Ophthalmologic apparatus

Abstract

To provide an ophthalmologic apparatus capable of facilitating detection of the ocular deviation when the brightness difference between visual targets presented to the left and right subject eyes is increased from a binocular vision state.SOLUTION: An ophthalmologic apparatus 1 includes a visual target presentation mechanism (visual target projection system 44) that presents a left-eye visual target OtL to a left subject eye EL and a right-eye visual target OtR to a right subject eye ER. The left-eye visual target OtL and the right-eye visual target OtR are configured in the same manner. The visual target presentation mechanism (visual target projection system 44) presents the left-eye visual target OtL to the left subject eye EL and the right-eye visual target OtR to the right subject eye ER, enlarges a brightness difference of a common portion between the left-eye visual target OtL and the right-eye visual target OtR, and maintains a brightness difference of remaining portions between the left-eye visual target OtL and the right-eye visual target OtR.SELECTED DRAWING: Figure 10

Description

[Technical Field]

[0001] The present disclosure relates to ophthalmic devices. [Background technology]

[0002] Conventionally, an ophthalmic device is known that estimates the degree of fatigue of a subject's eye based on the timing at which fusion is destroyed when the field of view of one of the subjects' eyes is gradually darkened from a state in which the subject is viewing a visual target with both eyes (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2017-169601 Summary of the Invention [Problem to be solved by the invention]

[0004] Conventional ophthalmologic devices acquire the timing at which fusion is destroyed by detecting that the line of sight of one of the examinee's eyes deviates and eye position deviation (gaze deviation) occurs. Therefore, if the conventional ophthalmologic device cannot detect eye position deviation, it cannot acquire the timing at which fusion is destroyed, and it becomes impossible to appropriately estimate the degree of fatigue of the examinee's eye.

[0005] The present invention has been made with a focus on the above-mentioned problem, and aims to provide an ophthalmic device that can easily detect eye position deviation when the brightness difference between the optotypes presented to the left and right eyes to be examined is increased from the binocular vision state. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems, the ophthalmologic device of the present disclosure includes an optotype presentation mechanism that presents a left-eye optotype to the left eye to be examined and a right-eye optotype to the right eye to be examined, the left-eye optotype and the right-eye optotype being of equal configuration, and the optotype presentation mechanism presents the left-eye optotype to the left eye to be examined and the right-eye optotype to the right eye to be examined, and is characterized in that it increases the brightness difference in a portion common to the left-eye optotype and the right-eye optotype while maintaining the brightness difference in the remaining portion between the left-eye optotype and the right-eye optotype. [Effects of the Invention]

[0007] According to the ophthalmologic apparatus of the present disclosure, it is possible to easily detect eye position deviation when the brightness difference between the optotypes presented to the left and right eyes to be examined is increased from the binocular vision state. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a perspective view showing the appearance of an ophthalmologic apparatus according to a first embodiment. [Figure 2] 3 is an explanatory diagram schematically illustrating a driving mechanism of a measurement head of the ophthalmologic apparatus of the first embodiment. FIG. [Figure 3] FIG. 10 is an explanatory diagram showing a convergence angle and a target presentation distance. [Figure 4] 2 is an explanatory diagram showing the configuration of a left measurement optical system of the ophthalmologic apparatus of the first embodiment. FIG. [Figure 5] FIG. 2 is an explanatory diagram showing a visual target for the left eye and a visual target for the right eye according to the first embodiment. [Figure 6] FIG. 6 is an explanatory diagram showing a state in which the first optotype symbol in FIG. 5 is fused. [Figure 7] FIG. 6 is an explanatory diagram showing a state in which the second optotype symbol in FIG. 5 is fused. [Figure 8] 10 is a flowchart showing the flow of an eye fatigue estimation process performed by a control unit of the first embodiment. [Figure 9] 1 is an explanatory diagram showing a right eye and a left eye to be examined seen from the front, and showing corresponding optotypes for the right eye and the left eye below the respective eyes. FIG. [Figure 10]FIG. 9 is an explanatory diagram showing how the brightness of the first optotype symbol for the left eye is reduced, and how the line of sight of the left eye to be examined is accordingly shifted away from the first optotype symbol and directed toward the second optotype symbol. [Figure 11] 11 is an explanatory diagram showing a state in which the line of sight of the left eye to be examined in FIG. 10 is directed toward the second optotype symbol, and the line of sight of the right eye to be examined is directed away from the first optotype symbol and toward the second optotype symbol. [Figure 12] FIG. 10 is an explanatory diagram showing another example of a visual target for the left eye and a visual target for the right eye. DETAILED DESCRIPTION OF THE INVENTION

[0009] An embodiment of an ophthalmic apparatus according to the present disclosure will be described below with reference to FIGS. [Example]

[0010] The ophthalmic apparatus 1 of the first embodiment has an optical system for measuring ocular characteristics of the subject's eye and is capable of objectively and subjectively measuring the ocular characteristics of the subject's eye. An examiner can use the ophthalmic apparatus 1 to perform any objective or subjective examination. In an objective examination, the ophthalmic apparatus 1 irradiates the subject's eye with light and measures (acquires) information about the subject's eye (ocular characteristics) based on the detection result of the returned light. This objective examination includes measurement for acquiring the ocular characteristics of the subject's eye and photography for acquiring an image of the subject's eye. In addition, the objective examination includes objective refraction measurement (REF measurement), corneal topography measurement (KERATOM measurement), intraocular pressure measurement, fundus photography, tomography using optical coherence tomography (OCT photography), measurement using OCT, etc. In the subjective test, the ophthalmologic apparatus 1 presents a visual target or the like to the subject and measures information about the subject's eye (ocular characteristics) based on the subject's response to the visual target or the like. The subjective test includes subjective refraction measurements such as a distance test, intermediate test, near test, contrast test, and glare test, as well as a red-green test and a visual field test.

[0011] The ophthalmic apparatus 1 of the first embodiment is an open-eye type ophthalmic apparatus that can measure the eye characteristics of both eyes simultaneously while the subject keeps both eyes open, as shown in Fig. 1. Note that the ophthalmic apparatus 1 of the first embodiment can also measure the eye characteristics of each eye separately by blocking one eye or turning off the fixation target.

[0012] The ophthalmic apparatus 1 includes a support base 10, a measurement unit 20, an examiner's controller 30, a control unit 40, and a subject's controller (not shown). In the following, when viewed from the subject facing the ophthalmic apparatus 1, the left-right axis in the left-right direction (horizontal direction) is indicated by arrow X (X-axis), the up-down axis in the up-down direction (vertical direction) is indicated by arrow Y (Y-axis), and the direction perpendicular to the left-right and up-down directions (depth direction of the ophthalmic apparatus 1) is the front-back direction (front-back axis) and is indicated by arrow Z (Z-axis).

[0013] The support base 10 has a support column 11 that stands up from the floor and an optometry table 12 supported by the support column 11. The optometry table 12 is a platform on which devices and tools used in optometry, such as the examiner controller 30, are placed and which supports the posture of the examinee. The optometry table 12 may be supported by the support column 11 so that its position in the Y direction (height position) is adjustable.

[0014] The measurement unit 20 has an arm 21 and a measurement head 22. One end of the arm 21 is supported by the tip of the support column 11, and the other end extends from the support column 11 toward the front side (the subject side) along the Z direction, with the measurement head 22 attached to the tip. As a result, the measurement head 22 is suspended from the support column 11 via the arm 21 above the optometry table 12. The arm 21 is movable in the Y direction relative to the support column 11. The arm 21 may also be movable in the X direction or the Z direction relative to the support column 11.

[0015] The measurement head 22 is a location where the eye characteristics of the subject's left eye E (left eye EL) and the subject's right eye E (right eye ER) are measured individually. The measurement head 22 has a left eye drive mechanism 23L and a right eye drive mechanism 23R attached to the tip of the arm 21, a left measurement unit 24L provided below the left eye drive mechanism 23L, and a right measurement unit 24R provided below the right eye drive mechanism 23R.

[0016] The left measurement unit 24L and the right measurement unit 24R are paired to individually correspond to the left eye EL and the right eye ER of the subject. The left measurement unit 24L has a built-in left measurement optical system 25L that measures the ocular characteristics of the left eye EL. The right measurement unit 24R has a built-in right measurement optical system 25R that measures the ocular characteristics of the right eye ER. The measurement results by the left measurement unit 24L and the right measurement unit 24R are output to the control unit 40.

[0017] The left-eye drive mechanism 23L is a mechanism that drives the left measurement unit 24L to move horizontally (in the X direction), move vertically (in the Y direction), rotate in the X direction, and rotate in the Y direction. As shown in FIG. 2, the left-eye drive mechanism 23L includes a left vertical drive unit 26L, a left horizontal drive unit 27L, a left Y-axis rotation drive unit 28L, and a left X-axis rotation drive unit 29L. The right-eye drive mechanism 23R is a mechanism that drives the right measurement unit 24R to move horizontally (in the X direction), move vertically (in the Y direction), rotate in the X direction, and rotate in the Y direction. The right-eye drive mechanism 23R includes a right vertical drive unit 26R, a right horizontal drive unit 27R, a right Y-axis rotation drive unit 28R, and a right X-axis rotation drive unit 29R.

[0018] The left-eye drive mechanism 23L and the right-eye drive mechanism 23R are configured to be plane-symmetrical with respect to a vertical plane located midway between them in the X direction. Hereinafter, unless otherwise described individually, the left-eye drive mechanism 23L and the right-eye drive mechanism 23R will be referred to as drive mechanisms 23, the left measurement unit 24L and the right measurement unit 24R will be referred to as measurement units 24, the left vertical drive unit 26L and the right vertical drive unit 26R will be referred to as vertical drive units 26, the left horizontal drive unit 27L and the right horizontal drive unit 27R will be referred to as horizontal drive units 27, the left Y-axis rotation drive unit 28L and the right Y-axis rotation drive unit 28R will be referred to as Y-axis rotation drive units 28, and the left X-axis rotation drive unit 29L and the right X-axis rotation drive unit 29R will be referred to as X-axis rotation drive units 29.

[0019] Vertical drive unit 26 is provided between arm 21 and horizontal drive unit 27, and moves horizontal drive unit 27 in the Y direction (vertical direction) relative to arm 21. Horizontal drive unit 27 is provided between vertical drive unit 26 and Y-axis rotation drive unit 28, and moves Y-axis rotation drive unit 28 in the X and Z directions (horizontal direction) relative to vertical drive unit 26. Vertical drive unit 26 and horizontal drive unit 27 are configured by providing an actuator that generates a driving force, such as a pulse motor, and a transmission mechanism that transmits the driving force, such as a combination of gears or a rack-and-pinion. Horizontal drive unit 27 can be easily configured and horizontal movement can be easily controlled, for example, by providing a combination of an actuator and a transmission mechanism separately for the X and Z directions.

[0020] The Y-axis rotation drive unit 28 is provided between the horizontal drive unit 27 and the X-axis rotation drive unit 29, and rotates the X-axis rotation drive unit 29 relative to the horizontal drive unit 27 about the Y-axis of ocular rotation that passes through the center of rotation O of the corresponding subject's eye E and extends in the Y direction. The X-axis rotation drive unit 29 is provided between the Y-axis rotation drive unit 28 and the corresponding measurement unit 24, and rotates the corresponding measurement unit 24 relative to the Y-axis rotation drive unit 28 about the X-axis of ocular rotation that passes through the center of rotation O of the corresponding subject's eye E and extends in the X direction.

[0021] The Y-axis rotation drive unit 28 and the X-axis rotation drive unit 29 each have an actuator and a transmission mechanism, similar to the vertical drive unit 26 and the horizontal drive unit 27, and the transmission mechanism receives a driving force from the actuator and moves along an arc-shaped guide groove. The Y-axis rotation drive unit 28 can rotate the measurement unit 24 around the Y-axis of rotation of the corresponding subject's eye E by aligning the center position of the guide groove with the Y-axis of rotation of the eye. The X-axis rotation drive unit 29 can rotate the measurement unit 24 around the X-axis of rotation of the corresponding subject's eye E by aligning the center position of the guide groove with the X-axis of rotation of the eye. In other words, the measurement unit 24 can rotate left and right (rotational directions around the Y-direction) and up and down (rotational directions around the X-direction) around the center of rotation O of the corresponding subject's eye E by aligning the center positions of the guide grooves of the Y-axis rotation drive unit 28 and the X-axis rotation drive unit 29 with the center of rotation O of the corresponding subject's eye E.

[0022] The Y-axis rotation drive unit 28 may support the measurement unit 24 rotatably about a Y-axis rotation axis provided therein, and may cooperate with the horizontal drive unit 27 to rotate the measurement unit 24 via the X-axis rotation drive unit 29 while changing the position at which the measurement unit 24 is supported, thereby rotating the measurement unit 24 about the Y-axis of ocular rotation of the corresponding subject's eye E. The X-axis rotation drive unit 29 may support the measurement unit 24 rotatably about an X-axis rotation axis provided therein, and may cooperate with the vertical drive unit 26 to rotate the measurement unit 24 while changing the position at which the measurement unit 24 is supported, thereby rotating the measurement unit 24 about the X-axis of ocular rotation of the corresponding subject's eye E.

[0023] In this way, the drive mechanism 23 moves the left measurement unit 24L and the right measurement unit 24R in the X, Y, and Z directions, either individually or in conjunction with each other, and also rotates the left measurement unit 24L up, down, left, and right about the center of rotation O of the left subject's eye EL, and rotates the right measurement unit 24R up, down, left, and right about the center of rotation O of the right subject's eye ER. In this way, the drive mechanism 23 can move the left measurement unit 24L and the right measurement unit 24R to desired positions (postures) with respect to the corresponding subject's eyes E.

[0024] The drive mechanism 23 adjusts the positions of the left measurement unit 24L and the right measurement unit 24R to diverge (divergence movement) or converge (convergence movement) the left and right test eyes EL and ER. That is, the drive mechanism 23 (the left-eye drive mechanism 23L and the right-eye drive mechanism 23R) functions as a convergence adjustment mechanism that adjusts the convergence distance Lc. As shown in FIG. 3, the convergence distance Lc is the distance along the Z direction from both test eyes E (EL, ER) to the line-of-sight intersection Is when the left and right test eyes E (EL, ER) are viewed in a planar view. The line-of-sight intersection Is is the position (convergence position) where the line-of-sight direction SL (line of sight) of the left test eye EL intersects with the line-of-sight direction SR (line of sight) of the right test eye ER. The angle between the line-of-sight direction SL and the line-of-sight direction SR is the convergence angle θc. The convergence distance Lc is set by controlling the convergence angle θc.

[0025] In the ophthalmologic apparatus 1 of the first embodiment, the left measurement unit 24L and the right measurement unit 24R are each provided with a deflecting member 24a (see FIGS. 1 and 2). The left measurement optical system 25L and the right measurement optical system 25R acquire the ocular characteristics of the corresponding subject's eye E through the deflecting member 24a. The ophthalmologic apparatus 1 adjusts the positions of the left measurement unit 24L and the right measurement unit 24R so that the deflecting members 24a are positioned corresponding to the left and right subject's eyes E (EL, ER), respectively, thereby enabling simultaneous acquisition of ocular characteristics of both eyes when the subject has both eyes open (binocular vision). The ophthalmologic apparatus 1 can also acquire ocular characteristics of the subject's eye E while it is looking down or up by changing the rotational orientation of the left measurement unit 24L and the right measurement unit 24R around the X-axis of eyeball rotation using the X-axis rotation drive unit 29. The ophthalmologic device 1 can acquire eye characteristics while the subject eye E is looking left or right by changing the rotational posture of the left measurement unit 24L and the right measurement unit 24R around the eyeball rotation Y axis using the Y-axis rotation drive unit 28.

[0026] The examiner's controller 30 is an information processing device that receives operations by the examiner and outputs a control signal to the control unit 40. The examiner's controller 30 is, for example, a tablet terminal or a smartphone, and is separated from the measurement unit 20 so as to be portable by the examiner. The examiner's controller 30 may be a notebook personal computer, a desktop personal computer, or a controller dedicated to the ophthalmic apparatus 1. The examiner's controller 30 exchanges information with the control unit 40 via wireless communication or network communication.

[0027] 1, the examiner's controller 30 includes a display unit 31, and an operation-side control unit and input buttons, both of which are not shown. The display unit 31 is made up of a touch panel display provided on the surface of the examiner's controller 30, and has input buttons set thereon. The operation-side control unit is made up of a microcomputer built into the examiner's controller 30. The operation-side control unit controls the images displayed on the display unit 31 based on the measurement results and detection results transmitted from the control unit 40. The operation-side control unit also outputs control signals to the control unit 40 in response to operations on the input buttons.

[0028] The control unit 40 is an information processing device provided below the optometry table 12. The control unit 40 comprehensively controls each part of the measurement unit 20, including the left measurement optical system 25L and the right measurement optical system 25R, based on a control signal transmitted from the examiner's controller 30. The control unit 40 also transmits to the examiner's controller 30 measurement results of the ocular characteristics of the left and right eyes E (EL, ER) measured by the left measurement unit 24L and the right measurement unit 24R.

[0029] The control unit 40 of the present disclosure can perform an eye fatigue estimation process to estimate eye fatigue of the subject's eye E. In the eye fatigue estimation process, the control unit 40 first controls a target presentation mechanism (a target projection system 44 described later) to present a left-eye target OtL and a right-eye target OtR (see FIG. 5, etc.) as target Ots described later, which are in a manner equal to an arbitrary target presentation distance Lp, to the left subject's eye EL and the right subject's eye ER. At this time, the control unit 40 controls the drive mechanism 23 (the left-eye drive mechanism 23L and the right-eye drive mechanism 23R) to adjust the positions (orientations) of the left measurement unit 24L and the right measurement unit 24R, and set the convergence angle θc to a predetermined angle, thereby setting an arbitrary convergence distance Lc. This convergence distance Lc may be different from or the same as the target presentation distance Lp.

[0030] As shown in FIG. 3, the target presentation distance Lp is the distance along the Z direction from the left eye EL to the target Ot presented to the left eye EL, and the distance along the Z direction from the right eye ER to the target Ot presented to the right eye ER. Here, the target presentation distance Lp for the left eye EL and the target presentation distance Lp for the right eye ER are set to the same distance. In the first embodiment, the target presentation distance Lp can be set by the target projection system 44 (see FIG. 4), which is a target presentation mechanism. The target presentation distance Lp is calculated from the power of the target projection system 44 (the force of deflecting light rays by the lens force) and can be expressed in diopter equivalent value.

[0031] That is, the control unit 40 controls the power of the target projection system 44 by moving the focusing lens 44e of the target projection system 44 so that the target Ot is presented at an arbitrary predetermined distance (target presentation distance Lp) based on the position corresponding to the far point in accordance with the refraction values ​​(spherical equivalent powers) of the left and right eyes E (EL, ER). For example, when the target presentation distance Lp is set to 50 cm, the control unit 40 moves the focusing lens 44e to the position corresponding to the far point of both eyes E (for example, the refraction values ​​of both eyes E are -5.0 D) by the power difference (2.0 D) between when the target Ot is presented at the position corresponding to the far point (zero D) and at 50 cm (2.0 D), thereby changing the power of the target projection system 44 to present the target Ot at a position corresponding to the refraction value of -2.0 D. As a result, the control unit 40 can make the target Ot presented at a position 50 cm away from both eyes E by the target projection system 44.

[0032] Furthermore, when performing the eye fatigue estimation process, the control unit 40 can set the convergence distance Lc, which is determined by the convergence angle θc, to a distance shorter than the target presentation distance Lp. In this case, the control unit 40 maintains the target presentation distance Lp and sets the line-of-sight intersection Is, determined by the positions (orientations) of the left measurement unit 24L and the right measurement unit 24R, to a position closer to the eye (shorter distance) than the target presentation distance Lp. That is, during the eye fatigue estimation process, the control unit 40 sets the convergence angle θc1, determined by the positions (orientations) of the left measurement unit 24L and the right measurement unit 24R, to a value greater than the convergence angle θc2 when viewing the position where the target Ot is presented with both eyes. This allows the left and right test eyes EL and ER to perform a convergence movement so as to view a distance closer than the target presentation distance Lp, thereby rotating the left and right test eyes EL and ER inward (see FIG. 3).

[0033] Next, the subject is instructed to gaze at a common portion of the left eye target OtL and the right eye target OtR and fuse the common portion. In this state, the control unit 40 gradually increases the difference (brightness difference (contrast difference)) between the brightness of a portion of the left eye target OtL (the contrast of the target against the background) and the brightness of at least a portion of the right eye target OtR (the contrast of the target against the background). With the brightness difference increased, the control unit 40 detects the gaze direction SL of the left eye EL and the gaze direction SR of the right eye ER based on the eye information (anterior eye image E' (see FIG. 4)) acquired by the eye information acquisition unit (anterior eye observation system 45, described later) and the rotation angles of the left measurement unit 24L and the right measurement unit 24R.

[0034] To detect the gaze directions SL and SR, the control unit 40 first determines the two-dimensional positions of the pupil centers of the left and right subjects' eyes EL and ER based on the anterior-segment images E' of the left and right subjects' eyes EL and ER, the magnification, and the rotation angles of the left and right measurement units 24L and 24R controlled by the drive mechanism 23. Next, the control unit 40 determines a reference position, which is the two-dimensional position of the bright spot (bright spot image Br) depicted by the XY alignment system 42, based on the anterior-segment images E' of the left and right subjects' eyes EL and ER, the magnification, and the rotation angles of the left and right measurement units 24L and 24R controlled by the drive mechanism 23. The control unit 40 then determines the gaze directions SL and SR based on the reference position and the pupil center positions. The method for determining the gaze directions SL and SR is not limited to the above method, and other well-known methods may be used. Then, the control unit 40 estimates the degree of fatigue (eye strain) of the left and right subjects' eyes EL and ER based on the line of sight SL of the left and right subjects' eyes EL and ER.

[0035] Furthermore, when detecting the line of sight SL of the left eye EL and the line of sight SR of the right eye ER during the eye fatigue estimation process, the control unit 40 detects the focus position (accommodation position) of the left eye EL and the focus position (accommodation position) of the right eye ER based on the eye information (ring image by fundus reflected light) acquired by the eye information acquisition unit (a reflex measurement projection system 46 and a reflex measurement light receiving system 47, which will be described later). The focus position is represented by the refractive power of the left eye EL or the right eye ER when observing the eye at a predetermined position.

[0036] Next, the detailed configurations of the left measurement optical system 25L and the right measurement optical system 25R will be described with reference to Fig. 4. The left measurement optical system 25L and the right measurement optical system 25R have the same configuration. Therefore, in the following, the description of the right measurement optical system 25R will be omitted, and only the left measurement optical system 25L will be described.

[0037] The left measurement optical system 25L is an optical system that performs an examination by presenting any optotype (including the optotype Ot described below) to the left test eye EL. The left measurement optical system 25L includes a Z alignment system 41, an XY alignment system 42, a keratometry system 43, an optotype projection system 44, an anterior eye observation system 45, a reflex measurement projection system 46, and a reflex measurement light-receiving system 47. In the following description, the fundus conjugate position P and the pupil conjugate position Q are used. The fundus conjugate position P is a position that is approximately optically conjugate with the fundus Ef of the left test eye EL after alignment is complete, and refers to an optically conjugate position or a position close to the fundus Ef. The pupil conjugate position Q is a position that is approximately optically conjugate with the pupil of the left test eye EL after alignment is complete, and refers to an optically conjugate position or a position close to the pupil Ef.

[0038] The Z alignment system 41 projects light (infrared light in the first embodiment) onto the left eye EL for alignment in the optical axis direction (front-back direction) of the anterior-segment observation system 45. The Z alignment system 41 emits light from the Z alignment light source 41a, collimates the light with the projection lens 41b, and projects the light onto the cornea Ec of the left eye EL through an alignment hole formed in the keratoplasty plate 43a. Based on the bright spot projected onto the cornea Ec, the controller 40 or the examiner moves the left measurement unit 24L (right measurement unit 24R) and moves the left measurement optical system 25L in the Z axis direction so that the ratio between the distance between two point images formed by the Z alignment light source 41a on the image sensor 45h of the anterior-segment observation system 45 and the diameter of the keratoplasty image falls within a predetermined range. This allows the left measurement optical system 25L to be positioned appropriately in the optical axis direction relative to the left eye EL.

[0039] The XY alignment system 42 irradiates the left eye EL with light (infrared light in the first embodiment) that aligns the left eye EL in the X-axis and Y-axis directions perpendicular to the optical axis (Z-axis) of the anterior-segment observation system 45. The XY alignment system 42 has an XY alignment light source 42a and a projection lens 42b on an optical path branched from the anterior-segment observation system 45 by a half mirror 45c. The XY alignment system 42 causes the light emitted from the XY alignment light source 42a to travel to the anterior-segment observation system 45 through the projection lens 42b. The XY alignment system 42 reflects the light by the half mirror 45c and projects it onto the left eye EL through the anterior-segment observation system 45. The light reflected by the cornea Ec of the left eye EL is guided to the image sensor 45h through the anterior-segment observation system 45. The control unit 40 or the examiner moves the left measurement unit 24L (right measurement unit 24R) in the vertical or horizontal direction based on the bright spot projected on the cornea Ec, thereby performing alignment in directions perpendicular to the optical axis L of the anterior eye observation system 45 (Y direction, vertical direction and X direction, horizontal direction). This allows the left measurement optical system 25L to be positioned appropriately in the X-axis direction and Y-axis direction with respect to the left eye EL to be examined. Note that the alignment method in each of the X, Y, and Z directions is not limited to using the Z alignment system 41 or the XY alignment system 42. For example, a method in which the position of the eye E to be examined can be measured using a stereo camera installed in the ophthalmologic apparatus 1 may also be used.

[0040] Here, an image (bright spot image Br) based on light reflected by the cornea Ec is formed superimposed on the anterior eye image E'. The control unit 40 controls the display unit 31 to display the anterior eye image E' including the bright spot image Br and the alignment mark. When performing XY alignment manually, the examiner uses the examiner controller 30 to move the left measurement optical system 25L in the X-axis and Y-axis directions, and moves it so as to guide the bright spot image into the alignment mark. When performing XY alignment automatically, the control unit 40 moves the left measurement unit 24L (right measurement unit 24R) so as to cancel the displacement of the bright spot image relative to the alignment mark, and moves the left measurement optical system 25L in the X-axis and Y-axis directions.

[0041] The keratometry system 43 projects a ring-shaped light beam (infrared light) onto the cornea Ec of the left subject's eye EL to measure the shape of the cornea Ec. The keratometry system 43 includes a keratometry plate 43a disposed between the objective lens 45a of the anterior segment observation system 45 and the left subject's eye EL, and a keratometry ring light source 43b disposed on its rear side (the side of the objective lens 45a). The keratometry system 43 projects a ring-shaped light beam onto the cornea Ec of the left subject's eye EL by emitting light from the keratometry ring light source 43b through a slit in the keratometry plate 43a. The reflected light (keratometry ring image) from the cornea Ec of the left subject's eye EL can be detected by the imaging element 45h together with the anterior segment image E'. The control unit 40 performs known calculations based on the keratometry ring image to calculate corneal Ec shape parameters that represent the shape of the cornea Ec.

[0042] The target projection system 44 presents various targets, such as a fixation target, a target for subjective testing, and a target Ot, to the left eye EL by setting the target presentation distance Lp to an arbitrary distance. The target projection system 44 includes a display 44a, a half mirror 44b, a relay lens 44c, a reflecting mirror 44d, a focusing lens 44e, a relay lens 44f, a field lens 44g, a variable cross cylinder lens (VCC) 44h, a reflecting mirror 44k, and a pinhole plate 44m. The target projection system 44 shares a dichroic mirror 46h with the reflector measurement projection system 46. The target projection system 44 shares a dichroic mirror 45b and an objective lens 45a with the anterior segment observation system 45. Furthermore, the visual target projection system 44 has at least two glare light sources 44n that irradiate glare light onto the left test eye EL, located on an optical path separate from the optical path leading to the display 44a that displays various visual targets, etc., and at positions surrounding the optical axis.

[0043] The display 44a functions as a target presentation unit that presents various targets and is provided at a fundus conjugate position P on the optical path of the target projection system 44. The display 44a displays fixation targets or dot targets to which the gaze is fixed when performing an objective test or when fogging the left subject's eye EL, or subjective test targets for subjectively testing the ocular characteristics of the left subject's eye EL (such as visual acuity, distance power, and near power). The display 44a may be an electroluminescent (EL) or liquid crystal display (LCD), and can display targets in a desired shape, form, and contrast (brightness). Under the control of the control unit 40, the display 44a can display any target and can arbitrarily change the brightness of the displayed target (the contrast of the target against the background). In Example 1, the display 44a, under the control of the control unit 40, displays the visual target OtL for the left eye (the visual target OtR for the right eye in the right measurement optical system 25R), which is the visual target Ot (see Figure 5, etc.) used in the eye fatigue estimation process, and changes the brightness of part of it as appropriate.

[0044] The visual target projection system 44 reflects light from the display 44a by a half mirror 44b, passes it through a relay lens 44c, reflects it by a reflecting mirror 44d, and passes it through a focusing lens 44e. The visual target projection system 44 passes the light through a relay lens 44f, aligns the direction of travel of the light by a field lens 44g, passes it through a VCC 44h, reflects it by a reflecting mirror 44k, passes it through a dichroic mirror 46h, and is reflected by a dichroic mirror 45b. The visual target projection system 44 projects the light reflected by the dichroic mirror 45b onto the fundus Ef through an objective lens 45a.

[0045] The focusing lens 44e is driven to move back and forth along the optical axis by a drive motor (not shown) controlled by the control unit 40. When the control unit 40 controls the focusing lens 44e to move toward the left eye EL, the spherical power of the left eye EL is changed to a minus diopter (-D), i.e., the refractive index is changed to a minus side. When the control unit 40 controls the focusing lens 44e to move away from the left eye EL, the spherical power of the left eye EL is changed to a plus diopter (+D), i.e., the refractive index is changed to a plus side (distance vision direction). Furthermore, by controlling the driving of the focusing lens 44e to move back and forth, the control unit 40 can change the presentation position of the optotype displayed on the display 44a, i.e., the optotype presentation distance Lp from the left eye EL to the optotype presentation position, to any value. Here, the focusing lens 44 e is configured to move in conjunction with the reflector measurement light source 46 a of the reflector measurement projection system 46 and the focusing lens 47 d of the reflector measurement light receiving system 47 .

[0046] When conducting a subjective test, the control unit 40 moves the focusing lens 44e in the optical axis direction based on the results of the objective measurement, controlling the optotype presentation distance Lp and the spherical power of the left test eye EL. The control unit 40 then displays a predetermined optotype selected by the examiner or the like on the display 44a. This allows the predetermined optotype to be presented to the test subject at the predetermined optotype presentation distance Lp, relative to the left test eye EL, which has been adjusted to a predetermined spherical power. When the test subject responds to the optotype, the control unit 40 receives input of the response. For example, in the case of visual acuity testing, the control unit 40 determines the visual acuity value by repeatedly selecting and presenting the next optotype based on the subject's subjective response to a Landolt ring or the like. Therefore, the optotype projection system 44 functions as a subjective test system.

[0047] For these reasons, the ophthalmologic apparatus 1 can individually present optotypes (including the left-eye optotype OtL) to the left eye EL, and can set the optotype presentation distance Lp to any distance. Therefore, the display 44a of the left measurement optical system 25L serves as a left-eye display that presents the left-eye optotype OtL. The same is true for the right measurement optical system 25R, whose display 44a serves as a right-eye display that presents the right-eye optotype OtR. This allows the ophthalmologic apparatus 1 to individually change the brightness of the optotype presented to the left eye EL and the right eye ER, either partially or entirely, and thereby appropriately increase the brightness difference between the left and right optotypes.

[0048] The pinhole plate 44m is provided at the pupil conjugate position Q in the visual target projection system 44, and in the first embodiment, it is provided between the field lens 44g and the VCC 44h. The pinhole plate 44m is formed by providing a through-hole in a plate member. The pinhole plate 44m can be inserted into and removed from the optical path of the visual target projection system 44 under the control of the control unit 40. When inserted into the optical path, the through-hole is positioned on the optical axis. When the pinhole plate 44m is inserted into the optical path in the subjective test mode, it enables a pinhole test to be performed to determine whether or not the left subject's eye EL can be corrected with glasses. The pinhole plate 44m is also inserted when measuring convergence accommodation, which will be described later. Note that the pinhole plate 44m may be provided at a position on the optical path that is approximately conjugate with the pupil of the left subject's eye EL, and is not limited to the configuration of the first embodiment.

[0049] The anterior-segment observation system 45 observes the anterior segment of the left eye EL to obtain an anterior-segment image E'. The anterior-segment observation system 45 irradiates the anterior segment of the left eye EL with illumination light (infrared light in the first embodiment) from an anterior-segment illumination light source 48. The anterior-segment observation system 45 passes light reflected by the anterior segment of the left eye EL through an objective lens 45a, a dichroic mirror 45b and a half mirror 45c, a relay lens 45d and a relay lens 45e, and a dichroic mirror 45f. The anterior-segment observation system 45 forms an image of the light on the imaging surface of an image sensor 45h using an imaging lens 45g. The imaging surface of the image sensor 45h is located at the pupil conjugate position Q. As a result, an anterior-segment image E' is formed on the imaging element 45h by projecting (emitting) the keratinizing image, the light beam from the Z alignment light source 41a, and the light beam (bright spot image Br) from the XY alignment light source 42a. The imaging element 45h captures images and outputs signals at a predetermined rate, and outputs the video signals to the control unit 40. The control unit 40 displays the anterior-segment image E' (moving image) based on the video signals output from the imaging element 45h on the display unit 31 of the examiner's controller 30. The control unit 40 can also detect the line of sight SL of the left eye EL based on the anterior-segment image E' and the rotation angle of the left measurement unit 24L.

[0050] The refraction measurement projection system 46 and the refraction measurement light-receiving system 47 are objective measurement optical systems used for objective refraction measurement (refraction measurement) that measures the objective refraction value (refraction characteristics) as an ocular characteristic of the left subject's eye EL. The refraction measurement projection system 46 projects a ring-shaped light beam (infrared light) for objective measurement from a refraction measurement light source 46a onto the fundus Ef. The refraction measurement light-receiving system 47 receives the return light of this ring-shaped light beam from the left subject's eye EL. Note that the refraction measurement projection system 46 and the refraction measurement light-receiving system 47 are not limited to the configuration of Example 1, as long as they project a measurement light beam onto the fundus Ef of the left subject's eye EL and acquire the measurement light beam reflected by the fundus Ef as a measurement ring image. Another example of the configuration of the REF measurement projection system 46 and the REF measurement light receiving system 47 is one in which a point-shaped spot light is projected onto the fundus Ef as a measurement light beam, and the measurement light beam (the reflected light beam) reflected by the fundus Ef is converted into a ring-shaped light beam by passing it through a ring-shaped slit or lens, thereby obtaining a measurement ring image.

[0051] In the first embodiment, the reflex measurement light source 46a is an SLD (Super Luminescent Diode) light source, which is a high-brightness light source with a light-emitting diameter equal to or smaller than a predetermined size. The reflex measurement light source 46a is movable in the optical axis direction in conjunction with the focusing lens 44e and the focusing lens 47d, and is disposed at the fundus conjugate position P. The ring diaphragm 46e is a light-transmitting portion formed in a ring shape, and is disposed at the pupil conjugate position Q. The focusing lens 47d is movable in the optical axis direction in conjunction with the reflex measurement light source 46a and the focusing lens 44e. This focusing lens 47d may be a known variable-focus lens whose focal position can be changed under the control of the control unit 40. The imaging surface of the image sensor 45h in the optical system of the reflex measurement light-receiving system 47 is disposed at the fundus conjugate position P.

[0052] The reflective measurement projection system 46 causes light emitted from a reflective measurement light source 46a to pass through a relay lens 46b and be incident on the conical surface of a conical prism 46c. The reflective measurement projection system 46 deflects the light that has entered the conical surface, causing it to exit from the bottom surface of the conical prism 46c, pass through a field lens 46d, and pass through a ring diaphragm 46e (its light-transmitting portion). The reflective measurement projection system 46 reflects the light (ring-shaped light beam) from the reflective surface of an aperture prism 46f, passes through a rotary prism 46g, and is reflected by a dichroic mirror 46h. The reflective measurement projection system 46 reflects the reflected light from a dichroic mirror 45b, passes through an objective lens 45a, and projects it onto the left test eye EL.

[0053] Here, it is desirable that the conical prism 46c be positioned as close as possible to the pupil conjugate position Q. The conical prism 46c may have a ring diaphragm 46e attached to its bottom surface facing the field lens 46d. In this case, for example, a light-shielding film is vapor-deposited on the bottom surface of the conical prism 46c so as to form a ring-shaped light-transmitting portion. Alternatively, the ring diaphragm 46e may be located on the conical surface side of the conical prism 46c.

[0054] Furthermore, the field lens 46d may have a ring diaphragm 46e attached to its lens surface facing the left eye EL. In this case, for example, a light-shielding film is deposited on the lens surface of the field lens 46d to form a ring-shaped light-transmitting portion. The reflex measurement projection system 46 may be configured without the field lens 46d. The ring diaphragm 46e 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 46. The diaphragm may also have two or more light-transmitting portions. The rotary prism 46g is used to average the light intensity distribution of the ring-shaped light beam relative to the blood vessels and diseased areas of the fundus Ef and to reduce speckle noise caused by the light source.

[0055] The reflective measurement light-receiving system 47 passes the returning light of the ring-shaped light beam projected onto the fundus Ef through the objective lens 45a and reflects it off the dichroic mirror 45b and dichroic mirror 46h. The reflective measurement light-receiving system 47 passes the reflected returning light through the rotary prism 46g, the hole in the aperture prism 46f, and the relay lens 47a, reflects it off the reflecting mirror 47b, and passes it through the relay lens 47c and focusing lens 47d. The reflective measurement light-receiving system 47 reflects the transmitted light off the reflecting mirror 47e and the dichroic mirror 45f, and forms an image on the imaging surface of the imaging element 45h via the imaging lens 45g.

[0056] The control unit 40 calculates eye refractive power parameters by performing known calculations based on the output from the image sensor 45h. The eye refractive power parameters include the refraction values ​​(refractive powers), spherical power, astigmatism power, and astigmatism axis angle of the left and right test eyes EL and ER. The control unit 40 comprehensively controls the left and right measurement optical systems 25L and 25R, each of which includes a refraction measurement projection system 46, a refraction measurement light-receiving system 47, and a target projection system 44, as well as each component of the measurement unit 20, based on control signals transmitted from the examiner's controller 30. The control unit 40 also transmits measurement results of the eye characteristics of the left and right test eyes EL and ER measured by the measurement head 122 to the examiner's controller 30.

[0057] Next, the optotype Ot used in the eye fatigue estimation process will be described with reference to FIGS. 5 to 7. The optotype Ot includes a left-eye optotype OtL presented to the left eye EL by the left measurement optical system 25L and a right-eye optotype OtR presented to the right eye ER by the right measurement optical system 25R. The optotype Ot in Example 1 is formed by displaying white symbols on a black background on the displays 44a of the left measurement optical system 25L and the right measurement optical system 25R. As shown in FIG. 5, the left-eye optotype OtL and the right-eye optotype OtR have a first optotype symbol s1 and a second optotype symbol s2 that are identical in shape and size. Hereinafter, when referring to the left-eye optotype OtL individually, they will be referred to as the left first optotype symbol s1L and the left second optotype symbol s2L, and the right-eye optotype OtR individually as the right first optotype symbol s1R and the right second optotype symbol s2LR.

[0058] Both first optotype symbols s1 are asterisks, and are displayed at the center of a rectangular display 44a, such as a liquid crystal frame. Both second optotype symbols s2 are annular symbols surrounding the first optotype symbol s1. When these second optotype symbols s2 are fused, the convergence angle θc is smaller than when both first optotype symbols s1 are fused, and the convergence distance Lc is larger (farther). Specifically, the left second optotype symbol s2L has a center position shifted outward (leftward) than the left first optotype symbol s1L, and the right second optotype symbol s2LR has a center position shifted outward (rightward) than the right first optotype symbol s1R. The left second optotype symbol s2L and the right second optotype symbol s2LR are offset from the center of the display 44a by the same amount of eccentricity. For this reason, the left eye optotype OtL and the right eye optotype OtR are configured as left-right inverted versions of the first optotype symbol s1 and the second optotype symbol s2, which have the same design, size, and line segment width on each display 44a. The design, size, and line segment width of the first optotype symbol s1 and the second optotype symbol s2 are determined so as to provide an appropriate fusion stimulus to the left and right eyes E (EL, ER) to be examined during fusion, in which images reflected on the retina are combined into one and viewed as a single image when viewed with both eyes.

[0059] When the left eye optotype OtL and the right eye optotype OtR are fused with binocular vision by focusing on the first optotype symbol s1, two second optotype symbols s2 appear to overlap on the left and right outside the single first optotype symbol s1, as shown in Fig. 6. When the left eye optotype OtL and the right eye optotype OtR are fused with binocular vision by focusing on the second optotype symbol s2, two first optotype symbols s1 appear to be lined up on the left and right inside the single second optotype symbol s2, as shown in Fig. 7.

[0060] Next, the configuration and operation flow of the eye fatigue estimation process executed in the ophthalmic apparatus 1 will be described with reference to the flowchart shown in Fig. 8. This measurement process is started when a mode for estimating the degree of fatigue of the subject's eye is selected in the ophthalmic apparatus 1.

[0061] In step S1, the eye refractive power is measured, and the process proceeds to step S2. In step S1, the control unit 40 measures the eye refractive power of the left eye EL and the right eye ER. Specifically, the control unit 40 first aligns the left measurement unit 24L with the left eye EL and the right measurement unit 24R with the right eye ER. Next, the control unit 40 performs fogging control while the left eye EL and the right eye ER are fixating on a fixation target, and measures the eye refractive power of each of the left and right eyes E (EL, ER) based on ring images of fundus reflected light obtained using the REF measurement projection system 46 and the REF measurement light receiving system 47. From the measured eye refractive power, the position of the focusing lens 44e in the target projection system 44 is adjusted so that the spherical power of the left eye EL and the right eye ER is fully corrected at the far vision position. Thereafter, a subjective eye examination may be performed to measure the position of the far point in more detail and determine the position of the focusing lens 44e in the target projection system 44.

[0062] In step S2, the optotype Ot is presented, and the process proceeds to step S3. In step S2, the control unit 40 controls the optotype projection system 44 of the left measurement optical system 25L to display the left-eye optotype OtL on its display 44a, and controls the optotype projection system 44 of the right measurement optical system 25R to display the right-eye optotype OtR on its display 44a. At this time, the control unit 40 sets the optotype presentation distance Lp between the left-eye optotype OtL and the right-eye optotype OtR to an arbitrary equal distance, and sets the left-eye optotype OtL and the right-eye optotype OtR to an equal brightness (contrast of the optotype against the background). In addition, the control unit 40 controls the drive mechanism 23 (the left-eye drive mechanism 23L and the right-eye drive mechanism 23R) to adjust the positions (orientations) of the left measurement unit 24L and the right measurement unit 24R, and sets the convergence angle θc with respect to the optotype Ot to an arbitrary angle. In Example 1, the target presentation distance Lp is set to 33 cm, and the convergence distance Lc is adjusted to the target presentation distance Lp, and the convergence angle θc is further adjusted inward by 20Δ (prism) (10Δ for each of the left and right test eyes E (EL, ER)). At this time, the convergence distance Lc when fused to the second target symbol s2 is set to be no greater than the target presentation distance Lp. The target presentation distance Lp and the convergence angle θc may be appropriately set depending on the age, visual acuity, etc. of the test subject, and are not limited to the configuration of Example 1. Additionally, in the ophthalmologic apparatus 1 of Example 1, when the control unit 40 presents the target Ot, the control unit 40 controls the display unit 31 of the examiner's controller 30 to display an anterior eye image E′ of the left test eye EL and the right test eye ER, acquired by the anterior eye observation system 45. The display of the anterior eye image E′ continues until the eye fatigue estimation process is completed.

[0063] In step S3, the reference gaze directions SL and SR are detected, and the process proceeds to step S4. In step S3, the subject is asked to fuse a common portion of the optotype Ot presented in step S2, and the gaze directions SL and SR in that state are detected. In Example 1, after the subject is asked to focus on the first optotype symbol s1 and fusion is confirmed, the control unit 40 detects the reference gaze direction SL of the left subject's eye EL and the reference gaze direction SR of the right subject's eye ER. Therefore, the reference gaze directions SL and SR are the gaze directions of the left subject's eye EL and the right subject's eye ER in a state in which the first optotype symbol s1, which is the common portion of the optotype Ot, is fused. The gaze directions SL and SR are detected based on the anterior segment image E' of the left subject's eye EL and the right subject's eye ER acquired by the anterior segment observation system 45 and the rotation angles of the left measurement unit 24L and the right measurement unit 24R controlled by the drive mechanism 23. Therefore, the anterior eye observation system 45 functions as an eye information acquiring unit that acquires eye information for detecting the gaze direction SL of the left eye EL and the gaze direction SR of the right eye ER. In the ophthalmologic apparatus 1 of the first embodiment, the control unit 40 displays the gaze directions SL and SR (information thereof) that serve as references as the detection results on the display unit 31 of the examiner controller 30.

[0064] If step S3 determines that fusion has not been achieved, the subject gazes at the first optotype symbol s1 again to re-acquire the reference gaze directions SL and SR. This lack of fusion can be determined by a large difference between the convergence angle θc obtained from the acquired gaze directions SL and SR and the convergence angle θc set in step S2, or by the subject reporting that the first optotype symbol s1 appears double. If re-detecting the gaze directions SL and SR does not improve the situation, the control unit 40 may return to step S2, change the optotype presentation distance Lp or the convergence angle θc for presenting the optotype Ot, and then proceed to step S3 again. Fusion can be facilitated by increasing the optotype presentation distance Lp, decreasing the convergence angle θc, shortening the convergence distance Lc and the optotype presentation distance Lp based on the convergence angle θc, or setting the convergence distance Lc and the optotype presentation distance Lp based on the convergence angle θc in consideration of the heterophoria angle of the subject's eye E.

[0065] In step S4, the brightness difference is increased, and the process proceeds to step S5. In step S4, the control unit 40 controls the left and right displays 44a to increase the brightness difference (contrast difference) between the brightness of the left first optotype symbol s1L of the left eye optotype OtL and the brightness of the right first optotype symbol s1R of the right eye optotype OtR by a predetermined amount. In step S4 of the first embodiment, the brightness difference is increased by decreasing the brightness of one of the left first optotype symbol s1L and the right first optotype symbol s1R while fixing (maintaining) the brightness of the other. This brightness difference may be increased continuously or stepwise over time. Therefore, the brightness difference (contrast difference) between the left first optotype symbol s1L and the right first optotype symbol s1R increases continuously or stepwise over time, making the first optotype symbol s1, whose brightness has been decreased, less visible.

[0066] In step S5, the gaze directions SL and SR are detected, and the process proceeds to step S6. In step S5, the control unit 40 detects the gaze direction SL of the left eye EL and the gaze direction SR of the right eye ER, similar to the method of detecting SR in step S3. The control unit 40 displays the gaze directions SL and SR (information thereof) as the detection results on the display unit 31 of the examiner's controller 30.

[0067] In step S6, the focus position is detected, and the process proceeds to step S7. In step S6, the control unit 40 detects the focus position of the left subject eye EL (eye refraction value when observed at a predetermined position) and the focus position of the right subject eye ER (eye refraction value when observed at a predetermined position). The control unit 40 detects the focus position based on a ring image formed by fundus reflected light obtained using the refraction measurement projection system 46 and the refraction measurement light receiving system 47. That is, the control unit 40 determines the focus position (accommodation position) on each visual axis from the refractive power of the left subject eye EL or the right subject eye ER. Therefore, the refraction measurement projection system 46 and the refraction measurement light receiving system 47 function as an eye information acquisition unit that acquires eye information for detecting the focus position of the left subject eye EL and the right subject eye ER.

[0068] In step S7, it is determined whether fusion has been destroyed. If YES (destroyed), the process proceeds to step S8. If NO (not destroyed), the process returns to step S4. In step S7, the control unit 40 determines whether fusion has been destroyed based on the reference gaze directions SL and SR detected in step S3, the gaze directions SL and SR detected in step S5, and the focal positions of the left and right test eyes E (EL, ER) detected in step S6. In Example 1, the control unit 40 determines whether the gaze directions SL and SR have shifted by a predetermined amount (e.g., ±0.5°) from the reference gaze directions SL and SR, determining whether the change in the gaze directions SL and SR (eye position deviation) has occurred. If the change has occurred, the control unit 40 determines that the fusion of the first optotype symbol s1 has been destroyed. The control unit 40 can also determine that fusion has been destroyed when it detects that the gaze directions SL and SR are directed toward the second optotype symbol s2. Whether the eye is directed toward the second optotype symbol s2 can be determined based on the position of the second optotype symbol s2 on the display 44a, and the optotype presentation distance Lp and convergence angle θc of the presented optotype Ot. Furthermore, in the first embodiment, if the focal positions of the left eye EL and the right eye ER deviate from the optotype presentation distance Lp of the optotype Ot by a predetermined amount (for example, ±1.0D in diopter equivalent value) or more, it is determined that the fusion of the first optotype symbol s1 is destroyed.

[0069] In this way, the control unit 40 repeatedly executes the processes from step S4 to step S7 until it determines in step S7 that fusion has been destroyed. As a result, the brightness difference between the left first optotype symbol s1L of the left eye optotype OtL and the right first optotype symbol s1R of the right eye optotype OtR increases over time until the fusion of the first optotype symbol s1 is destroyed. At this time, the display unit 31 continues to display the anterior eye segment images E' of the left and right test eyes E (EL, ER) and the detection results of the gaze directions SL and SR, so the examiner can grasp the condition of the left and right test eyes E (EL, ER) in real time.

[0070] In step S8, the fusional destructive brightness difference is determined, and the process proceeds to step S9. In this step S8, the control unit 40 acquires the fusional destructive brightness difference, which is the brightness difference between the left first optotype symbol s1L and the right first optotype symbol s1R at the time when it was determined in step S7 that fusion was destroyed. The control unit 40 appropriately displays the acquired fusional destructive brightness difference (information thereof) on the display unit 31 of the examiner's controller 30.

[0071] In step S9, eye fatigue is estimated, and the eye fatigue estimation process is terminated. In step S9, the control unit 40 estimates eye fatigue in the left and right test eyes E (EL, ER) based on the information on the fusional destructive brightness difference at the time when it is determined in step S8 that fusion has been destroyed, and appropriately displays the estimated result on the display unit 31 of the examiner's controller 30. For example, the control unit 40 compares the fusional destructive brightness difference of the subject during a different test with the fusional destructive brightness difference of the current test and determines that the subject has a higher level of eye fatigue (more fatigued) if the fusional destructive brightness difference in the current test is smaller (if fusion is destroyed earlier). Alternatively, the control unit 40 may, for example, acquire a typical fusional destructive brightness difference in advance and compare the typical fusional destructive brightness difference with the fusional destructive brightness difference in the current test to determine whether the subject is experiencing eye fatigue. Furthermore, the control unit 40 may, for example, acquire the fusional destructive brightness differences of multiple subjects in advance, determine the relationship between the fusional destructive brightness differences and the degree of fatigue (quantified, etc.), and calculate the degree of eye fatigue from that relationship.

[0072] Next, the flow of operations of the above-mentioned eye fatigue estimation process (each step) will be described. The eye fatigue estimation process starts when the subject faces the ophthalmologic apparatus 1 and places his / her face in a predetermined position, and a mode for estimating the degree of eye fatigue is selected, and proceeds through steps S1, S2, and S3. Then, the control unit 40 measures the ocular refractive power of the left and right eyes E (EL, ER) to be examined, and then presents the eye target Ot at a predetermined eye target presentation distance Lp and convergence angle θc. Then, the control unit 40 detects the reference gaze directions SL and SR of the left and right eyes E (EL, ER) with the first eye target symbol s1, which is a common part of the eye target Ot, fused.

[0073] The eye fatigue estimation process then proceeds from step S4 to step S5 to step S6, where the control unit 40 increases the brightness difference between the left first optotype symbol s1L and the right first optotype symbol s1R to detect the gaze directions SL and SR and the focal positions of the left and right test eyes E (EL, ER). Next, the eye fatigue estimation process proceeds to step S7, where it determines whether fusion has been destroyed based on the reference gaze directions SL and SR, the current gaze directions SL and SR, and the focal positions. The eye fatigue estimation process then repeats steps S4, S5, S6, and S7 until it determines that fusion has been destroyed. If it determines that fusion has been destroyed, it proceeds to steps S8 and S9. The control unit 40 then determines the fusional destruction brightness difference at the time of fusional destruction and estimates eye fatigue based on that fusional destruction brightness difference. Note that the brightness reduction may be performed on only one eye (e.g., the non-dominant eye) or both eyes in turn.

[0074] In this way, the eye fatigue estimation process increases the brightness difference between the left first optotype symbol s1L and the right first optotype symbol s1R while the first optotype symbol s1 is fused through binocular vision, and estimates eye fatigue based on the fusional destruction brightness difference when fusion is destroyed. Therefore, in order to accurately estimate eye fatigue, the eye fatigue estimation process is required to appropriately detect the timing of fusional destruction and obtain an appropriate fusional destruction brightness difference. When increasing the brightness difference, the eye fatigue estimation process detects the current gaze directions SL and SR and checks for any change (eye position deviation) from the reference gaze directions SL and SR to detect the timing of fusional destruction. This eye fatigue estimation process detects the gaze directions SL and SR based on the anterior eye image E' of the actual state of the subject's eye acquired in real time by the anterior eye observation system 45 and the rotation angles of the left measurement unit 24L and the right measurement unit 24R. Therefore, the eye fatigue estimation process can more accurately detect the timing of fusional destruction compared to detecting the timing of fusional destruction based on the subject's response.

[0075] As described above, this eye fatigue estimation process utilizes the fact that when the fusional image of the first optotype symbol s1 is destroyed, the gaze directions SL and SR of the left and right test eyes E (EL, ER) change from the left first optotype symbol s1L and the right first optotype symbol s1R to other directions (eye position deviation). In other words, even if the fusional image of the first optotype symbol s1 is destroyed, if the gaze directions SL and SR do not deviate from the left first optotype symbol s1L and the right first optotype symbol s1R, it becomes impossible to detect that the fusional image has been destroyed.

[0076] Here, if the optotype Ot is composed only of the first optotype symbol s1, the following may occur. For simplicity's sake, it is assumed below that the brightness difference between the left first optotype symbol s1L and the right first optotype symbol s1R is increased by reducing the brightness of the right first optotype symbol s1R. As the brightness of the right first optotype symbol s1R decreases, the right eye ER becomes less able to see the right first optotype symbol s1R, and eventually becomes less able to visually recognize the right first optotype symbol s1R. As a result, the right eye ER no longer has anything to look at, and the state of looking at the first optotype symbol s1 is eliminated, causing the gaze direction SR to deviate from the first optotype symbol s1. Here, if the optotype Ot is composed only of the first optotype symbol s1, when it becomes more difficult to visually recognize the right first optotype symbol s1R, the gaze direction SR may not change from the state of looking at the first optotype symbol s1 because the object to look at no longer exists. As a result, it becomes impossible to detect a change in the line of sight direction SR, and therefore it becomes impossible to properly detect the timing at which fusion is destroyed.

[0077] Furthermore, since the optotype Ot is displayed and presented on the display 44a, if the optotype Ot is formed by displaying a white symbol on a black background as in Example 1, reducing the brightness of the right first optotype symbol s1R (substantially turning it off) will make the edge of the display 44a stand out. This is because reducing the brightness of the right first optotype symbol s1R darkens the entire screen, and the edge of the display 44a appears to glow faintly due to the influence of the backlight. As a result, the edge of the display 44a becomes a fusional stimulus, and if the gaze direction SR (center position) of the right first optotype symbol s1R and the edge of the display 44a is the same, the gaze direction SR does not change even if the fusion of the first optotype symbol s1 is destroyed, and it becomes impossible to detect the timing when the fusion is destroyed.

[0078] In contrast, the ophthalmologic apparatus 1 of the present disclosure has a first optotype symbol s1 and a second optotype symbol s2 having a different parallax as the optotype Ot. In the eye fatigue estimation process, the ophthalmologic apparatus 1 increases the brightness difference of only the first optotype symbol s1 or the second optotype symbol s2 that is being gazed upon. Therefore, when the fusion of the first optotype symbol s1 is released, the gaze directions SL and SR of the subject's eye E, which has become difficult to see, move toward the second optotype symbol s2. More specifically, the process is as follows. For simplicity's sake, it is assumed below that the brightness difference between the left first optotype symbol s1L and the right first optotype symbol s1R is increased by decreasing the brightness of the right first optotype symbol s1R.

[0079] First, Figure 9 shows a situation in which a left-eye optotype OtL is presented to the left eye EL and a right-eye optotype OtR is presented to the right eye ER, and the subject focuses on the first left optotype symbol s1L and the first right optotype symbol s1R, respectively, resulting in the first optotype symbol s1 being fused through binocular vision. At this time, the first left optotype symbol s1L and the second left optotype symbol s2L of the left eye optotype OtL and the first right optotype symbol s1R and the second right optotype symbol s2LR of the right eye optotype OtR are all displayed equally bright, allowing the first optotype symbol s1 to be fused through binocular vision. Therefore, the left eye EL is directed in the line of sight SL toward the first left optotype symbol s1L, and the right eye ER is directed in the line of sight SR toward the first right optotype symbol s1R.

[0080] Next, as shown in Figure 10, the brightness of the right first optotype symbol s1R of the right eye optotype OtR is reduced until it becomes difficult to see, while the brightness of the other left first optotype symbol s1L, left second optotype symbol s2L, and right second optotype symbol s2LR is fixed (maintained). Then, when the right first optotype symbol s1R becomes difficult to see, the right eye ER is guided to look at the right second optotype symbol s2LR, whose brightness is fixed (maintained), and the gaze direction SR changes toward the right second optotype symbol s2LR. At this time, because the brightness of the left first optotype symbol s1L is fixed (maintained), by the subject focusing on the left first optotype symbol s1L, the left eye EL maintains the gaze direction SL toward the left first optotype symbol s1L. In addition, the left subject's eye EL may be guided to look at the left second optotype symbol s2L and change its gaze direction SL toward the right second optotype symbol s2LR as the right subject's eye ER becomes less able to see the right first optotype symbol s1R and receives a fusion stimulus from the right second optotype symbol s2LR, as shown in Fig. 11. Here, it can also be determined that the degree of eye fatigue (tiredness) is higher when the left subject's eye EL also changes to the left second optotype symbol s2L (Fig. 11) than when only the right subject's eye ER changes to the right second optotype symbol s2LR (Fig. 10).

[0081] In this way, the ophthalmologic apparatus 1 defines the optotype Ot as having the first optotype symbol s1 and the second optotype symbol s2 having a different disparity. Therefore, when it becomes difficult to visually recognize the right first optotype symbol s1R, the ophthalmologic apparatus 1 can guide the subject to look at the right second optotype symbol s2LR having a different disparity. Therefore, when it becomes difficult to visually recognize the right first optotype symbol s1R, the ophthalmologic apparatus 1 can change the gaze direction SR of the right eye ER from toward the right first optotype symbol s1R to toward the right second optotype symbol s2LR. This allows the ophthalmologic apparatus 1 to appropriately detect the timing when the fusion of the right first optotype symbol s1R is destroyed.

[0082] In particular, the ophthalmologic apparatus 1 of Example 1 sets the convergence distance Lc, which is determined by the convergence angle θc of the first optotype symbol s1, to be smaller than the optotype presentation distance Lp, and sets the convergence angle θc of the second optotype symbol s2 to be smaller than the convergence angle θc of the first optotype symbol s1. Therefore, when it becomes difficult to visually recognize the right first optotype symbol s1R, the right second optotype symbol s2LR is present in the divergence direction for the right eye ER and in a direction close to the optotype presentation distance Lp, so that the gaze direction SR of the right eye ER can be more naturally directed toward the right second optotype symbol s2LR. As a result, when it becomes difficult to visually recognize the right first optotype symbol s1R, the ophthalmologic apparatus 1 can more reliably direct the gaze direction SR of the right eye ER toward the right second optotype symbol s2LR, thereby more reliably detecting a change in the gaze direction SR.

[0083] Furthermore, in the ophthalmologic apparatus 1 of Example 1, the control unit 40 detects the focus position of the left eye EL and the focus position of the right eye ER when detecting the gaze directions SL and SR of the left and right eyes E (EL, ER). Here, the control unit 40 can determine the positions (distances) at which the left eye EL and the right eye ER are looking based on the focus position detection results. Therefore, by detecting the focus positions of the left and right eyes E (EL, ER), the control unit 40 can appropriately determine whether the right first optotype symbol s1R or the right second optotype symbol s2LR is being viewed based on the focus position determination results when determining whether the gaze directions SL and SR have changed, thereby improving the accuracy of determining whether the gaze directions SL and SR have changed.

[0084] Furthermore, in the ophthalmologic apparatus 1 of Example 1, when the control unit 40 gradually increases the brightness difference of a portion of the visual target Ot, the control unit 40 displays anterior eye images E' of the left and right test eyes EL and ER, which are eye information acquired by the anterior eye observation system 45, on the display unit 31 simultaneously with the increase in brightness difference (contrast difference) between the left and right test eyes Ot. Here, the anterior eye images E' of the left and right test eyes E (EL, ER) are eye information used to detect the gaze directions SL and SR. Therefore, by visually checking the display unit 31, the examiner can monitor the movement of the left and right test eyes E (EL, ER) while the brightness difference of a portion of the visual target Ot is increasing, and determine whether the gaze directions SL and SR have changed. Based on this determination, the examiner can determine the fusional destructive brightness difference and estimate eye fatigue. The examiner may also directly observe the movement of the left and right test eyes E (EL, ER) of the subject to determine whether the gaze directions SL and SR have changed.

[0085] In the ophthalmologic apparatus 1 of Example 1, the second optotype symbol s2 in the optotype Ot is an annular design surrounding the first optotype symbol s1. This reduces the amount of displacement of the center positions of the first optotype symbol s1 and the second optotype symbol s2, i.e., the parallax between the first optotype symbol s1 and the second optotype symbol s2, so that when it becomes difficult to visually recognize the right first optotype symbol s1R, the line of sight SR of the right eye ER can be more reliably directed toward the right second optotype symbol s2LR.

[0086] The ophthalmologic apparatus 1 of the first embodiment according to the present disclosure can achieve the following effects. The ophthalmologic apparatus 1 includes a target projection system 44 as a target presentation mechanism that presents a left-eye target OtL to the left eye EL and a right-eye target OtR to the right eye ER, and the left-eye target OtL and the right-eye target OtR are in the same form. The target projection system 44 presents the left-eye target OtL to the left eye EL and the right-eye target OtR to the right eye ER, and enlarges the brightness difference in a portion common to the left-eye target OtL and the right-eye target OtR while maintaining the brightness difference in the remaining portions between the left-eye target OtL and the right-eye target OtR. Therefore, when a portion of the fusion image common to the left eye target OtL and the right eye target OtR is destroyed, the ophthalmologic apparatus 1 can guide the gaze directions SL and SR of the subject's eye E on the side where vision has become difficult to see to the remaining portion of the left eye target OtL and the right eye target OtR, thereby ensuring detection of changes in the gaze directions SL and SR (eye position deviation). This allows the ophthalmologic apparatus 1 to properly detect the timing at which fusion is destroyed and to properly estimate eye fatigue based on that timing.

[0087] Furthermore, in the ophthalmologic apparatus 1, the left eye optotype OtL and the right eye optotype OtR have two or more optotype symbols (s1, s2) of the same shape, and the parallax of at least one of the optotype symbols (s1, s2) is different. Therefore, the ophthalmologic apparatus 1 increases the brightness difference of one optotype symbol while maintaining the brightness difference of the remaining optotype symbols, so that when one optotype symbol becomes difficult to see, the gaze directions SL, SR of the subject's eye E can be guided toward the remaining optotype symbols. This allows the ophthalmologic apparatus 1 to more reliably detect changes in the gaze directions SL, SR (eye position deviation).

[0088] The ophthalmologic apparatus 1 further includes a drive mechanism 23 as a convergence adjustment mechanism that adjusts the convergence angle θc, an anterior-eye observation system 45, a refraction measurement projection system 46, and a refraction measurement light-receiving system 47 as an eye information acquisition unit that acquires eye information about the left eye EL and the right eye ER, and a control unit 40 that controls the drive mechanism 23, the anterior-eye observation system 45, the refraction measurement projection system 46, and the refraction measurement light-receiving system 47. The control unit 40 controls the drive mechanism 23 to set an arbitrary convergence angle θc and controls the refraction measurement projection system 44 to present the left-eye optotype OtL and the right-eye optotype OtR at an equal optotype presentation distance Lp, and then increases the brightness difference of one optotype symbol (s1, s2) of the left-eye optotype OtL and the right-eye optotype OtR while maintaining the brightness difference of the other optotype symbol (s1, s2). At this time, the control unit 40 detects the line of sight SL of the left eye EL and the line of sight SR of the right eye ER based on the eye information acquired by the anterior eye observation system 45, the reflex measurement projection system 46, and the reflex measurement light receiving system 47, determines the timing at which the fusion between the left eye EL and the right eye ER is destroyed, and estimates the degree of fatigue based on the timing at which the fusion is destroyed. Therefore, the ophthalmologic apparatus 1 can appropriately determine the timing at which the fusion is destroyed and appropriately estimate the degree of fatigue.

[0089] The ophthalmologic apparatus 1 includes a left-eye optotype OtL and a right-eye optotype OtR, each having at least a first optotype symbol s1 of identical shape and a second optotype symbol s2 of identical shape with a convergence angle θc smaller than that of the first optotype symbol s1. The control unit 40 increases the brightness difference of the first optotype symbol s1 while maintaining the brightness difference of the second optotype symbol s2. Therefore, when it becomes difficult to visually recognize the first optotype symbol s1, the ophthalmologic apparatus 1 positions the second optotype symbol s2L in the divergence direction for the subject's eye E, allowing the subject's eye E to more naturally orient its gaze directions SL and SR toward the second optotype symbol s2L.

[0090] The ophthalmologic apparatus 1 further includes a display unit 31 that is visible at least to the examiner, and the control unit 40 causes the fatigue level estimation result to be displayed on the display unit 31. Therefore, the ophthalmologic apparatus 1 makes it easy to understand the fatigue level estimation result.

[0091] When the control unit 40 of the ophthalmologic apparatus 1 gradually increases the brightness difference using the optotype projection system 44 as an optotype presentation mechanism, the control unit 40 displays the eye information acquired by the anterior eye observation system 45, the reflex measurement projection system 46, and the reflex measurement light receiving system 47 as eye information acquisition units on the display unit 31. Therefore, the ophthalmologic apparatus 1 allows the examiner to monitor the movements of the left and right test eyes EL, ER while the brightness difference of the optotype is increasing by viewing the display unit 31, and also enables the examiner to determine whether or not there is a change in the gaze directions SL, SR.

[0092] The control unit 40 of the ophthalmologic apparatus 1 can set the convergence distance Lc indicated by the convergence angle θc to be shorter than the target presentation distance Lp. Therefore, the ophthalmologic apparatus 1 can fuse a common part of the left eye target OtL and the right eye target OtR in a convergent state, and can induce changes in the gaze directions SL and SR when fusion is broken, making it easy to grasp the timing when fusion is broken.

[0093] The ophthalmologic apparatus 1 has a target projection system 44 as a target presenting mechanism, which includes a display 44a as a left-eye display that presents a left-eye target OtL and is capable of arbitrarily changing the brightness of the left-eye target OtL, and a display 44a as a right-eye display that presents a right-eye target OtR and is capable of arbitrarily changing the brightness of the right-eye target OtR. Therefore, the ophthalmologic apparatus 1 can finely change the brightness of the left-eye target OtL and the right-eye target OtR, respectively, and can appropriately increase the brightness difference between them.

[0094] When the control unit 40 of the ophthalmologic apparatus 1 detects the gaze directions SL and SR of the left and right eyes EL and ER, it detects the focus position of the left and right eyes EL and ER based on eye information acquired by the anterior eye observation system 45, the reflex measurement projection system 46, and the reflex measurement light-receiving system 47, which serve as eye information acquisition units. Therefore, when determining whether or not there has been a change in the gaze directions SL and SR, the ophthalmologic apparatus 1 can appropriately determine whether the right first optotype symbol s1R or the right second optotype symbol s2LR is being viewed from the determination result of the focus position, thereby improving the accuracy of determining whether or not there has been a change in the gaze directions SL and SR.

[0095] Therefore, the ophthalmologic apparatus 1 as one embodiment of the present disclosure can easily detect eye position deviation when the brightness difference between the visual targets Ot presented to the left and right test eyes E is increased from the binocular vision state.

[0096] The ophthalmic device of the present disclosure has been described above based on Example 1, but the specific configuration is not limited to Example 1, and design changes and additions are permitted as long as they do not deviate from the gist of the invention according to each claim in the claims.

[0097] For example, in Example 1, an application example was shown for an ophthalmic apparatus 1 that observes, photographs, and records an anterior segment image of the eye to be examined, a fundus image of the eye to be examined, and a tomographic image of the fundus of the eye to be examined, and provides them as electronic images for diagnosis. However, any ophthalmic apparatus that can increase the brightness difference in a portion common to the left eye optotype OtL and the right eye optotype OtR while maintaining the brightness difference in the remaining portion between the left eye optotype OtL and the right eye optotype OtR in a state where the left eye optotype OtL and the right eye optotype OtR are viewed binocularly can be applied regardless of whether it is a subjective ophthalmic apparatus or an objective ophthalmic apparatus, and is not limited to the configuration of Example 1.

[0098] In addition, in Example 1, the first optotype symbol s1 is an asterisk design, and the second optotype symbol s2 is an annular design. However, the first optotype symbol s1 and the second optotype symbol s2 may be designs that suggest different things, and are not limited to the configuration of Example 1. Furthermore, although the second optotype symbol s2 surrounds the first optotype symbol s1, it may also be arranged next to the first optotype symbol s1 as shown in Fig. 12, and is not limited to the configuration of Example 1.

[0099] Furthermore, in Example 1, the first optotype symbol s1 is displayed at the center position of the display 44a, and the second optotype symbol s2 is displayed at a position eccentric to the outside from the center position of the display 44a. However, as long as the convergence angle θc of the second optotype symbol s2 is smaller than that of the first optotype symbol s1, the first optotype symbol s1 may be displayed at a position eccentric to the inside and the second optotype symbol s2 may be displayed at the center, or the first optotype symbol s1 may be displayed inward and the second optotype symbol s2 may be displayed in eccentric positions outward, and this is not limited to the configuration of Example 1.

[0100] In Example 1, the optotype Ot (first optotype symbol s1, second optotype symbol s2) is displayed as a white symbol on a black background. However, as long as the optotype Ot can be visually recognized and the first optotype symbol s1 and the second optotype symbol s2 can be fused, the colors of the background and the symbols may be set appropriately, and are not limited to the configuration of Example 1.

[0101] In Example 1, the optotype presenting mechanism includes two optotype projection systems 44 corresponding to the left and right eyes E (EL, ER), and each optotype projection system 44 is capable of displaying an arbitrary optotype and has a display 44a with variable brightness. However, the optotype presenting mechanism is not limited to the configuration of Example 1 as long as it has the function of increasing the brightness difference between one of the first optotype symbols s1 and the second optotype symbols s2 while maintaining the other in a non-bright state. For example, the optotype presenting mechanism may be configured such that liquid crystal shutters are disposed between the optotype and the left and right eyes E (EL, ER) and the transmittance of the liquid crystal shutters is partially changed. Furthermore, the optotype presenting mechanism does not need to be provided independently for the left and right eyes as long as it has the above function.

[0102] In the ophthalmologic apparatus 1 of the first embodiment, when determining whether or not there is a change in the gaze directions SL and SR, the focus positions of the left and right eyes E (EL and ER) to be examined are detected. However, since the focus positions are detected to ensure the accuracy of determining whether or not there is a change in the gaze directions SL and SR, they do not necessarily have to be detected.

[0103] In the ophthalmologic apparatus 1 of the first embodiment, the estimated results of the fatigue levels of the left and right eyes E (EL, ER) to be examined and anterior eye images E' of the left and right eyes E (EL, ER) to be examined when the brightness difference of the visual target is gradually increased are displayed on the display unit 31 of the examiner controller 30. However, the display unit may be any display that is at least visible to the examiner, and may be, for example, a monitor installed on the optometry table 12 or a display provided in the measurement unit 20.

[0104] In the ophthalmologic apparatus 1 of Example 1, the increase in the brightness difference of the common portion of the optotype Ot is stopped when a change in the gaze directions SL and SR begins (occurs), and the fusional destructive brightness difference is determined. However, the control unit 40 may continue to detect changes in the gaze directions SL and SR until the brightness of the portion of one of the optotypes Ot becomes zero, that is, until the portion of one of the optotypes Ot becomes the same color as the background. Alternatively, the brightness difference may be changed by finely setting a predetermined amount, or the brightness difference may be continuously changed to continuously acquire the gaze directions SL and SR. The slope may then be detected from a graph showing the relationship between the gaze directions SL and SR and the brightness difference, and the point where the change is large may be determined as the fusional destructive brightness difference. Furthermore, the focus position may be continuously acquired, and the degree of fluctuation in the focus position may be determined as the fusional destructive brightness difference, or the fusional destructive brightness difference may be determined by combining the change in the gaze directions SL and SR with the fluctuation in the focus position.

[0105] In the ophthalmologic apparatus 1 of Example 1, the optotype Ot has a first optotype symbol s1 and a second optotype symbol s2. However, the optotype may have three or more optotype symbols as long as it has a plurality of optotype symbols with different parallaxes, and is not limited to the configuration of Example 1. For example, if a configuration is adopted in which a third optotype symbol is included in addition to the first optotype symbol s1 and the second optotype symbol s2, by arranging the third optotype symbol biased toward the inside of the first optotype symbol s1, when it becomes difficult to visually recognize the first optotype symbol s1, the gaze can be naturally directed to the third optotype symbol even if the gaze tends to move in the convergence direction, and the movement of the gaze directions SL and SR from the first optotype symbol s1 can be reliably detected.

[0106] In the ophthalmologic apparatus 1 of the first embodiment, the optotype Ot has a first optotype symbol s1 and a second optotype symbol s2. However, the optotype Ot may use the edge of the display 44a as the second optotype symbol s2, i.e., only the first optotype symbol s1 is drawn on the display 44a. In this case, the first optotype symbol s1 is drawn not at the center of the display 44a but at a position biased inward from the center of the display 44a (the left first optotype symbol s1L is drawn on the right side, and the right first optotype symbol s1R is drawn on the left side). Then, while the first optotype symbol s1 is fused, the brightness difference between the left first optotype symbol s1L and the right first optotype symbol s1R is increased until the gaze directions SL and SR move, or the brightness difference when the subject responds that the first optotype symbol s1 appears as two is determined to be the fusional destructive brightness difference. When the first optotype symbol s1 becomes difficult to see, this optotype Ot can guide the line of sight SL, SR of the subject's eye E toward the edge of the display 44a, which is the second optotype symbol s2, thereby achieving the same effect as in Example 1.

[0107] [1] a target presenting mechanism for presenting a target for the left eye to the left eye to be examined and a target for the right eye to be examined; The visual target for the left eye and the visual target for the right eye are of the same form, the optotype presenting mechanism presents the optotype for the left eye to the left eye to be examined and the optotype for the right eye to be examined, and increases the brightness difference of a part that is common to the optotype for the left eye and the optotype for the right eye, while maintaining the brightness difference of the remaining part between the optotype for the left eye and the optotype for the right eye.

[0108] [2] The ophthalmologic device described in [1] is characterized in that the optotype for the left eye and the optotype for the right eye have two or more optotype symbols of the same shape, and the parallax of at least one of the optotype symbols is different.

[0109] [3] a distance from the left eye to the left target and a distance from the right eye to the right target are defined as target presentation distances, a line-of-sight intersection point is defined as a line-of-sight intersection point, and a convergence angle is defined as an angle formed by a line segment connecting the left eye to the line-of-sight intersection point and the right eye to the line-of-sight intersection point, a convergence adjustment mechanism for adjusting the convergence angle; an eye information acquiring unit that acquires eye information of the left eye and the right eye; a control unit that controls the target presentation mechanism, the convergence adjustment mechanism, and the eye information acquisition unit, The control unit controls the convergence adjustment mechanism to set the convergence angle at an arbitrary value, while controlling the optotype presentation mechanism to present the left eye optotype and the right eye optotype at the same optotype presentation distance, and increases the brightness difference of one of the optotype symbols between the left eye optotype and the right eye optotype while maintaining the brightness difference of the other optotype symbol, detects the gaze direction of the left test eye and the gaze direction of the right test eye based on the eye information acquired by the eye information acquisition unit, determines the timing when fusion between the left test eye and the right test eye is destroyed, and estimates the degree of fatigue based on the timing when fusion is destroyed.

[0110] [4] The optotype for the left eye and the optotype for the right eye have at least a first optotype symbol having an identical shape and a second optotype symbol having an identical shape and a smaller convergence angle than the first optotype symbol, The ophthalmologic apparatus according to [3], wherein the control unit increases the brightness difference of the first optotype symbol while maintaining the brightness difference of the second optotype symbol.

[0111] [5] Furthermore, a display unit that is visible at least to the examiner is provided, The ophthalmologic apparatus according to [3] or [4], wherein the control unit causes the display unit to display the fatigue level estimation result.

[0112] [6] The ophthalmologic device described in [5] is characterized in that the control unit displays the eye information acquired by the eye information acquisition unit on the display unit when the brightness difference is gradually increased by the optotype presentation mechanism.

[0113] [7] The ophthalmologic apparatus according to any one of [3] to [6], wherein the control unit sets a convergence distance indicated by the convergence angle to be shorter than the target presentation distance.

[0114] [8] The ophthalmologic device described in any one of [3] to [7], characterized in that the visual target presenting mechanism has a left eye display that presents the visual target for the left eye and is capable of arbitrarily changing the brightness of the visual target for the left eye, and a right eye display that presents the visual target for the right eye and is capable of arbitrarily changing the brightness of the visual target for the right eye.

[0115] [9] The ophthalmic device described in any one of [3] to [8] is characterized in that, when detecting the gaze direction of the left test eye and the right test eye, the control unit detects the focus position of the left test eye and the focus position of the right test eye based on the eye information acquired by the eye information acquisition unit. [Explanation of symbols]

[0116] 1 ophthalmic device 23 drive mechanism (as an example of a convergence adjustment mechanism) 31 display unit 40 control unit 44 target projection system (as an example of a target presentation mechanism) 44a display (as an example of a display for the left eye and a display for the right eye) 45 anterior eye observation system (as an example of an eye information acquisition unit) 46 reflex measurement projection system (as an example of an eye information acquisition unit) 47 reflex measurement light receiving system (as an example of an eye information acquisition unit) EL left eye to be examined ER right eye to be examined Is line of sight intersection Lp target presentation distance OtL left eye target OtR right eye target s1 first target symbol s2 second target symbol θc convergence angle

Claims

1. a target presenting mechanism for presenting a target for the left eye to the left eye to be examined and a target for the right eye to be examined; The visual target for the left eye and the visual target for the right eye are of the same form, the optotype presenting mechanism presents the optotype for the left eye to the left eye to be examined and the optotype for the right eye to be examined, and increases the brightness difference of a part that is common to the optotype for the left eye and the optotype for the right eye, while maintaining the brightness difference of the remaining part between the optotype for the left eye and the optotype for the right eye.

2. 2. The ophthalmologic apparatus according to claim 1, wherein the optotype for the left eye and the optotype for the right eye have two or more optotype symbols of the same shape, and at least one of the optotype symbols has a different parallax.

3. a distance from the left eye to the left target and a distance from the right eye to the right target are defined as target presentation distances, a line-of-sight intersection point is defined as a line-of-sight intersection point, and a convergence angle is defined as an angle formed by a line segment connecting the left eye to the line-of-sight intersection point and the right eye to the line-of-sight intersection point, a convergence adjustment mechanism for adjusting the convergence angle; an eye information acquiring unit that acquires eye information of the left eye and the right eye; a control unit that controls the target presenting mechanism, the convergence adjustment mechanism, and the eye information acquisition unit, 3. The ophthalmologic apparatus according to claim 2, wherein the control unit controls the convergence adjustment mechanism to set the convergence angle at an arbitrary value, and controls the optotype presentation mechanism to present the left eye optotype and the right eye optotype at the equal optotype presentation distance, and then increases the brightness difference of one of the optotype symbols between the left eye optotype and the right eye optotype while maintaining the brightness difference of the other optotype symbol, detects the gaze direction of the left eye and the gaze direction of the right eye based on the eye information acquired by the eye information acquisition unit, determines the timing when fusion between the left eye and the right eye is destroyed, and estimates a degree of fatigue based on the timing when fusion is destroyed.

4. the optotype for the left eye and the optotype for the right eye have at least a first optotype symbol having an identical shape and a second optotype symbol having an identical shape and a smaller convergence angle than the first optotype symbol, The ophthalmologic apparatus according to claim 3 , wherein the control unit increases the brightness difference of the first optotype symbol while maintaining the brightness difference of the second optotype symbol.

5. Furthermore, a display unit that is visible at least to the examiner is provided, 5. The ophthalmologic apparatus according to claim 3, wherein the control unit causes the display unit to display the fatigue level estimation result.

6. The ophthalmologic apparatus according to claim 5 , wherein the control unit causes the display unit to display the eye information acquired by the eye information acquisition unit when the optotype presenting mechanism gradually increases the brightness difference.

7. 5. The ophthalmologic apparatus according to claim 3, wherein the control unit sets a convergence distance indicated by the convergence angle to be shorter than the target presentation distance.

8. 5. The ophthalmologic apparatus according to claim 3, wherein the optotype presenting mechanism includes a left-eye display that presents the left-eye optotype and is capable of arbitrarily changing the brightness of the left-eye optotype, and a right-eye display that presents the right-eye optotype and is capable of arbitrarily changing the brightness of the right-eye optotype.

9. 5. The ophthalmologic apparatus according to claim 3, wherein when detecting the gaze direction of the left eye to be examined and the right eye to be examined, the control unit detects the focus position of the left eye to be examined and the focus position of the right eye to be examined based on the eye information acquired by the eye information acquisition unit.

Images