Ophthalmic device

Abstract

[Problem] To provide technology for assisting in alignment. [Solution] Constructed is an ophthalmic device comprising: a measurement optical system that measures a subject eye on the basis of reflected light output from the subject eye in response to incident light input to the subject eye; a relative position detection optical system that detects the relative position of the subject eye, which is present within a prescribed range where detection is possible, with respect to the measurement optical system; a visual target optical system that guides light output from a visual target to a prescribed range where the visual target is visible; and a switching unit that switches the visual target being viewed by the subject eye when the subject eye moves from outside to inside of a prescribed range which constitutes at least a portion of the range where detection is possible.

Description

ophthalmology equipment

[0001] The present invention relates to an ophthalmic apparatus.

[0002] Conventionally, there are known ophthalmologic apparatuses in which the subject performs positioning. Specifically, there are known apparatuses in which the subject himself / herself moves to align the subject's eye with the measurement position or to position the subject's eye within a range where auto-alignment is possible.

[0003] Furthermore, when a measurement is performed using an ophthalmologic apparatus, the subject may be asked to gaze at a fixation target in order to fix the line of sight of the subject's eye in a specific direction. Patent Document 1, for example, is known as a technique for causing the subject to gaze at a fixation target. Patent Document 1 discloses a technique for changing the shape of a fixation light beam while moving an optical system.

[0004] Patent No. 6912554

[0005] In ophthalmic devices where a subject performs alignment, for example, the subject performs alignment while looking into the ophthalmic device. However, in the past, the subject did not know which direction to move their head. This made it difficult to align the subject's eye to the measurement position. The present invention has been made in consideration of the above-mentioned problem, and aims to provide a technology that supports alignment.

[0006] In order to achieve the above-mentioned object, the ophthalmic device comprises a measurement optical system that measures the test eye based on reflected light output from the test eye in response to incident light input to the test eye, a relative position detection optical system that detects the relative position of the test eye, which is located within a predetermined detectable range, with respect to the measurement optical system, a visual target optical system that guides light output from a visual target into a predetermined visual target visible range, and a switching unit that switches the visual target that is visible by the test eye when the test eye moves from outside a predetermined range that is at least a part of the detectable range to inside the predetermined range.

[0007] According to the above configuration, when the subject's eye moves from outside to inside the predetermined range, the optotype switches. Therefore, the subject can recognize that the subject's eye is located within the predetermined range included in the detectable range. As a result, the subject can easily position the subject's eye within the predetermined range by moving their face. As described above, it is possible to provide assistance with alignment when the subject moves the subject's eye within the predetermined range.

[0008] 8A is a perspective view of an ophthalmic apparatus. FIG. 8B is a block diagram of an ophthalmic apparatus. FIG. 8C is a diagram illustrating an optical system of the ophthalmic apparatus. FIG. 8D is a diagram illustrating a detectable range. FIG. 8E is a diagram illustrating a visual target visible range. FIG. 8F is a flowchart of a measurement process. FIG. 8G is a diagram illustrating a relationship between a detectable range and a visual target visible range, and FIG. 8H to FIG. 8I are diagrams illustrating examples of visual targets. FIG. 8G is a flowchart of a measurement process. FIG. 8H is a flowchart of a measurement process.

[0009] Here, the embodiments of the present invention will be described in the following order: (1) Configuration of the ophthalmic device: (2) Measurement process: (3) Other embodiments, etc.:

[0010] (1) Configuration of the Ophthalmic Apparatus: Fig. 1 is a perspective view of an ophthalmic apparatus 1 according to one embodiment of the present invention. The ophthalmic apparatus 1 is placed on a desk or the like, and is equipped with an optical system for measuring each of the examinee's eyes inside the ophthalmic apparatus 1. Openings H1 and H2 are provided at the top of the ophthalmic apparatus 1 to allow light from each of the examinee's eyes to enter the ophthalmic apparatus 1.

[0011] A forehead rest Fp for the subject's forehead to contact is provided at the top of the ophthalmologic apparatus 1. Furthermore, nose rests Np for the subject's nose to contact are provided below the openings H1 and H2. That is, during measurement, the subject looks into the openings H1 and H2 with their left and right eyes, respectively, with their forehead in contact with the forehead rest Fp and their nose in contact with the nose rests Np.

[0012] In this embodiment, the ophthalmologic apparatus 1 has an auto-alignment function (described in detail below), and can automatically adjust the relative position of the subject's eye with respect to the measurement optical system so that it is at the measurement position if the subject's eye is within a predetermined detectable range. Even if the subject has their forehead in contact with the forehead support Fp and their nose in contact with the nose support Np, they can still move their face. Therefore, before measurement, the subject moves their face so that the subject's eye is within the detectable range.

[0013] When a subject moves his / her face, if the subject is uncertain about the direction in which to move his / her face, it is difficult to move the subject's eye within the detectable range. Therefore, in this embodiment, a configuration is provided to assist the subject so that the subject can easily move the subject's eye within the detectable range.

[0014] 2 is a block diagram showing the internal configuration of the ophthalmic apparatus 1. In this embodiment, the ophthalmic apparatus 1 includes a control unit 10, an optical system 20, and a drive unit 30. The control unit 10 controls each unit included in the optical system 20 (e.g., a display device described below) and the drive unit 30. The control unit 10 also performs various processes based on output signals from each unit included in the optical system 20 (e.g., a sensor). The control unit 10 can be configured, for example, by a processor, a memory, etc.

[0015] The optical system 20 includes optical components for measuring the subject's eye and has various functions. Details of the optical system 20 will be described later. The drive unit 30 is a mechanism for moving the optical system 20 within the housing of the ophthalmic apparatus 1. When the drive unit 30 moves the optical system 20, the relative positional relationship between the subject's eye and the optical system 20 changes. In this embodiment, the optical system 20 can move in the front-to-back direction of the subject's eye when the subject is looking through the openings H1 and H2, and in a direction perpendicular to the front-to-back direction. In this specification, the front-to-back direction is referred to as the Z direction, and perpendicular to the Z direction, the left-to-right direction as seen from the subject's eye is referred to as the X direction, and the up-to-down direction as seen from the subject's eye is referred to as the Y direction. The drive unit 30 can have various configurations, and can have various mechanisms for moving the optical system 20 in the X direction, Y direction, and Z direction, respectively. The mechanism can have a variety of configurations, for example, the rotational force of the motor may be converted into linear reciprocating motion by a power transmission mechanism such as a slider crank mechanism or a cam, or a ball screw mechanism may be used, or various other configurations may be used.

[0016] 3 is a diagram showing the optical system 20 of the ophthalmologic apparatus 1. In this embodiment, the optical system 20 includes a measurement optical system 21, a relative position detection optical system 22, a visual target optical system 23, and a diaphragm 24. An optical system 20 may be provided for each of the openings H1 and H2, or a single optical system 20 may move to measure the subject's eyes E facing each of the openings H1 and H2.

[0017] The measurement optical system 21 is an optical system for measuring the subject's eye E based on reflected light output from the subject's eye E in response to incident light input to the subject's eye E. In this embodiment, the measurement optical system 21 includes a measurement unit 21a, a mirror 21b, and a dichroic mirror 22a. In this embodiment, the reflected light output from the subject's eye E is reflected by the dichroic mirror 22a and further reflected by the mirror 21b, and then enters the measurement unit 21a.

[0018] The measurement object in the measurement optical system 21 is arbitrary. That is, the measurement optical system 21 can adopt various configurations as long as it can measure the characteristics of the measurement object based on reflected light output from the subject's eye E. Here, the measurement optical system 21 is an optical system for performing measurements using OCT (Optical Coherence Tomography). Therefore, the measurement optical system 21 according to this embodiment can capture a tomographic image of the subject's eye E and measure various characteristics obtained from the tomographic image. The measurement unit 21a includes optical components for capturing a tomographic image of the subject's eye E, an interface for outputting the capture results to the control unit 10, and the like.

[0019] The relative position detection optical system 22 is an optical system that detects the relative position of the subject's eye E, which is present within a predetermined detectable range, with respect to the measurement optical system 21. The relative position detection optical system 22 includes dichroic mirrors 22 a and 22 b, a half mirror 22 d, lenses 22 c, 22 e, and 22 g, light sources 22 f and 22 i, a camera 22 h, and a sensor 22 j.

[0020] The light source 22f is a light source that outputs light for measuring the relative position of the subject's eye E in the X-Y directions, and is configured, for example, by an infrared LED. The camera 22h is a two-dimensional sensor. The light output from the light source 22f passes through the lens 22e, is reflected by the half mirror 22d, and travels toward the subject's eye E. The light reflected by the half mirror 22d passes through the lens 22c and the dichroic mirrors 22b and 22a, and is incident on the subject's eye E. The light that has entered the subject's eye E is scattered and reflected by the subject's eye E. The light reflected by the subject's eye E passes through the dichroic mirrors 22a and 22b, the lens 22c, the half mirror 22d, and the lens 22g, and reaches the camera 22h.

[0021] When light reflected from the corneal apex of the subject's eye E reaches the detection surface of the camera 22h, the detection intensity at the irradiation position of the light becomes greater than the detection intensity at other positions, and the light is detected as a bright spot. Therefore, the position in the X-Y directions of the corneal apex of the subject's eye E can be identified from the position where the bright spot is detected by the camera 22h. The position of the corneal apex in the X-Y directions can be considered as the relative position of the subject's eye E in the X-Y directions with respect to the relative position detection optical system 22.

[0022] The light source 22i is a light source that outputs light for measuring the relative position of the subject's eye E in the Z direction, and is configured by, for example, an infrared LED or a white light LED. The sensor 22j is a line sensor. The light output from the light source 22i is reflected by the cornea of ​​the subject's eye E and reaches the sensor 22j.

[0023] When light specularly reflected from the vertex of the subject's eye E reaches the detection unit of the sensor 22j, the detected intensity at the irradiation position of the light becomes greater than the detected intensity at other positions, and the light is detected as a bright spot. Therefore, the position of the cornea of ​​the subject's eye E in the Z direction can be identified from the position where the bright spot is detected by the sensor 22j. The position of the cornea in the Z direction can be considered as the relative position of the subject's eye E in the Z direction with respect to the relative position detection optical system 22.

[0024] In this embodiment, the optical system 20, which includes the measurement optical system 21, the relative position detecting optical system 22, the visual target optical system 23, and the diaphragm 24, is moved as a unit by the drive unit 30. That is, the positional relationship between the measurement optical system 21 and the relative position detecting optical system 22 does not change with this movement. Therefore, the relative position of the subject's eye E with respect to the relative position detecting optical system 22, detected by the relative position detecting optical system 22, is also the relative position of the subject's eye E with respect to the measurement optical system 21.

[0025] As described above, the relative position of the subject's eye E is determined by the light output from the light sources 22f and 22i reflected by the subject's eye E, and therefore the detectable range is limited depending on the travel range of the light, etc. Fig. 4 is a diagram for explaining the detectable range in the XY direction. In Fig. 4, the range of light output from the light source 22f that can enter the subject's eye E is indicated by a dashed dotted line. In Fig. 4, the range of light reflected by the subject's eye E that can reach the camera 22h is indicated by a dashed dotted line.

[0026] 4, the range of light that reaches the eye E, is reflected by the eye E, and reaches the camera 22h is range Rs. That is, in the configuration shown in FIG. 4, the range in which light is detected by the camera 22h is narrowed (limited) to range Rs in advance. The range Rs in which light can be detected by the camera 22h corresponds to range Rs' in the vicinity of the eye E. That is, of the light that reaches the eye E, only light within range Rs' reaches range Rs of the camera 22h. Therefore, if the corneal apex of the eye E is outside range Rs', the relative position of the eye E cannot be detected. If the corneal apex of the eye E is within range Rs', the relative position of the eye E can be detected.

[0027] In the Y direction, light output from the light source 22f reaches the subject's eye E over a similar range. Therefore, the range in which the relative position of the subject's eye E can be detected is also limited in the Y direction. As described above, in this embodiment, the range in which the relative position of the subject's eye E in the X-Y directions can be detected is limited, and this range is called the detectable range. In this embodiment, the sizes of the detectable ranges in the X- and Y-directions are equal, and the shape of the detectable range in the X-Y plane is a square.

[0028] In this embodiment, the detectable range of the subject's eye E also exists in the Z direction. Specifically, when the position of the subject's eye E changes in the Z direction in Fig. 4, the light output from the light source 22i is reflected by the subject's eye E, and the position at which the reflected light reaches the sensor 22j changes. However, if the position of the subject's eye E in the Z direction changes significantly, the reflected light will not reach the sensor 22j. Therefore, the range in which the light reflected by the subject's eye E reaches the sensor 22j is the detectable range in the Z direction.

[0029] The visual target optical system 23 is an optical system that guides light output from the visual target to a predetermined visual target visibility range. In this embodiment, the visual target is a mark that serves as a guide when the subject approaches the face to a measurable position. The visual target optical system 23 includes lenses 23a and 23b, a display device 23c, and dichroic mirrors 22b and 22a. The display device 23c is a device that can display any image on a two-dimensional display surface. In this embodiment, the display surface is parallel to the ZY direction. The display device can be realized by various devices, and for example, a liquid crystal display device or the like can be adopted.

[0030] When an image is displayed on the display device 23c, light output from the display device 23c passes through the lenses 23b and 23a, is reflected by the dichroic mirror 22b, and travels toward the subject's eye E. The light reflected by the dichroic mirror 22b passes through the dichroic mirror 22a and enters the subject's eye E. When the light enters the subject's eye E, the subject can visually recognize the image displayed on the display device 23c.

[0031] In this embodiment, a target of a predetermined shape is displayed on the display device 23c. The subject visually recognizes the target displayed on the display device 23c. However, in this embodiment, the target visual recognition range in which the target can be recognized is limited. Specifically, the ophthalmologic apparatus 1 includes a diaphragm 24 that functions as a switching unit.

[0032] The diaphragm 24 is a member that limits the range of light that reaches the subject's eye E from the display device 23c, and in this embodiment, is disposed between the display device 23c and the lens 23b. In this embodiment, the diaphragm 24 is a plate-shaped member having an opening 24a of a predetermined size. The opening 24a may have any shape, such as a circle or a polygon. In this embodiment, an example in which the opening 24a is a square, for example, a square with one side measuring 6.7 mm, is assumed.

[0033] Of the light output from the display device 23c, light that does not pass through the opening 24a of the diaphragm 24 does not reach the subject's eye E. On the other hand, when light that passes through the opening 24a reaches the subject's eye E, the subject visually recognizes the optotype. Therefore, the range in which the optotype is visible is determined by the size of the opening 24a of the diaphragm 24. Fig. 5 is a diagram for explaining the range in which the optotype is visible. In Fig. 5, the range of light that is output from the display device 23c and enters the subject's eye E is indicated by a dashed dotted line.

[0034] In Fig. 5, the range of light reaching the subject's eye E is range Rc in the X direction. In the configuration shown in Fig. 5, since the opening 24a of the diaphragm 24 is square, the range of light reaching the subject's eye E via the lens 23b, etc. is also square in the XY direction. The size of the visual target visibility range is determined by the magnification of the visual target optical system 23. Specifically, the size of the opening 24a multiplied by the magnification is the size of the visual target visibility range. In this embodiment, the magnification from the diaphragm 24 to the pupil position of the subject's eye E, which is achieved by the lenses 23b, 23a and the dichroic mirrors 22b, 22a, is 1.5 times. Therefore, the length of one side of the visual target visibility range is 10 mm, which is 1.5 times the 6.7 mm side of the opening 24a.

[0035] The diaphragm 24 as a switching unit functions as an optical component that switches the optotype visually recognized by the eye E when the eye E moves from outside a predetermined range, which is at least a part of the range detectable by the relative position detection optical system 22, to within the predetermined range. The predetermined range may be any range that is included in the detectable range, but in this embodiment, the predetermined range coincides with the detectable range. In other words, the entire range detectable by the relative position detection optical system 22 is the predetermined range. As a result, in this embodiment, the diaphragm 24 as a switching unit switches the optotype visually recognized by the eye E when the eye E moves from outside the range detectable by the relative position detection optical system 22 to within the predetermined range.

[0036] Furthermore, the diaphragm 24 according to this embodiment narrows the light output from the optotype so that the optotype visible range coincides with the detectable range (predetermined range). That is, the optotype visible range (range Rc shown in FIG. 5 ) in which the optotype can be seen by the subject's eye E coincides with the detectable range (range Rs′ shown in FIG. 5 ) in which the relative position of the subject's eye E can be detected.

[0037] Specifically, the optical components are designed so that the size of the aperture 24a of the diaphragm 24, the size of the visual target visible range obtained from the magnification of the visual target optical system 23, and the size of the detectable range of the subject's eye E, which is defined corresponding to the range in which light can be detected by the camera 22h, match. Furthermore, the orientation of the optical components in each optical system is set so that the optical axis of the relative position detection optical system 22 and the optical axis of the visual target optical system 23 match between the dichroic mirror 22b and the subject's eye E.

[0038] In the above configuration, when the subject's eye E is within the detectable range, the subject's eye E visually recognizes the optotype, and when the subject's eye E is not within the detectable range, the optotype is not visually recognized by the subject's eye E. Therefore, when the subject moves his / her face to a position where the optotype is visible, the subject's eye E is placed within the detectable range, and the auto-alignment function can automatically adjust the subject's eye E to be positioned at the measurement position of the measurement optical system 21. In this way, in this embodiment, the subject only needs to move his / her face with the goal of being able to see the optotype, and the auto-alignment function can be used to assist the subject in moving his / her face to a position where the auto-alignment function can be used.

[0039] The measurement position of the measurement optical system 21 is the position where the subject's eye E should be placed when performing measurement using the measurement optical system 21. The pupil of the subject's eye E, which is placed at the measurement position for measuring the subject's eye E using the measurement optical system 21 according to this embodiment, is conjugate with the diaphragm 24. When the pupil of the subject's eye E is conjugate with the diaphragm 24, a clear switch occurs between a state in which the visual target is visible and a state in which it is not visible. That is, when the subject's eye E moves in the X-Y directions and the position of the subject's eye E changes from outside the detectable range to inside the detectable range, the visual target appears instantaneously. This allows the subject to clearly recognize whether or not the subject has entered the detectable range.

[0040] (2) Measurement Process: The measurement process for measuring the subject's eye E in the ophthalmic apparatus 1 will be described below. Fig. 6 is a flowchart of the measurement process. When measuring the subject's eye E, power is supplied to the ophthalmic apparatus 1 from a power source (not shown). When the supply of power starts, the control unit 10 performs a predetermined startup sequence, and then the measurement process starts.

[0041] When the measurement process begins, the control unit 10 controls the display device 23c of the visual target optical system 23 to display the visual target (step S100). The visual target may have any shape, color, or size. Next, the control unit 10 detects the relative position of the subject's eye E (step S105). Specifically, the control unit 10 turns on the light source 22f of the relative position detection optical system 22 and starts detecting bright spots using the camera 22h. Next, the control unit 10 determines whether the subject's eye E is within the detectable range (step S110). Specifically, the control unit 10 determines that the subject's eye E is within the detectable range if the image captured by the camera 22h contains a bright spot corresponding to light reflected from the corneal apex of the subject's eye E. If the control unit 10 does not determine that the subject's eye E is within the detectable range in step S110, the control unit 10 repeats the processes from step S105 onward.

[0042] While such control is being executed by the control unit 10, the subject moves his / her face to search for a position where the target can be seen. During this process, if the subject's eye E enters the detectable range, it is determined in step S110 that the subject's eye is within the detectable range.

[0043] If it is determined in step S110 that the subject's eye E is within the detectable range, the control unit 10 performs auto-alignment (step S120). Specifically, the control unit 10 continues detecting the relative position in step S105 and identifies the position of the bright spot in the image captured by the camera 22h. The control unit 10 then determines whether the position of the bright spot in the image matches the ideal position of the bright spot in the image that would be detected if the subject's eye E were located at the measurement position. The ideal position in the image is the position at which reflected light from the corneal apex of the subject's eye E would be detected if the subject's eye E were located at the measurement position.

[0044] If the position of the bright spot in the image does not match the ideal position, the control unit 10 determines the distance and direction from the position of the bright spot in the image to the ideal position based on the image from the camera 22h. Furthermore, the control unit 10 determines the distance and direction to move the optical system 20 based on the distance and direction to move the bright spot in the image closer to the ideal position. The control unit 10 then outputs a control signal to the drive unit 30 to move the optical system 20 the distance and direction.

[0045] Next, the control unit 10 determines whether the subject's eye E is within the detectable range by the same process as in step S110 (step S125). That is, the control unit 10 checks whether the subject's eye E has moved outside the detectable range during the process of performing auto-alignment. If it is not determined in step S125 that the subject's eye E is within the detectable range, the control unit 10 repeats the processes from step S105 onwards.

[0046] On the other hand, if it is determined in step S125 that the subject's eye E is present within the detectable range, the control unit 10 determines whether the subject's eye E is present at the measurement position (step S130). Specifically, if the position of the bright spot in the image captured by the camera 22h matches the ideal position, the control unit 10 determines that the subject's eye E is present at the measurement position.

[0047] If it is not determined in step S130 that the subject's eye E is present at the measurement position, the control unit 10 repeats the processes from step S120 onwards. That is, the auto-alignment is continued. If it is determined in step S130 that the subject's eye E is present at the measurement position, the control unit 10 measures the subject's eye E (step S135). That is, the control unit 10 controls the measurement unit 21a to measure the characteristics of the measurement target related to the subject's eye E.

[0048] In this embodiment, the optical system is designed so that the subject's eye E is located within the detectable range in the Z direction when the subject places their forehead on the forehead support Fp and their nose on the nose support Np. Therefore, it is assumed that the above-described relative position detection, the subject's facial movement, and auto-alignment are performed primarily in the X-Y directions. Of course, auto-alignment may also be performed in the Z direction. For example, if the subject's eye E is not located within the detectable range in the Z direction during auto-alignment, the control unit 10 may gradually move the optical system 20 in the Z direction until the subject's eye E is within the detectable range in the Z direction. After the subject's eye E is within the detectable range in the Z direction, the control unit 10 moves the optical system 20 in the Z direction based on the output of the sensor 22j so that the position of the subject's eye E in the Z direction is at a predetermined measurement position.

[0049] (3) Other Embodiments, etc.: The above embodiment is one example for implementing the present invention. Various other embodiments can be adopted as long as the optotype recognized by the test eye can be switched when the test eye moves from outside a predetermined range, which is at least a part of the detectable range, to inside the predetermined range. For example, the arrangement, type, number, etc. of optical components in the optical system 20 are not limited to the configuration shown in FIG. 3 , and various configurations can be adopted. Furthermore, the ophthalmologic apparatus 1 may be provided with only one opening. In this case, when measuring both eyes, the test subject first looks into the opening with only one eye to measure that eye, and after measuring that eye, looks into the opening with only the other eye to measure that other eye.

[0050] Furthermore, an ophthalmic apparatus without an auto-alignment function may employ a configuration for switching the optotype recognized by the subject's eye. Such a configuration can be realized, for example, by the same configuration as that shown in FIGS. 1 to 3. However, in this configuration, the ophthalmic apparatus 1 does not include the drive unit 30 shown in FIG. 2. Therefore, the ophthalmic apparatus 1 does not include the auto-alignment function. Furthermore, the control content by the control unit 10 also differs from that of the above-described embodiment.

[0051] Specifically, the control unit 10 executes the measurement process shown in Fig. 7. Most of the measurement process shown in Fig. 7 is similar to the measurement process shown in Fig. 6, but there are some differences. In Fig. 7, the same processes as in Fig. 6 are indicated by the same reference numerals. In the measurement process shown in Fig. 7, steps S100 to S110 are the same as in Fig. 6. On the other hand, since the ophthalmologic apparatus 1 according to this embodiment does not have an auto-alignment function, steps S120 and S125 are not executed.

[0052] Therefore, after the subject recognizes that the subject's eye E is within the detectable range based on the visual target, the subject further moves his or her face to align the subject's eye E with the measurement position. When it is determined in step S130 that the subject's eye E is aligned with the measurement position, the control unit 10 controls the display device 23c to switch the display content so that a visual target indicating that the subject's eye E is at the measurement position is displayed (step S131). Note that the visual target indicating that the subject's eye E is at the measurement position may have any shape, color, and size as long as it is different from the visual target displayed in step S100. As a result, the subject recognizes that the subject's eye E is at the measurement position, stops moving his or her face, and maintains his or her face at that position. In this state, the control unit 10 performs the measurement in step S135. Through the above process, the subject can recognize that the subject's eye E is within the detectable range and can further recognize that the subject's eye E is at the measurement position.

[0053] Furthermore, the configuration for switching the optotype recognized by the subject's eye is not limited to a configuration in which a diaphragm is used to limit light reaching the subject's eye E. For example, a configuration may be adopted in which the control unit 10 serves as a switching unit, and the optotype recognized by the subject's eye is switched by switching the display content displayed on the display device 23c.

[0054] For example, the switching unit may be configured to switch the display content of the optotype displayed on the display device when the subject's eye moves from outside a predetermined range to inside the predetermined range. Such a configuration can be realized, for example, by the same configuration as that shown in Figures 1 to 3. However, in this configuration, the relationship between the detectable range and the optotype visible range differs from that in the above-described embodiment, and the control content by the control unit 10 also differs from that in the above-described embodiment.

[0055] Specifically, an embodiment can be envisioned in which the detectable range is narrower than the visual target visible range, and the detectable range coincides with the predetermined range. Fig. 8A is a diagram schematically illustrating the detectable range Zs of the relative position detection optical system 22 and the visual target visible range Zc of the visual target optical system 23 in this embodiment. Fig. 8A also schematically illustrates each range on the X-Y plane as viewed from the subject's eye E. In the example shown in Fig. 8A, both the detectable range Zs and the visual target visible range Zc are square, but the former has a smaller side than the latter. Furthermore, the centers of both are coincident, and the sides are parallel. Of course, the shape of each range is not limited here either.

[0056] According to the above configuration, even in a situation where the relative position of the subject's eye E cannot be detected, the subject's eye E can visually recognize the visual target. Therefore, even before detection of the relative position of the subject's eye E is started, the subject's eye E can be made to visually recognize the visual target, and assistance can be provided when moving the face. FIG. 9 is a flowchart of the measurement process in this embodiment. This measurement process is similar to the measurement process shown in FIG. 6, but there are some differences. In FIG. 9, processes similar to those in FIG. 6 are indicated by the same reference numerals. In this embodiment, too, the control unit 10 starts the measurement process shown in FIG. 9 after power supply to the ophthalmologic apparatus 1 is started and a predetermined startup sequence is performed.

[0057] When the measurement process is started, the control unit 10 controls the display device 23c of the visual target optical system 23 to display a visual target indicating that the subject's eye E is outside the detectable range (step S101). The visual target indicating that the subject's eye E is outside the detectable range may have any shape, color, or size as long as it is different from the visual target indicating that the subject's eye E is within the detectable range. Here, it is assumed that the subject's eye E is outside the detectable range at the beginning of the measurement process. That is, at the beginning of the measurement process, the subject's eye E visually recognizes a visual target indicating that the subject's eye E is outside the detectable range.

[0058] Steps S105 and S110 are the same as the measurement process shown in Fig. 6. If it is determined in step S110 that the subject's eye E is within the detectable range, the control unit 10 switches to a visual target indicating that the subject's eye E is within the detectable range (step S115). That is, the control unit 10 controls the display device 23c to change the display content and display a visual target indicating that the subject's eye E is within the detectable range. As a result, the subject's eye E visually recognizes the visual target indicating that the subject's eye E is within the detectable range.

[0059] Steps S120 to S135 are the same as the measurement process shown in FIG. 6 , and the auto-alignment function automatically adjusts the position of the optical system 20 so that the subject's eye E is at the measurement position. Therefore, the subject can stop moving their face after visually recognizing the optotype indicating that the subject's eye E is within the detectable range. With the above configuration, the subject can recognize whether the subject's eye E is within the detectable range based on the content of the optotype. Therefore, this embodiment can provide assistance to the subject to move the subject's eye E into the detectable range.

[0060] The above-described measurement process is merely an example, and various modifications are possible. For example, step S101 may be omitted. In this case, the optotype cannot be seen when the subject's eye E is outside the detectable range, and when the subject's eye E moves into the detectable range, the display content of the display device 23c changes, making the optotype visible. Therefore, in this configuration, the subject simply moves his or her face so that the optotype is visible. In this configuration, the optotype visible range Zc and the detectable range Zs may coincide.

[0061] Furthermore, an ophthalmic apparatus without an auto-alignment function may be configured such that a switching unit switches the display content of the display device when the subject's eye moves from outside a predetermined range to inside the predetermined range. Such a configuration can be realized, for example, by the same configuration as in Figures 1 to 3, but the ophthalmic apparatus 1 does not include the drive unit 30 shown in Figure 2. The control content by the control unit 10 is similar to the measurement process shown in Figure 9, but there are some differences.

[0062] Specifically, the control unit 10 executes the measurement process shown in Fig. 10. This measurement process is similar to the measurement process shown in Fig. 9, but there are some differences. In Fig. 10, the same processes as those in Fig. 9 are indicated by the same reference numerals. In the measurement process shown in Fig. 10, steps S101 to S115 are the same as those in Fig. 9. On the other hand, since the ophthalmologic apparatus 1 according to this embodiment does not have an auto-alignment function, step S120 is not executed.

[0063] Therefore, after the subject recognizes that the eye E is within the detectable range based on the visual target, the subject further moves his or her face to align the eye E with the measurement position. When it is determined in step S130 that the eye E matches the measurement position, the control unit 10 controls the display device 23c to switch the display content so that the visual target indicating that the eye E is at the measurement position is displayed (step S131).

[0064] As a result, the subject can recognize that the subject's eye E is aligned with the measurement position, and when it is aligned, the control unit 10 stops moving the face and holds the face at that position. In this state, the control unit 10 performs the measurement in step S135. Through the above process, the subject can recognize that the subject's eye E is within the detectable range and further recognize that the subject's eye E is at the measurement position. Note that in the measurement process shown in FIG. 10 , the shape, color, and size of each optotype are not limited as long as the optotypes displayed in steps S101, S115, and S135 are different.

[0065] Furthermore, in a configuration in which the control unit 10 serves as a switching unit, various methods can be used to switch the optotype. For example, when the subject's eye is located within a predetermined range, the switching unit may be configured to switch the display content of the optotype displayed on the display device depending on the relative position. Such a configuration can be realized by a configuration that does not have an auto-alignment function. For example, this configuration can be realized by omitting the drive unit 30 shown in FIG. 2 from a configuration similar to that shown in FIGS. 1 to 3.

[0066] Specifically, an embodiment can be envisioned in which the detectable range is narrower than the range in which the visual target is visible, and the detectable range coincides with the predetermined range. The relationship between these ranges can be, for example, as shown in FIG. 8A . With the above configuration, even in a situation in which the relative position of the subject's eye E cannot be detected, the subject's eye E can visually recognize the visual target. Therefore, even before detection of the relative position of the subject's eye E begins, the subject's eye E can be made to visually recognize the visual target, and assistance can be provided when moving the face.

[0067] Fig. 11 is a flowchart of the measurement process in this embodiment. This measurement process is similar to the measurement process shown in Fig. 10, but there are some differences. In Fig. 11, the same processes as in Fig. 10 are indicated by the same reference numerals as in Fig. 10. That is, the processes other than step S116 are similar to the measurement process shown in Fig. 10. In this embodiment as well, the control unit 10 starts the measurement process shown in Fig. 11 after power supply to the ophthalmologic apparatus 1 is started and a predetermined startup sequence is performed.

[0068] When the measurement process is started, the control unit 10 displays a visual target indicating that the subject's eye E is outside the detectable range in steps S101 to S110, and continues to display the visual target until the subject's eye E is within the detectable range. Fig. 8B shows an example of a visual target indicating that the subject's eye E is outside the detectable range. In this example, the image of a filled circle indicates that the subject's eye E is outside the detectable range.

[0069] If it is determined in step S110 that the subject's eye E is within the detectable range, the control unit 10 switches to a visual target for guiding the subject's eye E to the measurement position (step S116). That is, the control unit 10 controls the display device 23c to change the display content and display a visual target for guiding the subject's eye E to the measurement position. The visual target for guiding the subject's eye E to the measurement position may be, for example, a visual target that indicates the direction in which the face should move in order to align the subject's eye E with the measurement position when the subject's eye E is not present at the measurement position.

[0070] 8C to 8F show examples of visual targets for guiding the subject's eye E to the measurement position. Fig. 8C shows a visual target for moving the face downward, Fig. 8D shows a visual target for moving the face upward, Fig. 8E shows a visual target for moving the face rightward, and Fig. 8F shows a visual target for moving the face leftward.

[0071] The control unit 10 identifies the position of the bright spot in the image captured by the camera 22h of the relative position detection optical system 22, and then identifies the distance and direction from the position of the bright spot in the image to its ideal position. Furthermore, the control unit 10 identifies the distance and direction of movement of the face required to move the bright spot in the image toward its ideal position. The control unit 10 then identifies whether the distance and direction of movement correspond to the up, down, left, or right direction when considered as a vector of a predetermined magnitude. If the vector is not parallel to either the up, down, left, or right direction, the control unit 10 breaks it down into its up, down, and left, and right components and selects the larger component.

[0072] When the direction of facial movement is determined to be either up, down, left, or right, the control unit 10 controls the display device 23c to display a visual target for moving the face in the determined direction. With the above configuration, the subject can recognize the direction in which to move the face by viewing the visual target. When the subject moves their face and the subject's eye E coincides with the measurement position, the control unit 10 controls the display device 23c to switch the display content so that a visual target indicating that the subject's eye E is at the measurement position is displayed (step S131). FIG. 8G shows an example of a visual target indicating that the subject's eye E is at the measurement position. Through the above process, the subject can recognize that the subject's eye E coincides with the measurement position and can measure the subject's eye E. The subject can also recognize that the subject's eye E is within the detectable range and further recognize that the subject's eye E is at the measurement position. Note that the above-described visual target is merely an example. For example, the visual target may be changed depending on the distance the face needs to move to move the bright spot in the image toward the ideal position. For example, a longer arrow may be used as the movement distance increases.

[0073] Furthermore, assistance may be provided when moving the subject's eye E in the Z direction based on the visual target. For example, the ophthalmic apparatus 1 may be configured to switch the visual target when the subject's eye E changes from being outside the detectable range of its relative position in the Z direction to being within the detectable range. Furthermore, in an ophthalmic apparatus that does not have an auto-alignment function, a visual target may be displayed to guide the subject's eye E to the measurement position of the subject's eye E in the Z direction.

[0074] 8H and 8I are examples of optotypes that guide the eye E to a measurement position in the Z direction. For example, a configuration can be adopted in which the control unit 10 displays Fig. 8H, which is an optotype that guides the eye E to the back when the eye E is located in front of the measurement position, and displays Fig. 8I, which is an optotype that guides the eye E to the front when the eye E is located behind the measurement position. Note that here, in the Z direction, the direction in which the eye E approaches the ophthalmic apparatus 1 is defined as the back direction, and the direction in which the eye E moves away from the ophthalmic apparatus 1 is defined as the front direction.

[0075] The measurement optical system may measure the subject's eye based on reflected light output from the subject's eye in response to incident light input to the subject's eye. That is, when incident light is incident on the subject's eye, reflected light corresponding to the characteristics of the subject's eye is output from the subject's eye, and the characteristics of the measurement object related to the subject's eye may be measured based on the reflected light. The measurement optical system may measure any object, and is not limited to optical systems for performing the above-described OCT measurements. Examples of optical systems include optical systems for measuring at least one of intraocular pressure, ocular refractive index, axial length, ultrasound tomography, corneal endothelium image, slit image, anterior segment image, lens image, staining observation image, and meibomian gland image. The incident light may be light output from a light source provided in the optical system, light output from a light source present around the subject, natural light, etc.

[0076] The relative position detection optical system is only required to detect the relative position of the test eye, which is located within a predetermined detectable range, relative to the measurement optical system. That is, the relative position detection optical system is only required to detect the position of the test eye as seen from the measurement optical system. The relative position may be defined by various methods. For example, it can be said that the relative position has been detected if the relationship between the position where reflected light from the test eye is detected and a specific position of the sensor is identified.

[0077] The predetermined detectable range is a range within which the relative position of the subject's eye can be detected by the relative position detection optical system. Therefore, if the subject's eye is within the detectable range, its relative position is detected. However, if the subject's eye is outside the detectable range, its relative position is not detected. The detectable range may be defined three-dimensionally, two-dimensionally, or one-dimensionally. For example, the detectable range may be defined in each of the X, Y, and Z directions, or in each of the X and Y directions, or in the Z direction.

[0078] The visual target optical system may be any optical system that guides light output from the visual target to a predetermined visual target visibility range. In other words, the subject can visually recognize the visual target when the subject's eye is within the visual target visibility range. The visual target visibility range preferably includes at least the range in which the subject's eye to be measured is planned to be placed. Note that each optical system included in the ophthalmic device may share at least some components with other optical systems.

[0079] The switching unit may be configured to switch the optotype visually recognized by the subject's eye when the subject's eye moves from outside a predetermined range, which is at least a part of the detectable range, to inside the predetermined range. In other words, the switching unit may be configured to change the optotype that may be present in the visual field of the subject's eye when the subject's eye moves from outside to inside the predetermined range, so that the subject can recognize that the subject's eye is within the predetermined range.

[0080] The optotype may be switched between the outside and inside of a predetermined range. For example, a configuration in which the optotype is not visible outside the predetermined range but is visible inside the predetermined range is also included. The manner in which the optotype is switched is not limited. That is, it is sufficient that the state of the visual field as seen by the subject's eye changes, thereby allowing the subject to recognize a change in the position of the subject's eye. The switching unit may be configured with a physical structure such as an aperture, or may be configured with a display device capable of displaying the optotype and a control unit for the display device. The change in the optotype may be realized, for example, by changing at least one of the shape, color, and size of the optotype.

[0081] The predetermined range may be defined three-dimensionally, two-dimensionally, or one-dimensionally. For example, the predetermined range may be defined in each of the X direction, the Y direction, and the Z direction, or may be defined in each of the X direction and the Y direction, or may be defined in the Z direction.

[0082] The predetermined range may be any range that serves as a target for moving the subject's eye within the predetermined range, and is not limited to a configuration in which the predetermined range and the detectable range coincide with each other. For example, the predetermined range may be a range that includes a measurement position for measuring the subject's eye in the measurement optical system.

[0083] The aperture of the light output from the visual target or the aperture of the light for relative position detection may be any structure, control, etc. that limits light. Therefore, for example, it may be realized by an aperture member with a hole, by limiting light with an optical component such as a lens, or by limiting the detectable range of a sensor.

[0084] Furthermore, the technique of switching the optotype recognized by the eye to be examined when the eye to be examined moves from outside a predetermined range, which is at least a part of the detectable range, to inside the predetermined range can also be applied as a method invention. In addition, the above-mentioned ophthalmic apparatus and method can be realized as a standalone apparatus or as part of an apparatus having multiple functions, and include various aspects.

[0085] DESCRIPTION OF SYMBOLS 1... ophthalmic device, 10... control unit, 20... optical system, 21... measurement optical system, 21a... measurement unit, 21b... mirror, 22... relative position detection optical system, 22a, 22b... dichroic mirror, 22c... lens, 22d... half mirror, 22e... lens, 22f... light source, 22g... lens, 22h... camera, 22i... light source, 22j... sensor, 23... visual target optical system, 23a, 23b... lens, 23c... display device, 24... aperture, 24a... opening, 30... drive unit

Claims

1. An ophthalmic device comprising: a measurement optical system that measures the test eye based on reflected light output from the test eye in response to incident light input to the test eye; a relative position detection optical system that detects the relative position of the test eye, which is located within a predetermined detectable range, with respect to the measurement optical system; a visual target optical system that guides light output from a visual target into a predetermined visual target visible range; and a switching unit that switches the visual target that is visible to the test eye when the test eye moves from outside a predetermined range that is at least a part of the detectable range to inside the predetermined range.

2. The ophthalmic device according to claim 1, wherein the switching unit is an aperture for the light output from the visual target, and the aperture narrows the light output from the visual target so that the visual target visible range coincides with the predetermined range.

3. The ophthalmic apparatus according to claim 2, wherein the pupil of the subject's eye, which is placed at a measurement position for measuring the subject's eye by the measurement optical system, is conjugate with the diaphragm.

4. The ophthalmologic apparatus according to any one of claims 1 to 3, wherein the predetermined range and the detectable range coincide with each other.

5. The ophthalmic device according to claim 1, wherein the visual target optical system includes a display device that displays the visual target, and the switching unit switches the display content of the visual target displayed on the display device when the subject's eye moves from outside the specified range to inside the specified range.

6. The ophthalmologic apparatus according to claim 1, wherein the visual target optical system includes a display device that displays the visual target, and the switching unit switches the display content of the visual target displayed on the display device depending on the relative position when the subject's eye is within the specified range.

7. The ophthalmologic apparatus according to claim 6, wherein the visual target is an image for guiding the subject's eye to a measurement position where the subject's eye is measured by the measurement optical system.

Images