Ophthalmic devices

Abstract

The present invention provides an ophthalmic device, which comprises: a first optical system for projecting measuring light onto the fundus of an eye to be inspected, and obtaining the ocular refractive power of the eye to be inspected based on the fundus reflected light of the measuring light; a second optical system for obtaining anterior ocular segment information, which is information related to the shape of the anterior ocular segment and is related to a cutting surface on which the optical axis of the first optical system is arranged; and an operation control unit for obtaining the axial length of the eye to be inspected based on the ocular refractive power on the cutting surface, i.e., the planar ocular refractive power, and the anterior ocular segment information related to the cutting surface.

Description

Technical Field

[0001] The present disclosure relates to an ophthalmologic apparatus for obtaining the axial length of an eye to be inspected. Background Art

[0002] Ultrasonic and optical interferometry eye axial length measuring devices are used for prescribing intraocular lenses.

[0003] The ultrasonic axial length measuring device is a contact type, and performs measurement by bringing a probe into contact with the cornea.

[0004] Among optical interferometry-based axial length measurement devices, the TD method (time domain method) and the SS method (swept light source method) have become mainstream. The TD method uses a coherent light source, while the SS method uses a wavelength-swept light source (see Patent Documents 1 and 2).

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 2012-224621

[0008] Patent Document 2: Japanese Patent Application Publication No. 2019-063044 Summary of the Invention

[0009] Problems to be solved by the invention

[0010] In recent years, the prevalence of myopia, particularly among young people, has increased significantly in all countries. Myopia progresses with increasing axial length, increasing the risk of blindness and becoming a major social issue. Against this backdrop, the evaluation of myopia progression based on axial length has attracted attention. To appropriately monitor young people, it is hoped that axial length measurement devices will be widely used in a wider range of facilities, not just cataract treatment facilities (hospitals and schools, etc.).

[0011] However, ultrasonic axial length measurement devices are contact-based, limiting the number of examiners and placing a heavy burden on the examinee. Furthermore, optical interferometry-based axial length measurement devices are expensive, including the light source. Consequently, the cost of these devices may hinder their widespread adoption in healthcare facilities.

[0012] In view of this, the inventors of the present application have studied a new method for measuring the axial length of the eye and a device structure for realizing the new method.

[0013] The present disclosure has been made in view of the above circumstances, and a technical object thereof is to provide an ophthalmic device having a novel method for measuring axial length of an eye and a novel device structure.

[0014] Technical means to solve problems

[0015] The ophthalmic device of the first scheme of the present disclosure comprises: a first optical system for projecting measuring light onto the fundus of the eye to be inspected, and obtaining the ocular refractive power of the eye to be inspected based on the fundus reflected light of the measuring light; a second optical system for obtaining anterior ocular segment information, which is information related to the shape of the anterior ocular segment and is related to a cutting surface on which the optical axis of the first optical system is arranged; and an operation control unit, which obtains the axial length of the eye to be inspected based on the ocular refractive power on the cutting surface, i.e., the planar ocular refractive power, and the anterior ocular segment information related to the cutting surface.

[0016] The ophthalmic device of the second scheme of the present disclosure is based on the ophthalmic device of the first scheme, wherein the second optical system includes a cross-sectional shooting optical system for shooting a cross-sectional image of the cutting surface set at the anterior segment of the eye to be inspected, and the calculation control unit obtains the axial length of the eye to be inspected based on the surface eye refractive power and the anterior segment information based on the cross-sectional image.

[0017] An ophthalmologic apparatus according to a third aspect of the present disclosure is the ophthalmologic apparatus according to the second aspect, wherein the cross-sectional image capturing optical system captures a range from the corneal anterior surface to at least the crystalline lens anterior surface of the subject's eye.

[0018] The ophthalmic device of the fourth scheme of the present disclosure is based on the ophthalmic device of the second scheme, and further includes a third optical system, wherein the third optical system has an index projector that projects a pattern index for measuring the corneal shape from the front side facing the eye to be inspected toward the anterior eye, and captures a corneal Purkinje image of the pattern index, and the calculation control unit obtains the axial length based on the surface eye refractive power, the anterior eye information, and the corneal shape information based on the corneal Purkinje image.

[0019] The ophthalmic device of the fifth embodiment of the present disclosure is based on the ophthalmic device of the first embodiment, and the anterior ocular information is information that can determine at least two of the corneal thickness, the radius of curvature of the anterior corneal surface, the radius of curvature of the posterior corneal surface, the anterior chamber depth, the lens thickness, the radius of curvature of the anterior lens surface, and the radius of curvature of the posterior lens surface.

[0020] The ophthalmic device of the sixth embodiment of the present disclosure is based on the ophthalmic device of the first embodiment, wherein the calculation control unit further obtains refractive index information related to the refractive index of the translucent body in the eye to be inspected, and the calculation control unit further obtains the axial length of the eye to be inspected considering the refractive index of the translucent body based on the refractive index information.

[0021] The ophthalmic device of the seventh scheme of the present disclosure is based on the ophthalmic device of the first scheme, wherein the anterior ocular segment information includes information that can determine the shape of the anterior ocular segment in a measurement area, the measurement area is the area of the anterior ocular segment that is the measurement object of the eye refractive power of the first optical system, and the calculation control unit obtains the axial length based on the surface refractive power and the anterior ocular segment information in the measurement area.

[0022] An ophthalmologic apparatus according to an eighth aspect of the present disclosure is the ophthalmologic apparatus according to the first aspect, wherein the arithmetic control unit acquires the axial length in consideration of decentering of a light-transmitting body of the anterior segment that can be identified by the anterior segment information.

[0023] The ophthalmic device of the ninth scheme of the present disclosure is based on the ophthalmic device of the first scheme, wherein the operation control unit controls the first optical system and the second optical system to respectively obtain the eye refractive power and the anterior ocular segment information when the adjustments in the eyes are the same, and obtains the axial length of the eye to be inspected based on the eye refractive power and the anterior ocular segment information obtained when the adjustments in the eyes are the same.

[0024] The ophthalmic device of the tenth scheme of the present disclosure is based on the ophthalmic device of the ninth scheme, and has a fixation mark presenting optical system for presenting a fixation mark, and the operation control unit controls the acquisition timing of the eye refractive power and the anterior ocular segment information in a manner that makes the adjustment of the fixation mark to the eye to be inspected be the same as when the eye refractive power is obtained and when the anterior ocular segment information is obtained.

[0025] An ophthalmologic apparatus according to an eleventh aspect of the present disclosure is the ophthalmologic apparatus according to the ninth aspect, wherein the arithmetic control unit synchronizes the timing of acquiring the eye refractive power and the anterior ocular segment information.

[0026] The ophthalmic device of the twelfth scheme of the present disclosure is based on the ophthalmic device of the tenth scheme, wherein the fixation mark presenting optical system is capable of changing the presentation distance of the fixation mark, and the operation control unit adds fog to the eye to be inspected by controlling the fixation mark presenting optical system, and obtains the eye refractive power and the anterior eye information respectively when the eye to be inspected is in a foggy state.

[0027] The ophthalmic device of the thirteenth embodiment of the present disclosure is based on the ophthalmic device of the ninth embodiment, wherein the first optical system irradiates infrared light as the measuring light, and the second optical system comprises: an irradiating optical system for irradiating the anterior ocular segment with slit light; and a light-receiving optical system having a lens system and a photographing element arranged in a Scheimpflug relationship relative to a cutting surface set on the anterior ocular segment by the slit light, and the second optical system obtains a cross-sectional image of the anterior ocular segment based on a signal from the photographing element.

[0028] The ophthalmic device according to the fourteenth aspect of the present disclosure is the ophthalmic device according to the thirteenth aspect, wherein the second optical system irradiates visible light as the slit light, the calculation control unit executes the eye refractive power acquisition operation, and acquires the anterior ocular segment information at the timing when the acquisition operation is completed.

[0029] An ophthalmologic apparatus according to a fifteenth aspect of the present disclosure is the ophthalmologic apparatus according to the thirteenth aspect, wherein a projection optical axis of the measurement light in the first optical system and a projection optical axis of the illumination light in the second optical system are coaxially arranged.

[0030] An ophthalmologic apparatus according to a sixteenth aspect of the present disclosure is the ophthalmologic apparatus according to the fourth aspect, wherein the index projector is arranged so as to avoid the light receiving optical axis in the second optical system.

[0031] An ophthalmologic apparatus according to a seventeenth aspect of the present disclosure is the ophthalmologic apparatus according to the sixteenth aspect, wherein the index projector projects the pattern index composed of a plurality of point images. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is an external view showing a schematic configuration of an ophthalmologic apparatus according to an embodiment.

[0033] Figure 2 This is a schematic diagram of the optical system of an ophthalmic device.

[0034] Figure 3 3 is a diagram showing a cross-sectional image of the anterior ocular segment captured by the cross-sectional capturing optical system.

[0035] Figure 4A This is a diagram showing the measurement unit as viewed from the side, and is a diagram for explaining the positional relationship between the index projector and the optical axis of the cross-sectional imaging optical system.

[0036] Figure 4B It is a perspective view of the measuring unit and is a diagram for explaining the positional relationship between the index projector and the optical axis of the cross-sectional imaging optical system.

[0037] Figure 5 This is a flowchart for explaining the operation of the device.

[0038] Figure 6 This is a schematic diagram used to illustrate the method of deriving the axial length of the eye based on ray tracing.

[0039] Figure 7 It is a diagram showing the diopter in each meridian direction when SPH=-5D, CYL=-2D, and AXIS=30°. DETAILED DESCRIPTION

[0040] "summary"

[0041] The following describes the embodiments of the present disclosure. The items categorized by <> below can be used independently or in conjunction with each other. For example, in a certain embodiment, multiple items can be appropriately combined. In addition, for example, items described in relation to a certain embodiment can be applied to other embodiments.

[0042] "First Implementation Method"

[0043] First, an ophthalmologic apparatus and an axial length calculation program according to a first embodiment are described. In the first embodiment, the ophthalmologic apparatus and the axial length calculation program obtain the axial length of the subject's eye based on the refractive power of the subject's eye obtained via a first optical system and anterior ocular segment information obtained via a second optical system.

[0044] <Device Structure>

[0045] The ophthalmologic apparatus of the first embodiment includes at least a first optical system, a second optical system, and a calculation control unit. The calculation control unit is the ocular axial length acquisition unit and the control unit in the embodiment. The ophthalmologic apparatus may additionally include a fixation mark presentation optical system.

[0046] For convenience, unless otherwise specified, the following description of the embodiment assumes that the axial length calculation program is executed in an ophthalmologic apparatus (an example of an ophthalmologic computer).

[0047] <First Optical System>

[0048] The first optical system is used to obtain the refractive power of the subject's eye. The first optical system projects measurement light onto the fundus of the subject's eye. The refractive power is obtained based on light reflected from the fundus of the eye. The first optical system can be, for example, the measurement optical system of an opthalmological refractive power measurement device such as an autorefractometer or a wavefront sensor.

[0049] In this embodiment, the measurement light from the first optical system is infrared light, but the present invention is not necessarily limited to this and may be visible light.

[0050] <Second Optical System>

[0051] The second optical system is used to obtain anterior segment information, which is information related to the shape of the anterior segment.

[0052] In the first embodiment, the anterior ocular segment information related to the cut surface can be acquired via the second optical system. In this case, the optical axis of the first optical system is arranged on the surface of the cut surface.

[0053] The second optical system can be a cross-sectional imaging optical system such as a Scheimpflug optical system, or another optical system. When a Scheimpflug optical system is used as the second optical system, the projection axis of the illumination light in the second optical system and the projection axis of the measurement light in the first optical system need to be coaxial.

[0054] <Example of anterior ocular information>

[0055] The anterior ocular information may include information on the shape of the translucent body in the anterior ocular segment. The anterior ocular information may be an image of the anterior ocular segment. Based on the anterior ocular information, the shape of the translucent body in the anterior ocular segment can be determined. For example, preferably, two or more of the following values can be determined based on the anterior ocular information: corneal thickness, anterior corneal curvature radius, posterior corneal curvature radius, anterior chamber depth, lens thickness, anterior lens curvature radius, and posterior lens curvature radius. Of course, these values for determining the shape of the translucent body may themselves be the anterior ocular information.

[0056] The anterior ocular segment information obtained by the second optical system may include at least information on the shape of the lens. Alternatively, the shape of the measurement area of the first optical system may be determined using the anterior ocular segment information obtained by the second optical system. The measurement area is the area of the eye whose refractive power is measured by the first optical system.

[0057] <Fixation Mark Presentation Optical System>

[0058] The ophthalmologic apparatus may include a fixation target presenting optical system. The fixation target presenting optical system is an optical system for presenting a fixation target to the subject's eye and can be used when the first optical system and the second optical system are in operation.

[0059] The fixation target presentation optical system in this embodiment may be capable of changing the presentation distance of the fixation target. Such a fixation target presentation optical system can be used to add clouding to the subject's eye when measuring refractive power using the first optical system. Furthermore, the first optical system can also be used to apply accommodation to the eye.

[0060] <Axial Length Derivation Method (Axial Length Calculation Program)>

[0061] In the first embodiment, the calculation control unit acquires the axial length of the eye to be inspected based on the eye refractive power and the anterior ocular segment information.

[0062] The eye refractive power and anterior ocular segment information can be obtained by measurement or imaging. Alternatively, the eye refractive power and anterior ocular segment information measured or imaged by a separate device can be stored in a memory.

[0063] In this case, the axial length can also be obtained based on the ocular refractive power at the cutting surface, i.e., the planar ocular refractive power, and information about the anterior ocular segment related to the cutting surface. By using the information used to determine the ocular refractive power and the shape of the anterior ocular segment related to the same cutting surface, it is easier to accurately derive the axial length. It should be noted that in this case, by using information determining the shape of the measurement area of the first optical system as information about the anterior ocular segment related to the cutting surface, the axial length can be more accurately determined.

[0064] Here, for example, the calculation control unit can derive the axial length of the eye through ray tracing calculation. In the ray tracing calculation, the position of the far point can be determined based on the surface eye refractive power.

[0065] In the ray tracing operation, the distance between the intersection point of the light rays incident from the far point to the specified position of the anterior eye and the corneal vertex when they intersect on the optical axis after being refracted by the translucent body is derived as the axial length of the eye. At this time, instead of using the equivalent spherical power generally used in the field of ophthalmology to determine the far point, the eye refractive power on the cutting surface (surface refractive power) can be used. As a result, the position of the far point in the light rays on the cutting surface is more appropriately determined. As a result, the axial length of the eye can be more appropriately calculated. At this time, a ray tracing operation can also be performed on each of the multiple light rays, and the axial length of the eye can be calculated as the result of the ray tracing operation of each light ray. For example, the average value (which can also be a weighted average) of the axial lengths obtained by each ray tracing operation can be calculated as the axial length of the eye to be examined.

[0066] It should be noted that in the ray tracing calculation, the incident position of the light rays relative to the boundary surfaces of each translucent body and the angular variation at the boundary surfaces are determined by taking into account the shape of the translucent body on the cut surface determined based on the anterior ocular information. A more detailed description of the ray tracing method will be provided in the examples described later.

[0067] Furthermore, when deriving the axial length based on the ocular refractive power and anterior ocular segment information associated with the same cut surface, the calculation control unit may also consider the decentration of the translucent body in the anterior ocular segment. The decentration is determined based on the anterior ocular segment information. By considering the decentration of the translucent body within the cut surface, the axial length can be more appropriately determined. In this case, for example, a ray tracing operation may be performed on each of a plurality of light rays, including at least a first light ray and a second light ray, to determine the axial length for each ray, and the final measured value may be determined based on the plurality of axial lengths. The first light ray and the second light ray are arranged on the cut surface so as to sandwich the axial length of the eye.

[0068] <Specific Example of the Second Optical System: Cross-Sectional Photography Optical System>

[0069] In the first embodiment, the second optical system may be a cross-sectional shooting optical system that shoots a cross-sectional image of a cutting surface set in the anterior part of the eye to be inspected. The cross-sectional shooting optical system may be, for example, a Scheimpflug optical system or an OCT optical system. Based on the cross-sectional image, not only the shape of the boundary surface (surface) in each translucent body but also the distance between the boundary surfaces can be determined. As a result, the axial length of the eye can be determined with higher accuracy. In the case where the second optical system is a cross-sectional shooting optical system, the shooting range of the cross-sectional shooting optical system preferably includes the area from the anterior surface of the cornea of the eye to be inspected to at least the anterior surface of the lens. Needless to say, it is further preferred if the shooting range includes the area from the anterior surface of the cornea to the posterior surface of the lens. Since the corneal thickness, the radius of curvature of the anterior surface of the cornea, the radius of curvature of the posterior surface of the cornea, the anterior chamber depth, the lens thickness, the radius of curvature of the anterior surface of the lens and the radius of curvature of the posterior surface of the lens can be obtained without omission, the axial length of the eye can be obtained more appropriately.

[0070] It should be noted that when the second optical system is a Scheimpflug optical system, the projection axis of the illumination light must be coaxial with the projection axis of the measurement light in the first optical system. Furthermore, the projection optical system of the Scheimpflug optical system can irradiate slit light as the illumination light. The slit light irradiation area is set to the cutting surface. Furthermore, the light receiving optical system of the Scheimpflug optical system includes a lens system and an imaging element arranged in a Scheimpflug relationship with the cutting surface. The light receiving optical system is configured with a light receiving axis that is inclined relative to the cutting surface.

[0071] The slit light can be either visible light or infrared light. Visible light is more likely to be scattered by a translucent body than infrared light. On the other hand, infrared light can reduce the burden on the subject during imaging.

[0072] Furthermore, when the second optical system is an OCT optical system, it is also possible to capture not only anterior segment OCT but also fundus OCT. In this case, the anterior segment OCT and fundus OCT do not need to be captured simultaneously, and the anterior segment OCT and fundus OCT can be captured separately by switching a portion of the OCT optical system.

[0073] <Specific Example of the Second Optical System: Purkinje Image Acquisition Optical System>

[0074] Alternatively, a Purkinje image acquisition optical system may be used as the second optical system instead of the cross-sectional shooting optical system. The Purkinje image acquisition optical system includes an index projector that projects a measurement index (called a pattern index) based on a certain pattern from the front side facing the eye to be examined toward the anterior eye, and a front shooting optical system that captures a Purkinje image based on the pattern index. At this time, a first Purkinje image (a reflected image of the anterior surface of the cornea), a second Purkinje image (a reflected image of the posterior surface of the cornea), a third Purkinje image (a reflected image of the anterior surface of the lens), and a fourth Purkinje image (a reflected image of the posterior surface of the lens) may be generated respectively. Based on the position information of each Purkinje image, the shape of the boundary surface corresponding to each Purkinje image may be considered. However, the corneal thickness, anterior chamber depth, and lens thickness, etc. cannot be obtained based solely on the position information of the Purkinje image. In other words, the distance between the boundary surfaces of the translucent body cannot be obtained. In contrast, the cross-sectional shooting optical system is more advantageous in obtaining the distance between the boundary surfaces. Furthermore, the third Purkinje image (a reflected image of the anterior lens surface) is generated closer to the optical axis of the frontal imaging optical system than the first, second, and fourth Purkinje images. Therefore, differences in the shape of the anterior lens surface are less likely to appear as differences in the appearance position of the third Purkinje image. Therefore, a cross-sectional imaging optical system whose imaging range extends from the anterior corneal surface of the subject's eye to at least the anterior lens surface is more advantageous in acquiring information on the shape of the anterior lens surface with higher accuracy than a Purkinje image acquisition optical system.

[0075] It should be noted that the pattern indicator projected from the indicator projector can be a ring-shaped pattern or other two-dimensional pattern formed by lines or multiple points. For example, multiple point indicators arranged on a circumference can be projected as pattern indicators. In addition, multiple patterns can also be combined.

[0076] <Measurement Control>

[0077] To accurately determine the axial length using the above method, it is preferable to include shape information for a wider range of translucent bodies in the anterior ocular segment information. In this case, at least the shape information for the lens can be included in the anterior ocular segment information. In this case, the refractive power measured by the first optical system and the shape information for the lens included in the anterior ocular segment information are both inevitably affected by intraocular accommodation. Therefore, to ensure the accuracy and reproducibility of the axial length, it is necessary to separately obtain the refractive power and anterior ocular segment information, taking into account the state of intraocular accommodation.

[0078] On the other hand, in this embodiment, the calculation control unit may control the first optical system and the second optical system so as to respectively obtain the eye refractive power and the anterior ocular segment information in a state where the intraocular accommodation is the same.

[0079] If the eye refractive power and the anterior ocular segment information are acquired in a state where the intraocular accommodation is the same, the acquired information is equally affected by the accommodation, and thus the axial length of the eye can be appropriately determined.

[0080] In this case, the calculation control unit may control the timing of acquiring the eye's refractive power and the anterior ocular segment information in the same manner as the adjustment provided to the subject's eye by the fixation mark between acquiring the eye's refractive power and acquiring the anterior ocular segment information. Alternatively, the acquisition timing may be controlled in conjunction with control of changing the presentation distance of the fixation mark.

[0081] For example, the acquisition timings may be controlled so that the presentation positions of the fixation marks are the same between when acquiring the eye refractive power and when acquiring the anterior ocular segment information.

[0082] Furthermore, for example, the calculation control unit may synchronize the timing of acquiring the eye's refractive power and the anterior ocular segment information. Synchronization does not necessarily require that the acquisition timings be exactly the same. For example, there may be a time difference between the acquisition timings that does not significantly affect the accommodation state.

[0083] Alternatively, the calculation and control unit can control the fixation mark presentation optical system to cloud the subject's eye, thereby obtaining the refractive power and anterior ocular segment information when the subject's eye is in a non-accommodated state. Determining the axial length based on the refractive power and anterior ocular segment information obtained in the non-accommodated state further improves the accuracy and reproducibility of the axial length compared to determining the axial length based on the refractive power and anterior ocular segment information measured in the accommodated state.

[0084] Incidentally, as previously mentioned, the second optical system used to acquire information about the anterior ocular segment may be a Scheimpflug optical system. In this case, visible light is used as illumination light to illuminate the anterior ocular segment, capturing a cross-sectional image of the anterior ocular segment. Meanwhile, infrared light is used as measurement light for measuring ocular refractive power.

[0085] When a cross-sectional image is captured by a Scheimpflug optical system, relatively strong visible light is irradiated as imaging light. In this case, the strong visible light irradiation may startle the subject, resulting in a change in alignment.

[0086] In contrast, the calculation control unit may first execute the eye refractive power acquisition operation, and then execute the anterior ocular information acquisition operation at the timing of the completion of the acquisition operation. In this way, the alignment deviation between the acquisition of the eye refractive power and the acquisition of the anterior ocular information, i.e., the cross-sectional image, is suppressed. In addition, in this case, the execution order of each operation may also be cloud fog. Achieving eye refractive power The order of acquiring anterior ocular segment information. Furthermore, as previously described, the completion timing of acquiring the eye's refractive power and the execution timing of acquiring the anterior ocular segment information are substantially simultaneous. This reduces the likelihood of discrepancies between the acquisition of the eye's refractive power and the acquisition of the anterior ocular segment information, i.e., the cross-sectional images, for each of the accommodation and alignment states. Consequently, the accuracy and reproducibility of axial length measurements are improved.

[0087] As described above, in the ophthalmologic apparatus of the first embodiment, the axial length of the eye is measured by a novel method and a novel apparatus configuration that are different from those of conventional axial length measuring apparatuses.

[0088] Here, the first optical system can obtain the refractive power of the subject's eye, which is important in evaluating myopia. The ophthalmologic apparatus of the first embodiment can obtain information such as the refractive power and the axial length of the eye, which are important in evaluating myopia, with a single apparatus.

[0089] In particular, when the Scheimpflug optical system is used as the second optical system in the first embodiment, it is easy to sufficiently suppress the device cost compared to the optical interference type axial length measurement device and meet the axial length measurement accuracy required for monitoring the progression of myopia.

[0090] <Obtaining Axial Length Based on Multiple Cutting Planes>

[0091] In the above description, the axial length is calculated using the anterior ocular segment information associated with a single cutting plane. However, this is not necessarily limited to this. Multiple pieces of anterior ocular segment information may be obtained for each of multiple cutting planes. In this case, the axial length may be derived using the above method for each cutting plane. For example, the average of the axial lengths obtained for each cutting plane may be calculated.

[0092] Note that, as a method of imaging a plurality of cut surfaces in a Scheimpflug optical system, there is a known method of imaging by rotating a light-receiving optical system around a light-projecting optical axis, and this method may also be used.

[0093] "Second Implementation Method"

[0094] Next, a second embodiment will be described.

[0095] The ophthalmologic apparatus of the second embodiment further includes a third optical system in addition to the apparatus configuration of the first embodiment. That is, the ophthalmologic apparatus of the second embodiment includes a first optical system, a second optical system, a third optical system, and a calculation control unit.

[0096] Regarding the configurations common to the first embodiment, the description of the first embodiment will be appropriately cited and details will be omitted. However, in the second embodiment, the second optical system is an anterior segment cross-sectional imaging optical system, and unless otherwise specified, it will be described as a Scheimpflug optical system.

[0097] In the second embodiment, the third optical system includes an index projector that projects a pattern index for measuring corneal shape from the frontal surface facing the eye to be examined toward the anterior segment of the eye. Alternatively, the third optical system may include a frontal imaging optical system that captures a corneal Purkinje image of the pattern index. The corneal Purkinje image may also be captured as a frontal image of the anterior segment of the eye.

[0098] In the second embodiment, the calculation control unit may acquire the axial length of the eye based on the eye refractive power and anterior ocular segment information related to the cut surface and the corneal shape information based on the corneal Purkinje image.

[0099] Here, corneal shape information, which includes at least the radius of curvature of the anterior corneal surface, can be derived with higher accuracy from a corneal-Purkinje image than from an anterior ocular segment cross-sectional image captured by a Scheimpflug optical system. Therefore, for example, in axial length calculations, a portion of the anterior ocular segment information related to the cornea can be replaced with corneal shape information derived from the corneal-Purkinje image. Furthermore, a portion or all of the anterior ocular segment information can be corrected based on the corneal shape information. As a specific example of correction, the entire anterior ocular segment cross-sectional image can be deformed so that the corneal shape in the anterior ocular segment cross-sectional image matches the corneal shape based on the corneal-Purkinje image, and the shapes of the translucent bodies based on the deformed image can then be used in axial length calculations.

[0100] By taking into account the corneal shape information derived from the corneal Purkinje image in the calculation of the axial length in this manner, the axial length can be determined more appropriately.

[0101] In the Scheimpflug optical system, or the second optical system, the smaller the inclination of the optical axis relative to the cutting plane (object plane), the easier it is to expand the imaging range in the depth direction. In other words, the smaller the inclination of the second optical system's light-receiving optical axis (photographing optical axis) relative to the cutting plane (object plane), the more advantageous it is for the second optical system to capture images from the anterior surface of the cornea to the posterior surface of the lens. However, if the light-receiving optical axis is tilted to the extent that it can capture images from the anterior surface of the cornea to the posterior surface of the lens, there is a risk of spatial interference between the light-receiving optical system of the second optical system and the index projector of the third optical system.

[0102] In general, in corneal measurement, which is one of the methods for measuring corneal shape, the In most cases, one or more circumferential areas within the range of are used as the measurement area. At this time, the light beam forming the pattern index is oriented at an angle of 14° (equivalent to )~29°(equivalent to )'s range of angular projection.

[0103] On the other hand, when the second optical system, namely the Scheimpflug optical system, is to be used to shoot from the anterior surface of the cornea to the posterior surface of the lens, it is preferable to make the angle between the light-receiving optical axis of the second optical system and the cutting surface smaller. Conventional Scheimpflug cameras for ophthalmology were mainly used in analytical devices for the anterior ocular segment, where less deformation and higher resolution were prioritized, and therefore the aforementioned angle was approximately 45° or larger. In contrast, the aforementioned angle in the Scheimpflug optical system of this embodiment is preferably approximately 40° or smaller, prioritizing the ability to shoot deeper. Therefore, the exit positions of each light beam in the index projector and the light-receiving optical axis of the second optical system can be arranged on approximately the same circumference relative to the visual axis. If the size of the optical elements of each part is taken into consideration on this basis, the aforementioned interference problem may arise.

[0104] In contrast, in the second embodiment, the index projector of the third optical system is arranged so as to avoid the light-receiving optical axis of the second optical system. More specifically, the index projector of the third optical system can also be arranged so as to avoid the normal direction of the cut surface of the anterior ocular segment formed by the second optical system (at least the direction in which the light-receiving optical system of the second optical system is placed). For example, if the normal direction is vertical, the index projector of the third optical system can also be arranged so as to avoid a position that is in the ±90° direction relative to the optical axis of the third optical system (with the horizontal direction being 0°).

[0105] The pattern indicator projected from the indicator projector is formed at a position that is not within the ±90° direction relative to the optical axis of the third optical system (with the horizontal direction set to 0°). The pattern indicator can have a symmetrical shape with respect to the optical axis of the third optical system. For example, it can be a two-dimensional pattern formed by lines or multiple points. For example, multiple point indicators arranged on a circumference can be projected as pattern indicators. In addition, multiple patterns can also be combined.

[0106] "Example"

[0107] Next, refer to Figures 1 to 7 An example corresponding to the first and second embodiments will be described.

[0108] <Overall Structure of the Embodiment>

[0109] First, refer to Figure 1 , showing a schematic structure of the ophthalmologic apparatus 10 of the embodiment.

[0110] In this embodiment, the ophthalmic device 10 is a combination device comprising a heterotopia-type refractive power measuring device (particularly, an autorefractometer in this embodiment) and a Scheimpflug camera. In this embodiment, the ophthalmic device 10 is a stationary examination device, but is not limited to this and may also be a handheld device.

[0111] like Figure 1 As shown, the ophthalmologic apparatus 10 includes at least a measurement unit 11 , a base 12 , an alignment drive unit 13 , a face support unit 15 , a monitor 16 , and a control unit 50 .

[0112] The measuring unit 11 is provided with a measuring system and an imaging system used in the examination of the subject's eye. Figure 2 The optical system shown.

[0113] The alignment driving unit 13 may be capable of moving the measurement unit 11 three-dimensionally relative to the base 12 .

[0114] The face support unit 102 is used to fix the face of the subject on the front side of the measurement unit 11. The face support unit 102 is fixed to the base 12 and supports the face of the subject.

[0115] The calculation control unit (also referred to as a processor, hereinafter simply referred to as a control unit) 50 manages the overall control of the ophthalmologic apparatus 10 and processes various test results acquired via the measurement unit 11 .

[0116] <Optical System>

[0117] Next, refer to Figure 2 The optical system in the ophthalmologic apparatus 10 will be described.

[0118] As an example, the ophthalmologic apparatus 10 includes a measurement optical system 100, a fixation mark presenting optical system 150, a frontal imaging optical system 200, cross-sectional imaging optical systems 300a and 300b, and an index projection optical system 400. Furthermore, it includes beam splitters 501, 502, and 503 for branching and combining optical paths of the respective optical systems.

[0119] <Measurement Optical System>

[0120] The measuring optical system 100 objectively measures the refractive power of the subject's eye E. For example, the values of SPH (spherical power), CYL (cylindrical power), and AXIS (axis angle of astigmatism) can be obtained as the measurement results of the refractive power.

[0121] The measuring optical system 100 includes a projection optical system 100 a and a light receiving optical system 100 b .

[0122] The projection optical system 100a includes at least a measurement light source 111, which projects a point-shaped measurement light onto the fundus of the eye E through the center of the pupil P or the corneal apex of the eye E. In this embodiment, infrared light is used as the measurement light. However, this is not necessarily limited to this, and the measurement light may also be visible light. The measurement light source 111 may be an SLD light source, an LED light source, or another light source.

[0123] In this embodiment, a prism 115 is arranged on the common path of the projection optical system 100a and the light receiving optical system 100b. As the prism 115 rotates around the optical axis L1, the projection light beam on the pupil rotates eccentrically at high speed. As an example, in this embodiment, the projection light beam on the pupil rotates eccentrically at high speed. The projection beam rotates eccentrically in the area of ​​the eye. This area becomes the measurement area of the eye's refractive power in this embodiment.

[0124] The light receiving optical system 100b includes at least an annular lens 124 and an imaging element 125. Figure 2 As shown, the measurement optical system 100 may also include optical elements such as lenses and apertures. The light-receiving optical system 100b extracts the reflected measurement beam from the fundus in a ring shape through the periphery of the pupil. The annular lens 124 is positioned at a conjugate position with the pupil, and the imaging element 125 is positioned at a conjugate position with the fundus. The annular image formed on the imaging element 125 by the annular lens 124 is analyzed to derive the refractive power of the eye.

[0125] As previously described, in this embodiment, since the measurement light rotates eccentrically at high speed on the pupil, analysis processing is performed on the output image from the imaging element 125, or the summed image of image data sequentially output from the imaging element 125, based on exposures sufficiently long relative to the rotation period, to derive the eye's refractive power. In this embodiment, at least the values of SPH (spherical power), CYL (cylinder power), and AXIS (axis angle of astigmatism) are obtained as the results of the analysis processing.

[0126] <Fixation Mark Presentation Optical System>

[0127] The fixation mark presenting optical system 300 presents a fixation mark to the eye E to be inspected. The fixation mark is presented on the optical axis of the measuring optical system 100. The fixation mark presenting optical system 300 is used to make the eye to be inspected fixate. In addition, it is used to provide fog and adjustment load to the eye to be inspected. For example, the fixation mark presenting optical system 300 has at least a light source 151 and a fixation mark plate 155. The fixation mark plate 155 can be moved along the optical axis by the driving unit 155a. Thereby, the presentation distance (presentation position) of the fixation mark relative to the eye E to be inspected can be changed.

[0128] <Front-facing optical system>

[0129] The frontal imaging optical system 200 captures a frontal image of the anterior segment of the subject's eye E. For example, the frontal imaging optical system 200 includes an imaging element 205, etc. As a frontal image, an observation image of the anterior segment can be obtained. The observation image is used for alignment, etc. Furthermore, the frontal imaging optical system 200 captures an index image (pattern index image) of a pattern index projected from the index projection optical system 400 onto the cornea of the subject's eye.

[0130] <Cross-Section Photography Optical System>

[0131] The cross-sectional imaging optical systems 300a and 300b are used to capture cross-sectional images of the anterior ocular segment. Each of the cross-sectional imaging optical systems 300a and 300b includes an illuminating optical system 300a and a receiving optical system 300b. The illuminating optical system 300a irradiates the anterior ocular segment with slit light coaxially with the projection optical axis (optical axis L1) of the measurement light from the measurement optical system 100. The illuminating optical system 300a includes a light source 311 and a slit 312. In this embodiment, the slit light serving as illumination is visible light. For example, a visible light source emitting blue light can be used as the light source 311.

[0132] In this embodiment, the cross section of the slit light in the anterior ocular segment is referred to as a "cutting plane." The cutting plane becomes the object plane of the cross-sectional imaging optical systems 300a and 300b. Figure 2 In the embodiment, the opening of the slit 312 is horizontal ( Figure 2 Thus, in this embodiment, the horizontal plane (XZ cross section) containing the optical axis L1 is set as the cutting surface. In this embodiment, the cutting surface is formed at least from the anterior surface of the cornea to the posterior surface of the lens.

[0133] The light receiving optical system 300b includes a lens system 322 and an imaging element 321. In the light receiving optical system 300, the lens system 322 and the imaging element 321 are arranged in a Scheimpflug relationship with the cutting surface set in the anterior ocular segment. That is, the cutting surface, the principal plane of the lens system 322, and the extensions of the imaging surface of the imaging element 321 form an optical configuration intersecting with a single intersection line (single axis). A cross-sectional image of the anterior ocular segment is obtained based on the signal from the imaging element 321 (see Figure 3 ).

[0134] <Indicator projection optical system>

[0135] In this embodiment, the index projection optical system 400 has a plurality of point light sources 401. In this embodiment, each point light source 401 emits infrared light. However, it can also be visible light. Figure 4A 、 Figure 4BAs shown, in this embodiment, the index projection optical system 400 is arranged as an index projector 410 on the front surface of the measuring unit 11. The index projection optical system 400 projects the pattern index for measuring the corneal shape from the front side facing the eye to be inspected toward the front eye. In this embodiment, the cornea is projected by pattern indexes based on point images of 4 points symmetrical with respect to the optical axis L1. The circumferential area of the projected pattern index is the measurement area of the corneal shape of the index projection optical system 400 and the front shooting optical system 200. As an example, in this embodiment, when a corneal model eye with a specified radius of curvature is placed at a position with a specified working distance, the corneal model eye The circumferential area is projected to form the individual point images of the pattern indicator. It should be noted that in this embodiment, the pattern indicator is configured to be composed of four point images, but the number of indicators is not necessarily limited to this. The pattern indicator can also be composed of multiple point images of three or more points, and can also include linear indicator images, etc.

[0136] Incidentally, in this embodiment, the light receiving optical axis L2 in the cross-sectional imaging optical system 300 is arranged directly below the optical axis L1 (in the -90° direction). In order to achieve an imaging range from the anterior surface of the cornea to the posterior surface of the lens, the inclination of the light receiving optical axis (photographing optical axis) of the second optical system relative to the cutting surface is sufficiently small. As a result, when the device is viewed from the side, the light of the pattern index projected from the index projection optical system 400 and the light receiving optical axis L2 are placed in a close positional relationship (refer to FIG. Figure 4A ).

[0137] Here, in Figure 4B In the figure, an indicator projector 450, virtually located (not actually located) on the measurement unit 13, is shown with a dotted line. The indicator projector 450 projects a Mayer ring onto the same circumferential area as the indicator projector 400. If the light from the pattern indicator and the light receiving axis L2 are in close proximity, projecting a pattern indicator such as a Mayer ring onto the ring will result in interference between the light receiving axis L2 and the indicator projector 450.

[0138] In contrast, the indicator projector 410 is arranged so as to avoid the lower side of the optical axis L1. Figure 4B In the example, a light source 401 and a reflector 402 for angle adjustment are respectively arranged at the upper right, lower right, upper left and lower left of the optical axis L1 (in Figure 2 (not shown in the figure). In this embodiment, a pattern index based on four point images symmetrically positioned about the optical axis L1 is projected onto the cornea. This configuration of the index projector 410 in this embodiment allows for both wide-range imaging with the cross-sectional imaging optical system 300 and acquisition of the corneal shape using the Purkinje image.

[0139] <Alignment Index Projection Optical System>

[0140] The ophthalmic device 10 also includes an alignment light source 600. One alignment light source 600 can be provided on each side. For example, a light beam is projected along a horizontal plane containing the optical axis L1. In this embodiment, the index projection optical system 400 and the light source 600 form an alignment index projection optical system. Diffuse light is projected from one of the index projection optical system 400 and the light source 600, while parallel light is projected from the other. Working distance adjustment can be performed by moving the system in the front-to-back direction so that a corneal Purkinje image based on parallel light and a Purkinje image based on diffuse light are captured at a predetermined ratio.

[0141] <Control Action>

[0142] Next, refer to Figure 5 The control operation of the ophthalmologic apparatus 10 will be described with reference to the flowchart of FIG.

[0143] In this embodiment, it is explained that “the ophthalmologic apparatus 10 sequentially performs corneal curvature measurement, captures an anterior ocular segment cross-sectional image, and eye refractive power measurement, and acquires the axial length of the eye based on the measurement and capture results.”

[0144] First, the measurement unit 11 is aligned with the subject's eye E (S1). The examiner instructs the subject to place their face on the face support unit 15. Then, presentation of a fixation target and acquisition of anterior ocular segment observation images are started.

[0145] Thereafter, for example, based at least on the observation image of the anterior ocular segment obtained via the front-facing imaging optical system 200, the subject's eye and the device are adjusted to a predetermined positional relationship. More specifically, alignment with respect to the XY directions is performed so that the optical axis L1 coincides with the corneal vertex of the subject's eye E. Furthermore, alignment with respect to the Z direction is performed so that the distance between the subject's eye and the device is a predetermined working distance. At this point, an alignment index (not shown) may be projected onto the cornea, and alignment may be adjusted based on the alignment index detected in the observation image.

[0146] Next, the corneal shape is measured (S2). A pattern index is projected from the index projector 410 (index projection optical system 400), and a corneal Purkinje image of the pattern index is captured by the front imaging optical system 200. Corneal shape information is acquired based on the corneal Purkinje image. Corneal shape information is derived based on the image height of the corneal Purkinje image. In this embodiment, at least the values of corneal curvature, astigmatism, and astigmatism axis angle are acquired as corneal shape information.

[0147] Next, in this embodiment, the eye refractive power is measured (S3). For example, a preliminary measurement may be performed first, followed by a main measurement.

[0148] During the preliminary measurement, the refractive power of the subject's eye E is measured with the fixation target positioned at a predetermined presentation distance. During the measurement, the fixation target plate 155 can be positioned at an initial position that is optically sufficiently far from the subject's eye E and corresponds to the far point of an 0D eye. The annular image captured by the imaging element 125 based on the measurement light irradiated in this state is analyzed by the calculation control unit 50. As a result of the analysis, the refractive power values in each meridian direction are determined. By performing predetermined processing on the refractive power in each meridian direction, at least the spherical power used in the preliminary measurement is obtained.

[0149] Next, the control unit 50 moves the fixation target plate 155 to the clouding start position, where the subject's eye E is in focus, based on the preliminarily measured spherical power of the subject's eye E. This allows the fixation target to be clearly seen by the subject's eye E. Thereafter, the control unit 50 moves the fixation target from the clouding start position, thereby adding clouding to the subject's eye E. This releases the accommodation of the subject's eye E.

[0150] The main measurement is performed with the subject's eye E clouded. Predetermined analysis processing is performed on the annular image captured of the clouded eye E to obtain the subject's eye's heteroptic values (SPH: spherical power), CYL: cylindrical power, and AXIS: astigmatism axis angle).

[0151] Next, a cross-sectional image of the anterior ocular segment is captured (S4). At this time, the capturing operation is performed immediately after the formal measurement of the ocular refractive power is completed. For example, the capture of the cross-sectional image can be triggered by the completion of the formal measurement of the ocular refractive power. That is, immediately after the formal measurement is completed, illumination light based on visible light is emitted from the illumination optical system 300a, and a cross-sectional image of the anterior ocular segment formed on the imaging element 321 is acquired. Since the cross-sectional image of the anterior ocular segment is captured immediately after the formal measurement of the ocular refractive power is completed, alignment misalignment between the measurement of the ocular refractive power and the capture of the cross-sectional image is reduced.

[0152] Furthermore, in this embodiment, since visible light is not irradiated before capturing a cross-sectional image, miosis is suppressed during capturing the cross-sectional image. As a result, cross-sectional images captured deeper into the anterior ocular segment can be captured with ease.

[0153] Next, the calculation control unit 50 calculates the axial length of the eye to be inspected based on the information or images acquired in each of steps S2 to S4 .

[0154] In this embodiment, the axial length of the eye is derived based on a ray tracing operation on the cutting plane.

[0155] like Figure 6 As shown, the light rays incident from the far point FP to the eye to be inspected are traced (for example, Figure 6 The ray Lx) is refracted by each light-transmitting body of the eye to be inspected and intersects with the optical axis, and the position of the intersection point is obtained. The distance between the obtained intersection point and the corneal vertex is derived as the axial length of the eye. It should be noted that in this embodiment, for the sake of convenience of explanation, the refractive index in each light-transmitting body (cornea, aqueous humor and lens) is assumed to be constant, and there is no refractive change inside each of them. However, it is not necessarily limited to this, and the change in the refractive index inside the light-transmitting body (for example, the change in the refractive index between the inside and outside of the lens) can also be considered to derive the axial length of the eye.

[0156] Furthermore, refractive index information related to the refractive index of the translucent body can be obtained independently of the cross-sectional image serving as anterior ocular information, and used when deriving the axial length of the eye. In other words, the refractive index of the translucent body based on the refractive index information can be further considered in addition to obtaining the axial length of the eye. Regarding refractive index information, for example, it is known that the refractive index of the lens changes with age. Therefore, the device can also include a calculation formula or lookup table that associates the refractive index of the lens with each age. In this case, the refractive index corresponding to the age is obtained by inputting the age. This refractive index can also be used for ray tracing operations.

[0157] In this method, in addition to the position of the far point FP, the following parameters are used. The following parameters are acquired based on the Scheimpflug image and corneal shape information.

[0158] Ra: radius of curvature of the anterior corneal surface

[0159] Rp: radius of curvature of the posterior surface of the cornea

[0160] CT: Corneal thickness

[0161] ACD: Anterior chamber depth

[0162] ra: radius of curvature of the anterior surface of the lens

[0163] rp: radius of curvature of the posterior surface of the lens

[0164] LT: Lens thickness

[0165] Furthermore, based on the refractive power measurement results, the position of the far point FP of the eye being examined relative to the corneal vertex is determined. For example, if the eye being examined E has no astigmatism, SPH = -5D, and VD = 12mm, then the distance from the corneal vertex to the far point FP is 12 + 1000 / 5 = 212mm. It can be assumed that light rays from this point form an image on the fundus of the eye being examined. It should be noted that the VD of 12mm represents a fixed distance between the corneal vertices, assuming the eye is wearing spectacle lenses. VD may vary depending on the device.

[0166] However, in the widely used representation of eye refractive power based on SPH, CYL, and AXIS, SPH represents the refractive power associated with the strong principal meridian (or weak principal meridian), and therefore does not necessarily provide an appropriate value for ray tracing of cut surfaces. For example, consider the case of SPH = -5D, CYL = -2D, and AXIS = 30°. In this case, if a horizontal cross-section is obtained in the above example of the optical system, the refractive power of the cross-section is neither -5D nor -7D with the addition of CYL.

[0167] In contrast, in this embodiment, the refractive power of the eye on the cut surface, that is, the surface refractive power, is calculated, and the position of the far point FP is set based on the surface refractive power. Here, the refractive power of any surface is expressed by the following formula.

[0168] P(θ)=S+C×[sin 2 (θ-A)]

[0169] Here, θ is the angle relative to the horizontal plane, and the horizontal direction is set to 0°. The cutting plane of this embodiment is the horizontal plane (θ = 0°). Therefore, when SPH = -5D, CYL = -2D, and AXIS = 30°, P(0°) = -5.5D (refer to Figure 7 In this case, 12+1000 / 5.5=194 mm is the distance from the corneal vertex to the far point FP in the cut surface.

[0170] Here, the light from the far point FP set in this way is tracked. For example, the light is guided from the far point FP toward a certain position (for example, at the position of the pupil of the eye to be examined (cornea depth of about 3 mm)). position) of the light (e.g., Figure 6 It should be noted that the fixed position is set at the position of the pupil of the eye to be inspected. This is just an example and can be modified appropriately.

[0171] The light ray first undergoes initial refraction at the anterior corneal surface. The intersection of the light ray and the anterior corneal surface is calculated based on the radius of curvature Ra of the anterior corneal surface, the position of the far point FP, and the angle of the light ray at the far point FP. Furthermore, the angle of incidence of the light ray at this intersection is also calculated. The light ray that has reached the anterior corneal surface changes its direction at an angle of refraction determined by the angle of incidence based on Snell's law. In this way, the light ray at each translucent body boundary surface is tracked sequentially. At this point, various parameters (Ra, Rp, CT, ACD, ra, rp, LT) obtained based on the Scheimpflug image and corneal shape information are appropriately utilized to determine the intersection of each boundary surface and the light ray. In this embodiment, the point at which the light ray finally intersects with the axis of the eye (here, the visual axis) after exiting the posterior surface of the lens is determined. The distance from the intersection point to the corneal vertex (here, the origin) is used as the axial length AL.

[0172] It should be noted that when the various parameters (Ra, Rp, CT, ACD, ra, rp, LT) described above are used in the ray tracing calculation, in this embodiment, at least the value of the corneal Purkinje image based on the pattern index is used for the curvature radius Ra of the anterior corneal surface, and the values based on the Scheimpflug image are used for the remaining values. This is because, generally speaking, the measurement accuracy of the anterior corneal surface shape based on the corneal Purkinje image is higher than that based on the Scheimpflug image. It should be noted that, as previously described, in this embodiment, at least the values of the corneal curvature, astigmatism, and astigmatism axis angle are obtained as corneal shape information. The corneal curvature (the curvature of the anterior corneal surface) at the cut surface can be calculated based on these values using the same method as the method for calculating the refractive power for the cut surface. The inverse of the calculated value is used as Ra.

[0173] As described above, the axial length of the eye can be obtained by tracing rays toward a certain position. However, the ray tracing method is not limited to the above method. For example, the point imaged from the far point can also be obtained by paraxial calculation. In addition, a plurality of rays incident on the eye to be inspected at different positions can be considered to obtain the point imaged from the far point. For example, the ray tracing of the paraxial ray and the ray toward a certain position different from the paraxial ray can be combined. In the case of performing ray tracing of multiple rays, the final measured value (calculated value) of the axial length of the eye can also be the average value (or weighted average value) of the axial lengths based on the ray tracing of each ray.

[0174] Alternatively, the measurement area (on the pupil) of the measuring optical system 100 may be tracked. ) to find the axial length of the eye. For example, you can also use the light toward the pupil The calculation results in that the axial length of the eye is obtained by tracing each of the multiple rays in the region and averaging the axial lengths obtained by tracing each ray. Since the ray tracing is performed under more appropriate conditions, the axial length of the eye can be obtained more accurately.

[0175] It should be noted that a predetermined offset value may be added to the axial length value obtained in this embodiment to correct the error between the calculated value and the measured value.

[0176] Alternatively, ray tracing can be performed by tracing a ray emitted from the far point and passing through the circumference of the projected corneal shape measurement pattern index. This allows for more accurate ray tracing, making it easier to obtain the axial length of the eye.

[0177] The obtained axial length is displayed on the monitor 16. In this embodiment, the axial length is displayed together with at least one of the eye's refractive power (SPH, CYL, AXIS) and corneal shape information. If there are past measurement results for the subject's eye, the current measurement result can also be displayed together with the past axial length measurement results. For example, the measurement results can be displayed by setting the horizontal axis to age (measurement date) and the vertical axis to a trend graph of the axial length. Of course, the display method of the measurement results is not limited to this.

[0178] <Modification>

[0179] Although the above description has been given based on the embodiment and the examples, the present disclosure is not limited to the above embodiment, and various modifications are possible.

[0180] For example, in the above embodiment, measured values were used for the various parameters (Ra, Rp, CT, ACD, ra, rp, LT) used in ray tracing. However, this is not necessarily limited to this, and standard values (assumed values) may be used for some of the various parameters. The standard value may be an average value or a value adopted in a prescribed ocular optical model (e.g., the Gullstrand model). Multiple standard values may be prepared for at least one of age, gender, and region, allowing the examiner to select which standard value to use when calculating the axial length of the eye.

[0181] In addition, for example, in the above-mentioned embodiment, the axial length of the eye to be examined is obtained as a result of a calculation based on the refractive power of the eye to be examined and the anterior ocular information. However, this is not necessarily limited to this, and the axial length can also be obtained using a mathematical model trained by a machine learning algorithm. A mathematical model, for example, refers to a data structure used to predict the relationship between input data and output data. The mathematical model is constructed by training using a training data set. The training data set is a collection of input training data and output training data. The input training data is sample data input to the mathematical model. For example, the refractive power and anterior ocular information of multiple eyes to be examined obtained in the past are used as input training data. The output training data is sample data of values predicted by the mathematical model. For example, the axial length values of multiple eyes to be examined obtained in the past are used as output training data. The axial length values can also be measured values obtained by an optical interference type or ultrasonic type axial length measuring device. The mathematical model is trained so that when certain input training data is input, it outputs corresponding output training data. In this embodiment, the calculation control unit may also obtain the axial length value of the eye to be inspected as the predicted value by inputting the eye refractive power and the anterior ocular segment information into the mathematical model.

[0182] Furthermore, for example, in the aforementioned embodiments and examples, anterior ocular information, including lens shape information, may be sequentially acquired while the fixation mark is moved to apply clouding. This allows changes in lens shape to be detected based on the anterior ocular information, and confirmation of appropriate clouding based on these changes.

[0183] (1) An ophthalmologic apparatus according to a second aspect of the present disclosure includes:

[0184] a first optical system for projecting measurement light onto the fundus of the eye to be inspected and acquiring the refractive power of the eye to be inspected based on light reflected from the fundus of the measurement light;

[0185] a second optical system for acquiring anterior ocular segment information, the anterior ocular segment information being information related to the shape of the anterior ocular segment and including at least shape information of the lens;

[0186] a control unit configured to control the first optical system and the second optical system to respectively obtain the eye refractive power and the anterior ocular information in a state where the intraocular adjustments are the same; and

[0187] The axial length acquisition unit acquires the axial length of the eye to be inspected based on the eye refractive power and the anterior ocular segment information acquired in a state where intraocular accommodation is the same as each other.

[0188] (2) In the ophthalmic device of the second embodiment,

[0189] The ophthalmic device of (1) above further comprises a fixation mark presenting optical system for presenting a fixation mark,

[0190] The control unit controls the acquisition timing of the eye refractive power and the anterior ocular segment information so that the adjustment of the fixation index to the subject's eye is added to the same timing between when the eye refractive power is acquired and when the anterior ocular segment information is acquired.

[0191] (3) In the ophthalmic device of the second embodiment,

[0192] In the ophthalmic device of (1) or (2) above,

[0193] The control unit synchronizes the acquisition timings of the eye refractive power and the anterior ocular segment information.

[0194] (4) In the ophthalmic device of the second embodiment,

[0195] In the ophthalmic device of (2) or (3) above,

[0196] The fixation mark presenting optical system is capable of changing the presentation distance of the fixation mark.

[0197] The control unit controls the fixation mark presenting optical system to add fog to the eye to be inspected, and obtains the eye refractive power and the anterior ocular segment information when the eye to be inspected is in the foggy state.

[0198] (5) In the ophthalmic device of the second embodiment,

[0199] In any of the ophthalmic devices of (1) to (4) above,

[0200] The first optical system irradiates infrared light as the measuring light,

[0201] The second optical system includes an irradiation optical system for irradiating the anterior ocular segment with slit light, and a light-receiving optical system having a lens system and an imaging element arranged in a Scheimpflug relationship with respect to a cutting surface set on the anterior ocular segment by the slit light, and acquires a cross-sectional image of the anterior ocular segment based on a signal from the imaging element.

[0202] (6) In the ophthalmic device of the second embodiment,

[0203] In the ophthalmic device of (5) above,

[0204] The second optical system irradiates visible light as the slit light,

[0205] The control unit executes the operation of acquiring the eye refractive power, and acquires the anterior ocular segment information at the timing when the acquisition operation is completed.

[0206] (7) In the ophthalmic device of the second embodiment,

[0207] In the ophthalmic device of (5) or (6) above,

[0208] The projection optical axis of the measurement light in the first optical system and the projection optical axis of the illumination light in the second optical system are coaxially arranged.

Claims

1. An ophthalmic device comprising: a first optical system for projecting measurement light onto the fundus of the eye to be inspected and acquiring the refractive power of the eye to be inspected based on light reflected from the fundus of the measurement light; a second optical system for acquiring anterior ocular segment information, the anterior ocular segment information being information related to a shape of the anterior ocular segment and related to a cut surface on which the optical axis of the first optical system is arranged; and Operation and control unit, The calculation control unit obtains the axial length of the eye to be inspected based on the ocular refractive power on the cutting surface, that is, the planar ocular refractive power and the anterior ocular segment information related to the cutting surface. The cutting plane used to obtain the planar ocular refractive power is the same as the cutting plane used to obtain the anterior ocular segment information, and the axial length of the eye to be inspected is calculated based on the planar ocular refractive power and the anterior ocular segment information obtained on the same cutting plane.

2. The ophthalmic device according to claim 1, The second optical system includes a cross-sectional imaging optical system that captures a cross-sectional image of the cut surface set in the anterior segment of the eye to be inspected, The calculation control unit acquires the axial length of the eye to be inspected based on the planar ocular refractive power and the anterior ocular segment information based on the cross-sectional image.

3. The ophthalmic device according to claim 2, The cross-sectional image capturing optical system captures a range from the front surface of the cornea to at least the front surface of the lens of the eye to be inspected.

4. The ophthalmic device according to claim 2, The third optical system includes an index projector that projects a pattern index for measuring the corneal shape from the front side facing the eye to be inspected toward the anterior ocular portion and captures a corneal Purkinje image of the pattern index. The calculation control unit obtains the axial length based on the surface ocular refractive power, the anterior ocular segment information, and corneal shape information based on the corneal Purkinje image.

5. The ophthalmic device according to claim 1, The anterior ocular information is information capable of determining at least two of the following: corneal thickness, anterior corneal curvature radius, posterior corneal curvature radius, anterior chamber depth, lens thickness, anterior lens curvature radius, and posterior lens curvature radius.

6. The ophthalmic device according to claim 1, The calculation control unit further obtains refractive index information related to the refractive index of the light-transmitting body in the eye to be inspected, The arithmetic control unit further acquires the axial length of the eye to be inspected by taking into account the refractive index of the light-transmitting body based on the refractive index information.

7. The ophthalmic device according to claim 1, The anterior ocular segment information includes information capable of specifying a shape of the anterior ocular segment in a measurement area, the measurement area being a region of the anterior ocular segment to be measured for the eye refractive power of the first optical system. The calculation control unit obtains the axial length of the eye based on the surface ocular refractive power and the anterior ocular segment information in the measurement area.

8. The ophthalmic device according to claim 1, The arithmetic control unit acquires the axial length of the eye in consideration of the decentering of a light-transmitting body of the anterior segment that can be determined by the anterior segment information.

9. The ophthalmic device according to claim 1, The calculation control unit controls the first optical system and the second optical system so as to obtain the eye refractive power and the anterior ocular segment information respectively while the intraocular adjustments are the same. Then, the axial length of the eye to be inspected is obtained based on the eye refractive power and the anterior ocular segment information obtained in a state where the intraocular accommodation is the same as each other.

10. The ophthalmic device according to claim 9, A fixation mark presenting optical system for presenting a fixation mark is provided. The arithmetic control unit controls the acquisition timing of the eye refractive power and the anterior ocular segment information so that the adjustment of the fixation index to the subject's eye is the same between when the eye refractive power is acquired and when the anterior ocular segment information is acquired.

11. The ophthalmic device according to claim 9, The arithmetic control unit synchronizes the timing of acquiring the eye refractive power and the anterior ocular segment information.

12. The ophthalmic device according to claim 10, The fixation mark presenting optical system is capable of changing the presentation distance of the fixation mark. The calculation control unit controls the fixation mark presenting optical system to add clouding to the eye to be inspected, and obtains the eye refractive power and the anterior ocular segment information when the eye to be inspected is in the clouded state.

13. The ophthalmic device according to claim 9, The first optical system irradiates infrared light as the measuring light, The second optical system comprises: an irradiation optical system for irradiating the anterior ocular segment with slit light; and The light receiving optical system includes a lens system and an imaging element arranged in a Scheimpflug relationship with respect to the cut surface set on the anterior ocular segment by the slit light. The second optical system acquires a cross-sectional image of the anterior ocular segment based on a signal from the imaging element.

14. The ophthalmic device according to claim 13, The second optical system irradiates visible light as the slit light, The arithmetic control unit executes the eye refractive power acquisition operation and acquires the anterior ocular segment information at the timing when the acquisition operation is completed.

15. The ophthalmic device according to claim 13, The projection optical axis of the measurement light in the first optical system and the projection optical axis of the illumination light in the second optical system are coaxially arranged.

16. The ophthalmic device according to claim 4, The index projector is arranged so as to avoid the light receiving axis in the second optical system.

17. The ophthalmic device according to claim 16, The index projector projects the pattern index composed of a plurality of point images.

Images