Ophthalmologic examination apparatus and ophthalmologic examination method

Abstract

To provide an ophthalmologic examination apparatus and an ophthalmologic examination method capable of evaluating whether a subject eye can easily adapt to stereoscopic vision in which a mismatch between convergence and adjustment occurs.SOLUTION: An ophthalmologic examination apparatus 100 includes a target projection system 4, objective measurement optical systems 6, 7, and a control unit 140. A display 41 presents a left-eye projection target 8L and a right-eye projection target 8R having different asterisks 82L, 82R, at target positions separated from left and right subject eyes EL, ER by a predetermined examination distance Lid. The target projection system 4 prescribes a condition in which the convergence distance L from the positions of the left and right subject eyes EL, ER to a convergence position R where two lines of sight intersect is changed by changing the parallax between the two asterisks 82L, 82R reflected on the retinas of the left and right subject eyes EL, ER. When fusion is attempted with the left and right subject eyes EL, ER for the change in the convergence distance L, the control unit 140 measures the ocular characteristics of the left and right subject eyes EL, ER using the objective measurement optical systems and acquires objective refractive values as objective measurement information.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to an ophthalmic examination apparatus and an ophthalmic examination method. [Background technology]

[0002] As ophthalmic examination techniques, for example, the techniques described in Patent Documents 1 to 5 have been proposed. Patent Document 1 describes a technique for providing ophthalmic examination information for more appropriately prescribing corrective lenses for subjects with heterophoria. Patent Document 2 describes a technique for providing an ophthalmic measurement device that can measure the subject's eye in a state where the subject's eye is close to natural vision and appropriately fused. Patent Document 3 describes a technique for providing an ophthalmic examination system that can easily confirm the position of the gaze of the subject's eye and perform an appropriate eye examination. Patent Document 4 describes a technique for providing an ophthalmic device that can appropriately perform an objective examination of the state related to eye position. Patent Document 5 describes a technique for providing an ophthalmic device that can appropriately perform an objective examination of the state related to eye position. Patent Document 6 describes a technique for easily confirming the fusion state when performing an examination with both eyes open and performing accurate measurement. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2022-038942 [Patent Document 2] Patent Publication No. 2021-019957 [Patent Document 3] JP 2020-069201 A [Patent Document 4] JP 2019-069049 A [Patent Document 5] JP 2019-063238 A [Patent Document 6] JP 2018-047050 A Summary of the Invention [Problem to be solved by the invention]

[0004] By the way, when watching normal 3D images, there is a mismatch between convergence, which is the eye movement when fusing two images with both eyes, and accommodation, which is the accommodative function when focusing on an image with both eyes. In other words, between convergence and accommodation, when fusing two visual targets with both eyes, there is a range of convergence where accommodation can be constant (relative convergence) and a range of accommodation where convergence can be constant (relative accommodation). For this reason, it is known that when the range of relative convergence or relative accommodation is exceeded, a convergence movement that cooperates with the accommodation response (accommodative convergence) or an accommodation action induced by convergence (vergence accommodation) occurs. Here, "vergence" refers to the eye movement in which the eyes move in different directions when the line of sight is moved to an object at a different distance (depth) from the observer, in which the eyes move in the direction in which the eyes come together.

[0005] In contrast, the prior art, none of Patent Documents 1 to 5, describes a configuration in which two targets are placed at a certain distance from the subject's eyes, and when the two targets are fused with both eyes, a convergence stimulus is applied to reproduce a state in which a mismatch occurs between convergence and accommodation. For this reason, the prior art cannot evaluate whether the left and right eyes to be examined are easily adapted to stereoscopic vision in which a mismatch occurs between convergence and accommodation.

[0006] The present invention has been made in consideration of the above-mentioned problems, and aims to provide an ophthalmic examination apparatus and an ophthalmic examination method that can evaluate whether the left and right eyes to be examined are likely to adapt to stereoscopic vision, in which a mismatch between convergence and accommodation occurs. [Means for solving the problem]

[0007] The ophthalmic examination device of the present invention includes a target projection system having a target presentation unit that presents fixation targets to the left and right test eyes, an objective measurement optical system that objectively measures the eye characteristics of the left and right test eyes, and a control unit that controls each unit of the device. The fixation targets are a left eye projected target and a right eye projected target that are projected onto the left and right test eyes, respectively, and have the same pattern at the same vertical position relative to a target frame. The target presentation unit presents the left eye projected target and the right eye projected target at a target position that is a certain test distance away from the left and right test eyes. The target projection system prescribes a state in which the convergence distance from the positions of the left and right test eyes to the convergence position where the two lines of sight intersect is changed by changing the parallax, which is the difference in the positions of the two patterns reflected on the retinas of the left and right test eyes. When fusion is attempted using the left and right test eyes in response to a change in the convergence distance, the control unit measures the ocular characteristics of the left and right test eyes using the objective measurement optical system and obtains objective refraction values ​​as objective measurement information.

[0008] The ophthalmic examination method of the present invention includes a complete correction prescription step, a target presentation step, a vergence distance control step, an accommodation response amount measurement step, and a judgment step. The complete correction prescription step sets the left and right test eyes in a state where a complete correction value in a subjective test is prescribed. The target presentation step, following the prescription of the complete correction value, presents a left eye projected target and a right eye projected target having the same pattern at the same vertical position relative to the target frame of the target presentation unit at a target position a certain test distance away from the left and right test eyes. The vergence distance control step prescribes a state in which the vergence distance from the position of the left and right test eyes to the convergence position where the two lines of sight intersect is changed by controlling to change the parallax, which is the difference in the positions of the two patterns reflected on the retinas of the left and right test eyes. The accommodation reaction amount measuring step is executed in parallel with the control of the convergence distance, and when the left and right test eyes attempt to fuse with respect to a change in the convergence distance, the eye characteristics of the left and right test eyes are measured by the objective measurement optical system, and objective refraction values ​​are obtained as objective measurement information. The judgment step judges the adaptability of the left and right test eyes to stereoscopic vision based on the objective refraction values. Effect of the Invention

[0009] The ophthalmic examination apparatus and the ophthalmic examination method according to the present invention can evaluate whether the left and right eyes to be examined are likely to adapt to stereoscopic vision in which a mismatch between convergence and accommodation occurs. [Brief description of the drawings]

[0010] [Figure 1] 1 is an external perspective view of an ophthalmic examination apparatus according to a first embodiment. [Diagram 2] 2 shows a schematic configuration example of a left measurement optical system in the ophthalmic examination apparatus of the first embodiment. [Diagram 3] 2 shows a control block configuration in the ophthalmic examination apparatus of the first embodiment. [Figure 4] 1 shows a flowchart illustrating a processing procedure of an ophthalmic examination method according to a first embodiment. [Figure 5A] The figure shows a pair of visual targets with the pattern position in the frame set to the initial disparity angle position. [Figure 5B] The figure shows a pair of optotypes in which the patterns are set at a position where the convergence distance is farther than the test distance. [Figure 5C] The figure shows a pair of optotypes in which the patterns are set at a position where the convergence distance is closer than the test distance. [Figure 6] An explanatory diagram of the convergence distance up to the convergence point where two lines of sight intersect is shown below. [Figure 7A] An example is shown in which the convergence distance to the convergence position coincides with the inspection distance. [Figure 7B] An example in which the convergence distance to the convergence position is closer than the test distance is shown. [Figure 7C] An example in which the convergence distance to the convergence position is farther than the test distance is shown. [Figure 8A] This shows the measurement of convergence and accommodation when observing a stereoscopic image. [Figure 8B] 1 shows a disparity time chart for measuring convergence and accommodation. [Figure 8C] Examples of measurement results of convergence and refraction (accommodation) in a normal eye are shown. [Figure 8D] Examples 1 and 2 of the measurement results of convergence and refraction (accommodation) in the fatigue group are shown. [Figure 8E]4 shows examples of analysis results of the refraction time change frequency for a healthy group and a fatigue group. [Figure 9] A plurality of test eyes show relationship characteristics between the parallax angle and the objective refraction value to be measured. [Figure 10] 13 is a flowchart showing the processing steps of an ophthalmic examination method according to a second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An ophthalmic examination apparatus and an ophthalmic examination method according to the present invention will be described below with reference to a first embodiment and a second embodiment shown in the drawings.

[0012] The ophthalmic examination apparatus applied to the first and second embodiments is an apparatus of a binocular open type that can measure the ocular characteristics of both eyes simultaneously while the examinee keeps both the right and left eyes open. This ophthalmic examination apparatus can also measure the ocular characteristics of one eye at a time by blocking one eye or turning off the fixation target. In addition, the ophthalmic examination apparatus is an objective measurement device with a subjective test function that has a target presentation function, a phoropter function, and an autoreflex-keratometer measurement function. In other words, the examiner can use the ophthalmic examination apparatus to perform any objective test and subjective test and objectively and subjectively measure the ocular characteristics of the examinee's eye.

[0013] Objective examinations that can be performed by an ophthalmic examination apparatus include measurements for acquiring eye characteristics of the subject's eye and photography for acquiring an image of the subject's eye. Objective examinations include refractive power measurement (refractometry), corneal shape measurement (keratometry), intraocular pressure measurement, fundus photography, tomography (OCT photography) using optical coherence tomography (hereinafter referred to as "Optical Coherence Tomography"), and measurements using OCT. In subjective examinations, visual targets are presented to the subject, and information about the subject's eye (eye characteristics) is measured based on the subject's response to the presented visual targets. Subjective examinations include subjective refraction measurements such as distance examination, intermediate distance examination, near examination, contrast examination, and glare examination, as well as visual field examination. EXAMPLES

[0014] [Overall configuration of the device (Fig. 1)] The overall configuration of the ophthalmic examination apparatus 100 will be described below with reference to Fig. 1. As shown in Fig. 1, the ophthalmic examination apparatus 100 includes a support base 110, a measurement unit 120, an examiner's controller 130, and a control unit 140. As for the axes used in the drawings and description, when viewed from the examinee, the left-right axis (horizontal axis) is the X-axis, the up-down axis (vertical axis) is the Y-axis, and the depth axis (front-rear axis) perpendicular to the X-axis and Y-axis is the Z-axis.

[0015] The support base 110 has a support column 111 standing up from the floor surface, and an optometry table 112 supported by the support column 111. The optometry table 112 is a platform on which devices and tools used in optometry, such as the examiner controller 130, are placed, and which supports the posture of an examinee. The optometry table 112 may have a fixed position in the Y-axis direction (height position), or may be supported by the support column 111 so that the position in the Y-axis direction (height position) is adjustable.

[0016] The measurement unit 120 has an arm 121, a measurement head 122, and a forehead rest 123. One end of the arm 121 is supported by the tip of the support 111, and the other end extends from the support 111 to the front side (subject side) along the Z direction, with the measurement head 122 attached to the tip. As a result, the measurement head 122 is suspended from the support 111 via the arm 121 above the optometry table 112. The arm 121 is movable in the Y-axis direction relative to the support 111. The arm 121 may also be movable in the X-axis direction or the Z-axis direction relative to the support 111.

[0017] The measurement head 122 measures the ocular characteristics of the subject's eye. The measurement head 122 has a drive unit 122a, a pair of left and right measurement head units 122L and 122R provided below the drive unit 122a, and a forehead rest unit 123. Here, the left measurement head unit 122L and the right measurement head unit 122R correspond to the left and right eyes of the subject, respectively.

[0018] The drive unit 122a is a mechanism that individually drives the left measurement head unit 122L and the right measurement head unit 122R to move in the horizontal direction (X-axis direction), move in the vertical direction (Y-axis direction), rotate around the X-axis, and rotate around the Y-axis.

[0019] The left measurement head unit 122L incorporates a left measurement optical system 125L. The left measurement optical system 125L presents a visual target to the subject's left eye (hereinafter, "left eye") and measures the eye characteristics of the left eye with the spherical power (correction power) set to an arbitrary value. The right measurement head unit 122R incorporates a right measurement optical system 125R. The right measurement optical system 125R presents a visual target to the subject's right eye (hereinafter, "right eye") and measures the eye characteristics of the right eye with the spherical power (correction power) set to an arbitrary value. The measurement results by the left measurement optical system 125L and the right measurement optical system 125R are hereinafter referred to as objective measurement information. The detailed configurations of the left measurement optical system 125L and the right measurement optical system 125R will be described in "Configuration of optical system" below.

[0020] The forehead rest 123 is provided in the measurement unit 120 and is disposed between the left measurement head 122L and the right measurement head 122R. The forehead rest 123 supports the subject's face by contacting a part of the face (forehead) with the forehead rest 123 during measurement of eye characteristics. That is, the subject facing the optometry table 112 presses his / her forehead against the forehead rest 123 to stabilize the direction and position of the face. The position of the forehead rest 123 in the height direction is adjusted by moving the arm 121 in the Y-axis direction relative to the support 111.

[0021] The examiner's controller 130 is an information processing device that accepts an input operation by the examiner and outputs a control signal to the control unit 140. The examiner's controller 130 is, for example, a tablet terminal or a smartphone, and is separated from the measurement unit 120 and can be carried by the examiner. The examiner's controller 130 may be a notebook personal computer or a desktop personal computer, or may be a dedicated controller provided in the ophthalmic examination apparatus 100. The examiner's controller 130 exchanges information with the control unit 140 via wireless communication or network communication.

[0022] As shown in Fig. 1, the examiner's controller 130 includes a display unit 131 and an operation-side control unit (not shown). The display unit 131 is made up of a touch panel display provided on the surface of the examiner's controller 130, and input buttons 132 (see Fig. 3) and the like are set by screen display. The operation-side control unit is made up of a microcomputer built into the examiner's controller 130. The operation-side control unit controls images to be displayed on the display unit 131 based on measurement results and detection results transmitted from the control unit 140. The operation-side control unit also outputs control signals to the control unit 140 in response to operations on the displayed input buttons 132 and the like.

[0023] [Optical system configuration (Fig. 2)] The detailed configurations of the left measurement optical system 125L and the right measurement optical system 125R will be described below with reference to Fig. 2. The left measurement optical system 125L and the right measurement optical system 125R have the same configuration. Therefore, in this document, illustration and description of the right measurement optical system 125R corresponding to the right test eye ER will be omitted, and only the left measurement optical system 125L corresponding to the left test eye EL will be described.

[0024] The left measurement optical system 125L is an optical system that performs an examination by presenting a visual target to the left test eye EL. As shown in FIG. 2, the left measurement optical system 125L includes a Z alignment system 1, an XY alignment system 2, a keratometry system 3, a visual target projection system 4, an anterior eye observation system 5, a reflex measurement projection system 6, and a reflex measurement light receiving system 7. In the following description, the "fundus conjugate position P" is a position that is optically approximately conjugate with the fundus ELf of the left test eye EL when alignment is completed, and means a position optically conjugate with the fundus ELf of the left test eye EL or its vicinity. The "pupil conjugate position Q" is a position that is optically approximately conjugate with the pupil of the left test eye EL when alignment is completed, and means a position optically conjugate with the pupil of the left test eye EL or its vicinity.

[0025] The Z alignment system 1 projects light (infrared light) for alignment in the optical axis direction (front-back direction = Z axis direction) of the anterior eye observation system 5 onto the left test eye EL. The light output from the Z alignment light source 11 is collimated by the projection lens 12 and projected onto the cornea of ​​the left test eye EL through an alignment hole formed in the keratoplasty plate 31. Based on the bright spot projected onto the cornea, the control unit 140 or the examiner controls the drive unit 122a to move the left measurement optical system 125L in the Z axis direction so that the ratio between the distance between the two point images on the imaging element 59 by the Z alignment light source 11 and the diameter of the keratoplasty image falls within a predetermined range.

[0026] The XY alignment system 2 irradiates the left test eye EL with light (infrared light) for alignment in the X-axis direction and the Y-axis direction perpendicular to the optical axis (Z-axis) of the anterior eye observation system 5. The XY alignment system 2 includes an XY alignment light source 21 and a projection lens 22, which are provided on an optical path branched from the anterior eye observation system 5 by a half mirror 54. The light output from the XY alignment light source 21 passes through the projection lens 22, is reflected by the half mirror 54, and is projected onto the left test eye EL through the anterior eye observation system 5. The light reflected by the cornea of ​​the left test eye EL is guided to the image sensor 59 through the anterior eye observation system 5. The alignment method in each of the XYZ directions is not limited to the method using the Z alignment system 1 and the XY alignment system 2. For example, any method can be used as long as it can measure the position of the test eye E by using a stereo camera installed in the ophthalmic apparatus 100.

[0027] Here, the image based on the light reflected by the cornea (bright spot image) is included in the anterior eye image. The control unit 140 controls the display unit 131 to display the anterior eye image including the bright spot image and the alignment mark. When performing manual XY alignment, the examiner uses the examiner controller 130 to control the drive unit 122a to guide the bright spot image into the alignment mark, and moves the left measurement optical system 125L in the X-axis direction and the Y-axis direction. When performing automatic XY alignment, the control unit 140 controls the drive unit 122a to cancel the displacement of the bright spot image relative to the alignment mark, and moves the left measurement optical system 125L in the X-axis direction and the Y-axis direction.

[0028] The keratometry system 3 projects a ring-shaped light beam (infrared light) onto the cornea of ​​the left subject eye EL to measure the shape of the cornea. The keratoplate 31 is disposed between the objective lens 52 and the left subject eye EL, and the keratoplate light source 32 is provided on the rear side (the objective lens 52 side). The keratoplate light source 32 projects a ring-shaped light beam onto the cornea of ​​the left subject eye EL by illuminating the keratoplate 31 with light from the rear. The reflected light (keratoplate image) from the cornea of ​​the left subject eye EL is detected by the imaging element 59 together with the anterior eye image. The control unit 140 calculates a corneal shape parameter that represents the shape of the cornea by performing a known calculation based on the keratoplate image.

[0029] The target projection system 4 presents various targets, such as a fixation target and a target for subjective testing, to the left eye EL. The target projection system 4 includes a display 41, a half mirror 42, a relay lens 43, a reflecting mirror 44, a focusing lens 45, a relay lens 46, a field lens 47, a variable cross cylinder lens (VCC) 48, and a reflecting mirror 49. The target projection system 4 shares a dichroic mirror 68 with the reflector measurement projection system 6. The target projection system 4 shares a dichroic mirror 53 and an objective lens 52 with the anterior eye observation system 5. Furthermore, the target projection system 4 includes at least two glare light sources 41a that irradiate the left eye EL with glare light at positions surrounding the optical axis on an optical path different from the optical path leading to the display 41 that displays the left eye projected target.

[0030] The light output from the display 41 is reflected by the half mirror 42, passes through the relay lens 43, is reflected by the reflecting mirror 44, and passes through the focusing lens 45. The light that passes through the focusing lens 45 passes through the relay lens 46, has its traveling direction aligned by the field lens 47, passes through the VCC 48, is reflected by the reflecting mirror 49, passes through the dichroic mirror 68, and is reflected by the dichroic mirror 53. The light reflected by the dichroic mirror passes through the objective lens 52 and is projected onto the fundus ELf.

[0031] The display 41 displays a fixation target or a dot target as a target to fix the gaze when performing an objective test or when fogging the left eye EL, or a subjective test target for subjectively testing the eye characteristics of the left eye EL (visual acuity, distance power, near power, etc.). The display 41 uses a liquid crystal display. Note that an organic EL display or the like can also be used as the display 41. The targets to be projected onto the left eye EL and the right eye ER can be arbitrarily created as still images or moving images, and the created targets can be registered as selectable chart icons on the chart page. The display 41 can select and display the created still image targets or moving image targets from the chart page. The display 41 is provided at a fundus conjugate position P on the optical path of the target projection system 4.

[0032] The focusing lens 45 is driven to move forward and backward in the optical axis direction by a drive motor (not shown) controlled by the control unit 140. When the control unit 140 controls the focusing lens 45 to move in a direction toward the left subject eye EL, the spherical power of the left subject eye EL is changed to the minus diopter side (-D side). When the control unit 140 controls the focusing lens 45 to move in a direction away from the left subject eye EL, the spherical power of the left subject eye EL is changed to the plus diopter side (+D side). Furthermore, the control unit 140 controls the forward and backward drive of the focusing lens 45 to change the test distance from the left subject eye EL to the optotype presentation position. Here, the focusing lens 45, the reflex measurement light source 61, and the focusing lens 74 are configured to move in conjunction with each other.

[0033] When a subjective test is performed, the control unit 140 moves the focusing lens 45 in the optical axis direction based on the result of the objective measurement, and controls the test distance and the spherical power of the left test eye EL. Then, the control unit 140 displays a predetermined optotype selected by the examiner or the control unit 140 on the display 41. As a result, the optotype is presented to the subject at a predetermined test distance for the left test eye EL adjusted to a predetermined spherical power. Also, when the subject gives a subjective response to the optotype, the control unit 140 receives an input of the response. For example, in the case of visual acuity measurement, the examiner selects and presents the next optotype based on the subject's subjective response to a Landolt ring or the like, and the control unit 140 determines the visual acuity value by repeating this process.

[0034] The anterior eye observation system 5 observes and photographs the anterior eye of the left eye EL. The anterior eye illumination light source 51 irradiates the anterior eye of the left eye EL with illumination light (e.g., infrared light). The light reflected by the anterior eye of the left eye EL passes through the objective lens 52, the dichroic mirror 53, the half mirror 54, the relay lens 55 and the relay lens 56, and the dichroic mirror 57. The light transmitted through the dichroic mirror 57 forms an image on the imaging surface of the imaging element 59 by the imaging lens 58. The imaging element 59 performs imaging and signal output at a predetermined rate. The output (video signal) of the imaging element 59 is input to the control unit 140. The control unit 140 displays an anterior eye image (moving image) based on the video signal output from the imaging element 59 on the display unit 131 of the examiner's controller 130. The imaging surface of the imaging element 59 in the optical system of the anterior eye observation system 5 is disposed at a pupil conjugate position Q.

[0035] The refraction measurement projection system 6 and the refraction measurement light receiving system 7 are objective measurement optical systems used for objective refraction measurement (refraction measurement) to measure the objective refraction value as an ocular characteristic of the left test eye EL. Hereinafter, the refraction measurement projection system 6 and the refraction measurement light receiving system 7 are referred to as the objective measurement optical systems 6, 7. The refraction measurement projection system 6 projects a ring-shaped light beam (infrared light) for objective measurement from a refraction measurement light source 61 onto the fundus ELf. The refraction measurement light receiving system 7 receives the return light of this ring-shaped light beam from the left test eye EL.

[0036] The reflex measurement light source 61 may be an SLD (Super luminescent Diode) light source, which is a high-brightness light source with a light emission diameter of a predetermined size or less. The reflex measurement light source 61 can move in the optical axis direction in conjunction with the focusing lens 45 and the focusing lens 74, and is arranged at the fundus conjugate position P. The ring diaphragm 65 (specifically, the light transmitting portion) is arranged at the pupil conjugate position Q. The focusing lens 74 can move in the optical axis direction in conjunction with the reflex measurement light source 61 and the focusing lens 45. The focusing lens 74 may be a known variable focus lens whose focal position can be changed under the control of the control unit 140. The imaging surface of the imaging element 59 in the optical system of the reflex measurement light receiving system 7 is arranged at the fundus conjugate position P.

[0037] The light output from the reflector measurement light source 61 passes through a relay lens 62 and is incident on the conical surface of a conical prism 63. The light incident on the conical surface is deflected and exits from the bottom surface of the conical prism 63. The light exiting from the bottom surface of the conical prism 63 passes through a field lens 64 and passes through a light-transmitting portion formed in a ring shape in an aperture ring 65. The light (ring-shaped light beam) that passes through the light-transmitting portion of the aperture ring 65 is reflected by the reflecting surface of an aperture prism 66, passes through a rotary prism 67, and is reflected by a dichroic mirror 68. The light reflected by the dichroic mirror 68 is reflected by a dichroic mirror 53, passes through the objective lens 52, and is projected onto the left test eye EL.

[0038] It is desirable that the conical prism 63 is disposed as close as possible to the pupil conjugate position Q. The conical prism 63 may have, for example, a ring diaphragm 65 attached to its bottom surface facing the field lens 64. In this case, for example, a light-shielding film is evaporated onto the bottom surface of the conical prism 63 so that a ring-shaped light-transmitting portion is formed. The ring diaphragm 65 may also be located on the conical surface side of the conical prism 63.

[0039] The field lens 64 may have a ring diaphragm 65 attached to the lens surface on the side of the left eye EL. In this case, for example, a light-shielding film is deposited on the lens surface of the field lens 64 so as to form a ring-shaped light-transmitting portion. The reflex measurement projection system 6 may be configured without the field lens 64. The ring diaphragm 65 may be a diaphragm formed with a light-transmitting portion having a shape corresponding to a predetermined measurement pattern, and the light-transmitting portion may be formed in this diaphragm at a position eccentric to the optical axis of the reflex measurement projection system 6. The diaphragm may have two or more light-transmitting portions. The rotary prism 67 is used to average the light amount distribution of the ring-shaped light beam for the blood vessels and diseased parts of the fundus ELf and to reduce speckle noise caused by the light source.

[0040] The return light of the ring-shaped light beam projected onto the fundus ELf passes through the objective lens 52 and is reflected by the dichroic mirror 53 and the dichroic mirror 68. The return light reflected by the dichroic mirror 68 passes through the rotary prism 67, passes through the hole of the aperture prism 66, passes through the relay lens 71, is reflected by the reflecting mirror 72, and passes through the relay lens 73 and the focusing lens 74. The light that passed through the focusing lens 74 is reflected by the reflecting mirror 75, is reflected by the dichroic mirror 57, and is imaged by the imaging lens 58 on the imaging surface of the imaging element 59.

[0041] The control unit 140 calculates the parameters of the eye refractive power by performing a known calculation based on the output from the image sensor 59. The parameters of the eye refractive power include the refraction value (refractive power), spherical power, cylindrical power, and cylindrical axis angle of the left and right test eyes EL, ER. The control unit 140 comprehensively controls each part of the measurement unit 120 including the left measurement optical system 125L and the right measurement optical system 125R having the refraction measurement projection system 6, the refraction measurement light receiving system 7, the visual target projection system 4, etc., and the drive unit 122a, based on a control signal transmitted from the examiner's controller 130. The control unit 140 also transmits the measurement results of the eye characteristics of the left test eye EL and the right test eye ER measured by the measurement head 122 to the examiner's controller 130.

[0042] [Control unit configuration (Fig. 3)] The configuration of the control unit 140 which comprehensively controls each unit of the device will be described below with reference to Fig. 3. As shown in Fig. 3, the control unit 140 includes a main control unit 141, a storage unit 142, and an adaptability evaluation inspection unit 143.

[0043] The main control unit 141 controls the change in light intensity and the on / off switching of the Z alignment light source 11 of the Z alignment system 1, the XY alignment light source 21 of the XY alignment system 2, and the keratometry light source 32 of the keratometry system 3. The main control unit 141 controls the on / off control of the visual target displayed on the display 41 of the visual target projection system 4, and the switching of the visual target. The main control unit 141 controls the change in light intensity and the on / off switching of the anterior eye illumination light source 51 of the anterior eye observation system 5. The main control unit 141 controls the change in exposure time and the detection sensitivity of the image sensor 59 of the anterior eye observation system 5. The main control unit 141 controls the change in light intensity and the on / off switching of the reflex measurement light source 61 of the reflex measurement projection system 6. The main control unit 141 controls the change in rotation speed of the rotary prism 67 of the reflex measurement projection system 6, and the on / off switching of the rotation operation. The main control unit 141 also controls the movement of the focusing lens 45 of the visual target projection system 4, the reflex measurement light source 61 of the reflex measurement projection system 6, and the focusing lens 74 of the reflex measurement light receiving system 7 in the optical axis direction in an interlocking manner. The main control unit 141 also controls the processing of writing data to the storage unit 142 and reading data from the storage unit 142.

[0044] The storage unit 142 stores various data. The data stored in the storage unit 142 include measurement information obtained by the keratometry system 3, measurement information obtained by the objective measurement optical systems 6 and 7, image data acquired by the image sensor 59, and information on the subject's eye. The information on the subject's eye includes information on the subject, such as a patient ID and name, and information on the left and right subject's eyes EL and ER, such as identification information of the left eye / right eye. The measurement information obtained by the keratometry system 3 is stored in the storage unit 142 when keratometry is performed on the left and right subject's eyes EL and ER. The measurement information obtained by the objective measurement optical systems 6 and 7 is stored in the storage unit 142 when refractometry is performed on the left and right subject's eyes EL and ER. The storage unit 142 may be used as a working memory for the calculation process of the corneal shape parameters and the calculation process of the refractive values ​​of the left and right subject's eyes EL and ER. In addition, the storage unit 142 stores various programs and data for operating the ophthalmic examination apparatus 100.

[0045] The adaptation evaluation test unit 143 performs a test to evaluate the adaptability of the left and right test eyes EL, ER to stereoscopic vision. The adaptation evaluation test unit 143 includes a subjective test processing unit 144, an objective measurement unit 145, and a determination unit 146.

[0046] The subjective test processing unit 144 sets the left and right test eyes EL, ER in a state where a perfect correction value in the subjective test is prescribed, and presents the left eye projection target and the right eye projection target at a target position a certain test distance (for example, 1 m) away from the left and right test eyes EL, ER. The left eye projection target and the right eye projection target are set on a display 41 (target presentation unit) that presents a fixation target to the left and right test eyes EL, ER in the target projection system 4. The left eye projection target and the right eye projection target are projected onto the left and right test eyes EL, ER, respectively. The left eye projection target and the right eye projection target have the same design at the same vertical position relative to the target frame, so that the two designs can be fused by the left and right test eyes EL, ER.

[0047] The subjective test processing unit 144 prescribes a state in which the convergence distance from the positions of the left and right test eyes EL, ER to the convergence position where the two lines of sight intersect is changed by controlling to change the parallax, which is the difference in the positions of the two patterns reflected on the retinas of the left and right test eyes EL, ER. The left eye projection optotype and the right eye projection optotype are set as stereoscopic optotypes with parallax by making the left and right positions of the patterns displayed on each of them different from each other. Then, a plurality of optotype pairs with different parallax are prepared for the left eye projection optotype and the right eye projection optotype having parallax. The subjective test processing unit 144 controls to change the parallax by controlling to change the parallax angle when attempting to fuse the two patterns by binocular vision. The control to change the parallax is performed by controlling the main control unit 141 to switch the optotype pairs displayed on the display 41 of the optotype projection system 4 based on a command from the subjective test processing unit 144.

[0048] The subjective test processing unit 144 prescribes a state in which the convergence distance changes stepwise in a distance range from a position farther than the test distance to a position closer than the test distance by controlling to gradually change the parallax, which is the difference in the positions of the two patterns reflected on the retinas of the left and right test eyes EL, ER. The subjective test processing unit 144 obtains a subjective answer from the subject when the left and right test eyes EL, ER attempt fusion in response to the stepwise change in the convergence distance.

[0049] The objective measurement unit 145 is executed in parallel with the processing in the subjective test processing unit 144. When the objective measurement unit 145 attempts fusion of the left and right test eyes EL, ER with respect to the change in the convergence distance, the objective measurement unit 145 measures the eye characteristics of the left and right test eyes EL, ER using the objective measurement optical systems 6, 7, and obtains the objective refraction value as the objective measurement information. Here, the processing in the subjective test processing unit 144 is a process of prescribing a state in which the convergence distance changes stepwise. For this reason, the objective measurement unit 145 measures the eye characteristics of the left and right test eyes EL, ER a predetermined number of times at each stage of the changing convergence distance, and obtains the objective refraction average value obtained by averaging the objective refraction values ​​obtained at each stage a predetermined number of times as the objective measurement information.

[0050] The determination unit 146 determines the adaptability of the left and right test eyes EL, ER to stereoscopic vision based on the subject's subjective response obtained by the subjective test processing unit 144 and the objective refraction value (Ref value) obtained by the objective measurement unit 145. The determination unit 146 determines that the left and right test eyes EL, ER are easily adapted to stereoscopic vision when a positive subjective response is obtained for binocular fusion regardless of the change in the convergence distance and the change range of the objective refraction value is suppressed within a predetermined range regardless of the change in the convergence distance. The determination unit 146 determines that the left and right test eyes EL, ER are not easily adapted to stereoscopic vision when a negative subjective response is obtained for binocular fusion when the convergence distance changes and the change range of the objective refraction value exceeds a predetermined range when the convergence distance changes.

[0051] [Configuration and operation flow of the process for evaluating the ability to adapt to stereoscopic vision (Fig. 4)] The configuration and operation flow of the process for evaluating the adaptability to stereoscopic vision executed in the adaptability evaluation test unit 143 will be described below with reference to the flowchart shown in Fig. 4. Fig. 4 shows an example of the operation of the adaptability evaluation test unit 143.

[0052] Step S1 is a preliminary measurement step in which the main controller 141 acquires eye characteristics including the refractive values ​​of the left and right test eyes EL and ER based on the captured image of the ring image. The preliminary measurement is performed two or more times, and the same type of measurement conditions may be determined by each preliminary measurement performed so that the measurement conditions converge each time. In each preliminary measurement, at least one of the light amount from the reflective measurement light source 61, the exposure time of the image sensor 59, the detection sensitivity of the image sensor 59, and the control contents for the focusing lens 74 is determined based on the obtained ring image.

[0053] Step S2 is a main measurement step in which the main controller 141 measures the objective refraction values ​​of the left and right test eyes EL, ER under the measurement conditions determined by the last performed preliminary measurement. The measurement of the objective refraction values ​​of the left and right test eyes EL, ER is performed in the following procedure. First, the main controller 141 projects a ring-shaped light beam (infrared light) for objective measurement onto the fundus ELf, ERf of the left and right test eyes EL, ER using the refraction measurement projection system 6. Then, the main controller 141 detects (receives) the return light of the ring-shaped light beam from the fundus ELf, ERf using the refraction measurement light receiving system 7, and obtains the objective refraction values ​​of the left and right test eyes EL, ER based on the image signal from the image sensor 59 using a well-known method.

[0054] Step S3 is a subjective test start setting step in which the main controller 141 sets the subjective test start for each of the left and right test eyes EL, ER. Here, "subjective test start setting" refers to adjusting the position of the focusing lens 45 in the optotype projection system 4 so that the spherical powers of the left and right test eyes EL, ER are perfectly corrected at the test distance of far vision based on the refractive values ​​of the left and right test eyes EL, ER obtained in this measurement.

[0055] Step S4 is an RG test step in which the main controller 141 performs an RG test using an RG chart. Here, the term "RG test" refers to a test in which the RG chart is used to subjectively check whether the correction state of each of the left and right test eyes EL, ER is a perfect correction state (proper) (whether overcorrection or undercorrection is not occurring) using a characteristic of light called chromatic aberration. Also, the "RG chart" is, for example, a red icon with optotypes of numbers of different sizes and ◎ and ◯ symbols of different sizes, and a green icon with an optotype of the same shape as the red icon, arranged side by side. In the RG test, the shorter the wavelength of light is, the greater the power at the refracting surface is, due to the characteristics of the ocular optic body, so that light of green wavelength is imaged at a position shifted toward the incident side compared to light of red wavelength. Therefore, when the left and right test eyes EL, ER are in an undercorrected state, the red optotype is more clearly seen, and when the left and right test eyes EL, ER are in an overcorrected state, the green optotype is more clearly seen. Therefore, the subject repeats steps S4 and S5 until the green and red targets on the RG chart are evenly viewed, and performs an operation to adjust the spherical power (corrective power) of the left and right test eyes EL, ER by changing the position of the focusing lens 45. As a result, the left and right test eyes EL, ER are in a state where perfect correction values ​​are prescribed based on the provisionally determined values ​​in the RG test.

[0056] Steps S1 to S4 correspond to a complete correction prescription step in which the left and right test eyes EL, ER are placed in a state where the complete correction value in the subjective test is prescribed. However, the complete correction value of the left and right test eyes EL, ER does not have to be the provisionally determined value in the RG test in the first embodiment, but may be, for example, any of values ​​measured separately, prescription values ​​for the current glasses, or values ​​determined by a series of subjective eye tests. At this time, the eye position of the test eyes EL, ER may be corrected by performing a strabismus or cross-eyes test.

[0057] Step S5 is a target presentation step in which the subjective test processing unit 144 sets an initial parallax angle and a test distance, and matches the convergence distance to the convergence position when the left eye projected target and the right eye projected target are fused with the test distance from the left and right test eyes EL, ER to the target position. Step S5 performs parallax angle control to set the initial parallax angle to 0° where the no-parallax condition is established, and performs focusing lens control to set the test distance from the left and right test eyes EL, ER to a position of, for example, 1 m. This step S5 corresponds to a target presentation step in which, following the prescription of the perfect correction value, the left eye projected target and the right eye projected target having the same pattern at the same vertical position relative to the target frame on the display 41 (target presentation unit) are presented at a target position a certain test distance away from the left and right test eyes EL, ER.

[0058] Step S6 is a subjective answer step in which the subjective test processing unit 144 acquires a subjective answer regarding the fusion of the left eye projected optotype and the right eye projected optotype when the convergence distance and the test distance are matched. As the subjective answer, for example, an answer is acquired as to whether the optotypes are seen as one by the fusion of the left eye projected optotype and the right eye projected optotype. Here, if the optotypes are not seen as one, it is confirmed whether the subject's eye is properly performing the test, and if not, the settings are reset to an appropriate state, and if it is, the test is stopped, or the eye position is corrected so that the optotypes are seen as one, and the test may be continued.

[0059] Step S7 is a parallax angle changing process step in which the subjective test processing unit 144 changes the parallax angle stepwise from the initial parallax angle 0° to the next parallax angle while maintaining the test distance (for example, 1 m). For example, the parallax angle is changed from the initial parallax angle 0° to the initial parallax angle of +0.5° in the approaching direction, changed from the initial parallax angle 0.5° to the final crossed parallax angle of +5°, then returned to the initial parallax angle 0°, and then changed to the initial parallax angle of -0.5° in the receding direction, and changed in 11 steps (0°, ±0.5°, ±1°, ±2°, ±3°, ±5°) from the initial parallax angle -0.5° to the final parallax angle -5°. In this example, the test is performed in a direction approaching the subject's eye from a parallax angle of 0°, and then the parallax angle is returned to 0° after changing to a predetermined parallax angle, and the test is performed in a direction away from the parallax angle. However, the present invention is not limited to this, and the test in the direction away from the parallax angle may be performed first, and then the test in the direction approaching. When switching between the approaching direction and the receding direction, the subjective test processing unit 144 may perform the test again when the parallax angle is returned to 0°, and then continue the test. Furthermore, the subjective test processing unit 144 expresses "parallax" by a parallax angle (in degrees) which is the angular difference of the eyeball when both eyes gaze at two optotypes. However, "parallax" may be expressed by a parallax distance (for example, in pixels, mm, cm, etc.) in the left-right direction of two patterns at the position of the test distance, other than by expressing it by the parallax angle. Here, the description will be made assuming that the parallax angle in the direction of inward rotation of the eye is positive, and the parallax angle in the direction of outward rotation of the eye is negative.

[0060] Step S8 is a subjective answer step in which the subjective test processing unit 144 obtains a subjective answer regarding the fusion of the left eye projected target and the right eye projected target from the subject when the subject attempts fusion with the left and right eyes EL and ER in response to a gradual change in the convergence distance. For example, the subjective answer is obtained as to whether the target is seen as one object due to fusion.

[0061] Step S9 is a final parallax angle determination step in which the subjective test processing unit 144 determines whether the parallax angle has been changed to the final parallax angle (for example, -5°). If the result of step S9 is NO, the process returns to step S7, and if the result of step S9 is YES, the process proceeds to step S13.

[0062] Steps S7 and S9 correspond to a convergence distance control step for prescribing a state in which the convergence distance from the positions of the left and right test eyes EL, ER to the convergence position where the two lines of sight intersect is changed by controlling the change in the parallax angle from the left and right test eyes EL, ER toward the left eye projection target and the right eye projection target. Steps S6 and S8 correspond to a subjective answer acquisition step for acquiring a subjective answer regarding fusion from the test subject when fusion is attempted with the left and right test eyes EL, ER in response to the change in the convergence distance.

[0063] Step S10 is a refraction measurement step in which the objective measurement unit 145 measures the ocular characteristics of the left and right test eyes EL, ER in response to a change in the convergence distance using an objective measurement optical system, and obtains an objective refraction value as objective measurement information. Step S11 is a refraction value display step in which the objective measurement unit 145 displays a plurality of objective refraction values ​​(refraction values) obtained at the timing when the parallax angle changes. Step S12 is a refraction average calculation step in which the objective measurement unit 145 compares a plurality of refraction values ​​obtained at the timing when the parallax angle changes, and calculates an average value. These steps S10 to S12 are executed in parallel with the control of the convergence distance, and correspond to an accommodation response amount measurement step in which, when fusion is attempted with the left and right test eyes EL, ER in response to a change in the convergence distance, the ocular characteristics of the left and right test eyes EL, ER are measured using an objective measurement optical system, and an objective refraction value is obtained as objective measurement information.

[0064] Step S13 is a step in which the judgment unit 146 judges the adaptability of the left and right test eyes EL, ER to stereoscopic vision based on the subjective answer from the subjective test processing unit 144 and the objective refraction value (average refraction value) from the objective measurement unit 145. When the judgment of the adaptability of stereoscopic vision is completed, step S13 proceeds to the end. This step S13 corresponds to a judgment step in which the adaptability of the left and right test eyes EL, ER to stereoscopic vision is judged based on the subjective answer and the objective refraction value.

[0065] The flow of the action of each step is explained as follows. The process in Fig. 4 starts when the subject places his / her face in a predetermined position facing the ophthalmic examination device 100, and the alignment is completed to properly adjust the positional relationship between the left and right test eyes EL, ER and the device, and proceeds to step S1 → step S2 → step S3 → step S4. After starting, the main control unit 141 performs a preliminary measurement (step S1), a main measurement (step S2), and a start setting for the subjective test (step S3). In step S4, after setting the start of the subjective test, the main control unit 141 performs an RG test using an RG chart, so that the left and right test eyes EL, ER are in a state where perfect correction values ​​are prescribed based on the provisionally determined values ​​in the RG test.

[0066] 4, after the perfect correction value is prescribed for the left and right test eyes EL, ER in step S4, the process proceeds from step S5 to step S6. In step S5, the subjective test processing unit 144 controls the target switching in the main control unit 141 to set the parallax angle to an initial parallax angle of 0°, and controls the movement of the focusing lens 45 to set the test distance to a constant distance. In step S6, the subjective test processing unit 144 obtains a subjective answer from the subject regarding fusion when the convergence distance and the test distance are matched.

[0067] In the process of FIG. 4, after a subjective answer regarding image fusion in the initial setting is acquired from the subject, the process proceeds to step S7, step S8, and step S9. In step S7, the subjective test processing unit 144 performs target switching control in the main control unit 141, which switches the parallax angle from the initial parallax angle of 0°, where the convergence distance is the target position, to the next parallax angle (e.g., +0.5°) while ensuring the switching time and the parallax angle maintenance time. In step S8, the subjective test processing unit 144 acquires a subjective answer regarding image fusion when the parallax angle is switched from the subject. In step S9, the subjective test processing unit 144 determines whether the parallax angle has been changed to the final parallax angle (e.g., -5°) where the convergence distance from the left and right test eyes EL and ER is the longest.

[0068] 4, while it is determined in step S9 that the parallax angle has not been changed to the final parallax angle (for example, -5°), the flow of proceeding from step S7 to step S8 to step S9 is repeated. In step S7, the subjective test processing unit 144 controls the parallax angle to be changed from the current parallax angle to the next parallax angle by the target switching control in the main control unit 141. The stepwise switching of the parallax angle is 0° (no parallax) → parallax angle +0.5° → parallax angle +1° → parallax angle +2° → parallax angle +3° → parallax angle +5° → parallax angle -0.5° → parallax angle -1° → parallax angle -2° → parallax angle -3° → parallax angle -5°, and the convergence distance from the left and right test eyes EL, ER to the virtual position is changed stepwise. In step S8, the subjective test processing unit 144 acquires a subjective answer regarding image fusion at each stage of the switched parallax angle from the subject.

[0069] In the process of FIG. 4, when the subjective test processing unit 144 performs control to make the convergence distance and the test distance coincide with each other in step S5, the objective measurement unit 145 starts objective measurement in parallel with the subjective test process. During the subjective test process, the objective measurement repeats a flow of proceeding from step S10 to step S11 to step S12, and ends when the subjective test process ends (YES in step S9). In step S10, the objective measurement unit 145 acquires an objective refraction value (Ref value) as objective measurement information by the Refraction measurement. In step S11, the objective measurement unit 145 displays a plurality of objective refraction values ​​(Ref values) acquired at the timing when the parallax angle changes. In step S12, the objective measurement unit 145 compares a plurality of Refraction values ​​acquired at the timing when the parallax angle changes, and calculates an average value.

[0070] 4, when it is determined in step S9 that the parallax angle has been changed to the final parallax angle (for example, -5°), the process proceeds from step S9 to step S13. In step S13, the determination unit 146 determines the adaptability of the left and right test eyes EL, ER to stereoscopic vision based on the subjective answer from the subjective test processing unit 144 and the objective refraction value (average refraction value) from the objective measurement unit 145.

[0071] In this way, the flow of the process of evaluating the adaptability to stereoscopic vision is to execute the subjective test process and the objective measurement in parallel, and when the subjective test process is completed, it merges with the objective measurement in step S13. Step S13 determines that the left and right test eyes EL, ER are easily adapted to stereoscopic vision when, for example, the subjective answer that binocular fusion is achieved is obtained regardless of the gradual change in the convergence distance and the change in the average refraction value is suppressed within a predetermined range. Step S13 determines that the left and right test eyes EL, ER are difficult to adapt to stereoscopic vision when, for example, the subjective answer that the target is seen as two due to the gradual change in the convergence distance is obtained and binocular fusion is not achieved, or the change in the average refraction value exceeds a predetermined range.

[0072] [Left eye projected target and right eye projected target (Figure 5)] The left eye projected visual target 8L and the right eye projected visual target 8R set on the display 41 (visual target presenting unit) will be described below with reference to FIG.

[0073] The left eye projection optotype 8L is a optotype projected onto the left eye EL when the adaptability test unit 143 performs an evaluation test of the adaptability of stereoscopic vision. The right eye projection optotype 8R is a optotype projected onto the right eye ER when the adaptability test unit 143 performs an evaluation test of the adaptability of stereoscopic vision. The left eye projection optotype 8L and the right eye projection optotype 8R are common in that they have rectangular optotype frames 81L, 81R made of liquid crystal frames or the like, and asterisks 82L, 82R (patterns) with the same design, size, and line width inside the optotype frames 81L, 81R. Here, the asterisks 82L, 82R have their design, size, and line width determined so as to provide an appropriate fusion stimulus to the left and right eyes EL, ER when fusion is performed in which images reflected on the retina when viewed with both eyes are combined into one and viewed as a single image.

[0074] As shown in Fig. 5A, the pair of the left eye projected optotype 8L and the right eye projected optotype 8R at the initial parallax angle is set with two asterisks 82L (0°), 82R (0°) at the center position in the left-right direction inside the optotype frames 81L, 81R. Therefore, when fusion is attempted with the left and right test eyes EL, ER, the two asterisks 82L (0°), 82R (0°) set the optotype position away from the left and right test eyes EL, ER by the test distance as the fusion position, and the no-parallax condition is established.

[0075] The pair of optotypes, 8L projected to the left eye and 8R projected to the right eye, with a parallax angle that makes the convergence distance longer than the test distance, is set as an optotype for stereoscopic vision with parallax by changing the left-right positions of two asterisks 82L (-5°) and 82R (-5°) relative to the optotype frames 81L and 81R, as shown in FIG. 5B. The asterisk 82L (-5°) is set at a position offset outward (left side) from the center position in the left-right direction in the optotype frame 81L. The asterisk 82R (-5°) is set at a position offset outward (right side) from the center position in the left-right direction in the optotype frame 81R. Therefore, when fusion is attempted without crossing the lines of sight from the left and right test eyes EL and ER, the two asterisks 82L (-5°) and 82R (-5°) are set at a position receding further back than the optotype position, which is the fusion position.

[0076] As shown in Fig. 5B, the pair of optotypes 8L and 8R projected to the left eye includes asterisks 82L and 82R with parallax angles of -0.5°, -1°, -2°, and -3°, in addition to the asterisks 82L and 82R with a parallax angle of -5°. Each asterisk 82L and 82R is set at an offset position determined in stages between the positions of asterisks 82L (-0.5°), 82R (-0.5°) shown by the dashed lines in Fig. 5B and the positions of asterisks 82L (-5°), 82R (-5°) shown by the solid lines in Fig. 5B. Therefore, when fusion is attempted by crossing the lines of sight from the left and right test eyes EL, ER, each asterisk 82L, 82R can be determined as the fusion position at the position where the amount of receding further back than the parallax position increases gradually from a parallax angle of -0.5° to a parallax angle of -5°.

[0077] The pair of optotypes, the left eye projected optotype 8L and the right eye projected optotype 8R, with a parallax angle that makes the convergence distance closer than the test distance, is set as an optotype for stereoscopic vision with parallax by changing the left and right positions of two asterisks 82L (+5°) and 82R (+5°) relative to the optotype frames 81L and 81R, as shown in FIG. 5C. The asterisk 82L (+5°) is set at a position offset inward (right side) from the center position in the left and right direction in the optotype frame 81L. The asterisk 82R (+5°) is set at a position offset inward (left side) from the center position in the left and right direction in the optotype frame 81R. Therefore, when the two asterisks 82L (+5°) and 82R (+5°) are crossed and fusion is attempted, the position that protrudes forward from the optotype position is set as the fusion position.

[0078] As shown in Fig. 5C, the pair of optotypes 8L projected to the left eye and 8R projected to the right eye includes asterisks 82L and 82R with a parallax angle of +5°, as well as asterisks 82L and 82R with parallax angles of +0.5°, +1°, +2°, and +3°. Each asterisk 82L and 82R is set at an offset position determined in stages between the positions of asterisks 82L (+0.5°), 82R (+0.5°) shown by the dashed lines in Fig. 5C and the positions of asterisks 82L (+5°), 82R (+5°) shown by the solid lines in Fig. 5C. Therefore, when fusion is attempted by crossing the lines of sight from the left and right test eyes EL, ER, each asterisk 82L, 82R can be determined as the fusion position at the position where the amount by which it protrudes forward from the parallax position increases stepwise from a parallax angle of +0.5° to a parallax angle of +5°.

[0079] In addition, since the fusional stimulus is weak when the target frames 81L and 81R are liquid crystal frames, the fusional stimulus can be increased by using a black frame with a thick line width. Furthermore, the strength of the fusional stimulus can be made variable by changing the line width of the black frame of the target frames 81L and 81R. Furthermore, the strength of the fusional stimulus can be made variable by changing the size or the width of the radial line segments of the asterisks 82L and 82R. Furthermore, the strength of the fusional stimulus can be made variable by changing the target design of the asterisks 82L and 82R to another design.

[0080] [Relationship between test distance and convergence distance (Fig. 6)] The subjective test processing unit 144 prescribes a state in which the convergence distance from the positions of the left and right test eyes EL, ER to the convergence position where the two lines of sight intersect is changed by controlling to change the parallax angle, which is the difference in the positions of the two asterisks 82L, 82R reflected on the retinas of the left and right test eyes EL, ER. The relationship between the convergence distance and the test distance is explained as follows with reference to FIG. 6.

[0081] As shown in FIG. 6, the "test distance Lid" refers to the distance along the Z-axis direction from the left and right test eyes EL, ER to the target position where the target is presented. This test distance Lid is realized by the target projection system 4 that presents the target on the display 41. The test distance Lid can also be said to be the focusing distance when the left and right test eyes EL, ER are focused on the target. The convergence distance refers to the distance along the Z-axis direction from the positions of the left and right test eyes EL, ER to the convergence position where the two lines of sight intersect. Here, the test distance Lid is the distance from the straight line connecting the left and right test eyes EL, ER to the target, but is not limited to this and may be the distance from each of the test eyes EL, ER to the target.

[0082] The convergence distance L3 is the distance along the Z-axis direction from the position of the left and right test eyes EL, ER to the convergence position R3 where the two lines of sight SL3, SL3 intersect when the two lines of sight SL3, SL3 from the left and right test eyes EL, ER are gazed at two asterisks 82L, 82R without intersecting, as shown in Fig. 6. Therefore, the convergence distance L3 is longer than the test distance Lid to the target position where the pair of the left eye projected target 8L and the right eye projected target 8R are presented.

[0083] The convergence distance L2 is the distance along the Z-axis direction from the position of the left and right test eyes EL, ER to the convergence position R2 where the two lines of sight SL2, SL2 from the left and right test eyes EL, ER intersect when the two lines of sight SL2, SL2 intersect at the target position, as shown in Fig. 6. Therefore, the convergence distance L2 coincides with the test distance Lid to the target position where the pair of the left eye projected target 8L and the right eye projected target 8R are presented.

[0084] The convergence distance L1 is the distance along the Z-axis direction from the position of the left and right test eyes EL, ER to the convergence position R1 where the two lines of sight SL1, SR1 intersect when the two lines of sight SL1, SL1 from the left and right test eyes EL, ER intersect and gaze at two asterisks 82L, 82R, as shown in Fig. 6. Therefore, the convergence distance L2 is shorter than the test distance Lid to the target position where the pair of targets, the left eye projected target 8L and the right eye projected target 8R, are presented.

[0085] Here, the two asterisks 82L, 82R are presented at positions separated by the parallax distance. The parallax angle at the convergence position R3 obtained when the two lines of sight SL3, SR3 do not cross is parallax angle (R3) = (convergence angle θ3 - vergence angle θ2), which is a negative value because it is in the direction of receding. The parallax angle at the convergence position R1 obtained when the two lines of sight SL1, SR1 cross is parallax angle (R1) = (convergence angle θ1 - vergence angle θ2), which is a positive value because it is in the direction of approaching.

[0086] Assume that the test distance is kept at test distance Lid, and the convergence distance is changed, for example, from convergence distance L2 to convergence distance L3. The convergence angle at this time changes from the convergence angle θ2 at which the lines of sight SL2, SL2 intersect to the convergence angle θ3 (<θ2) at which the lines of sight SL3, SL3 intersect. Therefore, the left and right test eyes EL, ER generate eyeball movement in the direction in which the left and right test eyes EL, ER move apart as the convergence angle changes from the convergence angle θ2 to the convergence angle θ3, and this eyeball movement becomes a stimulus that relieves the convergence.

[0087] Assume that the test distance is kept at the test distance Lid, and the convergence distance is changed, for example, from the convergence distance L2 to the convergence distance L1. The convergence angle at this time changes from the convergence angle θ2 at which the lines of sight SL2, SL2 intersect to the convergence angle θ1 (>θ2) at which the lines of sight SL1, SL1 intersect. Therefore, the left and right test eyes EL, ER generate eyeball movement in a direction in which the left and right test eyes EL, ER move closer together as the convergence angle changes from the convergence angle θ2 to the convergence angle θ1, and this eyeball movement becomes a convergence stimulus.

[0088] On the other hand, since the test distance Lid is kept constant, the focus accommodation distance of the left and right test eyes EL, ER is also constant. Therefore, since the focus accommodation distance of the left and right test eyes EL, ER is kept constant, the accommodation function due to the change in the test distance Lid does not work even if the convergence distance is changed from L3 to L1, and when the left and right test eyes EL, ER are objectively measured, in principle, the objective refraction value should not change. However, when the left and right test eyes EL, ER are objectively measured, the objective refraction value changes when the left and right test eyes EL, ER are objectively measured, if the accommodation function that changes the curvature of the crystalline lens is activated in response to the convergence stimulus.

[0089] As described above, the relationship in which the inspection distance is constant and the convergence distance changes becomes a relationship in which only a convergence stimulus is applied to the left and right eyes to be inspected EL and ER. Therefore, the adaptation evaluation inspection unit 143 of the first embodiment arranges two visual targets at positions at a constant distance from the left and right eyes to be inspected EL and ER, and when fusing the two visual targets with both eyes, a convergence stimulus is applied due to the change in the parallax angle, and a configuration is adopted to reproduce a state in which a discrepancy occurs between convergence and accommodation. For this reason, the adaptation evaluation inspection unit 143 can evaluate whether the left and right eyes to be inspected EL and ER are likely to adapt to stereoscopic vision in which a discrepancy occurs between convergence and accommodation.

[0090] [Stepwise Change Action of Convergence Distance (Fig. 7)] The subjective inspection processing unit 144 prescribes a state in which the convergence position R and the convergence distance L change stepwise within a distance range from a position farther than the inspection distance Lid to a position closer than the inspection distance Lid by controlling the parallax angle to change stepwise. The change action of the convergence distance L will be described as follows with reference to Fig. 7.

[0091] Fig. 7A shows a state in which the convergence distance L(0°) to the convergence position R(0°) when fusing two asterisks 82L(0°) and 82R(0°) is made to coincide with the inspection distance Lid from the left and right eyes to be inspected EL and ER to the visual target position (step S5). Fig. 7B shows a state in which the convergence distance L(+5°) to the convergence position R(+5°) when fusing two asterisks 82L(+5°) and 82R(+5°) with the lines of sight crossed is shorter than the inspection distance Lid from the left and right eyes to be inspected EL and ER to the visual target position. Note that the convergence distance L has a relationship such that it becomes shorter as a visual target with a larger parallax angle is selected, such as L(+0.5°) > L(+1°) > L(+2°) > L(+3°) > L(+5°). Fig. 7C shows a state in which the convergence distance L(-5°) to the convergence position R(-5°) when fusing two asterisks 82L(-5°) and 82R(-5°) without crossing the lines of sight is longer than the inspection distance Lid from the left and right eyes to be inspected EL and ER to the visual target position. Note that the convergence distance L has a relationship such that it becomes longer as a visual target with a larger parallax angle is selected, such as L(-0.5°) < L(-1°) < L(-2°) < L(-3°) < L(-5°).

[0092] In step S5 in Fig. 4, the subjective test processing unit 144 performs control to set the test distance Lid to 1 m and also performs control to set the parallax angle to the initial parallax angle (0°). Therefore, when the initial parallax angle (0°) is selected, the convergence position R (0°) when two asterisks 82L (0°) and 82R (0°) are fused coincides with the target position as shown in Fig. 7A.

[0093] In step S7 of Fig. 4, the subjective test processing unit 144 performs control to change the parallax angle in 11 steps of 0°, ±0.5°, ±1°, ±2°, ±3°, and ±5° while maintaining the test distance Lid (for example, 1 m). Therefore, when the parallax angle -0.5° is selected, the convergence position R (-0.5°) when the two asterisks 82L (-0.5°) and 82R (-0.5°) are fused is a position farther than the test distance Lid. When the parallax angle is controlled to be changed in five steps of -0.5° → -1° → -2° → -3° → -5°, the convergence position R becomes a position that is gradually farther from the left and right test eyes EL and ER in an area farther than the test distance Lid. When a parallax angle of -5° is selected, the convergence position R (-5°) when the two asterisks 82L (-5°) and 82R (-5°) are fused becomes the farthest position from the left and right test eyes EL, ER, as shown in Figure 7C.

[0094] On the other hand, when the parallax angle +0.5° is selected, the convergence position R (+0.5°) when the two asterisks 82L (+0.5°) and 82R (+0.5°) are fused is closer than the test distance Lid. When the cross parallax angle is controlled to change in five steps of 0.5° → +1° → +2° → +3° → +5°, the convergence position R is closer to the left and right test eyes EL, ER in a region closer than the test distance Lid. When the parallax angle +5° is selected, the convergence position R (+5°) when the two asterisks 82L (+5°) and 82R (+5°) are fused is closest to the left and right test eyes EL, ER as shown in FIG. 7B.

[0095] In this way, when the subjective test processing unit 144 performs control to change the parallax angle stepwise, a state of approaching the test distance Lid and a state of moving away from the test distance Lid are changed stepwise. Therefore, the subjective test processing unit 144 can provide a stepwise changing convergence stimulus to the left and right test eyes EL, ER by changing the convergence distance L (±n°) stepwise from a state farther than the test distance Lid to a state closer than the test distance Lid.

[0096] In addition, in the case of fusion by the parallel method without crossing the line of sight, the brain recognizes the two asterisks 82L (-5°) and 82R (-5°) of the left eye projection target 8L and the right eye projection target 8R as being superimposed on the retinas of the left and right test eyes EL and ER, as shown in Figure 7C. Therefore, the two line of sight frames 81L and 81R are centered on the asterisks 82L (-5°) and 82R (-5°) that are overlapped by fusion, and the frames are partially overlapped in a mutually shifted positional relationship. Therefore, the asterisks 82L (-5°) and 82R (-5°) that are fused at a position farther away from the target position can be made to appear to be recessed from the line of sight frames 81L and 81R by directing the appearance of the overlapping part of the two frames.

[0097] Similarly, in the crossing fusion method in which the lines of sight are crossed, the brain recognizes the two asterisks 82L (+5°) and 82R (+5°) of the left eye projection target 8L and the right eye projection target 8R as being superimposed on the retinas of the left and right test eyes EL and ER, as shown in FIG. 7B. Therefore, the two line of sight frames 81L and 81R are centered on the asterisks 82L (+5°) and 82R (+5°) that are overlapped by fusion, and the frames are partially overlapped in a mutually shifted positional relationship. Therefore, the asterisks 82L (+5°) and 82R (+5°) that are fused closer to the line of sight position can be made to appear to be protruding from the line of sight frames 81L and 81R by directing the appearance of the overlapping part of the two frames.

[0098] [Measurement of time changes in accommodation and vergence while observing 3D images (Figure 8)] The inventors measured the changes in accommodation and convergence over time when observing a stereoscopic image for the normal group of test eyes and the fatigue group of test eyes separately. The measurement of the changes in accommodation and convergence over time when observing a stereoscopic image will be described below with reference to Figs. 8A to 8E.

[0099] The visual target was a real visual target that appears three-dimensional with the naked eye, as shown in Figure 8A, and a stereoscopic image was observed using an autostereoscopic display with the real visual target. The viewing distance of the autostereoscopic display from the left and right test eyes was 60 cm, the parallax distance was 4 cm (parallax angle 3.8 degrees), and the protrusion amount of the stereoscopic image was 24 cm. As shown in Figure 8B, the measurement conditions were to maintain a parallax of 0 degrees for 1 to 2 seconds, change the crossed parallax from 0 degrees to 3.8 degrees over 2 seconds, and then fix the crossed parallax at 3.8 degrees.

[0100] The measurement results for a normal eye are shown in Figure 8C. When the crossed disparity is changed from 0 degrees to 3.8 degrees over two seconds, the convergence (MA) value decreases in accordance with the change in crossed disparity. When the crossed disparity is fixed at 3.8 degrees, the value fluctuates slightly, but the value at the protruding position after the decrease is maintained. "MA (short for Meter Angle)" is the unit of convergence force. When the crossed disparity is changed from 0 degrees to 3.8 degrees over two seconds, the focus adjustment function for the protruding position activates and the value decreases. However, when the crossed disparity is fixed at 3.8 degrees, the decreased value returns to the original value with good response, and the original value is maintained thereafter. "D (diopter)" is the unit of refractive power expressed as a number.

[0101] The measurement results of the stereoscopic image fatigue group are shown in Figure 8D. The measurement results of convergence (MA) and refraction (D) in Figure 8D(a) are examples of subjects who experienced headaches and eye fatigue after watching an IMAX movie ("IMAX" is a registered trademark) for about 15 minutes and stopped watching. Here, "IMAX movie" refers to a movie with high-definition images that uses a special standard (a standard in which the area of ​​the film used per frame is expanded from the usual 35 mm to 70 mm) moving image film and is screened by a special projection system. Both the convergence (MA) and refraction (D) show chaotic characteristics, including large value fluctuations and interruptions in the middle of the value, regardless of whether the cross parallax changes or is maintained.

[0102] The measurement results of vergence (MA) and refractive index (D) in Figure 8D(b) are examples of subjects who felt strong drowsiness and eye fatigue after watching a 3D movie for about 30 minutes, and stopped watching. Here, "3D movie" refers to a movie in which the image projected on the screen is viewed in three dimensions by wearing special glasses. When the crossed disparity is changed from 0 degrees to 3.8 degrees over two seconds, the value of vergence (MA) at the start of the change is lower than that of a normal eye example, but the value decreases following the change in the crossed disparity. When the crossed disparity is fixed at 3.8 degrees, vergence (MA) tries to maintain the value according to the protruding position, but the value is interrupted midway, showing a disordered characteristic. When the crossed disparity is changed from 0 degrees to 3.8 degrees over two seconds, the value of refractive index (D) decreases due to the focus adjustment function for this protruding position. When the dioptric power (D) is fixed at a crossed parallax of 3.8 degrees, it shows a disturbed characteristic due to fluctuations in the value that attempt to return the lowered value to the original value and interruptions in the value along the way.

[0103] An example of the analysis result of the time-varying frequency of the refraction (D) in the healthy group and the fatigue group is shown in FIG. 8E. When comparing the amplitude of the healthy group and the fatigue group, the amplitude (fluctuation range) is larger in the fatigue group than in the healthy group in all frequency bands of 0.5-1.5 Hz, 1.5-2.5 Hz, 2.5-3.5 Hz, and 3.5-4.5 Hz. Therefore, when the amplitude (fluctuation range) of the time-varying frequency of the refraction (D) of the subject's eye is measured, the analysis result example shown in FIG. 8E can be used for data that confirms that the subject's eye belongs to the fatigue group based on the magnitude of the fluctuation range. In particular, in the low frequency band, it can be used for data that confirms that the subject's eye belongs to the fatigue group based on the magnitude of the fluctuation range.

[0104] For example, in the low frequency band of 0.5 to 1.5 Hz, as shown in FIG. 8E, the threshold for judging whether the subject's eye belongs to the fatigue group is set to an amplitude of about 0.2 to 0.3. In this case, a stereoscopic vision adaptability evaluation test is performed on a specific subject's eye, and objective refraction data is acquired in a time series along the time axis, and the amplitude of the objective refraction characteristic of the data in the low frequency band of 0.5 to 1.5 Hz is measured. If the measured amplitude of the low frequency band is equal to or greater than the predetermined judgment threshold, the subject's eye can be judged to belong to the fatigue group. Here, the test was performed by changing the convergence distance with a naked eye stereoscopic display, but the present invention is not limited to this. For example, the image projected to the left and right eyes by the internal target can be changed to present an image with a changed line of sight angle to each of the left and right eyes, and a similar test can be performed.

[0105] [Stereoscopic Vision Adaptability Assessment (Figure 9)] The objective measurement unit 145 measures the eye characteristics of the left and right test eyes EL, ER a predetermined number of times at each stage of the convergence distance L, and obtains an average objective refraction value obtained by averaging the objective refraction values ​​obtained at each stage a predetermined number of times as objective measurement information. The function of determining the adaptability to stereoscopic vision is described below with reference to FIG. 9.

[0106] FIG. 9 shows the relationship characteristics between the disparity angle and the objective refraction value when the average objective refraction value was obtained for multiple subjects at each stage of the convergence distance L. The vertical axis is the objective refraction value, and the unit of each value is diopter (D). The horizontal axis is the disparity angle, and the unit of each value is angle (degrees). However, instead of the disparity angle, it may be converted to diopter (D) or the convergence angle (MA), which is expressed as the reciprocal of the convergence distance.

[0107] Among the relationship characteristics in Fig. 9, the first group G1 shows a characteristic that the numerical value of the objective refraction value tends to increase in response to the change in the parallax angle when the parallax angle is changed in seven steps from -0.5°→0°→+0.5°→+1°→+2°→+3°→+5°. In other words, the first group G1 has a characteristic that the numerical value of the objective refraction value increases to about D=3.0 when the cross parallax angle is changed from -0.5°→+1°→+2°→+3°→+5°.

[0108] For this reason, it is estimated that the subjects belonging to the first group G1 induce a focus accommodation response in the left and right test eyes EL, ER when a convergence stimulus is given due to a change in the convergence distance. Therefore, it can be determined that the left and right test eyes EL, ER of the subjects belonging to the first group G1 have difficulty adapting to stereoscopic vision.

[0109] On the other hand, in the relationship characteristics of FIG. 9, the second group G2 changes the parallax angle from -0.5° to 0° to + When the parallax angle is switched in seven steps from 0.5°→+1°→+2°→+3°→+5°, the objective refraction value remains stable. In other words, the second group G2 has a characteristic that the objective refraction value remains small, at D<1.0 or less, even when the parallax angle is changed from -0.5°→0°→+0.5°→+1°→+2°→+3°→+5°.

[0110] Therefore, it is estimated that the subjects belonging to the second group G2 do not induce a focus accommodation response in the left and right test eyes EL, ER, even though the convergence stimulus is given by changing the convergence distance. Therefore, the subjects belonging to the second group G2 can be judged to have a high adaptability to stereoscopic vision in the left and right test eyes EL, ER because there is no mismatch between the refractive value and the target position due to convergence.

[0111] [Effects of ophthalmic examination device and ophthalmic examination method] (1) The ophthalmic examination device 100 includes a target projection system 4 having a target presentation unit (display 41) that presents fixation targets to the left and right test eyes EL, ER, objective measurement optical systems 6, 7 that objectively measure the eye characteristics of the left and right test eyes EL, ER, and a control unit 140 that controls each unit of the device. The fixation targets are a left eye projected target 8L and a right eye projected target 8R that are projected onto the left and right test eyes EL, ER, respectively, and have the same patterns (asterisks 82L, 82R) at the same vertical position relative to the target frame 81. The target presentation unit presents the left eye projected target 8L and the right eye projected target 8R at target positions that are a certain test distance Lid away from the left and right test eyes EL, ER. The target projection system 4 prescribes a state in which the convergence distance L from the position of the left and right test eyes EL, ER to the convergence position R where the two lines of sight intersect is changed by changing the parallax, which is the difference in the positions of the two patterns (asterisks 82L, 82R) projected on the retinas of the left and right test eyes EL, ER. When the control unit 140 attempts to fuse the left and right test eyes EL, ER in response to the change in the convergence distance L, it measures the ocular characteristics of the left and right test eyes EL, ER using the objective measurement optical system and obtains objective refraction values ​​as objective measurement information. Therefore, the ophthalmic examination apparatus 100 can evaluate whether the left and right test eyes EL, ER are easily adapted to stereoscopic vision in which a mismatch between convergence and accommodation occurs.

[0112] (2) The ophthalmic examination device 100 is an objective measurement device with a subjective test function. The control unit 140 has an adaptation evaluation test unit 143 that evaluates the adaptability of the left and right test eyes EL, ER, and the adaptation evaluation test unit 143 includes a subjective test processing unit 144 and an objective measurement unit 145. The subjective test processing unit 144 presents a left eye projected optotype 8L and a right eye projected optotype 8R at an optotype position that is a certain test distance Lid away from the left and right test eyes EL, ER. By controlling to change the parallax (parallax angle), which is the difference in the positions of two patterns (asterisks 82L, 82R) reflected on the retinas of the left and right test eyes EL, ER, a state in which the convergence distance L from the positions of the left and right test eyes EL, ER to the convergence position R where the two lines of sight intersect is changed is prescribed. The objective measurement unit 145 is executed in parallel with the processing in the subjective test processing unit 144, and when fusion is attempted with the left and right test eyes EL, ER in response to a change in the convergence distance L, the objective measurement optical systems 6, 7 measure the eye characteristics of the left and right test eyes EL, ER, and obtain objective refraction values ​​as objective measurement information. Therefore, the ophthalmic examination apparatus 100 can save the effort and time required for the subjective examination compared to when the subjective examination processing is performed by manual operation. In addition, the ophthalmic examination apparatus 100 can accurately evaluate whether the left and right test eyes EL, ER are easily adapted to stereoscopic vision by simultaneously executing the subjective examination processing and the objective measurement in parallel processing.

[0113] (3) The left eye projection target 8L and the right eye projection target 8R are set as stereoscopic targets with parallax by changing the left and right positions of the two patterns (asterisks 82L, 82R) relative to the target frames 81L, 81R by changing the left and right positions of the patterns (asterisks 82L, 82R) displayed on the left and right targets. The subjective test processing unit 144 controls the parallax change by changing the parallax angle or the parallax distance when attempting to fuse the two patterns (asterisks 82L, 82R) by binocular vision. For this reason, when controlling the change of the parallax angle or the parallax distance, the subjective test processing unit 144 can make the fused asterisks 82L, 82R appear to be recessed or protruding relative to the line of sight frames 81L, 81R, whose overlap is shifted left and right. In addition, since the ophthalmic examination device 100 simply changes the pair of visual targets presented while keeping the visual axis and the optical axis aligned, it is possible to measure the eye position and gaze direction from the anterior eye image to confirm whether or not binocular vision is objectively achieved by the left and right test eyes EL, ER.

[0114] (4) The subjective test processing unit 144 acquires a subjective answer from the subject when the left and right test eyes EL, ER are attempted to fuse in response to a change in the convergence distance. The adaptation evaluation test unit 143 has, in addition to the subjective test processing unit 144 and the objective measurement unit 145, a judgment unit 146 that judges the adaptability of the left and right test eyes EL, ER to stereoscopic vision based on the subjective answer from the subject acquired by the subjective test processing unit 144 and the objective refraction value acquired by the objective measurement unit 145. Therefore, the judgment unit 146 can confirm whether or not the left and right test eyes EL, ER are subjectively fused when judging the adaptability of the left and right test eyes EL, ER to stereoscopic vision.

[0115] (5) The judgment unit 146 judges that the left and right test eyes EL, ER are easily adapted to stereoscopic vision when a positive subjective response is obtained for binocular fusion in response to a change in the convergence distance L and the change range of the objective refraction value is suppressed within a predetermined range. Therefore, the judgment unit 146 can judge that the left and right test eyes EL, ER are easily adapted to stereoscopic vision when a convergence stimulus is given by a change in the convergence distance L, subjective fusion is possible and the focus accommodation response of the left and right test eyes EL, ER is slow.

[0116] (6) The judgment unit 146 judges that the left and right test eyes EL, ER are difficult to adapt to stereoscopic vision when a negative subjective response is obtained for binocular fusion in response to a change in the convergence distance L and the change width of the objective refraction value exceeds a predetermined range. Therefore, the judgment unit 146 can judge that the left and right test eyes EL, ER are difficult to adapt to stereoscopic vision when a convergence stimulus is given by a change in the convergence distance L, subjective fusion is difficult, and a focus accommodation reaction occurs in the left and right test eyes EL, ER.

[0117] (7) The adaptability evaluation test unit 143 has a judgment unit 146 that judges the adaptability of the left and right test eyes EL, ER to stereoscopic vision based on the objective refraction value acquired by the objective measurement unit 145, in addition to the subjective test processing unit 144 and the objective measurement unit 145. The judgment unit 146 measures the amplitude, which is the fluctuation range of the refraction value characteristic on the time axis of the objective refraction value acquired by the objective measurement unit 145, and judges that the left and right test eyes EL, ER belong to the fatigue group when the amplitude is equal to or greater than the judgment threshold value when the fluctuation frequency of the refraction value characteristic is in the low frequency band. Therefore, the judgment unit 146 can judge that the left and right test eyes EL, ER belong to the fatigue group that is difficult to adapt to stereoscopic vision based on the refraction value characteristic on the time axis of the acquired objective refraction value.

[0118] (8) The subjective test processing unit 144 prescribes a state in which the convergence distance L changes stepwise in a distance range from a position farther than the test distance Lid to a position closer than the test distance Lid by controlling the parallax (parallax angle) which is the difference in the positions of the two patterns (asterisks 82L, 82R) reflected on the retinas of the left and right test eyes EL, ER to change stepwise. The objective measurement unit 145 measures the eye characteristics of the left and right test eyes EL, ER a predetermined number of times at each stage of the convergence distance L, and obtains an objective refraction average value obtained by averaging the objective refraction values ​​obtained at each stage a predetermined number of times as objective measurement information. Therefore, the subjective test processing unit 144 can give a stepwise changing convergence stimulus to the left and right test eyes EL, ER. In addition, the objective measurement unit 145 can obtain information representing the amount of accommodation reaction of the left and right test eyes EL, ER to the stepwise changing convergence stimulus from the objective refraction average value which is the objective measurement information.

[0119] (9) The ophthalmic examination method includes a complete correction prescription step (steps S1 to S4), a target presentation step (step S5), a convergence distance control step (steps S7 and S9), an accommodation response measurement step (steps S10 to S12), and a judgment step (step S13). In the complete correction prescription step, the left and right test eyes EL, ER are placed in a state in which a complete correction value is prescribed in a subjective test. In the target presentation step, following the prescription of the complete correction value, a left eye projected target 8L and a right eye projected target 8R having the same pattern (asterisk 82L, 82R) at the same vertical position relative to a target frame 81 in the target presentation unit (display 41) are presented at a target position a certain test distance Lid away from the left and right test eyes EL, ER. The convergence distance control step prescribes a state in which the convergence distance L from the position of the left and right test eyes EL, ER to the convergence position R where the two lines of sight intersect is changed by controlling the parallax (parallax angle), which is the difference in the positions of the two patterns (asterisks 82L, 82R) reflected on the retinas of the left and right test eyes EL, ER. The accommodation reaction amount measurement step is executed in parallel with the control of the convergence distance L, and when fusion is attempted by the left and right test eyes EL, ER in response to the change in the convergence distance L, the ocular characteristics of the left and right test eyes EL, ER are measured by the objective measurement optical systems 6, 7, and objective refraction values ​​are obtained as objective measurement information. The judgment step judges the adaptability of the left and right test eyes EL, ER to stereoscopic vision based on the objective refraction values. Therefore, the ophthalmic examination method (FIG. 4) can evaluate whether the left and right test eyes EL, ER are easily adapted to stereoscopic vision in which a mismatch between convergence and accommodation occurs. In addition, the ophthalmic examination method (Figure 4) can also train the left and right test eyes EL, ER to improve their ability to adapt to stereoscopic vision by utilizing the convergence distance control step to have the left and right test eyes EL, ER repeatedly observe images with shifted convergence distance L and become accustomed to them.

[0120] (10) The ophthalmic examination method includes a subjective answer acquisition step (steps S6 and S8) for acquiring a subjective answer regarding fusion from the subject when fusion is attempted with the left and right test eyes EL, ER in response to a change in convergence distance. The determination step determines the adaptability of the left and right test eyes EL, ER to stereoscopic vision based on the subjective answer and the objective refraction value. Therefore, the ophthalmic examination method (FIG. 4) can confirm whether or not fusion is subjectively achieved when determining the adaptability of the left and right test eyes EL, ER to stereoscopic vision. EXAMPLES

[0121] Example 2 is an example of prescribing a state in which the convergence distance L changes steplessly within a distance range from a position farther than the test distance Lid to a position closer to the test distance Lid. Note that Example 2 has the same configuration as that of Example 1 in Figs. 1, 2, and 3 with respect to "overall configuration of the device," "configuration of the optical system," and "configuration of the control unit," and therefore illustrations and explanations thereof are omitted.

[0122] [Configuration and operation flow of the process for evaluating the ability to adapt to stereoscopic vision (Figure 10)] The configuration and operation flow of the process for evaluating the adaptability to stereoscopic vision, which is executed in the adaptability evaluation test unit 143, will be described below with reference to the flowchart shown in FIG. It should be noted that steps S21, S22, S23, S24, S25, and S26 are the same processing steps as steps S1, S2, S3, S4, S5, and S6 in FIG. 4, respectively, and therefore their explanation will be omitted.

[0123] Step S27 is a parallax angle change processing step in which the subjective test processing unit 144 performs video target control of the main control unit 141 to change the parallax angle steplessly from the initial parallax angle (0°) or the previous parallax angle while maintaining the test distance (for example, 1 m). The left eye projected target 8L and the right eye projected target 8R of the second embodiment are set on the display 41 (target presenting unit) as targets for stereoscopic vision by video. Therefore, the two asterisks 42L and 42R change their positions steplessly from the position of the initial parallax angle (0°) to the position of the parallax angle (+5°). After that, the two asterisks 42L and 42R change their positions steplessly from the position of the parallax angle (+5°) to the position of the initial parallax angle (0°). Next, the two asterisks 42L and 42R change their positions steplessly from the position of the initial parallax angle (0°) to the position of the final parallax angle (-5°).

[0124] Step S28 is a subjective answer step in which the subjective test processing unit 144 acquires a subjective answer regarding the fusion of the left eye projected optotype and the right eye projected optotype when the left and right test eyes EL, ER are attempted to fuse with respect to a stepless change in the convergence distance from the subject. As the subjective answer, for example, when the convergence distance is changing steplessly, an answer as to whether the optotypes are seen as one by fusion is acquired at a predetermined time interval. Note that when the subjective answer is prompted, the change in the parallax angle may be temporarily stopped.

[0125] Step S29 is a final crossed parallax angle determination step in which the subjective test processing unit 144 determines whether the parallax angle has reached the final crossed parallax angle (±5°). While the determination in step S29 is NO, the process returns to step S27, and if the determination in step S29 is YES, the process proceeds to step S33. Note that in step S29, the time required for the parallax angle to reach the final crossed parallax angle (±5°) at the parallax angle change speed at which the parallax angle changes steplessly may be preset, and it may be determined whether the set time has elapsed.

[0126] Steps S27 and S29 correspond to a convergence distance control step for prescribing a state in which the convergence distance from the positions of the left and right test eyes EL, ER to the convergence position where the two lines of sight intersect is changed by controlling to change the parallax angle, which is the difference in the positions of the two asterisks 82L, 82R (designs) reflected on the left and right test eyes EL, ER. Steps S26 and S28 correspond to a subjective answer acquisition step for acquiring a subjective answer regarding fusion from the test subject when fusion is attempted with the left and right test eyes EL, ER in response to the change in the convergence distance.

[0127] Step S30 is a refraction measurement step in which the objective measurement unit 145 measures the ocular characteristics of the left and right test eyes EL, ER with respect to the change in the convergence distance by the objective measurement optical system, and acquires the objective refraction value in a time series as the objective measurement information. Step S31 is a refraction value display step in which the objective measurement unit 145 displays the objective refraction value (refraction value) in a time series acquired while the parallax angle changes steplessly. Step S32 is a time series refraction value comparison step in which the objective measurement unit 145 compares the refraction values ​​in a time series acquired while the parallax angle changes steplessly. These steps S30 to S32 are executed in parallel with the control of the convergence distance, and correspond to an accommodation reaction amount measurement step in which, when fusion is attempted with the left and right test eyes EL, ER with respect to the change in the convergence distance, the ocular characteristics of the left and right test eyes EL, ER are measured by the objective measurement optical system, and the objective refraction value is acquired as the objective measurement information.

[0128] Step S33 is a step in which the judgment unit 146 judges the adaptability of the left and right test eyes EL, ER to stereoscopic vision based on the subjective answer from the subjective test processing unit 144 and the objective refraction value (time-series refraction value) from the objective measurement unit 145. When the judgment of the adaptability of stereoscopic vision is completed, step S33 proceeds to the end. This step S33 corresponds to a judgment step in which the adaptability of the left and right test eyes EL, ER to stereoscopic vision is judged based on the subjective answer and the objective refraction value.

[0129] The flow of the action of each step is explained as follows. In the process of FIG. 10, after a subjective answer regarding fusion when the convergence distance and the test distance are matched is acquired from the subject in step S26, the process proceeds to step S27, step S28, and step S29. In step S27, the subjective test processing unit 144 controls the display speed of the moving target of the main control unit 141 that changes the parallax angle steplessly from the initial parallax angle (0°) to the parallax angle (e.g., +5°) at which the convergence distance is the shortest. In step S28, the subjective test processing unit 144 acquires a subjective answer regarding fusion when the parallax angle is changed to (e.g., +0.5°) from the subject. In step S29, the subjective test processing unit 144 determines whether the disparity angle is continuously changed to a final disparity angle (e.g., +5°) in the direction in which the convergence distance becomes closer, then changed to an initial disparity angle (e.g., 0°), and then changed to the final disparity angle (e.g., -5°) in which the convergence distance is the furthest.

[0130] 10, the flow of steps S27 → S28 → S29 is repeated while it is determined in step S29 that the parallax angle has not been changed to the final parallax angle (±5°). In step S27, the subjective test processing unit 144 controls the display speed of the moving target of the main control unit 141 that changes the parallax angle steplessly. In step S28, the subjective test processing unit 144 acquires subjective answers regarding image fusion at predetermined time intervals from the subject while the parallax angle is being changed steplessly.

[0131] In the process of FIG. 9, when the subjective test processing unit 144 performs control to make the convergence distance and the test distance coincide with each other in step S25, the objective measurement unit 145 starts objective measurement in parallel with the subjective test process. During the subjective test process, the objective measurement repeats a flow of proceeding from step S30 to step S31 to step S32, and ends when the subjective test process ends (YES in step S29) in accordance with the end of the subjective test process. In step S30, the objective measurement unit 145 acquires a time-series objective refraction value (Ref value) as objective measurement information by the Refraction measurement. In step S31, the objective measurement unit 145 displays the acquired time-series Refraction value. In step S32, the objective measurement unit 145 compares the time-series Refraction values.

[0132] 9, when it is determined in step S29 that the parallax angle has reached the final parallax angle (for example, −5°), the process proceeds from step S29 to step S33. In step S33, the determination unit 146 determines the adaptability of the left and right test eyes EL, ER to stereoscopic vision based on the subjective answer from the subjective test processing unit 144 and the time-series objective refraction value from the objective measurement unit 145.

[0133] In this way, the flow of the process for evaluating the adaptability to stereoscopic vision is to execute the subjective test process and the objective measurement in parallel, and when the subjective test process is completed, it merges with the objective measurement in step S33. Step S33 determines that the left and right test eyes EL, ER are easily adapted to stereoscopic vision when, for example, a subjective answer is obtained that binocular fusion has been achieved regardless of the stepless change in the convergence distance, and the change in the objective refraction value over time is suppressed within a predetermined range. Step S33 determines that the left and right test eyes EL, ER are difficult to adapt to stereoscopic vision when, for example, a subjective answer is obtained that the visual target appears as two objects due to the stepless change in the convergence distance, and binocular fusion has not been achieved, or the change in the objective refraction value over time exceeds a predetermined range. Furthermore, by obtaining the objective refraction value over time in response to the convergence stimulus, the fluctuation of the objective refraction value can also be measured. For example, frequency analysis can be performed to determine that adaptation to stereoscopic vision is difficult when the fluctuation range in a particular frequency band is large.

[0134] [Effects of ophthalmic examination equipment] (11) The subjective test processing unit 144 prescribes a state in which the convergence distance L changes steplessly in a distance range from a position farther than the test distance Lid to a position closer to the test distance Lid by controlling the parallax (parallax angle) which is the difference in the positions of the two patterns (asterisks 82L, 82R) reflected on the retinas of the left and right test eyes EL, ER to change steplessly. The objective measurement unit 145 measures the eye characteristics of the left and right test eyes EL, ER in a state in which the convergence distance L changes steplessly, and obtains objective refraction values ​​measured in time series as objective measurement information. Therefore, the subjective test processing unit 144 can give a convergence stimulus which changes steplessly to the left and right test eyes EL, ER. In addition, the objective measurement unit 145 can measure the fluctuation of the objective refraction value which represents the fluctuation of the accommodation response amount of the left and right test eyes EL, ER to the convergence stimulus which changes steplessly.

[0135] The ophthalmic examination apparatus 100 and the ophthalmic examination method of the first and second embodiments (FIGS. 4 and 9) have been described above with reference to the drawings. However, the specific configurations of the ophthalmic examination apparatus and the ophthalmic examination method of the present invention are not limited to those of the first and second embodiments, and design changes and additions are permitted as long as they do not deviate from the gist of the invention according to each claim of the claims.

[0136] The ophthalmic examination device 100 of the first and second embodiments is an example of an objective measurement device with a subjective test function using an internal target that is equipped with a target presentation function, a phoropter function, and an autoreflex keratometry function. However, the ophthalmic examination device is not limited to the device configuration examples of the first and second embodiments. For example, the ophthalmic examination device may be configured as a composite device consisting of a target projection device that presents a real target and prescribes a state in which the convergence distance changes, and a device with a phoropter function and an autoreflex measurement function. When a real target is presented, a polarizing filter or the like is used to make the target visible to both eyes separately.

[0137] The ophthalmic examination device 100 of the first and second embodiments shows an example in which the control for changing the parallax is performed by controlling the parallax angle (parallax distance) that determines the left-right position of one asterisk 82l, 82R as a design drawn on each of the target frames 81L, 81R. However, the ophthalmic examination device is not limited to the control example of the parallax angle (parallax distance) using a left eye projected target and a right eye projected target by one design as shown in the first and second embodiments. The ophthalmic examination device may be an example in which the control for changing the parallax angle (parallax distance) is performed by using, for example, a target for precision stereoscopic vision in which a plurality of designs are arranged in a target frame.

[0138] The determination unit 146 in the first and second embodiments has been described as an example for determining the adaptability of the left and right test eyes EL, ER to stereoscopic vision based on the subjective answer from the test subject acquired by the subjective test processing unit 144 and the objective refraction value acquired by the objective measurement unit 145. However, the determination unit is not limited to the examples of the determination unit in the first and second embodiments. The determination unit may be, for example, an example for determining the adaptability of the left and right test eyes to stereoscopic vision based only on the objective refraction value.

[0139] The subjective test processing unit 144 of the first embodiment performs control to change the disparity stepwise, and an average objective refraction value is obtained by averaging a predetermined number of objective refraction values ​​obtained at each step. The subjective test processing unit 144 of the second embodiment performs control to change the disparity steplessly, and obtains an objective refraction value measured in a time series. However, the subjective test processing unit is not limited to the first and second embodiments. The subjective test processing unit may perform control to change the disparity stepwise, and obtain an objective refraction value measured in a time series despite the stepwise control of the disparity.

[0140] The ophthalmic examination apparatus and the ophthalmic examination method of the present invention are also acceptable in the following respects. (a) The range of parallax angles may be determined, for example, by assuming the actual values ​​of the 3D images to be viewed or the head-mounted display, so that it is possible to determine whether the range is applicable to a specific stereoscopic image. (b) Images of the anterior eye segment may be continuously acquired during the measurement of the objective refraction value, and alignment may be automatically performed when the alignment is misaligned. (c) The ability of the left and right test eyes EL, ER to adapt to stereoscopic vision may be determined by acquiring anterior eye images in chronological order or at the timing when the parallax angle changes, and determining that the eyes are not able to adapt to stereoscopic vision when a near vision reaction in which the pupils constrict when the convergence distance becomes closer occurs to a predetermined extent or more. (d) The ability of the left and right eyes EL and ER to adapt to stereoscopic vision may be judged by combining a plurality of criteria to calculate an adaptation coefficient to stereoscopic vision. [Explanation of symbols]

[0141] 100 Ophthalmic examination equipment 4 Visual target projection system 41 Display (visual target presentation unit) 6 Reflector measurement projection system (objective measurement optical system) 7 Reflector measurement receiving system (objective measurement optical system) 140 Control section 141 Main control unit 143 Adaptation Assessment and Inspection Department 144 Self-examination Processing Unit 145 Objective Measurement Department 146 Judgment section 8L left eye projection optotype 8R Right eye projection optotype 81L, 81R Target frame 82L, 82R asterisk (design)

Claims

1. a target projection system having a target presenting unit for presenting fixation targets to the left and right eyes to be examined; an objective measurement optical system that objectively measures ocular characteristics of the left and right test eyes; A control unit that controls each unit of the device, the fixation target is a left eye projected target and a right eye projected target which are projected onto the left and right eyes, respectively, and have the same design at the same vertical position with respect to a target frame; the optotype presenting unit presents the left eye projected optotype and the right eye projected optotype at optotype positions spaced a certain test distance from the left and right eyes to be examined, the visual target projection system prescribes a state in which a convergence distance from the positions of the left and right test eyes to a convergence position where the two lines of sight intersect is changed by changing a parallax, which is a difference between the positions of the two patterns projected on the retinas of the left and right test eyes; When fusion is attempted using the left and right test eyes in response to a change in the convergence distance, the control unit measures the eye characteristics of the left and right test eyes using the objective measurement optical system and acquires an objective refraction value as objective measurement information. An ophthalmic examination apparatus comprising:

2. 2. The ophthalmic examination apparatus according to claim 1, The ophthalmic examination apparatus is an objective measurement apparatus having a subjective examination function, The control unit has an adaptation evaluation test unit that evaluates the adaptability of the left and right test eyes, and the adaptation evaluation test unit includes a subjective test processing unit and an objective measurement unit, the subjective test processing unit presents the left eye projected optotype and the right eye projected optotype at optotype positions that are a certain test distance away from the left and right test eyes, and prescribes a state in which a convergence distance from the positions of the left and right test eyes to a convergence position where two lines of sight intersect is changed by controlling to change a parallax, which is a difference in the positions of the two patterns projected on the retinas of the left and right test eyes; The objective measurement unit is executed in parallel with the processing in the subjective test processing unit, and when fusion is attempted with the left and right test eyes in response to a change in the convergence distance, the objective measurement unit measures the ocular characteristics of the left and right test eyes by the objective measurement optical system, and acquires an objective refraction value as objective measurement information. An ophthalmic examination apparatus comprising:

3. 3. The ophthalmic examination apparatus according to claim 2, The left eye projection optotype and the right eye projection optotype are set as optotypes for stereoscopic vision with parallax by making the left and right positions of the patterns displayed on each of the left and right projection optotypes different from each other relative to the optotype frame, The subjective test processing unit controls the parallax to change a parallax angle or a parallax distance when attempting to fuse the two patterns by binocular vision. An ophthalmic examination apparatus comprising:

4. 3. The ophthalmic examination apparatus according to claim 2, the subjective test processing unit acquires a subjective response from the subject when the subject attempts fusion of the left and right eyes to the change in the convergence distance; The adaptation evaluation test unit includes, in addition to the subjective test processing unit and the objective measurement unit, a determination unit that determines the adaptability of the left and right eyes to stereoscopic vision based on the subjective response from the subject acquired by the subjective test processing unit and the objective refraction value acquired by the objective measurement unit. An ophthalmic examination apparatus comprising:

5. 5. The ophthalmic examination apparatus according to claim 4, The determining unit determines that the left and right test eyes are easily adapted to stereoscopic vision when a positive subjective response is obtained for binocular fusion with respect to the change in the convergence distance and the change range of the objective refraction value is suppressed within a predetermined range. An ophthalmic examination apparatus comprising:

6. 5. The ophthalmic examination apparatus according to claim 4, The determining unit determines that the left and right test eyes are difficult to adapt to stereoscopic vision when a negative subjective response is obtained for binocular fusion with respect to the change in the convergence distance and the change in the objective refraction value exceeds a predetermined range. An ophthalmic examination apparatus comprising:

7. 3. The ophthalmic examination apparatus according to claim 2, The adaptation evaluation examination unit has a determination unit that determines the adaptability of the left and right test eyes to stereoscopic vision based on the objective refraction value acquired by the objective measurement unit, in addition to the subjective examination processing unit and the objective measurement unit, The determination unit measures an amplitude, which is a fluctuation range of a refraction value characteristic over a time axis of the objective refraction value acquired by the objective measurement unit, and when a fluctuation frequency of the refraction value characteristic is in a low frequency band, if the amplitude is equal to or greater than a determination threshold value, determines that the left and right test eyes belong to a fatigue group. An ophthalmic examination apparatus comprising:

8. An ophthalmic examination apparatus according to any one of claims 2 to 7, the subjective test processing unit prescribes a state in which the convergence distance changes stepwise in a distance range from a position farther than the test distance to a position closer than the test distance by controlling to gradually change a parallax, which is a difference in the positions of the two patterns reflected on the retinas of the left and right eyes to be examined; The objective measurement unit measures the eye characteristics of the left and right test eyes a predetermined number of times at each stage of the convergence distance, and obtains an average objective refraction value obtained by averaging the objective refraction values ​​obtained at each stage a predetermined number of times as objective measurement information. An ophthalmic examination apparatus comprising:

9. An ophthalmic examination apparatus according to any one of claims 2 to 7, the subjective test processing unit prescribes a state in which the convergence distance changes steplessly within a distance range from a position farther than the test distance to a position closer than the test distance by controlling to change steplessly a parallax, which is a difference between the positions of the two patterns reflected on the retinas of the left and right eyes to be examined; The objective measurement unit measures the eye characteristics of the left and right eyes to be examined while the convergence distance is continuously changed, and acquires objective refraction values ​​measured in a time series as objective measurement information. An ophthalmic examination apparatus comprising:

10. a target projection system having a target presenting unit for presenting fixation targets to the left and right eyes to be examined; an objective measurement optical system that objectively measures ocular characteristics of the left and right test eyes; A control unit that controls each unit of the device, The control unit is a perfect correction prescription step for prescribing the right and left test eyes to a state where a perfect correction value in a subjective test is prescribed; a target presenting step of presenting a left eye projected target and a right eye projected target having the same pattern at the same vertical position with respect to a target frame of the target presenting unit at a target position a certain test distance away from the left and right eyes to be examined, following the prescription of the perfect correction value; a convergence distance control step of prescribing a state in which a convergence distance from the positions of the left and right test eyes to a convergence position where the two lines of sight intersect is changed by controlling to change a parallax, which is a difference between the positions of the two patterns reflected on the retinas of the left and right test eyes; an accommodation reaction amount measuring step, which is executed in parallel with the control of the convergence distance, and measures the eye characteristics of the left and right test eyes by the objective measurement optical system when fusion is attempted with respect to a change in the convergence distance, and obtains an objective refraction value as objective measurement information; and a determining step of determining the adaptability of the left and right eyes to stereoscopic vision based on the objective refraction value. The ophthalmic examination method according to the present invention is characterized in that

11. 11. The ophthalmic examination method according to claim 10, The ophthalmologic examination method includes a subjective answer acquisition step of acquiring a subjective answer regarding the fusion from a subject when the subject attempts fusion with the left and right test eyes in response to a change in the convergence distance, The determining step determines the adaptability of the left and right eyes to stereoscopic vision based on the subjective response and the objective refraction value. The ophthalmic examination method according to the present invention is characterized in that

Images