Ophthalmologic apparatus

Abstract

To illuminate a pattern index more uniformly without complicating the composition.SOLUTION: An ophthalmologic apparatus for measuring a cornea shape of an eye to be examined includes a measurement pattern index plate where a pattern index for measuring a cornea shape of an eye to be examined, and a flat surface light emission panel for illuminating the measurement pattern index plate from behind and projecting the pattern index onto the cornea of the eye to be examined. The surface light emission panel includes a light guide plate for guiding light, an illumination light source arranged at an end part of the light guide plate, and a reflection pattern arranged on a rear surface side of the light guide plate for reflecting the light from the illumination light source on a front surface side of the light guide plate. The density of the reflection pattern is adjusted in correspondence with a positional relationship between the surface light emission panel and the pattern index.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to an ophthalmic apparatus that measures the corneal shape of a subject's eye. [Background technology]

[0002] An ophthalmic device is known that projects a pattern index (e.g., a number of ring pattern indexes) for measuring the corneal shape onto the cornea of ​​an examinee's eye and captures an image of the pattern index formed on the cornea to measure the detailed corneal shape. This type of ophthalmic device is provided with an illumination unit that illuminates from behind a pattern index plate on which light-transmitting portions and light-blocking portions are alternately formed.

[0003] As a conventional lighting unit, for example, a configuration has been proposed in which a pattern index is illuminated from behind by surface emission from a surface emission plate (see Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-279383 Summary of the Invention [Problem to be solved by the invention]

[0005] However, further improvements are desired in the projection of pattern indicators for measuring corneal shape. For example, in the configuration of Patent Document 1, the surface light-emitting plate is formed into a substantially spherical shape and the pattern indicator portion is integrally formed on the surface of the surface light-emitting plate, or two cone-shaped surface light-emitting plates are used behind the pattern indicator plate, which results in a problem of the surface light-emitting plate having a complex shape and being difficult to manufacture. Furthermore, Patent Document 1 discloses a configuration in which multiple flat surface light-emitting plates are divided and arranged behind a hemispherical pattern indicator plate, but if the position of the pattern indicator plate relative to the surface light-emitting plate varies depending on the location, it is difficult to uniformly illuminate the pattern indicator.

[0006] In view of the above-described conventional techniques, the present disclosure has as its technical object to provide an ophthalmic apparatus that can more uniformly illuminate a pattern target without complicating the configuration. [Means for solving the problem]

[0007] An ophthalmic device provided by a typical embodiment of the present disclosure is an ophthalmic device for measuring the corneal shape of a test eye, comprising: a measurement pattern indicator plate on which pattern indicators for measuring the corneal shape of the test eye are formed; and a flat surface-emitting panel that illuminates the measurement pattern indicator plate from behind and projects the pattern indicators onto the cornea of ​​the test eye, wherein the surface-emitting panel has a light-guiding plate that guides light, an illumination light source arranged at an end of the light-guiding plate, and a reflection pattern that is arranged on the back side of the light-guiding plate and reflects light from the illumination light source toward the front side of the light-guiding plate, and the density of the reflection pattern is adjusted corresponding to the positional relationship between the surface-emitting panel and the pattern indicators. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is an external view of an ophthalmic device. [Figure 2] FIG. 2 is a schematic configuration diagram of an optical system arranged in an optometry unit and a control system of the ophthalmic apparatus. [Figure 3] FIG. 2 is a diagram illustrating the configuration of a measurement pattern index plate. [Figure 4] 1 is a diagram illustrating the configuration of a surface light-emitting panel, and is a partial cross-sectional view of the surface light-emitting panel. FIG. [Figure 5] 1A and 1B are diagrams illustrating the configuration of a surface light-emitting panel, and are diagrams illustrating the surface light-emitting panel as viewed from the front. [Figure 6] 10A and 10B are diagrams illustrating the size of a surface light-emitting panel when no reflector is provided and adjustment of the reflection pattern. [Figure 7] 10A and 10B are diagrams illustrating the size of a surface light-emitting panel and adjustment of a reflection pattern when a reflector is provided. DETAILED DESCRIPTION OF THE INVENTION

[0009] [overview] Hereinafter, one exemplary embodiment will be described with reference to the drawings. Note that the items grouped in <> below can be used independently or in conjunction with each other.

[0010] An ophthalmic apparatus (e.g., ophthalmic apparatus 1) of the present disclosure includes a measurement pattern index projection unit (e.g., measurement pattern index projection unit 110). For example, the measurement pattern index projection unit includes a measurement pattern index plate (e.g., measurement pattern index plate 120) and a surface light-emitting panel (e.g., surface light-emitting panel 130). For example, a pattern index (e.g., pattern index 122) for measuring the corneal shape of the subject's eye is formed on the measurement pattern index plate. For example, the ophthalmic apparatus includes an imaging optical system (e.g., front imaging optical system 150). For example, the imaging optical system is used to capture an index image of the pattern index projected onto the cornea of ​​the subject. For example, the ophthalmic apparatus may include image processing means (e.g., control unit 50). The image processing means is used to analyze the pattern index image captured by the imaging optical system to obtain the corneal shape.

[0011] For example, the measurement pattern indicator plate may have an inclined portion (e.g., inclined portion 121B) inclined relative to the surface light-emitting panel. For example, the measurement pattern indicator plate may have a flat portion (e.g., flat portion 121A) centered on the imaging optical axis, and the inclined portion may be arranged on the outer periphery of the flat portion. In this case, the surface light-emitting panel is arranged parallel to the flat portion. Note that the inclined portion may be such that the entire measurement pattern indicator plate is approximately spherical.

[0012] When the measurement pattern indicator plate has an inclined portion, it is preferable to arrange a reflector (e.g., reflector 140) on the outer periphery of the inclined portion. For example, the reflector is used to reflect the illumination light emitted from the surface-emitting panel and guide the illumination light to the pattern indicator formed on the inclined portion. When a reflector is provided, the size of the surface-emitting panel can be prevented from increasing, and the pattern indicator can be efficiently illuminated. Furthermore, the size of the device itself can be prevented from increasing.

[0013] For example, the surface-emitting panel illuminates the measurement pattern indicator plate from behind and projects the pattern indicator onto the cornea of ​​the subject's eye. For example, the surface-emitting panel is formed in a flat plate shape. For example, the surface-emitting panel is arranged in a direction perpendicular to the imaging optical axis of the imaging optical system. Unlike when the surface-emitting panel is formed in a hemispherical or conical shape, forming the surface-emitting panel in a flat plate shape makes it easier to manufacture and does not make the configuration of the surface-emitting panel complicated.

[0014] For example, the surface-emitting panel includes a light guide plate (e.g., light guide plate 131) that guides light, an illumination light source (e.g., illumination light source 132), and a reflection pattern (e.g., reflection pattern 133). For example, the illumination light source is disposed at an end of the light guide plate. For example, the reflection pattern is disposed on the back side of the light guide plate and reflects light from the illumination light source toward the front side of the light guide plate. Furthermore, the surface-emitting panel may include a reflection sheet (e.g., reflection sheet 134) and a diffusion plate (e.g., diffusion plate 135). For example, the reflection sheet is disposed on the back side of the surface-emitting panel with the reflection pattern sandwiched therebetween. For example, the diffusion plate is disposed on the front side of the surface-emitting panel (the front side of the light guide plate) and diffuses light emitted from the surface of the surface-emitting panel.

[0015] For example, the reflective pattern may be reflective dots formed on the back surface of the light guide plate. For example, the reflective dots are formed by printing a dot-like pattern of paint having reflective properties on the back surface of the light guide plate. For example, the reflective pattern may be a printed reflective dot pattern, a groove pattern formed by forming grooves in the light guide plate with a plotter, a scratch pattern formed by scratching with laser light, or a molded pattern formed by pouring the resin of the light guide plate into a template.

[0016] For example, the distribution density of the reflection pattern is adjusted in accordance with the positional relationship between the surface-emitting panel and the pattern index. This allows a pattern index with a uniform amount of illumination light to be projected onto the cornea without complicating the configuration of the measurement pattern index projection unit. The density of the reflection pattern is also adjusted in accordance with the positional relationship between the reflection pattern and the illumination light source. In this case, for example, since the amount of light guided by the light guide plate attenuates with increasing distance from the illumination light source, the density of the reflection pattern should be adjusted so that it becomes denser with increasing distance from the illumination light source.

[0017] Furthermore, for example, the density of the reflection pattern may be adjusted according to the positional relationship between the pattern indicator and the surface-emitting panel relative to the imaging optical axis of the imaging optical system. For example, the density of the reflection pattern may be adjusted so that the density of the reflection pattern becomes denser as the distance from the imaging optical axis of the imaging optical system increases, compared to the density of the reflection pattern adjusted so that the amount of illumination light emitted from the entire surface of the surface-emitting panel is uniform. This allows the amount of light emitted from the surface-emitting panel to increase as the distance from the imaging optical axis increases, and pattern indicators farther from the imaging optical axis can be projected onto the cornea with approximately the same uniform amount of light as pattern indicators near the imaging optical axis.

[0018] For example, the inclination of the light rays that contribute to the formation of the pattern index image (the angle of inclination with respect to the vertical direction of the surface-emitting panel) increases as the distance from the photographing optical axis increases. Therefore, even if the amount of light when viewing the surface-emitting panel from the front (the vertical direction of the surface-emitting panel) is uniform across the entire surface, the amount of light rays that contribute to the formation of the pattern index image away from the photographing optical axis will not be the same as the amount of light near the photographing optical axis, and will become weaker as the distance from the optical axis increases. Therefore, as described above, it is preferable to adjust the density of the reflection pattern so that the density of the reflection pattern becomes denser as the distance from the photographing optical axis of the photographing optical system increases, compared to the density of the reflection pattern when the amount of illumination light emitted from the entire surface of the surface-emitting panel is adjusted to be uniform.

[0019] For example, if the measurement pattern indicator plate has a flat portion centered on the imaging optical axis and an inclined portion is disposed on the outer periphery of the flat portion, if the illumination light intensity on the surface of the surface-emitting panel is uniform across the entire surface, the diffuse reflection of the reflector will likely cause the illumination light intensity on the inclined portion of the measurement pattern indicator plate to be stronger than that on the flat portion of the measurement pattern indicator plate. Therefore, the density of the reflective patterns can be adjusted to weaken the illumination light intensity on the inclined portion. For example, the density of the reflective patterns can be adjusted so that the illumination light intensity on the surface of the surface-emitting panel corresponding to the pattern indicators formed on the inclined portion is relatively weaker than that on the surface of the surface-emitting panel corresponding to the flat portion. This allows both the pattern indicators on the flat portion of the measurement pattern indicator plate and the pattern indicators on the inclined portion to be uniformly illuminated with approximately the same amount of light when the reflector is disposed on the outer periphery of the inclined portion.

[0020] Furthermore, for example, the ophthalmic apparatus may include, as an optical system, an alignment optical system (e.g., a working distance detection optical system 160, an anterior segment illumination light source 155) that has an optical axis tilted relative to the imaging optical system and is used to align the imaging optical system with the subject's eye, in addition to the corneal shape measurement optical system. For example, the ophthalmic apparatus may additionally include, in addition to the corneal shape measurement optical system, an optical system (e.g., a cross-sectional imaging optical system 210) that has an optical axis separate from the optical axis of the imaging optical system and is used to measure optical characteristics of the subject's eye. In this case, the surface-emitting panel may have light-passing holes (e.g., light-passing holes 134a, 134b, 134c) formed to pass at least one of a light beam used for alignment or a light beam used to measure optical characteristics of the subject's eye other than corneal shape measurement. In this case, the density of the reflection pattern of the surface-emitting panel may be adjusted depending on the position of the light-passing holes. For example, the density of the reflection pattern is relatively higher when a light-passing hole is provided than when no light-passing hole is provided. This reduces the influence of light-passing holes formed in the surface-emitting panel (for example, the influence of the light-passing holes attenuating the illumination light from the illumination light source provided at the end of the surface-emitting panel) and enables the pattern indicator to be uniformly illuminated regardless of the position of the light-passing holes.

[0021] Furthermore, for example, the surface-emitting panel may be formed into a polygon with more sides than a square, corresponding to the shape of the measurement pattern indicator plate when viewed from the front direction where the test eye is positioned. For example, the surface-emitting panel may be formed into a polygon with octagons or more sides. The illumination light sources provided on the surface-emitting panel may be arranged on each side of the polygon. This allows the measurement pattern indicator plate to be illuminated from behind more efficiently and with reduced illumination unevenness, compared to a square surface-emitting panel. The measurement pattern indicator plate may also have a horizontally elongated shape, with the left and right directions being longer, and the surface-emitting panel may also have a horizontally elongated shape corresponding to this. For example, the measurement pattern indicator plate may have a shape that, when viewed from the front direction where the test eye is positioned, gradually becomes shorter in the vertical direction from the center toward the left and right ends, and the surface-emitting panel may have a horizontally elongated shape, with the left and right directions being longer, corresponding to the shape of the measurement pattern indicator plate when viewed from the front direction where the test eye is positioned.

[0022] [Example] <Overall structure> An example of this embodiment will be described with reference to the drawings. FIG. 1 is an external view of an ophthalmic apparatus 1. The ophthalmic apparatus 1 includes an opthalmological unit 10, a base 12, an alignment drive unit 13, a face support unit 15, a monitor 16, and a control unit 50. The opthalmological unit 10 includes a corneal shape measurement unit 100 for measuring the corneal shape of the subject's eye (E). A measurement pattern index projection unit 110 of the corneal shape measurement unit 100 is disposed on the front side (the subject's eye side) of the opthalmological unit 10. The measurement pattern index projection unit 110 is disposed facing the subject's eye. In addition to the corneal shape measurement unit 100, the ophthalmic apparatus 1 may also include an inspection unit for inspecting (measuring or photographing) optical characteristics of the subject's eye other than corneal shape measurement. In this example, an example will be described in which the opthalmological unit 10 includes an anterior segment cross-sectional imaging unit 200 (see FIG. 2).

[0023] The alignment drive unit 13 changes the positional relationship of the optometry unit 10 with respect to the subject's eye. For example, the alignment drive unit 13 moves the optometry unit 10 three-dimensionally with respect to the base 12, thereby moving the optometry unit 10 in the X direction (left-right direction), Y direction (up-down direction), and Z direction (front-back direction) with respect to the subject's eye. The face support unit 15 is used to fix the subject's face in front of the optometry unit 10. The face support unit 15 is fixed to the base 12, and fixes the subject's eye by supporting the subject's face.

[0024] <Optical system> 2 is a schematic diagram of the optical system arranged in the optometry unit 10 and the control system of the ophthalmologic apparatus 1. The corneal shape measurement unit 100 includes a measurement pattern target projection unit 110 for measuring the corneal shape of the subject's eye (E), a front photographing optical system 150, a working distance detection optical system 160, a front alignment target projection optical system 170, and a fixation target presenting optical system 180. The anterior segment cross-sectional photographing unit 200 includes a cross-sectional photographing optical system 210.

[0025] <Measurement pattern target projection unit> The measurement pattern indicator projection unit 110 includes a measurement pattern indicator plate 120 and a surface light emitting panel 130. The surface light emitting panel 130 is disposed behind the measurement pattern indicator plate 120. The measurement pattern indicator projection unit 110 may additionally include a reflector 140 on the outer periphery of the measurement pattern indicator plate 120.

[0026] <Measurement pattern index plate> Fig. 3 is a diagram for explaining the configuration of the measurement pattern index plate 120. Fig. 3(a) is a diagram showing the measurement pattern index plate 120 as viewed from the front direction on the side where the eye to be examined is positioned, and Fig. 3(b) is a cross-sectional view taken along the line AA in Fig. 3(a).

[0027] The measurement pattern indicator plate 120 is composed of a light guide plate 120a (e.g., acrylic resin) that guides illumination light from the surface light emitting panel 130. Pattern indicators 122 for measuring the corneal shape are formed on the front surface side of the measurement pattern indicator plate 120. The back surface side of the measurement pattern indicator plate 120 may be a diffusion surface that diffuses light that enters the inside of the light guide plate 120a.

[0028] The measurement pattern indicator plate 120 has a flat portion 121A in a plate shape and an inclined portion 121B arranged on the outer periphery of the flat portion 121A. The flat portion 121A has a central opening 123 through which the optical axis L1 of the front imaging optical system 150 passes, and the entire circumference is circular with the center of the central opening 123 as the reference, and a ring-shaped pattern indicator 122 is formed on almost the entire surface.

[0029] The inclined portion 121B is disposed on the outer periphery of the flat portion 121A and has a conical or curved shape based on the center of the central opening 12. In this embodiment, when the measurement pattern indicator plate 120 is viewed from the front (the side of the eye to be examined), the inclined portion 121B is formed in a shape that partially extends to the left and right sides of the circular flat portion 121A. In the example of Fig. 3, the inclined portion 121B is formed in a shape that extends left and right from the flat portion 121A so that its vertical length becomes shorter gradually or in stages.

[0030] For example, the pattern target 122 on the flat portion 121A is designed to measure the shape of the cornea of ​​a standard subject's eye within a diameter range of 8 mm. That is, in the corneal diameter range of 8 mm, where corneal shape measurement is important, the ring-shaped pattern target 122 is designed to be formed almost entirely. On the other hand, the pattern target 122 on the inclined portion 121B is designed to measure the shape of the cornea of ​​a standard subject's eye within a diameter range of 10 to 11 mm. In the ophthalmic apparatus 1 of this embodiment, in order to prevent the measurement pattern target projection unit 110 from becoming large in the vertical direction, the inclined portion 121B is not provided in the vertical direction (vertical direction) at the center of the flat portion 121A. This is because the light beam of the pattern target 122 is easily vignetted by the eyelids and cheeks in the vertical direction of the subject's eye, and therefore the absence of the inclined portion 121B in the vertical direction has little practical effect.

[0031] For example, the inclination angle α of the inclined portion 121B (the inclination angle with respect to the surface-emitting panel 130 arranged parallel to the flat portion 121A) is set to 40 to 70 degrees. In the embodiment, the inclination angle α is set to 55 degrees. If the inclination angle α is greater than 70 degrees, a deeper depth of field is required when capturing a pattern target image using the front imaging optical system 150 (to obtain a pattern target image that is as focused as possible), which is likely to be disadvantageous in obtaining a high-quality captured image. If the inclination angle α is less than 45 degrees, the overall external dimensions of the measurement pattern target plate 120 become large, which is likely to be disadvantageous in using the device.

[0032] The measurement pattern index plate 120 may have a hemispherical shape. In this case, the inclination angle of the inclined portion 121B is not constant, but is changed so as to gradually increase.

[0033] In this embodiment, the pattern indicator 122 is configured as a ring-shaped indicator. For example, the pattern indicator 122 is configured by forming light-transmitting sections 122a that transmit illumination light from the surface-emitting panel 130 and light-shielding sections 122b that block illumination light from the surface-emitting panel 130 on the measurement pattern indicator plate 120. A large number of light-transmitting sections 122a and light-shielding sections 122b are formed alternately in a concentric circle shape centered on the optical axis L1. When the measurement pattern indicator plate 120 is illuminated by the surface-emitting panel 130 behind it, a so-called Placido ring pattern is projected onto the cornea of ​​the subject's eye.

[0034] In addition to the central opening 123 through which the light beam for corneal shape measurement passes, the measurement pattern index plate 120 is formed with a light passing hole 124a through which the light beam of the cross-section photographing optical system 210 passes, a light passing hole 124b through which the light beam of the working distance detection optical system 160 passes, and a light passing hole 124c through which illumination light (light beam from an anterior eye illumination light source 155 described below) that illuminates the subject's eye during alignment and observation of the subject's eye passes. In the example of Fig. 3, the light passing hole 124a is formed below the central opening 123. The light passing holes 124b are formed in two places in the left and right directions around the optical axis L1. The light passing holes 124c are formed at six locations on a first concentric circle outside the light passing holes 124b, centered on the optical axis L1, at angles of 0 degrees, 45 degrees, 135 degrees, 180 degrees, 225 degrees, and 315 degrees, and at six locations on a second concentric circle outside the first concentric circle, at angles of 45 degrees, 135 degrees, 195 degrees, 225 degrees, 315 degrees, and 345 degrees.

[0035] <Surface-emitting panel> The surface-emitting panel 130 is used to illuminate the measurement pattern indicator plate 120 from behind and project the pattern indicator 122 onto the cornea of ​​the subject's eye. The surface-emitting panel 130 is disposed in a direction perpendicular to the imaging optical axis L1 of the front imaging optical system 150. FIG. 4 is a diagram illustrating the configuration of the surface-emitting panel 130, showing a partial cross-sectional view of the surface-emitting panel 130. FIG. 5 is a diagram illustrating the configuration of the surface-emitting panel 130, showing the surface-emitting panel 130 as viewed from the front, on the side where the subject's eye is located. Note that the surface-emitting panel 130 is formed in a flat plate shape, as opposed to a hemispherical or conical shape, which simplifies manufacturing and avoids complicating the configuration of the surface-emitting panel 130.

[0036] 4, the surface light-emitting panel 130 is configured with, as main elements, a light guide plate 131, an illumination light source 132, a reflection pattern 133, a reflection sheet 134, and a diffusion plate 135. The light guide plate 131 is a light-transmitting plate.

[0037] For example, the light guide plate 131 is made of a transparent resin such as acrylic, etc. The illumination light source 132 is made of an LED or the like that emits visible light.

[0038] A plurality of illumination light sources 132 are arranged in a row at the end of the light guide plate 131. The reflection pattern 133 is formed on the rear surface of the light guide plate 131 by reflective dots, which are formed by printing paint having reflective properties in the form of dots.

[0039] The reflective pattern 133 may be a printed reflective dot pattern, a groove pattern formed by forming grooves in the light guide plate 131 using a plotter, a scratch pattern formed by scratching with laser light, a molded pattern formed by pouring a resin such as acrylic into a template, or the like. The amount of illumination light emitted from the surface of the surface-emitting panel 130 can be changed by adjusting the density (distribution density) of the reflective pattern 133. Note that the reflective pattern 133 is illustrated schematically in Figure 4. For example, when the reflective pattern 133 is a reflective dot pattern, reflective dots of the same size are distributed and formed, and when the density of the reflective pattern 133 is increased, the reflective dots are formed so that the intervals between each reflective dot are narrower.

[0040] The reflective sheet 134 is disposed on the rear surface of the surface-emitting panel 130, sandwiching the reflective pattern 133 therebetween. This causes light from the illumination light source 132, which is guided by the light guide plate 131, to be reflected toward the front surface. The diffusion plate 135 is disposed on the front surface side of the surface-emitting panel 130, and diffuses the light emitted from the surface of the surface-emitting panel 130.

[0041] 4 additionally illustrates how the light emitted from the illumination light source 132 travels due to internal reflection in the light guide plate 131 and how it is emitted from the surface of the surface light emitting panel 130.

[0042] Here, the reflective pattern 133 is formed with its density (in the case of reflective dots, the density of the dot arrangement) adjusted according to the positional relationship between the reflective pattern 133 and the illumination light source 132. Light emitted from the illumination light source 132 is also guided to the distant reflective pattern 133 by internal reflection in the light guide plate 131, but as the distance increases, the guided light attenuates. Therefore, for example, if it is desired to emit a uniform amount of illumination light from the surface of the surface-emitting panel 130, the density of the reflective pattern 133 is adjusted to become denser as the distance from the illumination light source 132 increases.

[0043] 5, the outer shape of the surface light-emitting panel 130 is formed into a polygon with more angles than a square, corresponding to the shape of the measurement pattern indicator plate 120. The illumination light sources 132 are arranged on each side of the polygon. The surface light-emitting panel 130 of this embodiment is formed into an octagon.

[0044] 5, if the surface light-emitting panel 130 is rectangular, the light-emitting portions at the four corners of the dotted line portion 136 are far from the measurement pattern indicator plate 120, and the illumination light is wasted. This may also result in uneven illumination of the measurement pattern indicator plate 120.

[0045] In contrast, the surface light-emitting panel 130 in the embodiment of the present disclosure is octagonal, and by eliminating the waste of the dotted line portion 136, the measurement pattern indicator plate 120 can be illuminated efficiently and with reduced illumination unevenness.

[0046] 5, the surface-emitting panel 130 is formed with a central opening 133 through which the light beam for corneal shape measurement passes, as well as a light-passing hole 134a through which the light beam of the cross-section photographing optical system 210 passes, a light-passing hole 134b through which the light beam of the working distance detection optical system 160 passes, and a light-passing hole 134c through which illumination light that illuminates the subject's eye during alignment and observation of the subject's eye passes, just like the measurement pattern indicator plate 120. The positions and numbers of the light-passing holes 134a, 134b, and 134c are formed to correspond to the light-passing holes 124a, 124b, and 124c of the measurement pattern indicator plate 120, respectively.

[0047] <Reflector> 2, the reflector 140 is disposed on the outer periphery of the measurement pattern indicator plate 120 (i.e., on the outer periphery of the inclined portion 121B). The reflector 140 is a diffuse reflection surface that diffuses and reflects the illumination light emitted from the surface-emitting panel 130. The illumination light emitted from the surface-emitting panel 130 is guided to the inclined portion 121B by the reflector 140. The position and angle of the reflection surface of the reflector 140 with respect to the surface-emitting panel 130 are set according to the inclination angle α (see FIG. 3(b)) of the inclined portion 121B with respect to the surface-emitting panel 130. That is, the position and angle are set so that the illumination light emitted from the surface-emitting panel efficiently enters the translucent portion 122a formed on the inclined portion 121B and the loss of the amount of light passing through the translucent portion 122a is minimized (in other words, so that the pattern indicator 122 is efficiently projected onto the cornea).

[0048] Furthermore, when the reflector 140 is provided, the size of the surface-emitting panel 130 corresponds to the placement position of the reflector 140. That is, the size of the surface-emitting panel 130 is made smaller than when the reflector 140 is not provided. This prevents the surface-emitting panel from becoming larger, and allows the pattern target 122 to be efficiently illuminated. Furthermore, it also prevents the ophthalmologic apparatus 1 itself from becoming larger.

[0049] <Adjusting the density of the reflective pattern> The following describes the adjustment of the density of the reflection patterns 133 formed on the rear surface of the light guide plate 131. As described above, the distribution density of the reflection patterns 133 is adjusted in accordance with the positional relationship between the reflection patterns 133 and the illumination light source 132. For example, if it is desired to emit a uniform amount of illumination light from the surface of the surface-emitting panel 130, the density of the reflection patterns 133 is adjusted so that it becomes denser as the distance from the illumination light source 132 increases. In addition, in order to project the pattern target 122 with as uniform an amount of light as possible onto the cornea of ​​the test eye, the density of the reflection patterns 133 is adjusted in accordance with the positional relationship between the surface-emitting panel 130 and the pattern target 122. Furthermore, the density of the reflection patterns 133 is adjusted in accordance with the positional relationship of the pattern target 122 with respect to the optical axis L1 of the front imaging optical system 150 and the positional relationship of the surface-emitting panel 130 with respect to the optical axis L1.

[0050] FIG. 6 is a diagram for explaining the size of the surface light-emitting panel 130 when the reflector 140 is not provided and the adjustment of the reflection pattern 133. In FIG.

[0051] The light rays that contribute to the formation of the target image of the pattern target 122 captured by the front imaging optical system 150 (in other words, the edge detection of the pattern target image) are mainly light rays M1 traveling on the optical axis L1 toward point EP1, which is located at a distance of half the corneal curvature radius R. The design point EP1 is the position when an eye to be examined with a standard corneal curvature radius R (e.g., 7.8 mm) is in a state where alignment is complete at a predetermined working distance. Therefore, if the reflector 140 is not provided, the surface-emitting panel 130 is sized to extend to a position where it emits light rays M1 that pass through the outermost light-transmitting portion 122a of the pattern target 122. In other words, the surface-emitting panel 130 needs to be sized so that it exists on an extension of a line connecting point EP1 and the edge of the outermost light-transmitting portion 122a.

[0052] 6, the inclination (the angle of inclination of the light ray M1 with respect to the vertical direction of the surface-emitting panel 130) of the light ray M1 that contributes to the formation of the pattern index image increases as the pattern index 122 (in this embodiment, a ring pattern) on the measurement pattern index plate 120 moves farther from the optical axis L1. On the other hand, the directivity of the light amount of the light ray that exits one point on the surface-emitting panel 130 is reduced by the diffuser plate 135 arranged on the front side. However, even if the light amount when viewing the surface-emitting panel 130 from the front direction (vertical direction) is uniform over the entire surface, the amount of light illuminating the outer pattern index 122 away from the optical axis L1 will not be the same as the light amount near the optical axis L1, and will decrease with increasing distance from the optical axis L1.

[0053] Therefore, when the reflector 140 is not provided, the amount of light emitted from the surface-emitting panel increases as the distance from the optical axis L1 increases, so that the density of the reflection pattern 133 is adjusted so that the amount of illumination light emitted from the entire surface of the surface-emitting panel 130 is uniform, and the density of the reflection pattern 133 is adjusted so that it becomes denser as the distance from the optical axis L1 increases.

[0054] Note that, for the region K1 (region on the surface-emitting panel 130) of the surface-emitting panel 130 corresponding to the flat portion 121A of the measurement pattern indicator plate 120, the inclination of the light ray M1 is not as large as that of the light ray M1 corresponding to the outer periphery of the inclined portion 121B because the region K1 is near the optical axis L1. Therefore, in practice, the density of the reflection patterns 133 may be adjusted so that the amount of illumination light emitted from the surface-emitting panel 130 is uniform. In the region K2 corresponding to the inclined portion 121B, the density of the reflection patterns 133 may be adjusted so that it is denser in order to increase the amount of light exiting the surface-emitting panel with increasing distance from the optical axis L1. The amount of adjustment can be determined experimentally using a model eye with a standard corneal radius.

[0055] Furthermore, the adjustment of the density of the reflection pattern 133 when the reflector 140 is not provided can also be applied to a case where the measurement pattern indicator plate 120 does not have the inclined portion 121B and is entirely composed of a flat portion. In this case, the measurement pattern indicator plate 120 is sized to extend to the area K2 in FIG. 6.

[0056] FIG. 7 is a diagram for explaining the size of the surface light-emitting panel 130 when the reflector 140 is provided and the adjustment of the reflection pattern 133. In FIG.

[0057] When the reflector 140 is provided on the outer periphery of the inclined portion 121B, the surface-emitting panel 130 is sized to correspond to the position where the reflector 140 is disposed. The pattern index 122 formed on the inclined portion 121B is directly illuminated by light emitted from the surface-emitting panel 130 in an area K3 (an area outside the area K1 that extends to the reflector 140) corresponding to the inclined portion 121B, and is also illuminated by light reflected by the reflector 140. For example, the light ray M1 that contributes to the formation of the pattern index image on the outermost periphery of the pattern index 122 is a light ray that is generated in all directions from the surface-emitting panel 130 by reflection from the reflector 140 and has a relatively small inclination (with respect to the vertical direction of the surface-emitting panel 130). Therefore, the amount of light illuminating the pattern index 122 formed on the inclined portion 121B is stronger than in the case of FIG. 6 (when the reflector 140 is not provided). Furthermore, the light emitted from region K3 of the surface-emitting panel 130 is also reflected and diffused by the rear surface of the inclined portion 121B, heading toward the reflector 140, and is further reflected by the reflector 140 to illuminate the pattern index 122. This further increases the amount of light illuminating the pattern index 122 formed on the inclined portion 121B. Therefore, if the amount of light is uniform across the entire surface when the surface-emitting panel 130 is viewed from the front (vertical direction), the amount of light illuminating the pattern index 122 on the inclined portion 121B will be relatively stronger than the amount of light illuminating the flat portion 121A.

[0058] Therefore, when the reflector 140 is arranged, the density of the reflection pattern 133 is adjusted so that the amount of light emitted from the region K3 is relatively weaker than the amount of light emitted from the region K1. That is, the density of the reflection pattern 133 is adjusted so that the amount of illumination light on the surface (region K3) of the surface-emitting panel 130 corresponding to the pattern index 122 formed on the inclined portion 121B is relatively weaker than the amount of illumination light on the surface (region K1) of the surface-emitting panel 130 corresponding to the flat portion 121A. As a result, in a configuration in which the reflector 140 is arranged on the outer periphery of the inclined portion 121B, both the pattern index 122 on the flat portion of the measurement pattern index plate 120 and the pattern index 122 on the inclined portion can be uniformly illuminated with approximately the same amount of light.

[0059] Furthermore, it is more preferable that the density of the reflection patterns 133 of the surface-emitting panel 130 is adjusted according to the positions of the light passage holes (134a, 134b, 134c) shown in FIG. 5. The illumination light source 132 of the surface-emitting panel 130 is disposed at the end of the light guide plate 131, and illumination light from the illumination light source 132 is guided toward the center of the light guide plate 131. Therefore, if a hole is formed in the middle of the light guide plate 131, illumination light from the illumination light source 132 is difficult to guide to the rear portion around the light passage holes (134a, 134b, 134c) as viewed from the illumination light source 132 side. For this reason, illumination unevenness is likely to occur near the light passage holes (134a, 134b, 134c) corresponding to the rear portion. Therefore, to solve this problem, the density of the reflection patterns 133 in the rear portion of the light passage holes is adjusted so that it is denser than the front portion of the light passage holes as viewed from the illumination light source 132 side. In addition, since the uneven lighting caused by the location of the light passage holes varies depending on the position and distance from the lighting light sources 132 located on each side of the end of the surface-emitting panel 130, the density of the reflective pattern 133 can actually be adjusted through experimentation.

[0060] <Frontal shooting optical system> The front photographing optical system 150 includes an objective lens 151, an imaging lens 152, and an imaging element 153 on a measurement optical axis L1. For example, the imaging element 153 is disposed at a pupil conjugate position of the anterior segment of the subject's eye. The front photographing optical system 150 is used to capture an index image of the pattern index 122 projected onto the cornea of ​​the subject's eye when measuring the corneal shape. A front image of the anterior segment of the subject's eye illuminated by an anterior segment illumination light source 155 is captured by the imaging element 153. The front photographing optical system 150 also serves as a detection optical system that detects an index image projected onto the cornea of ​​the subject's eye by the front alignment index projection optical system 170. The index image by the front alignment index projection optical system 170 is captured by the imaging element 153. A color camera may be used as the imaging element 153.

[0061] <Working distance detection optical system> The working distance detection optical system 160 includes a light projecting optical system 161 and a light receiving optical system 165. The light projecting optical system 161 includes a light source 162 that emits infrared light and a lens 163. The light receiving optical system 165 includes a lens 166 and a light receiving element 167. The working distance detection optical system 160 is used to align the optometry unit 10 with respect to the subject's eye in the working distance direction (Z direction).

[0062] Light from the light source 162 is converted into a substantially parallel beam by a lens 163 and passes through a light passing hole 134b formed in the surface-emitting panel 130 and a light passing hole 124b formed in the measurement pattern indicator plate 120, and is then irradiated obliquely onto the cornea of ​​the subject's eye. The optical axis of the light-receiving optical system 165 is arranged symmetrically with the optical axis of the light-projecting optical system 161 with respect to the optical axis L1. Corneal reflection light from the light-projecting optical system 161 is incident on a light-receiving element 167 via the light passing hole 124b formed in the measurement pattern indicator plate 120, the light passing hole 134b formed in the surface-emitting panel 130, and a lens 166. When the subject's eye moves relatively in the working distance direction (Z direction), the target image (image of the light source 162) formed on the cornea of ​​the subject's eye also moves on the light-receiving element 167. Therefore, the target image on the light-receiving element 167 is detected and processed, and the alignment state of the optometry unit 10 in the working distance direction with respect to the subject's eye is detected.

[0063] <Front alignment target projection optical system> The front alignment target projection optical system 170 includes a light source 171 that emits infrared light, a target plate 172, a lens 173, and a half mirror 174. For example, a ring target is formed on the target plate 172. A light beam of the ring target on the target plate 172 illuminated by the light source 171 passes through the lens 173, is made coaxial with the optical axis L1 by the half mirror 174, and is projected onto the cornea of ​​the subject's eye, thereby forming a ring target image on the cornea of ​​the subject's eye. The ring target image projected onto the cornea of ​​the subject's eye is captured by the image sensor 153 of the front imaging optical system 150. The ring image captured by the image sensor 153 is then subjected to image processing, thereby detecting the alignment state in the X and Y directions of the relative positional relationship between the subject's eye and the optometry unit 10.

[0064] For example, a double ring index is formed on the index plate 172. When measuring the corneal shape, the front alignment index projection optical system 170 is also used as an optical system that projects an internal pattern index for corneal shape measurement.

[0065] <Fixation target presentation optical system> The fixation target presenting optical system 180 presents a fixation target to the subject's eye. The fixation target presenting optical system 180 includes at least a light source 181 that emits visible light and a fixation target plate 182. A fixation light beam from the light source 181 passes through the fixation target plate 182, a lens 183, a half mirror 184, and a lens 185, and is reflected by a half mirror 186 to be made coaxial with the optical axis L1. The fixation light beam then passes through the lens 151 and reaches the fundus of the subject's eye.

[0066] <Cross-section imaging optical system> The cross-section photographing optical system 210 is used to photograph a cross-sectional image of the anterior segment of the eye, and includes a light projecting optical system 210a and a light receiving optical system 210b.

[0067] The light projecting optical system 210a is coaxial with the optical axis L1 and projects slit light, which is an example of imaging light, onto the anterior segment. The light projecting optical system 210a includes a light source 211 and a slit 212. The light source 211 uses, for example, red visible light or near-infrared light as imaging light. The slit 212 may be disposed at a pupil conjugate position. For example, the slit 212 is disposed so that the slit light optically cuts the anterior segment in the horizontal direction (X direction).

[0068] The light receiving optical system 210b includes a lens system 222 and an image sensor 221, which is an example of a photodetector. In the light receiving optical system 210b, the lens system 222 and the image sensor 221 are disposed in a Scheimpflug relationship with respect to a cut surface set in the anterior segment. That is, the optical arrangement is such that the extensions of the cut surface, the principal plane of the lens system 222, and the image sensor 221 intersect at a single intersection (single axis). The image sensor 221 receives return light (reflected light or scattered light) from the anterior segment, which has been optically cut by the slit light. Then, a cross-sectional image of the anterior segment is acquired based on a signal from the image sensor 221.

[0069] In the cross-section photographing optical system 210, a photographing light beam from a light source 211 passes through a slit 212 to become a slit light beam, passes through a lens 213, a half mirror 184, and a lens 185, and is reflected by a half mirror 186 to be made coaxial with the optical axis 12. The photographing light beam then passes through an objective lens 174 to reach the anterior segment. Return light from a cut surface formed in the anterior segment passes through a light passing hole 124a formed in the measurement pattern indicator plate 120, a light passing hole 134a formed in the surface light-emitting panel 130, and a lens system 222 to reach the image sensor 221. In this way, a cross-sectional image of the anterior segment of the subject's eye is acquired.

[0070] <Control system> 2, the control unit 50 is responsible for overall control of the ophthalmologic apparatus 1. The control unit 50 is connected to various electrical elements, such as the image sensor 150, the image sensor 221, the light sources of the optical system, the monitor 16, and the alignment drive unit 13. The control unit 50 also has an image processing function for processing the images captured by the image sensor 153 and the image sensor 221. For example, the control unit 50 processes an image of a pattern target image projected onto the cornea of ​​the subject's eye during corneal shape measurement, and analyzes the corneal shape of the cornea of ​​the subject's eye according to a predetermined program. The control unit 50 also obtains a cross-sectional image of the anterior segment captured by the image sensor 221 and analyzes it according to a predetermined program to obtain the shape of the anterior segment tissue.

[0071] The monitor 16 functions as a touch panel that also serves as an operation unit. The monitor 16 also displays the measurement results of the subject's eye (anterior ocular segment cross-sectional images, corneal shape measurement results, etc.) on the screen. The control unit 50 is also connected to a memory 52, which is an example of a storage device. The memory 52 stores the frontal anterior ocular segment images acquired by the image sensor 150, the anterior ocular segment cross-sectional images acquired by the image sensor 221, the measurement results, etc. The memory 52 also stores various control programs.

[0072] <Control action> The operation of the ophthalmologic apparatus 1 having the above-described configuration will now be briefly described.

[0073] (Alignment) When the subject's face is supported by the face support unit 15, an illumination image of the subject's eye illuminated by the anterior-segment illumination light source 155 is captured by the front imaging optical system 150, and the anterior-segment image is displayed on the monitor 16. The control unit 50 processes the front image of the anterior segment acquired by the front imaging optical system 150 and detects the alignment state of the optometry unit 10 (optical axis L1) in the X and Y directions with respect to the corneal vertex based on the index (corneal reflection bright spot) projected onto the cornea of ​​the subject's eye by the front alignment index projection optical system 170. The control unit 50 also detects the alignment state in the Z direction based on the output of the light-receiving element 167 of the working distance detection optical system 160. The control unit 50 then controls the driving of the alignment drive unit 13 to move the optometry unit 10 in the X, Y, and Z directions so that the alignment states in the X, Y, and Z directions fall within predetermined tolerance ranges, respectively.

[0074] (Cornea topography measurement) Once alignment is complete, the illumination light source 132 of the surface-emitting panel 130 is turned on, and the pattern target 122 is projected onto the cornea of ​​the subject's eye. The image of the pattern target 122 projected onto the cornea of ​​the subject's eye is captured by the image sensor 153 of the front-view imaging optical system 150 and stored in the memory 52. ​​The control unit 50 performs image processing and analysis on the captured image of the pattern target 122 to obtain a detailed shape map of the anterior surface of the cornea. At this time, the pattern target 122 is uniformly (or substantially uniformly) illuminated by the illumination light from the surface-emitting panel 130, so that an image of the pattern target 122 with reduced illumination unevenness is projected onto the cornea. This makes it possible to obtain a good image of the pattern target image projected onto the cornea, resulting in accurate measurement of the corneal shape. The corneal shape measurement results are displayed on the monitor 16, for example, as a shape map.

[0075] (Measurement of cross-sectional shape of the anterior segment) Next, the alignment state of the optometry unit 10 with respect to the subject's eye is confirmed, and a cross-sectional image of the anterior segment of the subject's eye is captured when the alignment is complete. When the light source 211 of the cross-section photographing optical system 210 is turned on, the anterior segment of the subject's eye is optically sectioned by slit light from the slit 212. The image sensor 221 captures the return light from the optically sectioned anterior segment, and the control unit 50 acquires a cross-sectional image of the anterior segment. The control unit 50 processes and analyzes the cross-sectional image, for example, to acquire the positions of the anterior and posterior corneal surfaces of the corneal tissue. The analysis results are displayed on the monitor 16 together with the cross-sectional image. [Explanation of symbols]

[0076] 1 Ophthalmology equipment 50 control section 110 Measurement pattern index projection unit 120 Measurement pattern index plate 121A Flat part 121B Slope 122 Pattern Indicators 130 Surface emitting panel 131 Light guide plate 132 Lighting source 133 Reflective Pattern 140 Reflector 150 Frontal Shooting Optical System 160 Working distance detection optical system 210 Cross-sectional imaging optical system

Claims

1. An ophthalmic apparatus for measuring a corneal shape of a subject's eye, a measurement pattern index plate on which a pattern index for measuring the corneal shape of the subject's eye is formed; a flat-plate-shaped surface light-emitting panel that illuminates the measurement pattern index plate from behind and projects the pattern index onto the cornea of ​​the subject's eye; Equipped with The surface-emitting panel includes a light guide plate that guides light, an illumination light source disposed at an end of the light guide plate, and a reflection pattern that is disposed on the back surface side of the light guide plate and reflects light from the illumination light source toward the front surface side of the light guide plate, An ophthalmic apparatus, wherein the density of the reflection pattern is adjusted in accordance with the positional relationship between the surface light-emitting panel and the pattern indicator.

2. 2. The ophthalmic apparatus of claim 1, a photographing optical system for photographing an index image of the pattern index projected onto the cornea of ​​the subject's eye, An ophthalmic apparatus, characterized in that the density of the reflection pattern is adjusted in accordance with the positional relationship between the pattern index and the surface light-emitting panel with respect to the photographing optical axis of the photographing optical system.

3. 3. The ophthalmic apparatus according to claim 1 or 2, the measurement pattern indicator plate has an inclined portion inclined with respect to the surface light-emitting panel, a reflector is disposed on the outer periphery of the inclined portion to reflect the illumination light emitted from the surface-emitting panel and guide the illumination light to the pattern indicator formed on the inclined portion; The ophthalmic apparatus is characterized in that the surface light-emitting panel has a size corresponding to the position where the reflector is arranged.

4. The ophthalmic apparatus of claim 3, a photographing optical system for photographing an index image of the pattern index projected onto the cornea of ​​the subject's eye, the measurement pattern index plate has a flat portion centered on the imaging optical axis of the imaging optical system, the inclined portion is disposed on the outer circumferential side of the flat portion, An ophthalmic device characterized in that the density of the reflective pattern is adjusted so that the amount of illumination light on the surface of the surface-emitting panel corresponding to the pattern indicator formed on the inclined portion is relatively weaker than the amount of illumination light on the surface of the surface-emitting panel corresponding to the flat portion.

5. The ophthalmic apparatus according to any one of claims 1 to 4, the surface light-emitting panel has a light-passing hole formed to pass at least one of a light beam used for alignment or a light beam used for measuring optical characteristics of the subject's eye other than corneal shape measurement, An ophthalmic apparatus, wherein the density of the reflection pattern is adjusted according to the position where the light passing holes are formed.

6. The ophthalmic apparatus according to any one of claims 1 to 5, The surface light emitting panel is formed into a polygonal shape having more angles than a square in accordance with the shape of the measurement pattern indicator plate when viewed from the front direction where the subject's eye is positioned, An ophthalmic apparatus, characterized in that the illumination light sources are arranged on each side of the polygon.

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