Ophthalmologic measurement apparatus

Abstract

Provided is an ophthalmologic measurement apparatus for measuring eyes to be examined. The ophthalmologic measurement apparatus is provided with: an anterior segment observation optical system which has a telecentric diaphragm at a predetermined position on an optical axis for the purpose of configuring a telecentric system on the eyes-being-examined side, and which acquires a first anterior segment observation image of one eye among the eyes to be examined, by capturing an image of the one eye at a first magnification; and a magnification changing optical system for changing the magnification of the anterior segment observation optical system to a second magnification that is lower than the first magnification by moving an optical member in the optical axis direction, wherein the optical member is positioned on an optical axis between the eyes to be examined and the telecentric diaphragm. The anterior segment observation optical system acquires a second anterior segment observation image at the second magnification, wherein the second anterior segment observation image has a wider angle of view than that of the first anterior segment observation image and includes only one eye.

Description

Ophthalmology measuring device

[0001] The present disclosure relates to an ophthalmic measurement apparatus that measures an eye to be examined.

[0002] Known ophthalmic measurement devices for measuring the subject's eye include an ocular refractive power measurement device, an intraocular pressure measurement device, and a corneal shape measurement device. For example, these ophthalmic measurement devices are capable of capturing an anterior ocular segment observation image for observing the anterior ocular segment of the subject's eye, and alignment is performed using the anterior ocular segment observation image of the subject's eye (see Patent Document 1). Also, some ophthalmic measurement devices are known that capture a facial image including both eyes of the subject and perform fully automatic alignment using the facial image (see Patent Document 2).

[0003] JP 2008-054929 A JP 2017-217120 A

[0004] In the above-mentioned ophthalmic measurement device, when a face imaging optical system for capturing facial images is provided separately from an anterior eye observation optical system for capturing an image of the anterior eye, measurements using various optical systems may become difficult depending on the location of the face observation optical system. For example, in order to place the face observation optical system, it may be necessary to remove part of the pattern index for measuring the corneal shape, which may reduce measurement accuracy. Furthermore, since optical components constituting the face observation optical system must be newly placed, problems such as securing space may arise.

[0005] In view of the above-described conventional techniques, the present disclosure has as its technical object to provide an ophthalmic measurement device that can perform fully automatic alignment without using a face observation optical system.

[0006] The ophthalmic measurement device according to the present disclosure is an ophthalmic measurement device for measuring a subject's eye, comprising: an anterior segment observation optical system having a telecentric aperture at a predetermined position on the optical axis to form a telecentric system on the subject's eye side, the anterior segment observation optical system acquiring a first anterior segment observation image of one of the subjects' eyes by imaging the one eye at a first magnification; and a magnification changing optical system changing the magnification of the anterior segment observation optical system to a second magnification lower than the first magnification by moving an optical element located on the optical axis between the subject's eye and the telecentric aperture in the optical axis direction, wherein the anterior segment observation optical system acquires a second anterior segment observation image having a wider angle of view than the first anterior segment observation image and including only the one eye at the second magnification.

[0007] 1 is an external view of an ophthalmic measurement device; 2 is a schematic diagram of an optical system and a control system; 3 is an example of a ring lens; 4 is an example of a light guide plate and a placido plate; 5 is a diagram showing an optical arrangement and an anterior eye observation image when the anterior eye observation optical system is set to a first magnification; 6 is a diagram showing an optical arrangement and an anterior eye observation image when the anterior eye observation optical system is set to a second magnification;

[0008] <Overview> An overview of an ophthalmic measurement device according to an embodiment of the present disclosure will be described. Items classified in < > below may be used independently or in conjunction with each other. In this embodiment, the left-right direction of the subject's eye is represented as the X direction, the up-down direction of the subject's eye as the Y direction, and the front-back direction of the subject's eye as the Z direction. Furthermore, "conjugate" in this embodiment is not necessarily limited to a perfect conjugate relationship, but also includes "approximate conjugate." In other words, "conjugate" in this embodiment also includes cases where the components are positioned at a position that is shifted from a perfect conjugate position within a range that is permissible in relation to the technical significance of each component.

[0009] The ophthalmic measurement device of this embodiment is a device that measures the subject's eye. For example, the ophthalmic measurement device may be an eye refractive power measurement device that objectively measures the optical characteristics of the subject's eye. Furthermore, for example, the ophthalmic measurement device may be an ocular pressure measurement device that measures the intraocular pressure of the subject's eye. Furthermore, for example, the ophthalmic measurement device may be a corneal shape measurement device that measures corneal shape information of the subject's eye. Note that the ophthalmic measurement device of this embodiment may be equipped with at least an anterior eye observation optical system and a magnification change optical system, which will be described later, or may be a device different from these.

[0010] The ophthalmic measurement device of this embodiment may include an anterior eye illumination optical system (anterior eye illumination optical system 900). For example, the anterior eye illumination optical system may illuminate the anterior eye of the subject's eye with a visible light beam. For example, the visible light beam may be a light beam having a wavelength in the visible range of 400 nm to 800 mm.

[0011] The ophthalmic measurement device of this embodiment may include an anterior eye observation optical system (e.g., anterior eye observation optical system 200). For example, the anterior eye observation optical system may be an anterior eye observation optical system having a telecentric diaphragm (e.g., telecentric diaphragm 206) at a predetermined position on the optical axis to form a telecentric system on the subject's eye side (object side). In this case, for example, the telecentric diaphragm may be disposed at the back focal position of a condenser lens system including an objective lens.

[0012] For example, the anterior-segment observation optical system may be configured as a telecentric system on the test eye side, and a first anterior-segment observation image of one test eye (e.g., first anterior-segment observation image 250) may be acquired by capturing an image of one test eye at a first magnification. For example, the first anterior-segment observation image may be an image that includes only one eye (the test eye) and may be captured at an angle of view that allows at least the pupil of one eye to be detected. For example, the first anterior-segment observation image may be an image captured at an angle of view that allows only the pupil of one eye to be detected, or may be an image captured at an angle of view that allows the pupil and iris of one eye to be detected. As an example, the first anterior-segment observation image may be an image captured at an angle of view of 18 mm × 18 mm.

[0013] For example, the magnification of the anterior-segment observation optical system may be changed from a first magnification to a second magnification by the magnification change optical system, thereby acquiring a second anterior-segment observation image (e.g., second anterior-segment observation image 260) having a wider angle of view than the first anterior-segment observation image. For example, the second anterior-segment observation image may be an image including only one eye (the eye being measured) and may be captured at an angle of view sufficient to detect at least the pupil, iris, and surrounding area of ​​the iris of the one eye. For example, the second anterior-segment observation image may be captured at an angle of view that includes at least the pupil to surrounding area of ​​the iris of the one eye, or may be captured at an angle of view that includes at least the range from the inner corner to the outer corner of the one eye. As an example, the second anterior-segment observation image may be captured at an angle of view of 25 mm × 25 mm. This allows, for example, automatic alignment and the like to be performed using the first anterior-segment observation image and the second anterior-segment observation image without the need for a separate face observation optical system (such as a face camera). Furthermore, for example, since a wide-area second anterior segment observation image can be obtained for one eye, it can also be used for evaluation of the anterior segment.

[0014] For example, if the second anterior-segment observation image includes at least the range from the inner corner to the outer corner of one eye, the second anterior-segment observation image will capture the entire eye, facilitating pupil detection during alignment, etc. Furthermore, for example, the second anterior-segment observation image can be easily used to evaluate the anterior segment (ocular surface, etc.) of one eye.

[0015] The ophthalmic measurement device of this embodiment may include a magnification-changing optical system (e.g., a movable lens 206). For example, the magnification-changing optical system may change the magnification of the anterior-segment observation optical system to a second magnification lower than the first magnification by moving an optical element located on the optical axis between the subject's eye and the telecentric diaphragm in the optical axis direction. For example, the magnification-changing optical system may change the anterior-segment observation optical system from the first magnification to the second magnification by moving an optical element such as a lens or a prism in the optical axis direction. In this case, for example, the imaging positions on the optical axis of the first anterior-segment observation image when the anterior-segment observation optical system is set to the first magnification and the second anterior-segment observation image when the anterior-segment observation optical system is set to the second magnification are the same, so there is no need to move an image sensor or the like, and the optical system can be easily configured.

[0016] For example, the magnification changing optical system may change the magnification of the anterior-segment observation optical system to a second magnification lower than the first magnification by moving an optical element located on the optical axis between the telecentric aperture and the image sensor in the optical axis direction, instead of an optical element located on the optical axis between the subject's eye and the telecentric aperture. In this case, for example, at least one of the optical elements located on the optical axis between the telecentric aperture and the image sensor may be moved. Furthermore, in this case, for example, all of the optical elements located on the optical axis between the telecentric aperture and the image sensor may be moved as a single unit. That is, the imaging lens group constituting the anterior-segment observation optical system may be moved. In this case, the image sensor may be moved as a single unit together with the imaging lens group.

[0017] For example, the magnification-changing optical system may change the magnification of the anterior-segment observation optical system to a second magnification lower than the first magnification by disposing an optical element at a position corresponding to the visible light beam so that the anterior-segment observation optical system focuses a reflected light beam of visible light from the anterior segment. That is, for example, the magnification-changing optical system may change the magnification of the anterior-segment observation optical system to the second magnification by disposing an optical element at a position on the optical axis so that, of the reflected light beam of infrared light and the reflected light beam of visible light from the anterior segment, the reflected light beam of visible light is preferentially focused. For example, although aberration occurs when the anterior segment of the subject's eye is illuminated with an infrared light beam and a visible light beam, by setting the focus to be on the second color anterior-segment observation image, the second anterior-segment observation image can be more easily used for evaluating the ocular surface, for example.

[0018] For example, the magnification-changing optical system may further move the object focal position of the anterior-segment observation optical system by moving, in the optical axis direction, an optical element located on the optical axis of the anterior-segment observation optical system between the subject's eye and the telecentric diaphragm. For example, the magnification-changing optical system may move the object focal position of the anterior-segment observation optical system from the pupil position of the subject's eye to the cornea position (or from the cornea position of the subject's eye to the pupil position). This makes it possible to obtain an anterior-segment observation image focused at an appropriate position on the subject's eye, even if the magnification of the anterior-segment observation optical system is changed, without adjusting the working distance of the subject's eye (i.e., without moving the subject's eye or the image sensor in the optical axis direction).

[0019] In this embodiment, when the anterior-segment observation optical system is set to a first magnification, the object focal position of the anterior-segment observation optical system may be moved to the pupil position to acquire a first anterior-segment observation image focused on the pupil position of the subject's eye. Furthermore, for example, in this embodiment, when the anterior-segment observation optical system is set to a second magnification, the object focal position of the anterior-segment observation optical system may be moved to the cornea position to acquire a second anterior-segment observation image focused on the cornea position of the subject's eye. Of course, for example, the position to which the object focal position of the anterior-segment observation optical system is moved may be a position different from the pupil position or the cornea position.

[0020] The anterior-segment observation optical system of this embodiment may be a relay optical system that forms an intermediate image of the first anterior-segment observation image and the second anterior-segment observation image, and may have a telecentric aperture located behind the intermediate image position. For example, the anterior-segment observation optical system may have a telecentric aperture located behind a relay lens that forms the relay optical system. In this case, the magnification-changing optical system may move an optical element located on the optical axis between the intermediate image position and the telecentric aperture in the optical axis direction. For example, the magnification-changing optical system may move an optical element located on the optical axis between the relay lens and the telecentric aperture in the optical axis direction. This allows, for example, the optical path to branch off in front of the intermediate image position of the anterior-segment observation optical system (i.e., toward the examined eye), making it easy to arrange an optical system different from the anterior-segment observation optical system. Note that the light beam from the optical system different from the anterior-segment observation optical system reaches the examined eye without being blocked by the telecentric aperture.

[0021] The ophthalmic measurement device of this embodiment may include a measurement optical system (e.g., a corneal shape measurement target projection optical system 700). For example, the measurement optical system may project measurement light as a pattern target toward the cornea of ​​the test eye and receive the measurement light reflected from the cornea as a pattern image. For example, the measurement optical system may project measurement light as a concentric pattern target (e.g., multiple ring targets) toward the cornea of ​​the test eye and receive the measurement light reflected from the cornea as a concentric pattern image (e.g., multiple ring images).

[0022] The ophthalmic measurement device of this embodiment may include an analysis processing means (e.g., the control unit 50). For example, the analysis processing means may analyze and process a pattern image received by the measurement optical system to obtain corneal shape information of the subject's eye. For example, the corneal shape information of the subject's eye may be at least any of information such as the corneal curvature, corneal curvature distribution, and the three-dimensional shape of the corneal surface (corneal height distribution in the optical axis direction) of the subject's eye.

[0023] For example, if the ophthalmic measurement device is a device that performs auto-alignment using a face observation optical system, the pattern image (for example, multiple ring images) projected onto the subject's eye may be missing due to the arrangement of the face observation optical system, making it impossible to accurately acquire corneal shape information. However, if the magnification of the anterior eye observation optical system is changed to support auto-alignment, as in this embodiment, the pattern image will not be missing, and corneal shape information can be accurately acquired.

[0024] <Example> An example of the ophthalmic measurement device according to this embodiment will be described.

[0025] 1 is an external view of an ophthalmic measurement device 10. The ophthalmic measurement device 10 has at least a base 11, a measurement unit 12, an alignment drive unit 13, a face support unit 15, a monitor 16, an operation unit 17, a control unit 50, and the like.

[0026] The measurement unit 12 houses an optical system and other components used to measure the subject's eye. The face support unit 15 is fixed to the base 11 and supports the examiner's face, thereby fixing the subject's eye. The alignment drive unit 13 changes the positional relationship of the measurement unit 12 with respect to the subject's eye. For example, the alignment drive unit 13 moves the measurement unit 12 three-dimensionally relative to the base 11, thereby moving the measurement unit 12 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.

[0027] The monitor 16 displays various information (for example, an image of the anterior segment of the subject's eye, measurement results of the optical characteristics of the subject's eye, etc.). The operation unit 17 performs various settings. The monitor 16 may function as a touch panel and may also serve as the operation unit 17.

[0028] 2 is a schematic diagram of the optical system and control system of the ophthalmic measurement device 10. As an example, the measurement unit 12 includes a measurement optical system 100, a fixation target presenting optical system 150, an anterior eye observation optical system 200, an index projection optical system 400, an alignment index projection optical system 600, an index projection optical system 700 for corneal shape measurement, and an anterior eye illumination optical system 900. The measurement unit 12 also includes half mirrors 501 to 503 that branch and combine the optical paths of the respective optical systems, an objective lens 505, and the like.

[0029] <Measurement Optical System> The measurement optical system 100 is used to objectively measure the ocular refractive power of the subject's eye. The measurement optical system 100 has a light projecting optical system 110 and a light receiving optical system 120. The light projecting optical system 110 projects a spot-shaped measurement light beam onto the fundus of the subject's eye through the center of the pupil of the subject's eye. The light receiving optical system 120 extracts the measurement light beam reflected by the fundus through the pupil as multiple ring-shaped or multiple spot-shaped beams.

[0030] The light projection optical system 110 includes a light source 111, a relay lens 112, a hole mirror 113, an objective lens 505, etc. The light source 111 is arranged at a position conjugate with the fundus. For example, the light source 111 may be an infrared light source and project an infrared light beam as the measurement light beam. The opening of the hole mirror 113 is arranged at a position conjugate with the pupil. The measurement light beam emitted from the light source 111 passes through the relay lens 112 on the optical axis L1, is reflected by the hole mirror 113 in the direction of the optical axis L2, and is projected onto the fundus of the subject's eye via the half mirror 501 and the objective lens 505.

[0031] The light-receiving optical system 120 includes an objective lens 505, a hole mirror 113, relay lenses 121 and 122, a light-receiving diaphragm 123, a collimator lens 124, a ring lens 125, an image sensor 126, etc. The light-receiving diaphragm 123 is disposed at a position conjugate with the fundus. The ring lens 125 is disposed at a position conjugate with the pupil of the subject's eye. The image sensor 126 is disposed at a position conjugate with the fundus. A light beam reflected from the fundus of the subject's eye passes through the objective lens 505 to the collimator lens 124 on the optical axis L2, and is converted by the ring lens 125 into a multiple ring image (in other words, a plurality of ring images divided in the meridian direction of the optical axis L2), and is received (imaged) by the image sensor 126.

[0032] FIG. 3 shows an example of the ring lens 125. The left side of FIG. 3 shows a plan view of the ring lens 125, and the right side of FIG. 3 shows a cross-sectional view of the ring lens 125. The ring lens 125 has ring-shaped cylindrical lens portions RL1, RL2, RL3, RL4, RL5, RL6, and RL7 arranged from the inside to the outside, thereby forming seven ring images on the image sensor 126. Note that the ring lens 125 may be configured to form three or more multiple ring images on the image sensor 126, for example.

[0033] The diameter of the innermost lens portion RL1 on the pupil of the subject's eye is made as small as possible to reduce the influence of corneal reflection of the measurement light projected by the light projection optical system 110. For example, the diameter of the lens portion RL1 on the pupil is set to 1.5 mm or less. The diameter of the outermost lens portion RL7 on the pupil of the subject's eye is set to a size that covers the expected large pupil diameter of the human eye. For example, the diameter of the lens portion RL7 on the pupil is set to 6.0 mm or more. The lens portions RL1 to RL7 are formed with the same ring width W, and light-shielding portions 125b are formed in the inner region of the lens portion RL1, the regions between the lens portions RL1 to RL7, and the outer region of the lens portion RL7.

[0034] The measurement optical system 100 is not limited to the above configuration, and may be any optical system having a light projection optical system that projects a measurement light beam onto the fundus of the subject's eye and a light receiving optical system that receives the measurement light beam reflected by the fundus. For example, the measurement optical system 100 may be an optical system that projects a spot index onto the fundus and detects the reflected light beam of the spot index on the fundus using a Shack-Hartmann sensor. In this case, a Hartmann plate may be used instead of the ring lens 125. The reflected light beam of the spot index is separated and converted into multiple light beams by the Hartmann plate, and multiple point images are captured by the image sensor 126, thereby detecting multiple point-like measurement index images.

[0035] <Fixation Target Presenting Optical System> The fixation target presenting optical system 150 presents a fixation target to the subject's eye. The fixation target presenting optical system 150 is used to fixate the subject's eye. The fixation target presenting optical system 150 is also used to apply fogging and accommodation load to the subject's eye.

[0036] The fixation target presenting optical system 150 includes a light source 151, a fixation target plate 155, lenses 156 and 510, an objective lens 505, and the like. For example, the light source 151 may be a visible light source that projects a visible light beam as a fixation light beam. The fixation target plate 155 is disposed at a position conjugate with the fundus. The fixation light beam emitted from the light source 151 passes through the fixation target plate 155, the lens 156, and the lens 510 on the optical axis L4, is reflected by the half mirror 501, becomes coaxial with the optical axis L1, and further reaches the fundus of the subject's eye via the objective lens 505.

[0037] In this embodiment, the light source 111, ring lens 125, and image sensor 126 in the measurement optical system 100, and the light source 151 and fixation target plate 155 in the fixation target presenting optical system 150 can be moved integrally in the optical axis direction by a drive unit 160. For example, the drive unit 160 is moved by a drive unit 161 in accordance with the ocular refractive power of the subject's eye (i.e., the diopter of the subject's eye), thereby changing the presentation distance of the fixation target plate 155 relative to the subject's eye (i.e., the presentation position of the fixation target). The ring lens 125 and the image sensor 126 are moved along the optical axis so that the image sensor 126 is positioned near a conjugate position with respect to the fundus of the subject's eye, thereby adjusting the imaging state (focus state) of the ring image in accordance with the diopter of the subject's eye.

[0038] <Index Projection Optical System> The index projection optical system 400 is used to measure the corneal shape of the subject's eye. The index projection optical system 400 projects an index for measuring the corneal shape from the front surface facing the subject's eye to the anterior segment. The index projection optical system 400 includes multiple point light sources 401. The point light sources 401 are infrared light sources and may project an infrared light beam as the index light beam. The point light sources 401 project an index at infinity by irradiating the cornea with a parallel light beam. The point light sources 401 are arranged symmetrically both vertically and horizontally with respect to the optical axis L1. For example, in this embodiment, one point light source is provided on each side. This projects two point image indices onto the cornea. Note that the number of indices is not limited to this, and the system may be configured with three or more point image indices. Furthermore, the shape of the indices is not limited to this, and may include linear indices or the like.

[0039] <Alignment target projection optical system> The alignment target projection optical system 600 is used to align (position) the measurement unit 12 with respect to the subject's eye. The alignment target projection optical system 600 includes an alignment light source 601. The alignment light source 601 is an infrared light source, and may project an infrared light beam as the alignment target light beam. The alignment light source 601 projects a finite target by irradiating the cornea with a diverging light beam. The alignment light source 601 is arranged in a ring shape centered on the optical axis L1. This projects a ring target (a so-called Mayer ring image) onto the cornea.

[0040] In this embodiment, an alignment target projection optical system is formed by the alignment light source 601 and the target projection optical system 400. For example, the working distance may be adjusted by moving the measuring unit 12 in the forward / backward direction so that the point image by the alignment light source 601 and the Mayer ring image by the target projection optical system 400 are captured at a predetermined ratio.

[0041] <Corneal Topography Measurement Target Projection Optical System> The corneal topography measurement target projection optical system 700 is used to measure the corneal topography of the eye to be examined. The corneal topography measurement target projection optical system 700 includes an illumination light source 701, a light guide plate 702, a placido plate 703, etc. The illumination light source 701 illuminates the light guide plate 702. The illumination light source 701 is an infrared light source, and may project an infrared light beam as the illumination light beam. The light guide plate 702 and the placido plate 703 are both disk-shaped, and the placido plate 703 is disposed in front of the light guide plate 702.

[0042] 4 shows an example of the light guide plate 702 and the placido plate 703. The light guide plate 702 has an opening 705 and a hole 706. For example, the opening 705 allows the measurement light beam from the measurement optical system 100, the fixation light beam from the fixation target presenting optical system 150, the alignment light beam from the alignment target projection optical system 600, and the like to pass through the optical path. For example, the hole 706 allows the index light beam from the index projection optical system 400, the illumination light beam from the anterior eye illumination optical system 900, and the like to pass through the optical path. The placido plate 703 has a number of concentric placido rings formed around the optical axis L1. For example, the placido rings are formed by alternately arranging black-painted light-shielding portions and unpainted light-transmitting portions in a concentric pattern around the optical axis L1. The illumination light beam emitted from the illumination light source 701 passes through the light guide plate 702 and the Placido plate 703 in this order, becoming a predetermined pattern target before reaching the subject's eye, whereby multiple ring targets (so-called Placido ring images) are projected onto the cornea.

[0043] <Anterior Eye Segment Illumination Optical System> The anterior eye segment illumination optical system 900 is used to illuminate the anterior eye segment of the subject's eye with a visible light beam. The anterior eye segment illumination optical system 900 includes a point light source 901. The point light source 901 is a visible light source and may project a visible light beam as an illumination light beam. The point light sources 901 are arranged symmetrically in the vertical direction and the horizontal direction with respect to the optical axis L1. For example, in this embodiment, one point light source may be provided on each side. Note that when illuminating the anterior eye segment of the subject's eye with an infrared light beam, at least one of the target projection optical system 400, the alignment target projection optical system 600, the corneal shape measurement target projection optical system 700, etc. may be used.

[0044] <Anterior Eye Segment Observation Optical System> The anterior eye segment observation optical system 200 is used to acquire an anterior eye segment observation image of the subject's eye. The anterior eye segment observation optical system 200 also serves as a detection optical system that detects the target image projected onto the cornea from the target projection optical system 400 and the target image projected onto the cornea from the alignment target projection optical system 600, and an anterior eye segment observation image including each target image is used for alignment. The anterior eye segment observation optical system 200 also serves as a detection optical system that detects the target image projected onto the cornea from the corneal shape measurement target projection optical system 700, and an anterior eye segment observation image including the target image is used for corneal shape measurement. The anterior eye segment observation optical system 200 can also capture color images of the anterior eye segment illuminated by the anterior eye segment illumination optical system 900, and such anterior eye segment observation image is used for evaluating hyperemia, etc.

[0045] For example, the anterior-segment observation optical system 200 is an optical system that is telecentric on the side of the eye to be examined (in other words, on the object side). For example, the anterior-segment observation optical system 200 includes an image sensor 201, lenses 202 to 204, a telecentric aperture 205, a movable lens 206, a relay lens 207, a lens 510, an objective lens 505, and the like. The image sensor 201 is disposed at a pupil conjugate position. The telecentric aperture 205 is disposed at the rear focal position of a front lens group (i.e., a lens group from the objective lens 505 to the front of the telecentric aperture 205) including the objective lens 505 and the like. The movable lens 206 can be moved in the optical axis direction by a drive unit 210. An observation light beam from the anterior segment of the eye to be examined passes through the objective lens 505 and the lens 510 on the optical axis L3 and is reflected by the half mirror 502 to form an intermediate image at position K (intermediate image position R) on the optical axis. Furthermore, the observation light beam passes through optical members from the relay lens 207 to the lens 202 to form an intermediate image, and is received (re-imaged) by the image sensor 201 .

[0046] That is, for example, the anterior-segment observation optical system 200 is a relay optical system that forms an intermediate image of an anterior-segment observation image, and a telecentric diaphragm 205 is disposed behind the intermediate image position R, thereby constituting a telecentric system on the side of the eye to be examined. Note that, for example, when the anterior-segment observation optical system 200 is configured in this manner, the telecentric diaphragm 205 is disposed on the reflection side of the half mirror 502, so that an arbitrary optical system 800 can be easily disposed on the transmission side of the half mirror 502. For example, if the anterior-segment observation optical system 200 is not configured as a relay optical system, a telecentric system can also be constructed by disposing the telecentric diaphragm 205' between the half mirror 501 and the lens 510 and disposing the image sensor 201 on the reflection side of the half mirror 512. However, since the light beam emitted from the arbitrary optical system 800 is blocked by the telecentric diaphragm 205', it becomes difficult to perform measurement or photography using the arbitrary optical system 800.

[0047] In this embodiment, the optional optical system 800 may be an internal Placido optical system. For example, the internal Placido optical system projects a pattern index onto the subject's eye via the objective lens 505. For example, the internal Placido optical system may include a light source, a lens, an index plate, and the like. For details of the internal Placido optical system, see, for example, Japanese Patent Application Laid-Open No. 2020-49129. For example, by combining the internal Placido optical system with the index projection optical system 700 for corneal shape measurement, it is possible to project a pattern index onto the center of the cornea while projecting a Placido ring image onto the peripheral part of the cornea.

[0048] <Changing the Magnification of the Anterior Eye Observation Optical System> The anterior eye observation optical system 200 of this embodiment can change the magnification by moving optical members located on the optical axis between the subject's eye and the telecentric diaphragm 205 in the optical axis direction. For example, the anterior eye observation optical system 200 can change the magnification from a predetermined first magnification to a second magnification lower than the first magnification by moving the movable lens 206, among the lenses located between the objective lens 505 and the telecentric diaphragm 205, toward the image sensor 201. That is, in the anterior eye observation optical system 200, the movable lens 206 functions as a magnification-changing optical system. The movable lens 206 may be a single lens or a lens group composed of multiple lenses.

[0049] FIG. 5 shows the optical arrangement and anterior-segment observation image when the anterior-segment observation optical system 200 is set to a first magnification. The optical arrangement in FIG. 5 is the same as the optical arrangement in FIG. 2 , and a telecentric system is configured on the subject's eye side. For example, in the anterior-segment observation optical system 200, when the movable lens 206 is positioned at a predetermined position S1 closer to the relay lens 207, the pupil position (pupil plane) of the subject's eye becomes the object-side focal position f, and the pupil position, the intermediate image position R, and the image sensor 201 are in a conjugate relationship. For example, in this case, one of the subject's eyes is imaged by the image sensor 201 at the first magnification, and a first anterior-segment observation image 250 with a first angle of view focused on the pupil position of the one eye is acquired. For example, in this embodiment, an 18 mm × 18 mm first anterior-segment observation image 250 is acquired, which includes at least the pupil P and iris I of the one eye.

[0050] FIG. 6 shows an optical arrangement and an anterior-segment observation image when the anterior-segment observation optical system 200 is set to the second magnification. Compared to the optical arrangement in FIG. 5 , the optical arrangement in FIG. 6 moves the movable lens 206 in the optical axis direction and positions the movable lens 206 at a predetermined position S2 closer to the telecentric diaphragm 205. In this case, the telecentric system on the subject's eye side is broken, and the observation light beam reaches one eye as a divergent light beam, changing the anterior-segment observation optical system 200 to the second magnification. Furthermore, in this case, the object-side focal position f of the anterior-segment observation optical system 200 changes from the pupil position (pupil plane) of the subject's eye to the cornea position (corneal plane), and the cornea position, the intermediate image position R, and the image sensor 201 are in a conjugate relationship. For example, one of the subject's eyes is imaged by the image sensor 201 at the second magnification, and a second anterior-segment observation image 260 with a second angle of view focused on the cornea position of the one eye is acquired. For example, in this embodiment, a second anterior segment observation image 260 of 25 mm×25 mm is acquired, which includes at least the range from the inner corner to the outer corner of one eye.

[0051] In this embodiment, the magnification of the anterior-segment observation optical system 200 is changed by moving the movable lens 206, and further, the object-side focal position f of the anterior-segment observation optical system 200 is changed by moving the movable lens 206. That is, the movable lens 206 plays both the role of changing the magnification of the anterior-segment observation optical system 200 and the role of changing the object-side focal position f. Therefore, even when the magnification of the anterior-segment observation optical system 200 is changed to capture a wide-area anterior-segment observation image 260 focused on the cornea of ​​one eye, there is no need to adjust the working distance of the subject's eye.

[0052] It should be noted that the object focal position f can also be changed by, for example, moving other lenses (for example, at least one of the lenses 202 to 204) constituting the anterior eye observation optical system 200 in the optical axis direction, or by inserting or removing an additional lens on the optical axis, etc. In this case, however, it is necessary to adjust the working distance of the subject's eye, and the subject's eye may be moved in the Z direction or the image sensor 201 may be moved in the optical axis direction to capture a wide-area anterior eye observation image 260 focused on the cornea of ​​one eye.

[0053] Furthermore, in this embodiment, when the magnification of the anterior-segment observation optical system 200 is changed by moving the movable lens 206, the predetermined position S2 is set so that the reflected visible light beam by the anterior-segment illumination optical system 900 forms an image on the image sensor 201. For example, the reflected visible light beam by the anterior-segment illumination optical system 900 and the reflected infrared light beam by the target projection optical system 400 and the alignment target projection optical system 600 have different wavelengths, which causes aberrations and slightly shifts the image formation positions of the respective light beams. Therefore, when one of the test eyes is imaged in color at the second magnification, a second anterior-segment observation image 260 with a second angle of view is acquired, in which the corneal position of the one eye is clearly captured. When one of the test eyes is imaged in monochrome at the second magnification, a second anterior-segment observation image 260 with a second angle of view is acquired, in which the corneal position of the one eye is slightly blurred.

[0054] 2, the control unit 50 includes a CPU (processor), RAM, ROM, etc. For example, the CPU controls the driving of each unit in the ophthalmic measurement device 10. For example, the RAM temporarily stores various types of information. For example, the ROM stores various programs executed by the CPU. Note that the control unit 50 may be configured with multiple control units (i.e., multiple processors).

[0055] The control unit 50 is electrically connected to the light sources, image sensors, drive units, etc. of the measurement unit 12. The control unit 50 is also electrically connected to the alignment drive unit 13, monitor 16, operation unit 17, non-volatile memory 55 (hereinafter referred to as memory 55), etc. The memory 55 is a non-transitory storage medium that can retain its contents even when the power supply is cut off. For example, the memory 55 may be a hard disk drive, a flash ROM, a USB memory, etc. For example, the memory 55 may store measurement results of the subject's eye, etc.

[0056] The control unit 50 functions as an analysis processing means that processes the anterior eye segment observation images (the first anterior eye segment observation image 250 and the second anterior eye segment observation image 260) captured by the imaging element 201 of the anterior eye segment observation optical system 200 to obtain various pieces of information. The control unit 50 also functions as an analysis processing means that processes the captured image (e.g., multiple ring images) captured by the imaging element 126 of the measurement optical system 100, or an added image of data sequentially output from the imaging element 126, to obtain ocular refractive power information.

[0057] <Control Operation> A description will be given of the control operation of the ophthalmic measurement apparatus 10. The ophthalmic measurement apparatus 10 of this embodiment performs alignment between the subject's eye (one eye) and the measurement unit 12 in a fully automatic manner.

[0058] <Alignment> The examiner instructs the subject to fixate their face with the face support unit 15 and observe the fixation target. The examiner also operates the operation unit 17 to operate a switch to start full-automatic alignment for the right eye (eye to be measured). Based on an operation signal from the operation unit 17, the control unit 50 places the movable lens 206 of the anterior eye observation optical system 200 at a predetermined position S2, thereby setting the anterior eye observation optical system 200 to the second magnification. Based on an operation signal from the operation unit 17, the control unit 50 also turns on the light source 151 of the fixation target presenting optical system 150, the point light source 401 of the target projection optical system 400, and the alignment light source 601 of the alignment target projection optical system 600. As a result, a point image at infinity and a Mayer ring image at finite distance are projected onto the right eye.

[0059] The control unit 50 performs image processing on the second anterior-segment observation image 260 captured by the image sensor 201 of the anterior-segment observation optical system 200. For example, as described above, the second anterior-segment observation image 260 is obtained at the second angle of view that can include the right eye from the inner corner to the outer corner. Therefore, even if the measurement unit 12 is misaligned with respect to the right eye in at least one of the X direction (left-right direction) and Y direction (up-down direction), the pupil P appears in the second anterior-segment observation image 260.

[0060] For example, the control unit 50 may detect the pupil P from a change in luminance information of the second anterior eye segment observation image 260. Furthermore, for example, the control unit 50 controls the driving of the alignment drive unit 13 to move the measurement unit 12 in the X direction and the Y direction so that the approximate pupil center position calculated by circular approximation of the pupil P coincides with the optical axes L1 to L4. This, for example, completes rough alignment of the measurement unit 12 with the subject's eye.

[0061] Next, based on a completion signal of the rough alignment of the measurement unit 12 with respect to the subject's eye, the control unit 50 sets the anterior-segment observation optical system 200 to a first magnification by placing the movable lens 206 of the anterior-segment observation optical system 200 at a predetermined position S1. This enlarges the anterior-segment observation image captured by the image sensor 201. For example, as described above, a first anterior-segment observation image 250 is obtained at a first angle of view that can include at least the pupil P and iris I of the right eye.

[0062] In the above-described coarse alignment, the approximate center position of the pupil of the subject's eye coincides with the optical axis, so even if the anterior-segment observation image is enlarged, the pupil P will not be missing from the first anterior-segment observation image 250. In addition, in the above-described coarse alignment, the approximate center position of the pupil of the subject's eye coincides with the optical axis, so a point image at infinity and a Mayer ring image at a finite distance are appropriately projected and appear in the first anterior-segment observation image 250.

[0063] The control unit 50 detects the point image and the Mayer ring image from the first anterior segment observation image 250, and controls the driving of the alignment drive unit 13 to move the measurement unit 12 in the X direction, Y direction, and Z direction so that the pupil center position calculated based on the positional relationship between these images coincides with the optical axes L1 to L4. For example, this completes fine alignment of the measurement unit 12 with the subject's eye, and the right eye and the measurement unit 12 are at a predetermined working distance.

[0064] When the examiner completes the alignment (coarse alignment and fine alignment) between the subject's eye and the measurement unit 12, he operates the operation unit 17 to operate switches to start various measurements on the right eye (measurement eye). Based on the operation signals from the operation unit 17, the control unit 50 measures the corneal shape information of the subject's eye, measures ocular refractive power information, evaluates the anterior segment, etc.

[0065] <Measurement of Corneal Topography Information> A case of measuring corneal topography information of the subject's eye will be described. With the movable lens 206 of the anterior segment observation optical system 200 positioned at a predetermined position S1, the control unit 50 turns on the illumination light source 701 of the corneal topography measurement target projection optical system 700 to project a Placido ring image onto the cornea of ​​the right eye. Note that, for example, if an internal Placido optical system is provided as the optional optical system 800, a pattern target may also be projected by turning on the light source of the internal Placido optical system.

[0066] The control unit 50 captures the first anterior segment observation image 250 including the Placido ring image and stores it in the memory 55. The control unit 50 also performs image processing on the first anterior segment observation image 250 including the Placido ring image to acquire corneal shape information. For example, the control unit 50 acquires the corneal curvature distribution, the three-dimensional shape of the corneal surface (the corneal height distribution in the optical axis direction), etc.

[0067] <Measurement of Eye Refractive Power Information> A case of measuring eye refractive power information of the subject's eye will be described. With the movable lens 206 of the anterior eye observation optical system 200 positioned at a predetermined position S1, the control unit 50 turns on the light source 111 of the measurement optical system 100, projects a measurement light beam onto the fundus of the right eye, and causes the image sensor 126 to capture the reflection of the measurement light beam from the fundus as a multiple ring image.

[0068] The control unit 50 captures a measurement image including multiple ring images and stores it in the memory 55. The control unit 50 also performs image processing on the measurement image including the multiple ring images to obtain ocular refractive power information. For example, the control unit 50 thins the multiple ring images and determines the ocular refractive power in each meridian direction based on the position of the ring images in each meridian direction. Furthermore, for example, the control unit 50 performs predetermined processing on these ocular refractive powers to obtain the ocular refractive power (spherical power, cylindrical power, astigmatic axis angle, etc.) of the right eye.

[0069] <Evaluation of the Anterior Eye Segment> A case of evaluating the anterior eye segment of the subject's eye will be described. The control unit 50 turns on the point light source 901 of the anterior eye segment illumination optical system 900 to illuminate the anterior eye segment of the right eye with a visible light beam. The control unit 50 also positions the movable lens 206 of the anterior eye segment observation optical system 200 again at the predetermined position S2. At this time, the predetermined working distance between the right eye and the measurement unit 12 may be maintained, and the object side focal position f of the anterior eye segment observation optical system 200 moves so that the cornea of ​​the right eye is in focus, and a second anterior eye segment observation image 260 having a wider area than the first anterior eye segment observation image 250 is captured in color.

[0070] The control unit 50 captures the second anterior eye observation image 260 and stores it in the memory 55. The control unit 50 also processes the second anterior eye observation image 260 and uses it for evaluating hyperemia, etc. For example, the control unit 50 may determine the degree or presence of hyperemia.

[0071] As described above, for example, the ophthalmic measurement device of this embodiment includes an anterior-segment observation optical system having a telecentric aperture at a predetermined position on the optical axis to form a telecentric system on the subject's eye side, the anterior-segment observation optical system capturing an image of one of the subject's eyes at a first magnification to acquire a first anterior-segment observation image of the one eye, and a magnification-changing optical system that changes the magnification of the anterior-segment observation optical system to a second magnification lower than the first magnification by moving an optical element located on the optical axis between the subject's eye and the telecentric aperture in the optical axis direction. The anterior-segment observation optical system acquires a second anterior-segment observation image at the second magnification, the second anterior-segment observation image having a wider angle of view than the first anterior-segment observation image and including only one eye. This allows, for example, automatic alignment and the like to be performed using the first and second anterior-segment observation images without the need for a separate face observation optical system (such as a face camera). Furthermore, since a wide-area second anterior-segment observation image of one eye can be obtained, the anterior-segment observation optical system can also be used for anterior-segment evaluation and the like.

[0072] Furthermore, for example, the ophthalmic measurement device of this embodiment includes an illumination optical system that illuminates the anterior segment of the subject's eye with a visible light beam, and the magnification-changing optical system positions the optical element corresponding to the visible light beam so that the reflected light beam from the anterior segment is imaged in the anterior segment observation optical system. For example, when the anterior segment of the subject's eye is illuminated with an infrared light beam and when it is illuminated with a visible light beam, aberrations occur due to the difference in wavelength. For example, when aligning the subject's eye, an infrared light beam is illuminated and a low-magnification second anterior segment observation image is used for coarse alignment, but pupil detection is possible even if the second anterior segment observation image is somewhat out of focus. On the other hand, when evaluating the ocular surface of the subject's eye, a visible light beam is illuminated and a low-magnification second anterior segment observation image is used, but if the second anterior segment observation image is out of focus, various evaluations become difficult. For this reason, the visible light beam may be prioritized over the infrared light beam, and the optical element may be positioned on the optical axis so that the visible light beam forms an image. Note that by obtaining a wide-area second anterior segment observation image of one eye, which is also in color, the second anterior segment observation image can be easily used for evaluation of the ocular surface, etc.

[0073] Furthermore, for example, in the ophthalmic measurement device of this embodiment, the magnification-changing optical system further moves the object focal position of the anterior-segment observation optical system by moving the optical elements located on the optical axis between the test eye and the telecentric diaphragm in the optical axis direction. As a result, even if the magnification of the anterior-segment observation optical system for observing the test eye is changed, a second anterior-segment observation image focused on an appropriate position on the test eye can be obtained without adjusting the working distance of the test eye (i.e., without moving the test eye or the image sensor in the Z direction). As an example, a second anterior-segment observation image focused on the cornea of ​​the test eye can be obtained in comparison with a first anterior-segment observation image focused on the pupil of the test eye. Obtaining a second anterior-segment observation image that is a wide-area second anterior-segment observation image for one eye and focused on the cornea of ​​the test eye makes it easier to use the second anterior-segment observation image for evaluating the ocular surface, etc.

[0074] Furthermore, for example, in the ophthalmic measurement device of this embodiment, the anterior eye observation optical system is a relay optical system that forms intermediate images of a first anterior eye observation image and a second anterior eye observation image, and a telecentric diaphragm is disposed behind the intermediate image position (i.e., on the image sensor side), and the magnification changing optical system moves an optical element located on the optical axis between the intermediate image position and the telecentric diaphragm in the optical axis direction. This allows, for example, the optical path to be branched in front of the intermediate image position of the anterior eye observation optical system (i.e., on the test eye side), and an optical system different from the anterior eye observation optical system to be disposed. In this case, the light beam from the optical system different from the anterior eye observation optical system reaches the test eye without being blocked by the telecentric diaphragm.

[0075] Furthermore, for example, in the ophthalmic measurement device of this embodiment, the anterior-segment observation optical system acquires a second anterior-segment observation image at a second magnification, the second anterior-segment observation image including at least the range from the inner corner to the outer corner of one eye. This allows, for example, the entire eye to be captured in the second anterior-segment observation image, facilitating pupil detection during alignment of the eye. Furthermore, for example, the second anterior-segment observation image can be easily used to evaluate the anterior segment (ocular surface, etc.) of the eye.

[0076] Furthermore, for example, the ophthalmic measurement device of this embodiment includes a measurement optical system that projects measurement light as a pattern index toward the cornea of ​​the test eye and receives the measurement light reflected from the cornea as a pattern image, and an analysis processing unit that analyzes and processes the pattern image to acquire corneal shape information. For example, if the ophthalmic measurement device is a device that performs auto-alignment using a face observation optical system, the pattern image (e.g., a placido ring image) projected onto the test eye may be missing depending on the arrangement of the face observation optical system. For example, if the face observation optical system is arranged in the dotted line area 710 in Figure 4, it may physically block part of the light guide plate 702 and the placido ring plate 703, resulting in an anterior eye observation image including a missing part of the pattern image. In this case, corneal shape information cannot be acquired accurately. However, if the magnification of the anterior eye observation optical system is changed to support auto-alignment, as in this embodiment, the pattern image is not missing and corneal shape information can be acquired accurately.

[0077] <Modification Example> In the ophthalmic measurement device 10 of this embodiment, the magnification of the anterior eye observation optical system 200 is changed by moving the movable lens 206, which is located on the optical axis between the test eye (objective lens 505) and the telecentric diaphragm 205, in the optical axis direction. However, the present invention is not limited to this. For example, the magnification of the anterior eye observation optical system 200 can also be changed by moving, in the optical axis direction, at least one of the lenses 202 to 204, which are located on the optical axis between the telecentric diaphragm 205 and the image sensor 201. In this case, the lenses 202 to 204 and the image sensor 201 may be moved integrally. Furthermore, for example, the magnification of the anterior eye observation optical system 200 can also be changed by inserting or removing a lens on the optical axis between the test eye (objective lens 505) and the telecentric diaphragm 205. However, in this case, the observation light beam from the anterior segment of the subject's eye will no longer form an image on the image sensor 201, so it becomes necessary to either insert or remove a lens behind the telecentric aperture 205 (on the image sensor side), or to provide a drive unit or the like to move the image sensor 201 in the optical axis direction.

[0078] In the ophthalmic measurement device 10 of this embodiment, the magnification of the anterior eye observation optical system 200 is changed by moving the movable lens 206, and further, the object focal position f of the anterior eye observation optical system 200 is changed by moving the movable lens 206. However, the present invention is not limited to this. For example, the object focal position f of the anterior eye observation optical system 200 does not necessarily have to be changed. That is, in both a first magnification state in which the movable lens 206 is disposed at a predetermined position S1 and a second magnification state in which the movable lens 206 is disposed at a predetermined position S2, the pupil position (pupil plane) of the subject's eye may be the object focal position f.

[0079] The ophthalmic measurement device 10 of this embodiment has been described with reference to an example in which the position of the movable lens 206 is automatically switched depending on the measurement mode, such as alignment of the measurement unit 12 with respect to the subject's eye, measurement of corneal shape information of the subject's eye, measurement of ocular refractive power information of the subject's eye, evaluation of the anterior segment of the subject's eye, etc. However, the present invention is not limited to this. For example, the ophthalmic measurement device 10 of this embodiment may be configured to be manually switched between a state in which the movable lens 206 is positioned at a predetermined position S1 and a state in which the movable lens 206 is positioned at a predetermined position S2. That is, for example, the ophthalmic measurement device 10 may be configured to be manually switched between a high-magnification mode in which an anterior-segment observation image is acquired at a high magnification and a low-magnification mode in which an anterior-segment observation image is acquired at a low magnification.

[0080] In the ophthalmic measurement device 10 of this embodiment, after the completion of coarse and fine alignment between the subject's eye and the measurement unit 12, the arrangement of the movable lens 206 is switched as a measurement mode for evaluating the anterior segment, thereby capturing the second anterior segment observation image 260 used for evaluating hyperemia, etc., as an example. However, the present invention is not limited to this. For example, the second anterior segment observation image 260 may be captured and stored in the memory 55 when the completion of coarse alignment between the subject's eye and the measurement unit 12 is complete. This allows the alignment of the subject's eye and the evaluation of the anterior segment to proceed efficiently.

[0081] REFERENCE SIGNS LIST 10 Ophthalmic measurement device 16 Monitor 17 Operation unit 50 Control unit 100 Measurement optical system 150 Fixation target presenting optical system 200 Anterior eye observation optical system 400 Target projection optical system 600 Alignment target projection optical system 700 Target projection optical system for corneal shape measurement

Claims

1. An ophthalmic measurement device for measuring a subject's eye, comprising: an anterior segment observation optical system having a telecentric aperture at a predetermined position on the optical axis to form a telecentric system on the subject's eye side, the anterior segment observation optical system acquiring a first anterior segment observation image of the subject's eye by imaging the subject's eye at a first magnification; and a magnification changing optical system that changes the magnification of the anterior segment observation optical system to a second magnification lower than the first magnification by moving an optical element located on the optical axis between the subject's eye and the telecentric aperture in the optical axis direction, wherein the anterior segment observation optical system acquires a second anterior segment observation image having a wider angle of view than the first anterior segment observation image, the second anterior segment observation image including only the subject's eye, at the second magnification.

2. An ophthalmic measurement device according to claim 1, further comprising an anterior segment illumination optical system for illuminating the anterior segment of the subject eye with a visible light beam, and wherein the magnification changing optical system positions the optical element at a position corresponding to the visible light beam so as to form an image of the reflected light beam of the visible light beam from the anterior segment in the anterior segment observation optical system.

3. An ophthalmic measurement device according to claim 1 or 2, characterized in that the magnification changing optical system further moves the object side focal position of the anterior segment observation optical system by moving the optical element in the optical axis direction.

4. An ophthalmic measurement device according to any one of claims 1 to 3, wherein the anterior segment observation optical system is a relay optical system which forms an intermediate image of the first anterior segment observation image and the second anterior segment observation image, the telecentric aperture being disposed behind the intermediate imaging position, and the magnification changing optical system moves the optical element located on the optical axis between the intermediate imaging position and the telecentric aperture in the optical axis direction.

5. An ophthalmic measurement device according to any one of claims 1 to 4, characterized in that the anterior segment observation optical system acquires a second anterior segment observation image including at least the range from the inner corner to the outer corner of the one eye at the second magnification.

6. An ophthalmic measurement device according to any one of claims 1 to 5, comprising: a measurement optical system which projects measurement light as a pattern index towards the cornea of ​​the subject's eye and receives the measurement light reflected from the cornea as a pattern image; and an analysis processing means which analyzes and processes the pattern image to obtain corneal shape information of the subject's eye.

Images