Visual inspection device and visual inspection device set

Abstract

To provide a technology of performing a proper visual inspection irrespective of presence / absence of a correction lens or a spherical diopter of a correction lens.SOLUTION: A visual inspection device includes: a display optical system and a display element for displaying a visual target to an eye of a subject who receives a visual inspection; and a visual target display control unit for correcting a display position of an inspection visual target to be displayed within an inspection possible area on the display element in accordance with a spherical diopter of a correction lens that can be fitted to the display optical system and allows a subject to view the visual target.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a vision inspection device and a vision inspection device set.

Background Art

[0002] One of the eye examinations is "vision inspection" for inspecting the visual function of the eye. Also, a typical vision inspection is "visual field inspection". Visual field inspection is performed for the diagnosis of visual field constriction, visual field defect, etc. caused by, for example, glaucoma or retinal detachment, and various inspection devices have been proposed for this purpose (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The main object of the present invention is to provide a technique capable of performing appropriate vision inspection regardless of the presence or absence of a corrective lens or the spherical power of the corrective lens.

Means for Solving the Problems

[0005] The first aspect is a display optical system and a display element for displaying a test target on the eye of a subject undergoing vision inspection, a corrective lens that can be attached to the display optical system, and a test target display control unit that corrects the display position of the test target for inspection displayed within the testable area on the display element according to the spherical power of the corrective lens that enables the subject to visually recognize the test target, and a vision inspection device comprising the same.

[0006] The second aspect is the vision inspection device according to the first aspect, The target display control unit corrects the display position of the test target according to the spherical power of the corrective lens, so that the coordinate position of the test target as seen from the subject is the same as when the corrective lens is not worn.

[0007] A third aspect is a visual inspection device as described in the first aspect, The display optical system and the display element are provided independently on the left and right sides, respectively, corresponding to the left and right eyes of the subject.

[0008] A fourth aspect is a visual inspection device as described in the first aspect, The system further includes an observation optical system for the examiner to observe the subject's eyes and an image sensor for imaging the subject's eyes through the observation optical system.

[0009] The fifth aspect is a visual inspection device as described in the fourth aspect, The target display control unit changes the amount of correction used to correct the display position of the test target when the subject's gaze deviates from the fixation target displayed on the display element, according to the spherical power of the corrective lens.

[0010] The sixth aspect is a visual inspection device as described in the fourth aspect, The system further includes a corrective lens identification unit that automatically recognizes the spherical power of the corrective lens based on the external characteristics of the corrective lens present in the image of the eye captured by the image sensor.

[0011] The seventh aspect is a visual inspection device as described in the sixth aspect, A storage unit for storing the spherical power of the corrective lens, A determination unit that determines whether the spherical power automatically recognized by the corrective lens identification unit matches the spherical power stored in the storage unit, It is further equipped with [this feature].

[0012] The eighth aspect is a visual inspection device described in any one of the first to seventh aspects, The inspectable area is the background image displayed on the display element.

[0013] The ninth aspect is, Display optical systems and display elements are provided independently for the left and right eyes of the subject undergoing a visual examination, respectively. An observation optical system for the examiner to observe the subject's eye and an image sensor for imaging the subject's eye through the observation optical system, A target display control unit that corrects the display position of the test target displayed within the testable area on the display element according to the spherical power of a corrective lens that can be attached to the display optical system and allows the subject to see the target, A visual inspection device equipped with, A plurality of corrective lenses having different spherical powers, wherein each corrective lens has an external appearance that allows the spherical powers to be distinguished within the image of the eye captured by the image sensor, This is a visual inspection device set that includes the following features. [Effects of the Invention]

[0014] According to the present invention, appropriate vision tests can be performed regardless of whether or not corrective lenses are used or the spherical power of the corrective lenses. [Brief explanation of the drawing]

[0015] [Figure 1] Figure 1 shows the coordinate positions of the gray monochrome background image (broadly speaking, the testable area) located at the center of the display element and the test target (shown as a black circle in the figure) displayed within the background image, both in the case when a corrective lens is not attached to the visual examination device and for each spherical power of the corrective lens. Figure 1A shows the case when a corrective lens is not attached to the visual examination device. Figure 1B shows the case when a -6D (diopter) corrective lens is attached to the visual examination device. Figure 1C shows the case when a -12D (diopter) corrective lens is attached to the visual examination device. Figure 1D shows the case when a +6D (diopter) corrective lens is attached to the visual examination device. [Figure 2] Figure 2 is a schematic diagram showing an example of the configuration of a visual inspection device according to an embodiment of the present invention. [Figure 3] FIG. 3 is a schematic diagram including the configuration of the optical system of the visual inspection apparatus according to an embodiment of the present invention. [Figure 4] FIG. 4 is a block diagram including the configuration of the control system of the visual inspection apparatus according to an embodiment of the present invention. [Figure 5] FIG. 5 is a diagram showing the coordinate positions of a gray monochromatic background image (inspection possible region in a broad sense) located at the center on the display element and inspection visual targets (displayed as black circles in the figure) displayed within the background image, for each spherical power of the corrective lens, when the corrective lens is not attached to the visual inspection apparatus and when the corrective lens is attached to the visual inspection apparatus, in an embodiment of the present invention. FIG. 5A is a diagram when the corrective lens is not attached to the visual inspection apparatus. FIG. 5B is a diagram when a -6D (diopter) corrective lens is attached to the visual inspection apparatus. FIG. 5C is a diagram when a -12D (diopter) corrective lens is attached to the visual inspection apparatus. FIG. 5D is a diagram when a +6D (diopter) corrective lens is attached to the visual inspection apparatus. [Figure 6] FIG. 6 is a schematic diagram showing an image of the eye of a subject when looking at a fixation target, in an embodiment of the present invention. FIG. 6A is a diagram when the corrective lens is not attached to the visual inspection apparatus. FIG. 6B is a diagram when a -6D (diopter) corrective lens is attached to the visual inspection apparatus. FIG. 6C is a diagram when a -12D (diopter) corrective lens is attached to the visual inspection apparatus.

Embodiments for Carrying Out the Invention

[0016] <Findings Obtained by the Inventor> First, the findings obtained by the inventor will be described. In the visual inspection apparatus described in Patent Document 1, a visual target is displayed to the subject by a display optical system and a display element. At that time, it may be possible that the subject has poor visual acuity and cannot clearly recognize the visual target (hereinafter, this will also be referred to as "difficult to visually recognize", and the opposite will also be referred to as "visually recognizable"). In that case, the subject wears a corrective lens that enables the subject to visually recognize the visual target on the display optical system.

[0017] The inventors conducted thorough research on the case where the above-mentioned corrective lens is mounted on a display optical system, and discovered the following problems.

[0018] Figure 1 shows the coordinate positions of the gray monochrome background image 121 (broadly defined as the testable area 121) located at the center of the display element and the test target displayed within the background image 121 (shown as a black circle in the figure) in the conventional case where a corrective lens is not attached to the visual examination device, and for each spherical power of the corrective lens. The numerical values ​​(unit:°) in the figure refer to the maximum degree of eccentricity that can be tested. The cross in the figure indicates the fixation target displayed on the display element. Figure 1A shows the case where a corrective lens is not attached to the visual examination device. Figure 1B shows the case where a -6D (diopter) corrective lens is attached to the visual examination device. Figure 1C shows the case where a -12D (diopter) corrective lens is attached to the visual examination device. Figure 1D shows the case where a +6D (diopter) corrective lens is attached to the visual examination device. In this specification, the coordinate position of the test target refers to, for example, the position of the test target as seen from the subject, with the fixation target as the origin, and the display position of the test target refers to the position of the test target on the display element.

[0019] As shown in Figure 1, when a corrective lens with negative spherical power is worn, the background image 121 as seen by the subject becomes smaller compared to when no corrective lens is worn on the visual examination device (Figure 1A) (Figures 1B and 1C). This tendency becomes more pronounced as the absolute value of the negative spherical power increases. Conversely, when a corrective lens with positive spherical power is worn, the background image 121 as seen by the subject becomes larger (Figure 1D).

[0020] As shown in Figures 1B and 1C, when corrective lenses with negative spherical power are worn, the test target is reduced in size along with the background image 121. Therefore, compared to when no corrective lenses are worn, the size of the test target as seen by the subject becomes smaller, and its coordinate position shifts closer to the center. Conversely, as shown in Figure 1D, when corrective lenses with positive spherical power are worn, the test target is enlarged along with the background image 121. Therefore, compared to when no corrective lenses are worn, the size of the test target as seen by the subject becomes larger, and its coordinate position shifts further outward. In such a situation, the spherical power of the corrective lens changes the coordinate position of the test target as seen by the subject (i.e., the degree of eccentricity being tested), which may prevent the proper performance of the visual examination.

[0021] The inventors of the present invention have diligently investigated the above-mentioned problems. As a result, they have found that by providing a target display control unit that corrects the display position of the test target displayed within the inspectable area on the display element according to the spherical power of the corrective lens, it is possible to perform an appropriate visual examination regardless of whether or not a corrective lens is used or the spherical power of the corrective lens.

[0022] Embodiments of the present invention will be described in detail below with reference to the drawings. In this embodiment, the case in which the visual inspection device is a perimeter is illustrated. All the contents described in Patent Document 1 can be incorporated into this specification.

[0023] <1. Visual Inspection Equipment> Figure 2 is a schematic diagram showing an example of the configuration of a visual examination device according to an embodiment of the present invention. The illustrated visual examination device 1 is a head-mounted type visual examination device used by being attached to the head 3 of a subject 2. The visual examination device 1 broadly comprises a device body 5 and a mounting device 6 mechanically connected to the device body 5.

[0024] The main body of the device 5 is equipped with a housing 7 that has an internal space. The internal space of the housing 7 is divided into left and right sections. This is because the visual examination is performed separately on the left eye 8L and the right eye 8R of the subject 2. In this visual examination, when the left eye 8L is the eye being examined, subject 2 will look at the target through the pupil 9L of the left eye 8L, and when the right eye 8R is the eye being examined, subject 2 will look at the target through the pupil 9R of the right eye 8R.

[0025] As used herein, "visual target" refers to a device displayed (presented) to provide a light stimulus to the subject's eyes in order to examine their vision. In this specification, "visual target" includes fixation targets designed to compel the subject to fixate on them, and test targets used to confirm whether the subject can see them. Hereafter, unless otherwise specified, "visual target" encompasses both.

[0026] There are no particular restrictions on the size, shape, or other aspects of the visual target. For example, during a glaucoma examination, a dot of light of a predetermined size can be displayed as a visual target, and by changing the position of this dot, it is possible to examine (identify) the presence and location of any visual field defects.

[0027] The main body of the device 5 incorporates a display optical system 11 and a display element 12. The main body of the device 5 is equipped with the display optical system 11 and display element 12 independently for the left and right eyes, allowing for visual examination with both eyes open, regardless of which eye is being examined. Specifically, one space of the housing 7 contains the display optical system 11L and display element 12L, corresponding to the right eye 8R of the subject 2, while the other internal space of the housing 7 contains the display optical system 11R and display element 12R, corresponding to the right eye 8R of the subject 2. The display optical system 11L and display element 12L are primarily for visual examination of the left eye 8L of the subject 2. The display optical system 11R and display element 12R are primarily for visual examination of the right eye 8R of the subject 2. The distance between the optical axes of the left and right display optical systems 11L and 11R can be adjusted to match the interpupillary distance of the subject 2 by an adjustment mechanism (not shown).

[0028] The attachment device 6 is for attaching the main unit of the device 5 to the head 3 of the subject 2. The attachment device 6 comprises a belt 13 that is U-shaped and stretched from both sides of the subject 2's head to the back of the head, and a belt 14 that is stretched across the top of the subject 2's head. With the length of belt 14 appropriately adjusted, the device 5 can be securely fixed and attached to the head 3 of the subject 2 by pulling and tightening belt 13 from the back of the head. The distance between the optical axes of the display optical systems 11L and 11R described above is adjusted to match the interpupillary distance when the subject 2 is facing forward, after the device 5 has been fixed to the head 3 of the subject 2 by the attachment device 6.

[0029] In the following explanation, when describing subject 2's left eye 8L and right eye 8R without distinguishing between left and right, the symbols L and R will be omitted and they will be collectively referred to as eye 8 and pupil 9. Similarly, when describing the above-mentioned display optical systems 11L and 11R and display elements 12L and 12R without distinguishing between left and right eye use, the symbols L and R will be omitted and they will be collectively referred to as display optical system 11 and display element 12, respectively.

[0030] (optical system) Figure 3 is a schematic diagram showing the configuration of the optical system of a vision testing device according to an embodiment of the present invention. As shown in the figure, in addition to the display optical system 11 and display element 12 described above, the vision testing device 1 includes an observation optical system 15 for observing the subject's eye 8, an image sensor 16 for imaging the subject's eye 8 through the observation optical system 15, an infrared light source (not shown) for irradiating the subject's eye 8 with infrared light, a control unit 30 that controls the entire vision testing device 1, and a response switch 31. The observation optical system 15, image sensor 16, and infrared light source are provided separately for the subject's left eye and right eye, respectively, similar to the display optical system 11 and display element 12 described above. One control unit 30 and one switch 31 are provided for each vision testing device 1. The display element 12, switch 31, and image sensor 16 are electrically connected to the control unit 30, as indicated by the reference numerals A, B, and C in the figure.

[0031] (Display optical system) The display optical system 11 is located on the optical axis 18 between the eye position where the subject's eye 8 is positioned and the display surface 12a of the display element 12. Specifically, the display optical system 11 is configured to include a first lens 19, a mirror 20, and possibly a second lens group (not shown), arranged in order from the subject's eye position. The following describes each component. In the following description, of the optical axis 18 from the subject's eye position to the display element 12, the optical axis from the eye position to the mirror 20 will be referred to as optical axis 18a, and the optical axis from the mirror 20 to the display element 12 will be referred to as optical axis 18b. This optical axis 18b is approximately parallel to the optical axis 18a described above.

[0032] The first lens 19 is positioned on the optical axis 18a from the eye position to the mirror 20. The first lens 19 is constructed using an aspherical lens (convex lens) with positive power. The first lens 19 focuses the light reflected by the mirror 20 and incident on the first lens 19 towards the subject's pupil 9, while suppressing the divergence of light when the subject views objects at a wide angle through the pupil 9.

[0033] Mirror 20 is positioned on the optical axis 18a from the eye position to Mirror 20, with the first lens 19 in between, on the opposite side from the eye position. Mirror 20 is constructed using a wavelength-selective mirror. Specifically, Mirror 20 is constructed using a hot mirror that transmits visible light and reflects infrared light.

[0034] The second lens group may be arranged on the optical axis 18b from the mirror 20 to the display element 12. The second lens group may be composed of three lenses (reference numerals 21a, 21b, and 21c as described in Patent Document 1; reference numerals omitted hereafter).

[0035] The corrective lenses listed in the section on the problems of the present invention may belong to either the first lens 19 or the second lens group. The corrective lenses are not limited as long as they can correct at least the subject's spherical power, and may also correct the subject's astigmatism, or a separate corrective lens for astigmatism may be attached to the visual examination device 1. The present invention is not limited to the attachment of corrective lenses.

[0036] Furthermore, when attaching corrective lenses to the display optical system 11, it is preferable to attach corrective lenses with the same spherical power to the left and right display optical systems 11L and 11R. In this case, the spherical power of the corrective lens may be selected to match the visual acuity of the eye of the person performing the examination. This ensures that the left and right visual fields (the size of the background image 121 as seen by the subject) are the same, allowing for an appropriate visual examination.

[0037] (Display this element) The display element 12 is positioned on the optical axis 18b from the mirror 20 to the display element 12, and in some cases, opposite the second lens group. The display element 12 is constructed using a planar display element such as a liquid crystal display element with a backlight. The display surface 12a of the display element 12 has a configuration in which a large number of pixels are arranged in a matrix. When actually displaying an image (including a visual target) on the display surface 12a, the display (on) and hidden (off) of the image can be controlled on a pixel-by-pixel basis. Furthermore, the display surface 12a of the display element 12 preferably has a display size with a diagonal length of 1.5 inches or less, more preferably with a diagonal length of 1 inch or less, and the optical axis 18b is aligned to the center of this display surface 12a.

[0038] In the display optical system 11 and display element 12 having the above configuration, when a visual target is displayed on the display surface 12a of the display element 12, the subject 2 will view the visual target from the eye position through the first lens 19, mirror 20, and second lens group. In this case, increasing the outer diameter of the first lens 19, which is closest to the eye position, allows for visual examination over a wider range. However, increasing the outer diameter of the first lens 19 causes the principal rays passing through the lens edge to be significantly tilted with respect to the optical axis 18 (18a). Therefore, if the power of the first lens 19 is low, the principal rays passing through the lens edge will diverge.

[0039] Therefore, in this embodiment, by using a high-power lens (preferably with a power of 20D or more and 60D or less) for the first lens 19, the principal rays passing through the lens end of the first lens 19 are greatly refracted and contained on the reflective surface of the mirror 20. However, when a high-power first lens 19 is used in this way, the light beam of the principal rays is focused and concentrated along the optical path from the first lens 19 to the second lens group. For this reason, the second lens group may be placed on the optical axis 18b to refocus (image) the light beam of the principal rays that has focused along the optical path on the display surface 12a of the display element 12. In addition, the second lens group may be composed of three lenses to correct chromatic aberration and image magnification.

[0040] (Observation optics) The observation optical system 15 is used to observe the subject's eye 8, for example, the anterior part of the eye including the pupil 9, iris, and sclera, or the fundus of the eye including the retina 10. The observation optical system 15 is located on the optical axis 18 from the subject's eye position to the image sensor 16. Specifically, the observation optical system 15 is configured with a first lens 19, a mirror 20, and a third lens 22 arranged in order from the subject's eye position. Of these, the first lens 19 and the mirror 20, including the optical axis 18a, are common (shared) with the display optical system 11 described above.

[0041] The third lens 22 is positioned on the optical axis 18c from the mirror 20 to the image sensor 16. The third lens 22 is constructed using an aspherical lens (convex lens) with positive power. When observing the eye 8 with the first lens 19 as the objective lens, the third lens 22 forms an image on the imaging surface 16a of the image sensor 16 of the light that enters the first lens 19 from the eye 8 and passes through the mirror 20.

[0042] (Image sensor) The image sensor 16 captures images of the eye (anterior segment, fundus, etc.) 8 that will be examined. The image sensor 16 is composed of a CCD (Charge Coupled Device) image sensor, a CMOS (Complementary Metal Oxide Semiconductor) image sensor, etc., that are sensitive to infrared light. The imaging surface 16a of the image sensor 16 is positioned on the optical axis 18c in a direction directly facing the eye 8, and the optical axis 18c is aligned with the center of this imaging surface 16a.

[0043] The infrared light source (not shown) emits infrared light towards the subject's eye position. The infrared light source is composed of a pair of infrared light-emitting diodes. The pair of infrared light-emitting diodes are positioned diagonally above and diagonally below the subject's eye position so as not to obstruct the subject's field of vision. One infrared light-emitting diode emits infrared light to the subject's eye 8 from diagonally above, and the other infrared light-emitting diode emits infrared light to the subject's eye 8 from diagonally below.

[0044] In the observation optical system 15 and image sensor 16 configured as described above, infrared light is irradiated onto the subject's eye 8 from an infrared light source, and an image of the eye 8 is captured by the image sensor 16 via the first lens 19, mirror 20, and third lens 22.

[0045] (Control system) Figure 4 is a block diagram showing the configuration of the control system of a visual inspection device according to an embodiment of the present invention. The control unit 30 implements various functions (means) during vision testing. For example, the control unit 30 has a housing structure smaller than the main body of the device 5 and is mounted on the occipital side of the head attachment 6. This allows for maintaining the front-to-back weight balance between the main body of the device 5 and the control unit 30.

[0046] The control unit 30 is composed of a computer consisting of a combination of a CPU (Central Processing Unit), RAM (Random Access Memory), ROM (Read Only Memory), HDD (Hard Disk Drive), and various interfaces. The control unit 30 is configured to realize various functions by having the CPU execute predetermined programs stored in the ROM or HDD. The predetermined programs for realizing each function are installed on the computer for use, but prior to installation, they may be provided on a storage medium readable by the computer, or they may be provided via a communication line connected to the computer.

[0047] The control unit 30 includes, as an example of the functions (means) realized by the execution of the above program, a pupillary constriction detection unit 41, a sensitivity map creation unit 42, and a display control unit 43. The control unit 30 also includes a memory 44 as an information storage unit.

[0048] The pupil constriction detection unit 41 has the function of detecting pupil constriction in the eye being examined. Pupillary constriction is a phenomenon in which the pupil 9 of the eye being examined constricts, and it occurs when light enters the pupil 9 of the eye of the person wearing the device body 5. Based on the image of the pupil 9 acquired by the image sensor 16, the pupil constriction detection unit 41 detects pupil constriction when the brightness of the target displayed on the display element 12 exceeds a predetermined brightness (luminance).

[0049] The sensitivity map creation unit 42 is a function that creates a sensitivity map in a visual examination. For example, in a subjective visual field test, when the subject presses the switch 31 in response to the light of the target, the sensitivity map creation unit 42 maps the brightness (luminance) of the target displayed by the display element 12 as the sensitivity of the retina 10. In an objective visual field test, the sensitivity map creation unit 42 also maps the brightness of the target displayed by the display element 12 as the sensitivity of the retina 10 when the pupil constriction detection unit 41 detects pupil constriction 9.

[0050] The display control unit 43 has the function of controlling the image displayed on the display element 12. The image displayed on the display element 12 includes at least an examination image for visual examination. The examination image is an image displayed (presented) to the subject during a visual field test, and includes, for example, fixation targets and examination targets which are visual targets in a visual field test, as well as a background image 121.

[0051] The background image 121 is located, for example, at the center of the display element 12. The geometric center of the background image 121 may be at or near the center of the display element 12. There are no limitations on the shape of the background image 121; it may be circular, as shown in Figure 1. There are no limitations on the type of background image 121; it may be a single color or a landscape image, as shown in Figure 1. In any case, the geometric center of the background image 121 is located at or near the center of the display element (a deviation of about 5 mm (preferably about 3 mm, more preferably about 1 mm) is acceptable). Furthermore, the background image 121 is not required. Even if there is no background image 121, the inspectable area 121 is defined.

[0052] The target display control unit 431 is included within the display control unit 43. The target display control unit 431 controls at least the display position of the test target. The target display control unit 431 is configured to correct the display position of the test target displayed within the testable area 121 on the display element 12 according to the spherical power of the corrective lens. As shown in Figure 1 above, there is an approximately proportional relationship (linear relationship) between the spherical power of the corrective lens and the size of the background image 121. This means that if the spherical power of the corrective lens is known, it is possible to return (correct) the coordinate position of the test target in the background image 121 when the corrective lens is attached to the visual examination device 1 (hereinafter also referred to as the "corrected state") back to the coordinate position of the test target in the background image 121 when the corrective lens is not attached to the visual examination device 1 (hereinafter also referred to as the "uncorrected state").

[0053] Figure 5 shows the coordinate positions of the gray monochrome background image 121 (broadly speaking, the inspectable area 121) located at the center of the display element 12 and the inspection target (shown as a black circle in the figure) displayed within the background image 121, for each spherical power of the corrective lens in this embodiment, and for each spherical power of the corrective lens. The numerical values ​​(unit:°) in the figure refer to the maximum degree of eccentricity that can be inspected. The cross in the figure indicates the fixation target displayed on the display element 12. The dashed circles in the figure indicate the coordinate positions of the inspection target before correction. Figure 5A shows the case when the corrective lens is not mounted on the visual inspection device. Figure 5B shows the case when a -6D (diopter) corrective lens is mounted on the visual inspection device. Figure 5C shows the case when a -12D (diopter) corrective lens is mounted on the visual inspection device. Figure 5D shows the case when a +6D (diopter) corrective lens is mounted on the visual inspection device.

[0054] As shown in Figure 5, in this embodiment as well, the size of the background image 121 as seen by the subject differs when corrective lenses are attached to the visual examination device 1 (Figure 5A) compared to when corrective lenses are attached (Figures 5B to 5D). On the other hand, the examination target as seen by the subject is displayed at the same coordinate position as when corrective lenses are not attached, even when corrective lenses are attached. Specifically, for example, as shown in Figures 5B and 5C, when corrective lenses with negative spherical power are attached, the display position of the examination target is corrected to be further outward, so that the examination target is displayed at the same coordinate position as when corrective lenses are not attached, as shown in Figure 5A. Also, as shown in Figure 5D, when corrective lenses with positive spherical power are attached, the display position of the examination target is corrected to be closer to the center, so that the examination target is displayed at the same coordinate position as when corrective lenses are not attached, as shown in Figure 5A. In other words, the target display control unit 431 of this embodiment is configured to correct the display position of the test target according to the spherical power of the corrective lens, so that the coordinate position of the test target as seen from the subject is the same as when the corrective lens is not worn. To put it another way, the target display control unit 431 of this embodiment is configured to correct the display position of the test target according to the spherical power of the corrective lens, so that the angle of the light beam that enters the subject's eye 8 (the center of the pupil 9 when the subject is fixated on the target) from the test target through the display optical system 11 is the same as when the corrective lens is not worn. As a result, an appropriate visual examination can be performed without the degree of eccentricity being examined changing depending on whether or not a corrective lens is worn or the spherical power of the corrective lens.

[0055] In the above example, it was assumed that the spherical power of the corrective lens and the size of the background image 121 (i.e., the spherical power of the corrective lens and the amount used to correct the display position of the test target) are in a linear relationship, but they may also be in a nonlinear relationship. For example, Figures 1 and 5 show a significant change in the size of the background image 121, but this is the change in the case of the corrective lens alone, and the display optical system 11 of the visual inspection device 1 according to the present invention also contains other lenses, etc. Therefore, the change in the size of the background image 121 is somewhat gradual. Reflecting this, it may be assumed that the spherical power of the corrective lens and the size of the background image 121 are in a nonlinear relationship (curvilinear relationship).

[0056] Furthermore, when wearing corrective lenses with negative spherical power, if the degree of eccentricity being tested is large, correcting the display position of the test target to the outside may result in the test target appearing outside the background image 121 (outside the range of the testable area 121). In this case, it is not necessary to correct the display position of the test target, or the display position of the test target may be corrected so that it is displayed near the outer edge of the background image 121.

[0057] As shown in Figure 5, in this embodiment, the size of the test target as seen by the subject differs depending on the spherical power of the corrective lens. It is preferable that the target display control unit 431 does not correct (change) the size of the test target on the display element 12. In this case, the amount of light (energy) of the test target incident on the subject's eye 8 is constant regardless of the spherical power of the corrective lens, so a more appropriate visual examination can be performed.

[0058] The display control unit 43 (or target display control unit 431) may display the fixation target on each of the display elements 12 based on the interpupillary distance (PD) of the subject, the display distance of the fixation target relative to the subject (L), and the convergence angle determined by the interpupillary distance (PD) and the display distance (L). The content of displaying the fixation target on each of the display elements 12 based on the above convergence angle may be the same as that described in Patent Document 1.

[0059] Figure 6 is a schematic diagram showing an image 161 of the subject's eye while looking at a fixation target (hereinafter also referred to as the fixation state). Figure 6A shows the case when no corrective lens is attached to the visual examination device. Figure 6B shows the case when a -6D (diopter) corrective lens is attached to the visual examination device. Figure 6C shows the case when a -12D (diopter) corrective lens is attached to the visual examination device.

[0060] Comparing the figures in Figure 6, it can be seen that the size of the subject's eye 8, and consequently the appearance of the pupil 9 (e.g., pupil diameter), differs. Specifically, it can be seen that when a corrective lens with negative spherical power is worn, the size of the subject's eye 8 and pupil 9 is smaller compared to when no corrective lens is worn.

[0061] One reason the examiner checks the image 161 of the subject's eye is to confirm that the subject's gaze is not directed at the test target. Visual field testing is highly important for checking for abnormalities in the peripheral vision while the subject is fixated on a fixation target in front of them. Nevertheless, if the subject's gaze is diverted from the fixation target, it may not be possible to perform a proper visual examination.

[0062] Therefore, it is preferable that the target display control unit 431 corrects the display position of the test target by a predetermined correction amount when the subject's gaze shifts away from the fixation target, for example, before displaying the test target on the display element 12. Specifically, for example, if the subject's gaze shifts 10 mm to the right from the fixation target while not wearing corrective lenses, correcting the display position of the test target by 10 mm in the same direction as the shift in gaze (to the right in this case) allows for an appropriate visual examination without changing the degree of eccentricity being tested. To confirm the direction and amount of the shift in the subject's gaze from the fixation target, for example, the image 161 of the subject's eye (especially the position of the center of the pupil 9) can be checked.

[0063] However, when wearing corrective lenses, for example, correcting the display position of the test target by 10 mm to the right does not necessarily mean that the coordinate position of the test target as seen by the subject will change by 10 mm to the right. Therefore, it is preferable for the target display control unit 431 to change the amount of correction used to correct the display position of the test target when the subject's gaze shifts from the fixation target displayed on the display element 12, according to the spherical power of the corrective lens, before displaying the test target on the display element 12. Specifically, for example, when wearing corrective lenses with negative spherical power, the correction amount should be changed to be larger than usual, and when wearing corrective lenses with positive spherical power, the correction amount should be changed to be smaller than usual. This allows for an appropriate visual examination to be performed without changing the degree of eccentricity being examined, even when the subject's gaze shifts from the fixation target.

[0064] Furthermore, when the subject's gaze shifts away from the fixation target, and the display position of the test target is corrected by a predetermined amount, the target display control unit 431 may correct the display position of the fixation target by, for example, the same amount as the test target, or it may not correct it at all. Also, if the subject's gaze shifts away from the fixation target after the test target has been displayed on the display element 12, correcting the display position of the test target afterward may not allow for a proper visual examination, so it is not necessary to correct the display position of the test target.

[0065] A state in which the center of the subject's eye image 161 and the center of the pupil 9 coincide or are near each other (for example, within a circle with a radius of 5 mm from the center of the eye image 161) may be considered a normal fixation state. On the other hand, the size of the testable area 121 changes depending on the presence or absence of corrective lenses or the spherical power of the corrective lenses. Since this effect also extends to the subject's eye image 161, the above-mentioned "within a circle with a radius of 5 mm" may be appropriately changed according to the spherical power of the corrective lenses.

[0066] The memory 44, which is the information storage unit, is used to store various types of information, including the information necessary for the visual examination. For example, the sensitivity map creation unit 42 sequentially stores the examination results obtained from the start to the end of the visual examination in the memory 44, and after the completion of the visual examination, it creates a sensitivity map using the examination results stored in the memory 44.

[0067] Memory 44 may store the spherical power of the corrective lens. There are no limitations on the manner in which the information is stored; the examiner may manually input the spherical power of the corrective lens into the visual examination device 1, or it may be stored in memory 44 via an internet connection. In yet another embodiment, the visual examination device 1 may be further provided with a corrective lens identification unit 46 that automatically recognizes the spherical power of the corrective lens based on the external characteristics of the corrective lens present in the image of the eye 161 captured by the image sensor, and the spherical power automatically recognized by the corrective lens identification unit 46 may be stored in memory 44.

[0068] "The external features of the corrective lens" include, for example, providing a notch on the outer edge of the corrective lens. If this configuration is adopted, the notch (reference numeral 161N) of the corrective lens can be visually confirmed on the eye image 161, as shown in Figures 6B and 6C. The form of the notch may differ for each spherical power, or it may be a feature that is not discernible to the naked eye but is visually discernible on the image 161. Such a feature could be, for example, a hidden mark that is identifiable on the image 161 when illuminated with infrared light. By having a corrective lens with such external features, for example, even after the visual examination is completed, it is possible to check the spherical power of the corrective lens from the saved eye image 161 and confirm whether an appropriate visual examination was performed.

[0069] Furthermore, the visual examination device 1 may also include a determination unit 47 that determines whether the spherical power automatically recognized by the corrective lens identification unit 46 matches the spherical power stored in the memory unit (memory 44). The advantages of including the determination unit 47 are envisioned in the following cases.

[0070] For example, the examiner may have prior knowledge of the spherical power of a corrective lens for a particular subject, and may perform a visual examination by mounting the corrective lens corresponding to that spherical power into the visual examination device 1. However, if the spherical power automatically recognized by the corrective lens identification unit 46 during the visual examination differs from the spherical power known to the examiner, the determination unit 47 determines this and issues a warning to the examiner from the visual examination device 1. This warning reveals that the wrong corrective lens has been mounted into the visual examination device 1. This allows the system to be corrected before obtaining results from an inappropriate visual examination.

[0071] In addition to the aforementioned switches 31, image sensors 16L and 16R, and display elements 12L and 12R, the control unit 30 is connected to a terminal 45 via wired or wireless communication. The terminal 45 is used by examiners, such as ophthalmologists, to perform various settings, adjustments, operations, and instructions necessary for the vision examination when using the vision examination device 1. The terminal 45 is configured, for example, using a personal computer with a monitor.

[0072] Switch 31 is operated by the subject undergoing the visual examination. Switch 31 is primarily operated by the subject in response during the visual examination. Preferably, the switch 31 is a manual switch that the subject holds and operates with their hand, and more preferably, a push-type switch that the subject presses with their fingers (for example, thumb or index finger). In this case, when the subject presses the switch 31, the switch 31 switches from the off state to the on state, and an on signal is output from the switch 31. This on signal is received by the control unit 30.

[0073] As described above, according to this embodiment, appropriate visual examinations can be performed regardless of whether or not corrective lenses are used or the spherical power of the corrective lenses.

[0074] <2. Visual Examination Methods> Next, a visual inspection method performed using the visual inspection device 1 according to an embodiment of the present invention will be described.

[0075] In the visual inspection device 1 according to an embodiment of the present invention, it is possible to perform dynamic quantitative perimetry (Goldmann perimetry), static quantitative perimetry, fundus perimetry (microperimetry), electroretinography (ERG), and other examinations. Here, as an example, the case of performing static quantitative perimetry will be described.

[0076] Static quantitative perimetry is performed as follows: First, a fixation target is presented in the center of the visual field, and the subject is instructed to fixate on this target. Next, while the subject continues to fixate on the target, another target is presented at a point in the visual field, and its brightness is gradually increased. When the target reaches a certain brightness, the subject will be able to see it. The value corresponding to the brightness at which the subject can see the target is defined as the retinal sensitivity at the point where the target is presented at that time. Then, by performing similar measurements at each point in the visual field, the differences in retinal sensitivity within the visual field are quantitatively investigated, and a map is created. There are two types of static quantitative perimetry: subjective perimetry and objective perimetry. Using the visual examination device 1 of this embodiment, either type of examination can be performed. These will be explained below.

[0077] A subjective visual field test is performed as follows. First, a head-mounted visual field testing device 1 (device body 5) is attached to the subject's head, and a switch 31 is placed in the subject's hand. Next, based on a command from the control unit 30, a fixation target is displayed on the display surface 12a of the display element 12, and the subject is instructed to fixate on it. While the subject is fixated on it, a visual field test target is displayed at a single point on the display surface 12a. At this time, the brightness of the target is initially kept low, and then the brightness of the target is gradually increased. As a result, even if the target is initially too dark for the subject to see, when the target reaches a certain brightness, the subject's retina reacts to the light stimulus, and the target becomes visible to the subject. Therefore, when the subject can see the target, they are asked to press the switch 31 as a response. When the subject presses the switch 31, an ON signal is sent to the control unit 30. Upon receiving this ON signal, the sensitivity map creation unit 42 sets the value corresponding to the brightness of the target point at that time as the sensitivity of the retina at that point. Subsequently, by performing similar measurements at each point within the visual field, the sensitivity map creation unit 42 quantitatively investigates the differences in retinal sensitivity within the visual field and creates a retinal sensitivity map.

[0078] Objective visual field testing is performed as follows: First, a head-mounted visual field testing device 1 is attached to the subject's head, and the subject is instructed to fixate on a fixation target as described above. Next, based on a command from the control unit 30, a visual field testing target is displayed at a single point on the display surface 12a of the display element 12. At this time, the brightness of the target is initially kept low, and then the brightness of the target is gradually increased. In this way, even if the target is initially too dark for the subject to see, once the target reaches a certain brightness, the subject's retina will react to the light stimulus, and the target will become visible to the subject.

[0079] Whether it is a subjective or objective visual field test, in this embodiment, after applying the conversion work based on spherical power described above, the target display control unit 431 controls the display position of the test targets (preferably test targets and fixation targets) displayed on the display element 12. During this control, the corrective lens identification unit 46 and determination unit 47 described above may be applied to confirm whether the information about corrective lenses (presence or absence, spherical power) input to the visual examination device 1 matches the spherical power of the corrective lenses actually mounted on the visual examination device 1.

[0080] During this process, the size of the subject's pupil 9 (pupil diameter) changes in accordance with the brightness of the target. Specifically, the diameter of the subject's pupil 9 constricts. The change in the state of the eye 8 at this time is imaged. Imaging of the eye 8 is performed by irradiating the eye 8 with infrared light from an infrared light source, and then focusing the resulting image of the eye 8 onto the imaging surface 16a of the image sensor 16 via the observation optical system 15 (19, 20, 22). The timing for starting imaging of the eye 8 can be set, for example, before displaying the target on the display surface 12a, or simultaneously with the display of the target. Incidentally, the human retina is not sensitive to infrared light, so it does not affect the change in the state of the eye 8.

[0081] The image 161 of the eye 8 captured using the image sensor 16 is taken into the control unit 30. At this time, the pupil constriction detection unit 41 determines, based on the image 161 data sent from the image sensor 16, whether the subject's pupil diameter has changed (contracted) in response to the brightness of the target as the brightness of the target is gradually increased. When the pupil constriction detection unit 41 determines that the subject's pupil diameter has changed, the sensitivity map creation unit 42 sets the value corresponding to the brightness of the target point at that time as the sensitivity on the retina of that point. Thereafter, by automatically performing similar measurements for each point in the field of view one after another, the sensitivity map creation unit 42 quantitatively examines the differences in sensitivity on the retina within the field of view and automatically creates a sensitivity map of the retina.

[0082] To detect whether the subject's pupil diameter has changed (contracted) in response to the brightness of the visual target, the conversion process based on spherical power described above may be applied. Specifically, in the image 161 of the captured eye 8, the change (contraction) of the pupil diameter differs depending on whether or not corrective lenses are present or on the spherical power of the corrective lenses. In response to this, the pupil diameter may be converted to the pupil diameter of the uncorrected state based on the spherical power described above, and the pupil constriction detection unit 41 may detect whether the subject's pupil diameter has changed based on that pupil diameter.

[0083] The coordinate position conversion work described above may be performed by the pupillary constriction detection unit 41 and the target display control unit 431 mentioned earlier, or the pupillary constriction detection unit 41 and the target display control unit 431 may each acquire the calculation results obtained by a calculation unit separately provided in the visual inspection device 1 and reflect them in pupillary constriction detection and target display, respectively.

[0084] In addition, in objective visual field testing, a single suprathreshold stimulation method may be used, in which a bright target is displayed at a single point on the display surface 12a of the display element 12, and a sensitivity map is created by observing the degree of pupil diameter reduction.

[0085] <3. Variations, etc.> The technical scope of the present invention is not limited to the embodiments described above, but also includes various modified and improved forms to the extent that specific effects can be obtained by the constituent elements of the invention or combinations thereof.

[0086] For example, in the above embodiment, the mounting device 6 for the visual examination device 1 is made up of belts 13 and 14, but any configuration of mounting device 6 is acceptable as long as it can be attached to the head 3 of the subject 2. However, if the position of the main body of the device 5 moves during the visual examination, it will be impossible to obtain accurate test results. For this reason, it is preferable that the mounting device 6 be configured in a way that can securely fix the main body of the device 5 to the head 3 of the subject 2.

[0087] Furthermore, although the above embodiment described a head-mounted type visual examination device 1 used by attaching the device body 5 to the head 3 of the subject 2, the present invention is not limited to this, and is applicable to any device that has a display optical system and display element configured independently for the left and right eyes, and that can perform visual examinations with both eyes open.

[0088] Furthermore, although the above embodiment uses a liquid crystal display element to constitute the display element 12, the present invention is not limited to this, and for example, the display element 12 may be composed of an organic EL (Electro-Luminescence) display element or the like.

[0089] Furthermore, in the above embodiment, the display optical system 11 may be composed of a total of four lenses, and the observation optical system 15 may be composed of a total of two lenses (one of which is shared with the display optical system 11). However, the number and shape of the lenses constituting each optical system, the lens spacing in the optical axis direction, etc., can be changed as needed. However, for the second lens group, it is preferable to have multiple lenses in order to correct chromatic aberration and image magnification by combining lenses with positive power and lenses with negative power. Also, the mirror 20 may be composed of a dichroic mirror.

[0090] Furthermore, in this embodiment, the display optical system 11 and the display element 12 are provided independently for the left eye 8L and right eye 8R of the subject. On the other hand, the main point of the present invention is to correct the display position of the test target displayed within the testable area 121 according to the spherical power of the corrective lens, and this can be achieved even without the above-described independent left and right structure. As a result, the technical idea of ​​the present invention is not limited to this configuration.

[0091] Furthermore, this embodiment further includes an observation optical system 15 for the examiner to observe the subject's eye and an image sensor 16 for imaging the subject's eye through the observation optical system 15. On the other hand, the main point of the present invention is to correct the display position of the examination target displayed within the examineable area 121 according to the spherical power of the corrective lens, and this can be achieved even without the observation optical system 15 and image sensor 16. As a result, the technical idea of ​​the present invention is not limited to this configuration.

[0092] Furthermore, in addition to correcting the display position of the test target displayed within the testable area 121 according to the spherical power of the corrective lens, the target display control unit 431 may, for example, control the brightness of the test target to maintain (or change) it.

[0093] Furthermore, although this embodiment explains that the size of the background image 121 as seen by the subject differs when corrective lenses are worn, the target display control unit 431 may change the size of the background image 121 displayed on the display element 12 according to the spherical power of the corrective lenses. Specifically, for example, the size of the background image 121 displayed on the display element 12 may be changed so that the size of the background image 121 as seen by the subject is the same as when corrective lenses are not worn. In this case, even when corrective lenses with negative spherical power are worn, the maximum eccentricity that can be examined can be maintained.

[0094] Furthermore, when a corrective lens for astigmatism is attached to the visual examination device 1, the target display control unit 431 may correct the display position of the test target displayed within the testable area 121 according to, for example, the cylindrical power and astigmatism axis of the corrective lens.

[0095] The technical concept of the present invention is also reflected in a visual inspection device set that includes the visual inspection device 1 described above, and a plurality of corrective lenses with different spherical powers, wherein the corrective lenses have external characteristics that allow the spherical powers to be distinguished within the image 161 of the eye captured by the image sensor 16. [Explanation of symbols]

[0096] 1…Visual inspection device 2… Subject 3…Head 5…Main unit of the device 6…Equipment 7…Cabinet 8…eyes 9...pupil 10…Retina 11...Display optical system 12…Display element 12a…display surface 121... Examineable area (background image) 13, 14… belt 15… Observation Optical System 16…Image sensor 161...Image of the subject's eyes 161N...Notch of the corrective lens on the eye image 18…Optical axis 19…First lens 20...Mirror 22...Third lens 30…Control Unit 31…Switch 41...Pupillary constriction detection unit 42…Sensitivity Map Creation Section 43…Display Control Unit 431... Target display control unit 44...Memory 45… Terminal 46... Correction lens identification section 47...Judgment section

Claims

1. A display optical system and display element for displaying a visual target to the eye of a subject undergoing a visual examination, A target display control unit that corrects the display position of the test target displayed within the testable area on the display element according to the spherical power of a corrective lens that can be attached to the display optical system and allows the subject to see the target, The system comprises an observation optical system for an examiner to observe the subject's eye and an image sensor for imaging the subject's eye through the observation optical system, The visual target display control unit changes the amount of correction used to correct the display position of the test target when the subject's gaze deviates from the fixation target displayed on the display element, according to the spherical power of the corrective lens, in a visual examination device.

2. A display optical system and display element for displaying a visual target to the eye of a subject undergoing a visual examination, A target display control unit that corrects the display position of the test target displayed within the testable area on the display element according to the spherical power of a corrective lens that can be attached to the display optical system and allows the subject to see the target, An observation optical system for the examiner to observe the subject's eye and an image sensor for imaging the subject's eye through the observation optical system, A vision testing device comprising: a corrective lens identification unit that automatically recognizes the spherical power of the corrective lens based on the external characteristics of the corrective lens present in the image of the eye captured by the image sensor.

3. The visual examination apparatus according to claim 1 or 2, wherein the visual target display control unit corrects the display position of the examination visual target according to the spherical power of the corrective lens, so that the coordinate position of the examination visual target as seen from the subject is the same as when the corrective lens is not worn.

4. The visual inspection apparatus according to claim 1 or claim 2, wherein the display optical system and the display element are provided independently on the left and right sides, corresponding to the left and right eyes of the subject.

5. The visual examination apparatus according to claim 2, wherein the visual target display control unit changes the amount of correction used to correct the display position of the examination target when the subject's gaze deviates from the fixation target displayed on the display element, according to the spherical power of the corrective lens.

6. The visual inspection apparatus according to claim 1, further comprising a corrective lens identification unit that automatically recognizes the spherical power of the corrective lens based on the external characteristics of the corrective lens present in the image of the eye captured by the image sensor.

7. A storage unit for storing the spherical power of the corrective lens, A determination unit that determines whether the spherical power automatically recognized by the corrective lens identification unit matches the spherical power stored in the storage unit, The visual inspection apparatus according to claim 2, further comprising the following:

8. The visual inspection apparatus according to claim 1 or claim 2, wherein the inspectable area is a background image displayed on the display element.

9. Display optical systems and display elements are provided independently for the left and right eyes of the subject undergoing a visual examination, respectively. An observation optical system for the examiner to observe the subject's eye and an image sensor for imaging the subject's eye through the observation optical system, A target display control unit that corrects the display position of the test target displayed within the testable area on the display element according to the spherical power of a corrective lens that can be attached to the display optical system and allows the subject to see the target, A visual inspection device equipped with, A plurality of corrective lenses having different spherical powers, wherein each corrective lens has an external appearance that allows the spherical powers to be distinguished within the image of the eye captured by the image sensor, A visual inspection device set equipped with the following features.

Images