code enables the function of the optometry device 100. The expression "at least one of a circuit and a processor" should be interpreted as disjunctive (logical OR) and not as at least one circuit and at least one processor.

[0092] In this embodiment (the first and second embodiments), all controls performed by the control unit when the subjective optometry device executes the optical property measurement method of this disclosure, such as detection of various states, various calculation processes, output of input signals based on the operation of various operation units, and various controls based on input signals, are described as being performed by the control unit 60. However, these various controls may be performed by multiple different control units. In this embodiment (the first and second embodiments), an example is given in which the subjective optometry device 100 is advanced by the examiner inputting the subject's response into the subjective optometry device 100. However, the subjective optometry device 100 may also advance subjective optometry (so-called "self-optometry") by the subject inputting the response via an operation unit or the like.

[0093] <Control Operation> The optical properties measurement method in the first embodiment will be described below.

[0094] Figure 5 is a flowchart of the control process based on the optical characteristic measurement method (astigmatism measurement) of the first embodiment, which is executed by the subjective optometry device 100. The control unit 60 of the subjective optometry device 100 executes the control process illustrated in Figure 5 by, for example, executing the optical characteristic measurement program stored in the memory 70. In the first embodiment, in order to facilitate understanding of the technology of this disclosure, the case in which the target correction value, which is the next astigmatism correction value, is determined by setting a vector (such as a reference vector described later) on a double-angle two-dimensional Cartesian coordinate system is illustrated as an example. However, it is also possible to determine the target correction value without setting a vector. Details of this will be described later.

[0095] <Acquisition of Objective Values ​​(Reference Corrected Values)> For example, prior to subjective eye examination, the examiner measures the objective refractive power (objective value) of the eye E being examined using an objective eye examination device (not shown).

[0096] Next, the examiner, for example, operates the examiner's controller 10 of the subjective optometry device 100 to input the acquired objective values ​​of the eye under examination E as the reference correction values ​​for the eye under examination E. For example, the control unit 60 receives each of the values ​​input as reference correction values ​​(i.e., spherical correction amount, cylindrical correction amount, and astigmatism axis correction amount) (i.e., acquires the reference correction values: step S1).

[0097] In this embodiment, the case where the reference correction value is an objective value is used as an example for explanation, but the invention is not limited to this. The reference correction value may be, for example, a spectacle value obtained by measuring the optical properties of spectacle lenses fitted to the eye E under examination, or it may be the result of past subjective examinations (subjective value) for the eye E under examination. The reference correction value should include the spherical correction amount, cylindrical correction amount, and astigmatism axis correction amount for the eye E under examination (it may also include cases where the spherical correction amount, cylindrical correction amount, and astigmatism axis correction amount are all zero). Furthermore, the reference correction value may be automatically input into the subjective optometry device 100 from an objective optometry device, a lens measuring device that measures spectacle values, or a PC that manages the reference correction value.

[0098] <Determination of Reference Vector> Next, the control unit 60 determines a reference vector representing the astigmatism component corresponding to the reference correction value on the two-dimensional orthogonal coordinate system 110 used in the optical characteristic measurement method of this embodiment (step S2).

[0099] Here, the two-dimensional Cartesian coordinate system 110 used in the optical properties measurement method of this embodiment will be explained with reference to Figure 6. Figure 6 is an example of a reference vector illustrated on the two-dimensional Cartesian coordinate system 110 used in the optical properties measurement method of this embodiment. The two-dimensional Cartesian coordinate system 110 used in the optical properties measurement method of this embodiment is a double-angle two-dimensional Cartesian coordinate system in which, when an arbitrary angle α is used, the components (J0) where the astigmatism axis angle is α degrees and α + 90 degrees are the X-axis, and the components (J45) where the astigmatism axis angle is α + 45 degrees and α + 135 degrees are the Y-axis. In this embodiment, the case where α = 0 will be used as an example for explanation. Therefore, the notation of the arbitrary angle "α" may be omitted in the following explanation. Although not shown in this embodiment, the spherical component M of the refractive value is represented as the Z-axis. If S is the spherical power, C is the cylindrical power (astigmatism power), and A is the astigmatism axis angle, then M = S + C / 2, J0 = -C / 2cos(2A), and J45 = -C / 2sin(2A). Therefore, (S, C, A) and (M, J0, J45) can be converted to each other. In addition, the origin 114, correctable value 115, coordinate point 111, etc. are set on the two-dimensional Cartesian coordinate system 110.

[0100] The correctable values ​​115 are values ​​that can be corrected by a subjective optometry device (for example, subjective optometry device 100) and are illustrated on a two-dimensional Cartesian coordinate system 110. In this embodiment, the correctable values ​​115 are arranged in multiple locations on each of multiple concentric circles centered on the origin 114 of the two-dimensional Cartesian coordinate system 110. For example, in the case of a subjective optometry device that can measure cylindrical power (C) from -0.25D to -8.00D in 0.25D increments and axis angle (A) from 0 degrees (=180 degrees) to 179 degrees in 1-degree increments, the correctable values ​​115 are represented by 5760 points. For example, when the cylindrical power (C) changes, the radius of the concentric circle on which the correctable values ​​115 are set changes. Also, when only the axis angle (A) changes while the cylindrical power (C) remains constant, the position of the correctable values ​​115 on the concentric circle changes. The number and location of the correctable values ​​115 may be appropriately changed based on values ​​measurable by a subjective optometry device.

[0101] In this embodiment, each coordinate point in the two-dimensional Cartesian coordinate system 110 can be determined based on the cylindrical degree (C) and the astigmatism axis angle (A). Coordinate point 111 is a point that indicates the endpoint position of the vector (in Figure 6, the reference correction value which is the endpoint position of the reference vector 112 described later).

[0102] In this embodiment, a reference vector 112 and the like are further set in the two-dimensional Cartesian coordinate system 110. In the example shown in Figure 6, the reference correction value obtained in step S1 is represented as coordinate point 111 on the two-dimensional Cartesian coordinate system 110. The reference vector 112 represents the astigmatism component corresponding to the reference correction value for the eye under examination. For example, the magnitude of the vector (i.e., the distance from the origin 114 to coordinate point 111) is expressed by dividing the cylindrical power (C) by minus 2. Similarly, when a vector connecting the origin 114 and a certain coordinate point is displayed, the slope of the vector (i.e., the angle formed by the J0 axis to the right of the origin 114 and the line segment connecting a certain coordinate and the origin 114) is expressed by doubling the astigmatism axis angle (A). In other words, the angle of the reference vector 112 corresponds to the component of the astigmatism axis angle in the reference correction value. In this case, half of the cylindrical power (C) is the spherical component, and the cylindrical power is expressed as a negative value. Therefore, the magnitude of a vector on the two-dimensional Cartesian coordinate system 110 is expressed as "C (cylindrical degree) ÷ (-2)". Also, since the astigmatism axis angle is periodic data with a period of 179 degrees from 0 degrees (the same as 180 degrees), it can be expressed as a double angle by assigning one period of data to the circumference of 360 degrees. Therefore, the apparent slope of the vector on the two-dimensional Cartesian coordinate system 110 (when viewing the angle of one rotation as 360 degrees) is expressed as "2 × A (astigmatism axis angle)".

[0103] In the case of Figure 6, for example, if the astigmatism component corresponding to the reference correction value obtained in step S1 is a cylindrical correction amount (C) of -0.75D and an astigmatism axis correction amount (A) of 15 degrees, the control unit 60 places the reference correction value at the position of the reference correction value (coordinate point 111) on the two-dimensional Cartesian coordinate system 110. The control unit 60 then determines a reference vector 112 that starts at the origin 114 and ends at the reference correction value (coordinate point 111). At this time, the cylindrical correction amount (C) of the reference correction value can be calculated based on the magnitude of the reference vector 112, and the astigmatism axis correction amount (A) of the reference correction value can be calculated based on the slope of the reference vector 112.

[0104] <Acquisition of response direction> Next, the control unit 60 controls the lens disc 50 of the refractive power measurement unit 40, which is an example of a correction means, and the optical element 52 of the lens disc 50, based on the amount of correction in the reference correction value (step S3). For example, the control unit 60 drives the drive unit 51 and the drive unit 53 to switch and position the lens disc 50 and the optical element 52 in the examination window 43 based on the reference correction value acquired in step S1. As a result, the light beam of the visual target presented to the eye E under examination is corrected to the reference correction value.

[0105] The examiner corrects the light beam of the target presented to the eye E to the standard correction value, then operates the examiner controller 10 to perform a subjective eye examination of the eye E (e.g., a visual acuity test, R / G test, etc.). At the time of measuring the astigmatism of the eye E, the examiner operates the examiner controller 10 to select, for example, a radial astigmatism chart as the target for astigmatism testing. When the control unit 60 receives the operation signal, it displays the radial astigmatism chart on the display 31.

[0106] Figure 7 shows an example of a radial astigmatism chart displayed on the display 31. For example, the radial astigmatism chart 120 shown in Figure 7 has, for instance, 24 line segments drawn radially at equal intervals with a central angle of 15 degrees, and the numbers 1 to 12 are arranged at 30-degree intervals like the face of a clock. Note that the radial astigmatism chart 120 is just one example, and the number of line segments in a radial astigmatism chart is not limited to 24. Furthermore, when performing the optical property measurement method of this disclosure, any astigmatism test target that can determine the astigmatism axis angle can be used, so it is not necessarily limited to a radial astigmatism chart.

[0107] The examiner shows the subject the radiation astigmatism chart 120 and asks if there are any line segments that appear darker or thicker (step S4). If there are line segments that appear darker or thicker (step S4: YES), the examiner asks the subject the direction of the line segments that appear darker or thicker. For example, if the subject answers "the line in direction 2 is darker," the subject's answer direction will be "60 degrees." This answer direction is equivalent to the axis angle of residual astigmatism of the subject's eye E in the standard corrected value. Based on the subject's answer, the examiner inputs the answer direction, for example, by operating the examiner controller 10. When the control unit 60 receives the input signal, it accepts the value of the answer direction (i.e., it obtains the answer direction: step S5).

[0108] Furthermore, if the subject responds in step S4 that there are no line segments that appear dark or thick (step S4: NO), it is highly likely that the subject's astigmatism is appropriately corrected with the standard correction value, and the astigmatism measurement of the subject's eye E is terminated at that point. For example, the control unit 60 stores the cylindrical correction amount and the astigmatism axis correction amount in the standard correction value in the memory 70 as the result of the astigmatism measurement.

[0109] <Determination of Target Correction Value Based on Angle Difference> When the control unit 60 obtains the answer direction in step S5, it calculates the angle difference between the direction of the reference vector on the two-dimensional Cartesian coordinate system 110 (hereinafter sometimes referred to as the "reference direction") and the answer direction (step S6). That is, the control unit 60 calculates the angle of the answer direction relative to the reference vector 112 (see Figure 6) on the two-dimensional Cartesian coordinate system 110. For example, for the eye under examination E, if the astigmatism axis correction amount (A) of the reference correction value is 15 degrees and the answer direction is 60 degrees, the angle difference between the reference direction of the reference vector 112 on the two-dimensional Cartesian coordinate system 110 (corresponding to the astigmatism axis correction amount (A), which is the astigmatism axis angle corrected in the reference correction value) and the answer direction is 45 degrees. Since the two-dimensional Cartesian coordinate system 110 is expressed using double angles where one full rotation is 180 degrees, if the angle difference is 45 degrees, then in the two-dimensional Cartesian coordinate system 110, the angle difference when viewed as 360 degrees (hereinafter referred to as the "apparent angle difference") is recognized as 90 degrees, which is double 45 degrees.

[0110] The control unit 60 determines, in step S7, which of the cylindrical power (C) and astigmatism axis angle (A) of the reference correction value to change, according to the angle difference between the reference direction and the response direction calculated in step S6. In other words, the control unit 60 determines, in accordance with the inclination (angle) of the response direction with respect to the reference direction, which of the cylindrical power and astigmatism axis angle (or both) of the reference correction value to change (correct) to determine an astigmatism correction amount that is closer to the true value.

[0111] In determining the amount of correction to be changed based on the angle difference calculated in step S6, the control unit 60 makes the determination by applying predetermined conditions. These conditions will be explained below using Figures 8A and 8B.

[0112] Figures 8A and 8B are examples of a condition map 130 that shows the conditions for determining the amount of correction to be applied to the object of change based on the angle difference calculated in step S6. Figure 8A illustrates an example of the first to fourth angle ranges, and Figure 8B illustrates an example of the first to fourth angle ranges and an intermediate angle range. In Figure 8A, for example, the condition map 130 includes a 45-degree axis 131, a 135-degree axis 132, a 0-degree axis 133, a 90-degree axis 134, a first angle range 135, a second angle range 136, a third angle range 137, and a fourth angle range 138, etc. The 45-degree axis 131 is based on the coordinate point 111 on the two-dimensional orthogonal coordinate system 110 in Figure 6 and indicates the 45-degree direction relative to the reference vector 112 (the apparent direction when viewing one rotation as 360 degrees is the 90-degree direction). The 135-degree axis 132 indicates the direction 135 degrees relative to the reference vector 112 (visually the direction is 270 degrees). The 0-degree axis 133 indicates the direction 0 degrees relative to the reference vector 112. The 90-degree axis 134 indicates the direction 90 degrees relative to the reference vector 112 (visually the direction is 180 degrees).

[0113] As shown in Figures 8A and 8B, in this embodiment, multiple angle ranges (the first to fourth angle ranges in Figure 8A, and the first to fourth angle ranges and an intermediate angle range in Figure 8B) are set within the range of 0 to 180 degrees that the angle difference between the reference direction and the response direction can take. In this embodiment, a determination procedure for determining the target correction value according to the angle difference described above is pre-associated with each of the set multiple angle ranges. Therefore, the target correction value can be easily and appropriately determined simply by knowing which of the multiple angle ranges the angle difference calculated in step S6 belongs to. A specific example of the method for determining the target correction value in this embodiment will be described in detail below.

[0114] In the example shown in Figure 8A, the first angular range 135 is set to a range greater than 0 degrees and less than 90 degrees, and includes the 45-degree direction (the apparent direction is the 90-degree direction). The first angular range 135 in Figure 8A can also be expressed as 45 degrees ± A degrees (A < 45 degrees). The second angular range 136 is set to a range greater than 90 degrees and less than 180 degrees, and includes the 135-degree direction (the apparent direction is the 270-degree direction). The second angular range 136 in Figure 8A can also be expressed as 135 degrees ± B degrees (B < 45 degrees). The third angular range 137 is set to a range greater than 135 degrees and less than or equal to 180 degrees (synonymous with 0 degrees), and within the range of 0 degrees or more and less than 45 degrees, and includes 0 degrees (180 degrees). The third angular range 137 in Figure 8A can also be expressed as 0 degrees ± C degrees (where C < 45 degrees, and if 0 degrees ± C degrees is negative, it is equivalent to the angle obtained by adding 180 degrees to the value of 0 degrees ± C degrees). The fourth angular range 138 is set within a range greater than 45 degrees and less than 90 degrees, and includes the 90-degree direction (the apparent direction is the 180-degree direction). The fourth angular range 138 in Figure 8A can also be expressed as 90 degrees ± D degrees (D < 45 degrees).

[0115] For example, in step S7, if the angle difference between the reference direction and the response direction is within the first angle range 135 or the second angle range 136, the true value of the astigmatism characteristic of the eye being examined is likely to be located near the endpoint of the reference vector 112 on the two-dimensional Cartesian coordinate system 110 shown in Figure 6, in a direction that is apparently orthogonal to the direction of the reference vector 112 (i.e., the 45-degree or 135-degree direction). In this case, it is understood that in order to bring the next correction value (target correction value) closer to the true value of the astigmatism characteristic of the eye being examined, it is necessary to change the astigmatism axis angle of the reference correction value at least. Therefore, in step S7, if the angle difference between the reference direction and the response direction is within the first angle range 135 or the second angle range 136, the control unit 60 decides to change the astigmatism axis angle of the correction amount of the reference correction value. Furthermore, for example, in step S7, if the angle difference between the reference direction and the response direction is within the third angle range 137 or the fourth angle range 138, the true value of the astigmatism characteristic of the eye being examined is likely to be located near the endpoint of the reference vector 112 on the two-dimensional Cartesian coordinate system 110 shown in Figure 6, in a direction that appears to be aligned with the reference vector 112 (i.e., the 0-degree or 90-degree direction). In this case, it is understood that in order to bring the next correction value (target correction value) closer to the true value of the astigmatism characteristic of the eye being examined, it is necessary to change the cylindrical power of the reference correction value at least. Therefore, in step S7, if the angle difference between the reference direction and the response direction is within the third angle range 137 or the fourth angle range 138, the control unit 60 decides to change the cylindrical power of the correction amount of the reference correction value.

[0116] For example, if the angle difference on the two-dimensional Cartesian coordinate system 110 calculated in step S6 is represented as vertical when viewed as 360 degrees (i.e., the angle difference is 45 degrees or 135 degrees), the control unit 60 determines the reference correction value to be changed as the astigmatism axis angle (A) (i.e., the target correction value is determined by changing the astigmatism axis angle in the reference correction value). More specifically, if the angle difference calculated in step S6 is 45 degrees (i.e., the direction of the response is the direction of the 45-degree axis 131 in the condition map 130), the astigmatism axis correction amount (A) of the reference correction value is increased, and if the angle difference is 135 degrees (i.e., the direction of the response is the direction of the 135-degree axis 132 in the condition map 130), the astigmatism axis correction amount (A) of the reference correction value is decreased.

[0117] As an example, if the angle difference on the two-dimensional Cartesian coordinate system 110 calculated in step S6 is represented as appearing parallel when viewed as 360 degrees (i.e., the angle difference is 0 degrees or 90 degrees), the control unit 60 determines the reference correction value to be changed as the cylindrical degree (C) (i.e., the target correction value is determined by changing the cylindrical degree in the reference correction value). More specifically, if the angle difference calculated in step S6 is 0 degrees (i.e., the response direction is the direction of the 0-degree axis 133 in the condition map 130), the cylindrical correction amount (C) of the reference correction value is increased (changed in the negative direction), and if the angle difference is 90 degrees (i.e., the response direction is the direction of the 90-degree axis 134 in the condition map 130), the cylindrical correction amount (C) of the reference correction value is decreased (changed in the positive direction).

[0118] As an example, if the angle difference calculated in step S6 falls within the first or second angle range, the control unit 60 determines the corrected value to be changed to be the astigmatism axis angle (A) (that is, the target corrected value is determined by changing the astigmatism axis angle of the reference corrected value). Specifically, if the angle difference calculated in step S6 falls within the first angle range 135, the astigmatism axis correction amount (A) of the reference corrected value is increased, and if it falls within the second angle range 136, the astigmatism axis correction amount (A) of the reference corrected value is decreased. If the angle difference calculated in step S6 falls within the third or fourth angle range, the control unit 60 determines the corrected value to be changed to be the cylindrical power (C) (that is, the target corrected value is determined by changing the cylindrical power of the reference corrected value). Specifically, if the angle difference calculated in step S6 falls within the third angle range 137, the cylindrical correction amount (C) of the reference corrected value is increased (changed in the negative direction), and if it falls within the fourth angle range 138, the cylindrical correction amount (C) of the reference corrected value is decreased (changed in the positive direction).

[0119] In the example shown in Figure 8B, the condition map 130 includes an intermediate angle range 139, etc. The intermediate angle range 139 is a range in which both the astigmatic axis angle and the prismatic cylinder power of the reference correction value are changed when the angle difference between the reference direction and the response direction falls within at least one of the following ranges: between the first angle range 135 and the third angle range 137, between the first angle range 135 and the fourth angle range 138, between the second angle range 138 and the third angle range 137, and between the second angle range 136 and the fourth angle range 139.

[0120] For example, if the angle difference calculated in step S6 falls within an intermediate angle range (e.g., intermediate angle range 139) set to at least one of the following: between the first and third angle ranges, between the first and fourth angle ranges, between the second and third angle ranges, and between the second and fourth angle ranges, the control unit 60 determines that the correction value to be changed is both the axis angle (A) and the cylindrical power (C) (that is, the target correction value is determined by changing both the astigmatism axis angle and the cylindrical power of the reference correction value). For example, if the angle difference calculated in step S6 falls within the intermediate angle range 139 set between the first and third angle ranges, the astigmatism axis correction amount (A) of the reference correction value is increased, and the cylindrical correction amount (C) is increased (changed in the negative direction).

[0121] Here, using Figure 9, we will explain an example of step S7, which determines which of the cylindrical power and astigmatism axis angle of the reference corrected value, indicated by the reference vector 112 on the two-dimensional Cartesian coordinate system 110, to change based on the angle difference calculated in step S6, using the measured values ​​of the eye under examination E.

[0122] Figure 9 illustrates an example of a process for determining which of the cylindrical power and astigmatism axis angle of the reference corrected value should be changed, using a two-dimensional Cartesian coordinate system 110. The two-dimensional Cartesian coordinate system 110 shows the J0 axis, J45 axis, origin 114, coordinate point 111 indicating the reference corrected value, reference vector 112, response direction 113, and target corrected value prediction region 116. The J0 axis, J45 axis, origin 114, coordinate point 111, and reference vector 112 are as described above. The response direction 113 is a line segment extending from coordinate point 111 in the direction of response obtained from the subject. The target corrected value prediction region 116 is a predetermined region near the response direction 113. The target corrected value prediction region 116 is a region where it is predicted that the true value of the astigmatism characteristic of the subject eye (subject eye E) is likely to be located, and the target corrected value may be set within or near this region.

[0123] In Figure 9, the reference correction value of the eye E being examined (cylindrical correction amount (C): -0.75D, astigmatism axis correction amount (A): 15 degrees) is shown by coordinate point 111 on the two-dimensional Cartesian coordinate system 110, and a reference vector 112 is shown extending from the origin 114 toward coordinate point 111. The response direction of 60 degrees for the eye E being examined at the reference correction value (coordinate point 111) is shown as the response direction 113, and is represented by a line segment extending 60 degrees (visually 120 degrees) from coordinate point 111. At this time, the angular difference between the reference vector 112 and the response direction 113 is 45 degrees (the apparent angular difference is perpendicular when viewing one rotation as 360 degrees in the two-dimensional Cartesian coordinate system 110). Therefore, in step S7, the control unit 60 determines that the correction value to be changed is the astigmatism axis angle (A).

[0124] Next, if the control unit 60 determines in step S7 that the corrected value to be changed is the astigmatism axis angle (A), it determines the amount of change (astigmatism axis correction amount) of the astigmatism axis angle (A) that it determined to be changed (step S8). The amount of change of the astigmatism axis angle is determined to be an arbitrary value. The control unit 60 may determine the amount of change based on a numerical value input by the examiner, or it may determine the amount of change based on a preset value (for example, every 1 degree, every 2 degrees, etc.).

[0125] Furthermore, when determining the amount of change in the astigmatism axis angle, the control unit 60 may adjust the amount of change in the astigmatism axis angle according to the magnitude of the cylindrical power corrected in the reference correction value. Using the reference vector 112 as an example, the control unit 60 may adjust the amount of change in the astigmatism axis angle according to the distance between the origin 114 on the two-dimensional Cartesian coordinate system 110 and the endpoint of the reference vector 112 (i.e., the magnitude of the reference vector 112 corresponding to the magnitude of the cylindrical power in the reference correction value). Regardless of the magnitude of the cylindrical power corrected in the reference correction value, if the astigmatism axis angle of the reference correction value is changed by the same amount, the degree of influence on the difference in the subject's vision between the examination using the reference correction value and the examination using the target correction value will vary according to the magnitude of the cylindrical power in the original reference correction value. The following explanation will use the double-angle two-dimensional Cartesian coordinate system 110. In the double-angle two-dimensional Cartesian coordinate system 110, the effect on the displacement of the endpoint of the reference vector 112 differs depending on whether the magnitude of the reference vector 112 is large or small, even when the same amount of change equivalent to the astigmatic axis angle is added. When the magnitude of the reference vector 112 is small, a small change in the astigmatic axis angle may not produce a difference that the subject can perceive. Therefore, when the magnitude of the reference vector 112 is small (i.e., when the magnitude of the cylindrical power in the reference corrected value is small), a larger change in the astigmatic axis angle may be determined compared to when the magnitude of the reference vector 112 is large (i.e., when the magnitude of the cylindrical power in the reference corrected value is large). For example, when the control unit 60 determines that the astigmatism axis angle is to be corrected when the cylindrical power of the reference corrected value is -1.00D, it may change the axis angle by 1 degree at a time to determine the amount of change (correction amount). On the other hand, when the cylindrical power of the reference corrected value is -0.25D, it may change the astigmatism axis angle by 4 degrees at a time to determine the amount of change (correction amount).

[0126] The control unit 60 determines the target correction value, which is the next astigmatism correction value, by determining the correction value to be changed and the amount of change (correction amount) (step S9). In this embodiment, the subject only answers the direction and does not answer information regarding the degree of deviation of the reference correction value from the true value of the astigmatism characteristics of the eye being examined. Therefore, although the correction value to be changed and whether the amount of change is positive or negative can be determined from the angle difference between the reference direction (the direction of the reference vector 112 on the two-dimensional Cartesian coordinate system 110) and the answered direction, the appropriate magnitude of the amount of change cannot be determined. Therefore, in step S9 of this embodiment, a value predetermined according to the magnitude of the cylindrical power in the reference correction value (the magnitude of the reference vector 112 on the two-dimensional Cartesian coordinate system 110) is used for the magnitude of the amount of change of the correction value to be changed. Even in this case, the target correction value approaches the true value of the astigmatism characteristics of the eye being examined appropriately. For example, if the astigmatism axis angle (A) of the reference corrected value is repeatedly changed in each of multiple tests, the magnitude of the change in the astigmatism axis angle may be predetermined so that the change in the astigmatism axis angle is 3 degrees in the first test, 2 degrees in the second test, and 1 degree in the third test, regardless of the magnitude of the cylindrical power (magnitude of the reference vector 112) in the reference corrected value. Alternatively, as mentioned above, the magnitude of the change in the astigmatism axis angle may be predetermined according to the magnitude of the cylindrical power (magnitude of the reference vector 112) in the reference corrected value.

[0127] The control unit 60 controls the lens disk 50 and the optical elements 52 on the lens disk 50 based on the amount of correction at the target correction value (step S10). For example, the control unit 60 drives the drive unit 51 and the drive unit 53 to switch and position the lens disk 50 and the optical elements 52 in the examination window 43 based on the target correction value determined in step S9. As a result, the optical characteristics of the target light beam presented to the eye E under examination are corrected to the target correction value.

[0128] Next, the examiner reconfirms the vision of the eye E at the corrected amount corresponding to the target correction value. For example, once the eye E is corrected to the target correction value, the examiner operates the examiner controller 10 to perform a subjective eye examination of the eye E. At the time of measuring the astigmatism of the eye E, the examiner operates the examiner controller 10 to select, for example, a radial astigmatism chart as the target for astigmatism testing. For example, when the control unit 60 receives an operation signal, it displays the radial astigmatism chart on the display 31.

[0129] The examiner shows the subject the radiation astigmatism chart 120 and asks if there are any lines that appear darker or thicker (Step S4).

[0130] If the subject responds that there are no line segments that appear dark or thick (Step S4: NO), it is highly likely that the subject's astigmatism is adequately corrected with the standard correction value, and the astigmatism measurement of the subject's eye E is terminated. For example, the control unit 60 stores the cylindrical correction amount and the astigmatism axis correction amount at the target correction value in the memory 70 as the result of the astigmatism measurement.

[0131] Furthermore, if the subject responds that there are still line segments that appear darker or thicker (Step S4: YES), the control unit 60 uses the target correction value determined in the previous Step S9 as the reference correction value and executes Steps S5 to S10 and Step S4 again in that order, repeating Steps S5 to S10 and Step S4 until the subject responds that there are no line segments that appear darker or thicker (Step S4: NO). Note that an upper limit may be set on the number of times the process of Steps S4 to S10 is repeated. In this case, the time required for the subjective examination will not become excessively long.

[0132] Thus, according to the optical property measurement method of this disclosure, a target correction value, which is the next astigmatism correction value, can be determined by obtaining two elements: a reference correction value and the direction of response that the subject answered based on their vision when the light beam of the astigmatism test target was corrected with the reference correction value. The target correction value is determined according to the angular difference between the reference direction (for example, in this embodiment, the direction of the reference vector 112 on the two-dimensional orthogonal coordinate system 110) and the response direction, making it possible to obtain a target correction value that is closer to the true value. Therefore, it becomes easier to efficiently reach an appropriate astigmatism correction value. Consequently, the examiner can measure the astigmatism characteristics of the eye being examined more smoothly.

[0133] In the first embodiment, in order to facilitate understanding of the technology of this disclosure, the example of determining the target correction value, which is the next astigmatism correction value, by setting a reference vector 112 on a double-angle two-dimensional Cartesian coordinate system 110 was explained. However, the angles of the two-dimensional Cartesian coordinate system 110 correspond to the astigmatism axis angle that was corrected in the reference correction value. Therefore, it is also possible to determine the target correction value without using the double-angle two-dimensional Cartesian coordinate system 110. For example, a procedure for determining the target correction value (in this disclosure, a procedure that determines how much to change one or both of the cylindrical power and astigmatism axis angle in the reference correction value to determine the target correction value) may be pre-associated by a program or table for each angle difference between the reference direction and the answer direction. If the two-dimensional Cartesian coordinate system 110 is not used, the process in step S2 of Figure 5 can be omitted. In the process in step S6 of Figure 5, the angle difference between the direction of the astigmatism axis angle that was corrected in the reference correction value (reference direction) and the answer direction is calculated. In the process of steps S7 to S9 in Figure 5, the target correction value may be automatically determined according to a procedure that is pre-associated with the angle difference calculated in step S6. Even in this case, the residual astigmatism is used to efficiently determine an appropriate target correction value. Furthermore, when associating the procedure for determining the target correction value for each angle difference between the reference direction and the response direction (for example, when a program or table is constructed), it is possible to appropriately associate the procedure for determining the target correction value with each angle difference by using the above two-dimensional orthogonal coordinate 110, which is shown in double angles.

[0134] <Second Embodiment> The optical properties measurement method of the second embodiment will be described with reference to Figures 10 to 12. The subjective optometry device used in the description of the second embodiment has the same configuration as the subjective optometry device 100 used in the description of the first embodiment. Therefore, the subjective optometry device used in the description of the second embodiment will also be described using the subjective optometry device 100. Furthermore, the two-dimensional Cartesian coordinate system 110 used in the description of the second embodiment has the same properties and configuration as the two-dimensional Cartesian coordinate system 110 used in the description of the first embodiment. Therefore, in the second embodiment, the description of the properties and configuration of the two-dimensional Cartesian coordinate system 110 will be omitted below.

[0135] <Control Operation> The optical properties measurement method in the second embodiment will be described below.

[0136] Figure 10 is a flowchart of the control process based on the second embodiment of the optical properties measurement method (astigmatism measurement) performed by the subjective optometry device 100. The control unit 60 of the subjective optometry device 100 executes the control process illustrated in Figure 10 by, for example, executing the optical properties measurement program stored in the memory 70.

[0137] <Acquisition of the First Correction Value> For example, prior to subjective eye examination, the examiner measures the objective refractive power (objective value) of the eye E being examined using an objective eye examination device (not shown).

[0138] Next, the examiner, for example, operates the examiner's controller 10 of the subjective ophthalmoscopic device 100 to input the acquired objective values ​​of the eye under examination E as the first corrected values ​​of the eye under examination E. For example, the control unit 60 accepts each of the values ​​input as the first corrected values ​​(i.e., spherical correction amount, cylindrical correction amount, and astigmatism axis correction amount) (i.e., acquires the first corrected values: step T1). In this embodiment, we will explain using the case where the astigmatism component corresponding to the first corrected values ​​of the eye under examination E is cylindrical correction amount (C): -0.75D and astigmatism axis correction amount (A): 15 degrees as an example.

[0139] In this embodiment, the first correction value is explained using the case where the objective value is used as an example, but the invention is not limited to this. The first correction value may be, for example, the spectacle value obtained by measuring the optical properties of the spectacle lens fitted to the eye E under examination, or it may be the result of a past subjective examination (subjective value) for the eye E under examination. The reference correction value should include the spherical correction amount, cylindrical correction amount, and astigmatism axis correction amount for the eye E under examination (it may also include cases where the spherical correction amount, cylindrical correction amount, and astigmatism axis correction amount are all zero). Furthermore, the first correction value may be automatically input into the subjective optometry device 100 from an objective optometry device, a lens measuring device that measures spectacle values, or a PC that manages the first correction value.

[0140] <Determination of the First Vector> Figure 11 illustrates an example of a two-dimensional Cartesian coordinate system 110 used when determining candidate correction values. The following explanation will use Figure 11 to describe the process from step T2 to step T17 in Figure 10. The two-dimensional Cartesian coordinate system 110 shown in Figure 11 includes the J0 axis, J45 axis, origin 114, correctable value 115, coordinate point 150 indicating the first correction value, first vector 151, first answer direction 152, first region 153, coordinate point 160 indicating the second correction value, second vector 161, second answer direction 162, second region 163, intersection position 170, correctable value within the intersection position 171, and coordinate point 172 indicating candidate correction values, etc. Coordinate point 150 is the coordinate point that represents the first correction value on the two-dimensional Cartesian coordinate system 110. The first vector 151 represents the first correction value as a vector on the two-dimensional Cartesian coordinate system 110. The first response direction 152 is a line segment extending from coordinate point 150 in the direction of the first response obtained from the subject. The first region 153 is a region extending from coordinate point 150 in the direction of the first response. Coordinate point 160 is a coordinate point that represents the second correction value on the two-dimensional Cartesian coordinate system 110. The second vector 161 represents the second correction value as a vector on the two-dimensional Cartesian coordinate system 110. The second response direction 162 is a line segment extending from coordinate point 160 in the direction of the second response obtained from the subject. The second region 163 is a region extending from coordinate point 160 in the direction of the second response.

[0141] The control unit 60 places a coordinate point 150 on the two-dimensional Cartesian coordinate system 110 that corresponds to the first correction value obtained in step T1. The control unit 60 determines a first vector 151 that represents the astigmatism component corresponding to the first correction value, with the origin 114 as the starting point and the coordinate point 150 as the ending point (step T2).

[0142] <Acquisition of the First Answer Direction> Next, the control unit 60 controls the lens disc 50 of the refractive power measurement unit 40, which is an example of a correction means, and the optical element 52 of the lens disc 50, based on the amount of correction in the first correction value (step T3). For example, the control unit 60 drives the drive unit 51 and the drive unit 53 to switch and position the lens disc 50 and the optical element 52 in the examination window 43 based on the first correction value acquired in step T1. As a result, the light beam of the visual target presented to the eye E under examination is corrected by the first correction value.

[0143] The examiner performs a subjective examination of the eye E at the correction amount of the first correction value (performance of the first examination). For example, when the light beam of the target presented to the eye E is corrected to the first correction value, the examiner operates the examiner controller 10 to perform a subjective examination of the eye E (e.g., a visual acuity test, R / G test, etc.). At the time of measuring the astigmatism of the eye E, the examiner operates the examiner controller 10 to select, for example, a radial astigmatism chart as the target for astigmatism testing. When the control unit 60 receives an operation signal, it displays the radial astigmatism chart 120 (Figure 7) on the display 31.

[0144] As mentioned above, the radiation astigmatism chart 120 shown in Figure 7 is just one example, and the number of line segments in the radiation astigmatism chart is not limited to 24. Furthermore, when performing the optical property measurement method of this disclosure, any astigmatism test target capable of determining the astigmatism axis angle can be used, so it is not necessarily limited to the radiation astigmatism chart.

[0145] The examiner shows the subject the radiation astigmatism chart 120 and asks if there are any line segments that appear darker or thicker (step T4). If there are line segments that appear darker or thicker (step T4: YES), the examiner asks the subject the direction of the line segment. For example, if the subject answers "the line between 1 and 2 is darker," the subject's answer direction will be "45 degrees." This answer direction is equivalent to the axis angle of residual astigmatism of the subject's eye E in the first corrected value. Based on the subject's answer, the examiner inputs the first answer direction, for example, by operating the examiner controller 10. When the control unit 60 receives the input signal, it accepts the value of the first answer direction (i.e., it obtains the first answer direction: step T5).

[0146] Furthermore, if the subject responds in step T4 that there are no line segments that appear dark or thick (step T4: NO), it is highly likely that the subject's astigmatism has been adequately corrected with the first correction value, and the astigmatism measurement of the subject's eye E is terminated at that point. For example, the control unit 60 stores the cylindrical correction amount and the astigmatism axis correction amount in the first correction value in the memory 70 as the results of the astigmatism measurement.

[0147] <Determination and Display of the First Region> The control unit 60 determines a first region 153 on the two-dimensional Cartesian coordinate system 110, extending in the direction of the first response direction 152 with the endpoint (coordinate point 150) of the first vector 151 as the base point (step T6). The first region 153 indicates a region that is estimated to contain or be in the vicinity of the true value of the astigmatism characteristic of the eye under examination E, based on the coordinate point 150 indicating the first corrected value and the first response direction 152. The first region may, for example, be a region that extends with a predetermined central angle centered on the base point. The central angle at this time may be determined, for example, according to the angular resolution of the astigmatism test target used to obtain the response direction. Furthermore, the first region may show the entire region that extends in the first response direction centered on the base point, or it may show a region that is divided into a part thereof.

[0148] The control unit 60 causes the monitor 12, which is the display unit of the subjective eye examination device 100, to display the two-dimensional Cartesian coordinate system 110 including the first region 153 (step T7).

[0149] <Determination of the second correction value> Next, the control unit 60 acquires the second correction value (step T8). The control unit 60 may determine (acquire) the second correction value in accordance with the instructions input by the examiner. Alternatively, the control unit 60 may automatically determine (acquire) the second correction value based on a value calculated by the calculation unit based on predetermined conditions.

[0150] <When manually determined (acquired)> When the second correction value is determined according to the instructions entered by the examiner, the control unit 60 displays a two-dimensional Cartesian coordinate system 110 including the first region 153 on the monitor 12, for example, as in step T7 (first region display step). The control unit 60 determines (acquires) the second correction value by, for example, receiving an instruction from the examiner to specify coordinate information (for example, coordinate point 160) corresponding to the desired second correction value on the two-dimensional Cartesian coordinate system 110 while the two-dimensional Cartesian coordinate system 110 including the first region 153 is displayed on the monitor 12 (coordinate information reception step). For example, the examiner can determine the second correction value after understanding the first region 153 displayed on the two-dimensional Cartesian coordinate system 110 so that the first region 153 and the second region 163 (details to be described later) intersect as perpendicularly as possible in the two-dimensional Cartesian coordinate system 110 when viewed as if one rotation is 360 degrees. As will be explained in more detail later, in the two-dimensional Cartesian coordinate system 110, the closer the apparent intersection angle of the first region 153 and the second region 163 is to perpendicular, the easier it becomes to pinpoint the intersection position 170 of the two regions. This makes it easier to determine the true value of the astigmatism characteristic of the eye being examined, which is likely to be located at or near the intersection position 170.

[0151] <When determined automatically> The case in which the second correction value is automatically determined by a value calculated by a calculation device based on predetermined conditions (the automatic determination step is executed) will be explained using Figure 12. In this embodiment, the explanation will be given using the case in which the calculation device is a subjective optometry device (subjective optometry device 100) as an example, but it is not limited to this. The calculation device may be an information processing device (for example, a PC, smartphone, and tablet terminal, etc.).

[0152] Figure 12 is an example of the conditions used by the calculation unit (control unit 60) when automatically determining the second correction value, shown on a two-dimensional Cartesian coordinate system 110. Figure 12 shows the J0 axis, J45 axis, origin 114, correctable value 115, coordinate point 150 indicating the first correction value, first vector 151, first answer direction 152, perpendicular line 155, intersection point 156, coordinate point 160 indicating the second correction value, and second vector 161, etc. The perpendicular line 155 is a perpendicular line that appears to be perpendicular (when viewing a full circle as 360 degrees) to the answer direction 152 at a position where the distance from the endpoint of the first vector (coordinate point 150) is greater than or equal to a threshold. The intersection point 156 is the intersection point where the perpendicular line 155 and the first answer direction 152 appear to be perpendicular.

[0153] In the automatic determination step, for example, the control unit 60 places a perpendicular line 155 that appears to be perpendicular to the first answer direction 152, which is a line segment extending in the first answer direction from the endpoint (coordinate point 150) of the first vector 151 on the two-dimensional Cartesian coordinate system 110, at a position where the distance from the endpoint of the first vector 151 is greater than a threshold. For example, the control unit 60 places an intersection point 156 at the intersection of the first answer direction 152 and the perpendicular line 155. For example, the control unit 60 determines the second correction value at a coordinate point 160, which is one of the coordinates on the perpendicular line 155 that is greater than a threshold distance from the intersection point 156. In this embodiment, as an example, the control unit 60 determines the second correction value at a coordinate point 160 that indicates a cylindrical correction amount (C): -1.00D and an astigmatism axis correction amount (A): 35 degrees.

[0154] <Determination of the second vector> The control unit 60 determines a second vector 161 on the two-dimensional Cartesian coordinate system 110, starting from the origin 114, which represents the astigmatism component corresponding to the second correction value 160 (step T9).

[0155] <Acquisition of the second response direction (conducting the second examination)> Next, the control unit 60 controls the lens disk 50 and the optical element 52 on the lens disk 50 based on the correction amount in the second correction value (step T10). For example, the control unit 60 drives the drive unit 51 and the drive unit 53 to switch and position the lens disk 50 and the optical element 52 in the examination window 43 based on the second correction value acquired in step T8. As a result, the light beam of the visual target presented to the eye E under examination is corrected by the second correction value.

[0156] Next, the examiner measures the astigmatism of the eye E at the correction amount of the second correction value (conducting the second test). For example, when the light beam of the target presented to the eye E is corrected at the second correction value, the examiner operates the examiner controller 10 to select the radial astigmatism chart, which is the target for astigmatism testing. For example, when the control unit 60 receives an operation signal, it displays the radial astigmatism chart 120 (Figure 7) on the display 31.

[0157] The examiner shows the subject the radiation astigmatism chart 120 and asks if there are any line segments that appear darker or thicker (step T11). If there are line segments that appear darker or thicker (step T11: YES), the examiner asks the subject the direction of the line segments that appear darker or thicker. For example, if the subject answers, "The line between 5 and 6 is darker," the subject's answer direction will be "165 degrees." This answer direction is equivalent to the axis angle of residual astigmatism of the subject's eye E in the second corrected value. Based on the subject's answer, the examiner inputs the second answer direction, for example, by operating the examiner controller 10. When the control unit 60 receives the input signal, it accepts the value of the second answer direction (i.e., it obtains the second answer direction: step T12).

[0158] Furthermore, if the subject responds in step T11 that there are no line segments that appear dark or thick (step T11: NO), it is highly likely that the subject's astigmatism has been appropriately corrected with the second correction value, and the astigmatism measurement of the subject's eye E is terminated at that point. For example, the control unit 60 stores the cylindrical correction amount and the astigmatism axis correction amount in the second correction value in the memory 70 as the result of the astigmatism measurement.

[0159] <Determination and Display of the Second Region> The control unit 60 determines a second region 163 on the two-dimensional Cartesian coordinate system 110, extending in the direction of the second response direction 162 with the endpoint (coordinate point 160) of the second vector 161 as the base point (step T13). The second region 163 indicates a region that is estimated to contain or be in the vicinity of the true value of the astigmatism characteristic of the eye under examination E, based on the coordinate point 160 indicating the second corrected value and the second response direction 162. The second region 163 may be, for example, a region that extends with a predetermined central angle centered on the base point. The central angle at this time may be determined, for example, according to the angular resolution of the astigmatism test target used to obtain the response direction. Furthermore, the second region 163 may show the entire region that extends in the second response direction 162 centered on the base point, or it may show a region that is divided into a part thereof.

[0160] The control unit 60, for example, causes the monitor 12 to display a two-dimensional Cartesian coordinate system 110 that includes the second region 163 (step T14).

[0161] <Determination of Candidate Correction Values> Once the first region 153 and the second region 163 are determined and displayed, an intersection point 170 appears on the two-dimensional Cartesian coordinate system 110, which is either a region or a point where the first region 153 and the second region 163 intersect. The intersection point may be a region or a point.

[0162] The intersection position 170 of the first region 153 and the second region 163 is the position where two different regions overlap, which are presumed to contain or be in the vicinity of the true value of the astigmatism characteristic of the eye under examination E. The true value of the astigmatism characteristic of the eye under examination E is presumed to be at or near the intersection position 170.

[0163] The control unit 60 detects, for example, the correctable values ​​within the intersection position 170, which are correctable values ​​at the intersection position 170 (step T15). At this time, the correctable values ​​within the intersection position 171 detected by the control unit 60 may be, for example, only correctable values ​​that are completely contained within the intersection position 170, or they may include correctable values ​​that are partially contained within the intersection position 170. Alternatively, the control unit 60 may detect, for example, correctable values ​​that are not contained within the intersection position 170 but are in the vicinity of the intersection position 170.

[0164] The control unit 60 selects a coordinate point 172, which is one of the correctable values ​​171 within the detected intersection position, and determines it as a candidate corrected value (step T16). When selecting one candidate corrected value (coordinate point 172) from among multiple correctable values ​​171 within the intersection position, the control unit 60 may, for example, select the correctable value closest to the center (or centroid) of the intersection position 170, select the correctable value closest to the first corrected value, or select the correctable value with the smallest cylindrical degree.

[0165] As shown in Figure 11, in the two-dimensional Cartesian coordinate system 110, the closer the intersection angle of the first region 153 and the second region 163 is to perpendicular (i.e., when considering a full rotation as 360 degrees), the easier it is to limit the intersection position 170 of the two regions. The more limited the intersection position 170 is, the easier it is to determine a correctable value that is close to the true value of the astigmatism characteristics of the eye being examined from among multiple correctable values. Therefore, when the second corrected value is automatically determined in step T8 described above, setting the second corrected value to a coordinate point 160 on a perpendicular line 155 that is perpendicular to the first response direction 152 makes it easier to determine a correctable value that is close to the true value of the astigmatism characteristics of the eye being examined.

[0166] The control unit 60 controls the lens disk 50 and the optical element 52 on the lens disk 50 based on the amount of correction in the candidate correction value 172 (step T17). For example, the control unit 60 drives the drive unit 51 and the drive unit 53 to switch and position the lens disk 50 and the optical element 52 in the examination window 43 based on the candidate correction value 172 obtained in step T16. As a result, the eye under examination E is corrected with the candidate correction value 172.

[0167] Next, the examiner checks the vision of the eye E at the correction amount of the candidate correction value 172. For example, when the eye E is corrected at the correction amount of the candidate correction value, the examiner operates the examiner controller 10 to select the radiation astigmatism chart. For example, when the control unit 60 receives an operation signal, it displays the radiation astigmatism chart 120 (Figure 7) on the display 31.

[0168] The examiner shows the subject a radiation astigmatism chart 120 and asks if there are any lines that appear darker or thicker (Step T18).

[0169] If the subject answers that there are no line segments that appear dark or thick (Step T18: NO), it is highly likely that the subject's astigmatism is adequately corrected with the candidate correction value 172, and the astigmatism measurement of the subject's eye E is terminated there. For example, the control unit 60 stores the cylindrical correction amount and the astigmatism axis correction amount at the candidate correction value 172 in the memory 70 as the result of the astigmatism measurement.

[0170] In this way, by performing subjective astigmatism measurements of the eye E at least twice (first and second tests), the examiner can efficiently determine candidate corrective values ​​to apply to the eye. Consequently, the astigmatism characteristics of the eye can be measured smoothly.

[0171] If the subject responds in step T18 that there is a line segment that appears darker or thicker (step T18: YES), the control unit 60 may, for example, return to step T8, determine (obtain) a different second correction value, and then perform the same process again (steps T9 to T16) to determine a different candidate correction value. Alternatively, the control unit 60 may determine a third correction value that is different from both the first and second correction values, and then determine a different candidate correction value based on the intersection position formed by the third region based on the third correction value and at least one of the first and second regions.

[0172] <Example of Modification: Determination of Target Correction Value Based on the Concept of Vector Synthesis> In the optical characteristic measurement method of the first embodiment described above, the target correction value is determined by determining the correction value to be changed in the reference correction value according to the angle difference between the reference direction of the astigmatism axis angle corrected in the reference correction value (for example, the direction of the reference vector 112 in the two-dimensional orthogonal coordinate system 110) and the answer direction. However, the method is not limited to this. For example, the control unit 60 may calculate a composite correction value by combining an additional correction value in which the astigmatism axis angle matches the answer direction with the reference correction value, and determine the calculated composite correction value as the target correction value, which is the next astigmatism correction value. The target correction value obtained in this modification example is not necessarily the true value of the astigmatism characteristics of the eye under examination, but by combining an additional correction value in which the astigmatism axis angle matches the answer direction with the reference correction value, the target correction value becomes closer to the true value. Therefore, it becomes easier to efficiently reach an appropriate astigmatism correction value. Consequently, it becomes easier to measure the astigmatism characteristics of the eye under examination more smoothly. In other words, by utilizing the residual astigmatism that results from the corrected eye, it becomes easier to efficiently reach the appropriate astigmatism correction value, and consequently, the astigmatism characteristics of the eye being examined can be measured more smoothly.

[0173] To facilitate understanding of this transformation example, the following explanation will illustrate the case where the target correction value is determined using the aforementioned two-dimensional Cartesian coordinate system 110. However, it is also possible to determine the target correction value by calculating the composite correction value without using the two-dimensional Cartesian coordinate system 110. In the optical property measurement method for the transformation example described below, in addition to the reference vector 112, a response vector 141 (see Figure 14) at the same angle as the response direction is further determined on the two-dimensional Cartesian coordinate system 110, and the target correction value is determined based on the endpoint coordinate of the composite vector 142, which is obtained by combining the reference vector 112 and the response vector 141 on the two-dimensional Cartesian coordinate system 110.

[0174] Figure 13 is a flowchart of the control process based on the optical characteristic measurement method (astigmatism measurement) performed by the subjective optometry device 100. The control unit 60 of the subjective optometry device 100 executes the control process exemplified in Figure 13 by, for example, executing the optical characteristic measurement program stored in the memory 70. Note that the control process of the control unit 60 exemplified in Figure 13 has some common parts with the control process of the control unit 60 exemplified in Figure 5 (for example, steps S1 to S5 and steps S9 to S10). The explanation of the common control process (steps) is omitted as it is the same as in the previously described example, and the control process of the control unit 60 in steps S11 to S13 will be explained below.

[0175] <Determination of the Answer Vector> Based on the answer direction obtained in step S5, the control unit 60 determines the answer vector 141 on the two-dimensional orthogonal coordinate system 110 (step S11). In this example of modification, as an example, the reference correction values ​​obtained in step S1 are cylindrical correction amount (C): -0.75D, astigmatism axis correction amount (A): 15 degrees, and the answer direction obtained in step S5 is 37.5 degrees.

[0176] Step S11, in which the answer vector 141 is determined on the two-dimensional Cartesian coordinate system 110, will be explained using Figure 14. Figure 14 will also be referred to when explaining the subsequent steps S12, S13, and S9.

[0177] Figure 14 illustrates an example of the process for determining the target correction value based on the endpoint coordinate of the composite vector 142, which is obtained by combining the reference vector 112 and the response vector 141 in a two-dimensional Cartesian coordinate system 110. The two-dimensional Cartesian coordinate system 110 is set to include coordinate point 111 indicating the reference correction value, the reference vector 112, the response vector 141, the composite vector 142, the endpoint 143 of the composite vector, and coordinate point 144 indicating the target correction value. The response vector 141 starts from the endpoint (coordinate point 111) of the reference vector 112 and extends in the direction of the response. As mentioned above, in the example shown in Figure 13, the subject only responds with the direction and does not respond with information regarding the degree of deviation of the reference correction value from the true value of the astigmatism characteristics of the eye being examined. Therefore, the magnitude of the response vector 141 (corresponding to the magnitude of the cylindrical power in the additional correction value) is determined to be a magnitude equivalent to a predetermined cylindrical power. The composite vector 142 is determined by vector compositing the reference vector 112 and the response vector 141. The endpoint 143 of the composite vector is the endpoint of the composite vector 142. Coordinate point 144 is a coordinate point that indicates the target correction value, which is the next astigmatism correction value determined based on the endpoint 143 of the composite vector.

[0178] The control unit 60 determines a response vector 141 with a predetermined cylindrical power (e.g., equivalent to -0.25D) in magnitude (length) from the endpoint (coordinate point 111) of the reference vector 112 placed on the two-dimensional Cartesian coordinate system 110, toward the angle of the response direction obtained in step S5 (the response direction is 37.5 degrees, which corresponds to a double angle of 75 degrees on the two-dimensional Cartesian coordinate system 110) (step S11). The magnitude (length) of the response vector 141 represents a predetermined cylindrical correction amount to be added to the reference correction value. For example, this predetermined cylindrical correction amount may be the minimum variable amount of cylindrical power when performing astigmatism measurement with the subjective ophthalmoscopic optometry device 100, or it may be any cylindrical correction amount unrelated to the minimum variable amount of cylindrical power.

[0179] Next, for example, the control unit 60 determines a composite vector 142, which is created by combining the reference vector 112 and the answer vector 141 on the two-dimensional Cartesian coordinate system 110 (step S12). This means that the astigmatism correction amount (C and A) in the reference correction value is combined with the astigmatism correction amount when the axis of a cylindrical lens having a predetermined cylindrical power (for example, -0.25D) is superimposed in the answer direction (residual astigmatism axis direction). In other words, determining the composite vector 142 by combining the reference vector 112 and the answer vector 141 is equivalent to calculating a composite correction value by combining the reference correction value with an additional correction value whose astigmatism axis angle coincides with the answer direction.

[0180] For example, the control unit 60 obtains the coordinates of the endpoint 143 of the composite vector, which is the endpoint of the composite vector 142 (step S13), and then determines the nearest correctable value, coordinate point 144, from the coordinates of the endpoint 143 of the composite vector as the target corrected value (step S9).

[0181] Next, the control unit 60 executes steps S10 and S4 in that order, and repeats steps S5, S11, S12, S13, S9, S10, and S4 in that order until it is no longer possible to obtain a response direction from the subject (step S4: NO).

[0182] As described above, with a configuration that determines the target correction value based on the endpoint coordinates of the composite vector, it is possible to calculate a target correction value that represents the composite astigmatism correction value when a cylindrical lens with a predetermined amount of cylindrical correction is superimposed on the reference correction value in the response direction (for example, the direction of the residual astigmatism axis angle). In this way, the amount of correction for both the cylindrical power and the astigmatism axis angle can be calculated at once, allowing the examiner to measure astigmatism characteristics more smoothly.

[0183] In the transformation examples shown in Figures 13 and 14, the case in which the target correction value is determined using the aforementioned two-dimensional Cartesian coordinate system 110 was illustrated to facilitate understanding of the technology of this disclosure. However, it is also possible to determine the target correction value by calculating the composite correction value without using the two-dimensional Cartesian coordinate system 110. In this case, the processes in steps S2 and S11 shown in Figure 13 can be omitted. In steps S12 and S13 shown in Figure 13, the control unit 60 calculates a composite correction value by combining an additional correction value (the magnitude of the cylindrical power is arbitrary in this disclosure) whose astigmatism axis angle matches the response direction with the reference correction value. In step S9, the control unit 60 determines the composite correction value calculated in steps S12 and S13 as the target correction value, which is the next astigmatism correction value. Even in this case, the residual astigmatism is used to efficiently determine an appropriate target correction value. In the process of step S10 in this transformation example, the optical member that corrects the additional correction value is not physically added to the optical member that corrects the reference correction value used in step S3. In detail, in step S10 of this modification example, the control unit 60 calculates a composite correction value by combining the reference correction value and the additional correction value, sets an optical element to perform the correction of the calculated composite correction value (replacing the optical element used in step S3), and performs a subjective inspection. Therefore, a subjective inspection can be performed smoothly without the simultaneous use of many optical elements.

[0184] 60 Control unit 100 Self-aware eye examination device 110 Two-dimensional Cartesian coordinates 112 Reference vector 120 Radial astigmatism chart 130 Condition map 141 Response vector 151 First vector 153 First region 161 Second vector 163 Second region 170 Intersection position

Claims

1. An optical properties measurement method for subjectively measuring the optical properties of an eye, including astigmatism, comprising: a first vector determination step of determining a first vector representing the astigmatism component corresponding to a first correction value for the eye, on a two-dimensional Cartesian coordinate system where, with an arbitrary angle α, the components of the astigmatism component in the refractive value with astigmatism axis angles of α degrees and α+90 degrees are the X-axis, and the components with astigmatism axis angles of α+45 degrees and α+135 degrees are the Y-axis,; a first response direction acquisition step of obtaining a first response direction, which is the direction of the first response given by the subject, with the light beam of the astigmatism test target presented to the eye corrected by the first correction value; a first region determination step of determining a first region extending in the first response direction with the endpoint of the first vector as the base point on the two-dimensional Cartesian coordinate system; and a second vector determination step of determining a second vector representing the astigmatism component corresponding to a second correction value different from the first correction value on the two-dimensional Cartesian coordinate system. A method for measuring optical properties, comprising: a second response direction acquisition step of acquiring the second response direction, which is the direction of the second response given by the subject, while the light beam of the astigmatism test target presented to the eye under examination is corrected by the second correction value; a second region determination step of determining a second region extending in the second response direction with the endpoint of the second vector as the base point on the two-dimensional Cartesian coordinate system; and a candidate correction value determination step of determining a candidate correction value to be applied to the eye under examination based on the intersection position of the first region and the second region.

2. An optical property measurement method according to claim 1, characterized in that at least the second correction value is determined in accordance with instructions input by the examiner.

3. An optical property measurement method according to claim 2, further comprising: a first region display step of displaying the two-dimensional orthogonal coordinates including the first region on a display unit; and a coordinate information reception step of receiving an input of an instruction to specify coordinate information corresponding to the second correction value on the two-dimensional orthogonal coordinates while the two-dimensional orthogonal coordinates are displayed on the display unit, wherein in the second vector determination step, the second vector is determined based on the second correction value corresponding to the coordinate information specified in the coordinate information reception step.

4. An optical property measurement method according to claim 1, further comprising an automatic determination step of automatically determining at least the second correction value by a value calculated by a computing device based on predetermined conditions.

5. An optical property measurement method according to claim 4, characterized in that, in the automatic determination step, the second correction value is determined in the two-dimensional Cartesian coordinate system, which passes through a position on a half-line extending from the endpoint of the first vector in the first answer direction, where the distance from the endpoint of the first vector is greater than or equal to a threshold, and is on a perpendicular line perpendicular to the half-line, where the distance from the intersection of the half-line and the perpendicular line is greater than or equal to a threshold.

6. An optical properties measurement method according to any one of claims 1 to 5, characterized in that the first response acquisition step and the second response acquisition step are performed by presenting the astigmatism test target as a radial astigmatism chart to the eye of the subject and obtaining the first response direction or the second response direction from the subject.

7. An optical properties measurement method for subjectively measuring the optical properties of an eye under test, including astigmatism characteristics, comprising: a response direction acquisition step of acquiring the response direction answered by the subject while the light beam of an astigmatism test target presented to the eye under test is corrected to a reference correction value; and a target correction value determination step of determining a target correction value, which is the next astigmatism correction value, according to the angular difference between the reference direction, which is the direction of the astigmatism axis angle corrected at the reference correction value, and the response direction.

8. An optical properties measurement method for subjectively measuring the optical properties of an eye under test, including astigmatism characteristics, comprising: a response direction acquisition step of acquiring the response direction answered by the subject while the light beam of an astigmatism test target presented to the eye under test is corrected to a standard correction value; and a target correction value determination step of determining a composite correction value, which is the next astigmatism correction value, by combining the standard correction value with an additional correction value in which the astigmatism axis angle coincides with the response direction.

9. An optical properties measurement program executed in an information processing device for subjectively measuring the optical properties of an eye, including astigmatism, wherein the information processing device comprises at least a control unit, and the optical properties measurement program is executed by the control unit to determine a first vector representing the astigmatism component corresponding to a first correction value for the eye, on a two-dimensional Cartesian coordinate system where, with an arbitrary angle α, the components of the astigmatism component in the refractive value have astigmatism axis angles of α degrees and α+90 degrees as the X-axis, and the components have astigmatism axis angles of α+45 degrees and α+135 degrees as the Y-axis; a first response direction acquisition step to acquire a first response direction, which is the direction of the first response given by the subject, when the light beam of the astigmatism test target presented to the eye is corrected by the first correction value; and a first region determination step to determine a first region extending in the first response direction with the endpoint of the first vector as the base point on the two-dimensional Cartesian coordinate system. An optical property measurement program characterized by causing the information processing device to execute the following steps: a second vector determination step of determining a second vector representing an astigmatism component corresponding to a second correction value different from the first correction value on the two-dimensional Cartesian coordinate system; a second response direction acquisition step of acquiring the second response direction, which is the direction of the second response given by the subject, when the light beam of the astigmatism test target presented to the eye under examination is corrected by the second correction value; a second region determination step of determining a second region extending in the second response direction with the endpoint of the second vector as the base point on the two-dimensional Cartesian coordinate system; and a candidate correction value determination step of determining a candidate correction value to be applied to the eye under examination based on the intersection position of the first region and the second region.

10. An optical characteristic measurement program to be executed in an information processing device for subjectively measuring the optical characteristics of an eye, including astigmatism characteristics, wherein the information processing device comprises at least a control unit, and the optical characteristic measurement program is executed by the control unit to cause the information processing device to perform the following steps: an answer direction acquisition step to acquire the answer direction answered by the subject while the light beam of an astigmatism test target presented to the eye is corrected to a reference correction value; and a target correction value determination step to determine a target correction value, which is the next astigmatism correction value, according to the angle difference between the reference direction, which is the direction of the astigmatism axis angle corrected by the reference correction value, and the answer direction.

11. A subjective optometry device for subjectively measuring the optical properties of an eye, including astigmatism, comprising: a correction means for changing the optical properties of a target light beam presented to the eye; and a control unit, wherein the control unit performs a first vector determination step of determining a first vector representing the astigmatism component corresponding to a first correction value for the eye, on a two-dimensional Cartesian coordinate system where, with an arbitrary angle α, the components of the astigmatism component in the refractive value with astigmatism axis angles of α degrees and α+90 degrees are the X-axis, and the components with astigmatism axis angles of α+45 degrees and α+135 degrees are the Y-axis; a first response direction acquisition step of acquiring a first response direction, which is the direction of the first response given by the subject, while the light beam of the astigmatism test target presented to the eye is corrected by the correction means with the first correction value; and a first region determination step of determining a first region extending in the first response direction on the two-dimensional Cartesian coordinate system, with the endpoint of the first vector as the base point. A subjective eye examination device characterized by performing the following steps: a second vector determination step of determining a second vector representing an astigmatism component corresponding to a second correction value different from the first correction value on the two-dimensional Cartesian coordinate system; a second response direction acquisition step of acquiring the second response direction, which is the direction of the second response given by the subject, while the light beam of the astigmatism test target presented to the eye under examination is corrected by the correction means with the second correction value; a second region determination step of determining a second region extending in the second response direction with the endpoint of the second vector as the base point on the two-dimensional Cartesian coordinate system; and a candidate correction value determination step of determining a candidate correction value to be applied to the eye under examination based on the intersection position of the first region and the second region.

12. A subjective optometry device for subjectively measuring the optical properties of an eye, including astigmatism, comprising: a correction means for changing the optical properties of a target light beam presented to the eye; and a control unit, wherein the control unit performs: an answer direction acquisition step for acquiring the answer direction answered by the subject when the light beam of an astigmatism test target presented to the eye is corrected by the correction means to a standard correction value; and a target correction value determination step for determining a target correction value, which is the next astigmatism correction value, according to the angle difference between the answer direction and the standard direction, which is the direction of the astigmatism axis angle corrected at the standard correction value.

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