JP2013052048A - Fundus photographing apparatus with wavefront compensation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To capture a good fundus image with a corrected wavefront aberration.SOLUTION: The fundus photographing apparatus includes: a fundus imaging optical system for capturing a fundus image by receiving the light reflected from a fundus of an examinee's eye; a wavefront compensation device disposed in an optical path of the fundus imaging optical system for compensating the wavefront aberration of the examinee's eye by controlling the wavefront of incident light; a wavefront aberration measuring optical system for projecting measuring light toward the fundus of the examinee's eye and detecting the light reflected from the fundus by a wavefront sensor; and a control means for obtaining information on a pupil of the examinee's eye and changing the size of an effective region where the aberration correction control is effective by controlling the wavefront compensation device according to the obtained information on the pupil.

Description

  The present invention relates to a fundus imaging apparatus with wavefront compensation that captures a fundus image of a subject's eye while correcting the wavefront aberration of the subject's eye.

  An apparatus for detecting wavefront aberration of an eye using a wavefront sensor such as a Shack-Hartmann sensor, controlling a wavefront compensation device based on the detection result, and photographing a fundus image after wavefront compensation at a cellular level is disclosed ( For example, see Patent Document 1). On the wavefront sensor, a predetermined effective area in which aberration correction by the wavefront compensation device is effective is set. Then, aberration compensation is performed based on the result of detecting the aberration of the Hartmann image in the effective area among the Hartmann images reflected by the fundus and received through the pupil.

JP-T-2001-507258

  Conventionally, the effective area of the wavefront compensation device has a fixed size (for example, φ = 5.5 mm). However, since the size of the pupil differs depending on the subject, the size of the Hartmann image received through the pupil is received at different sizes. Therefore, depending on the size of the pupil of the subject, a difference occurs between the size of the effective area and the size of the Hartmann image, which affects the aberration detection.

  For example, when the pupil diameter of the eye to be examined is larger than the effective region (for example, φ6.5 mm), a certain region (for example, φ5.5 mm of the effective region) of the entire incident light incident on the wavefront compensation device Is limited to the luminous flux. The other incident light is reflected toward the light receiving element, but the wavefront is not compensated. That is, the fundus reflection light in the region from φ5.5 mm to φ6.5 mm out of the fundus reflection light that has passed through the pupil region (φ6.5 mm region) cannot be corrected for aberrations, and therefore, from 5.5 mm to φ6. Information on a region up to .5 mm cannot be contributed when a high-resolution image is captured. For this reason, it is difficult to capture a high-resolution image.

  When the pupil diameter of the eye to be examined is smaller than the effective region (for example, φ5.0 mm), the entire incident light incident on the wavefront compensation device cannot satisfy the effective region, and no Hartmann image is formed. In the region, no aberration is detected. If a part of the wavefront measurement data is missing in this way, information on the entire wavefront cannot be obtained, and therefore the wavefront aberration is not properly measured. When wavefront compensation control is performed based on the detection result obtained in such a state, the wavefront compensation device is controlled with an incorrect aberration compensation amount. That is, in the region from φ5.0 mm to φ5.5 mm in the effective region (φ5.5 mm), the fundus reflection light that has passed through the pupil region (φ5.0 mm region) cannot enter, and aberration detection is performed. Can not do it. For this reason, optimal aberration correction cannot be performed, and a good fundus image with the wavefront aberration corrected cannot be captured.

  In view of the above problems, it is an object of the present invention to provide a fundus photographing apparatus with wavefront compensation that can smoothly photograph a good fundus image with a wavefront aberration corrected.

  In order to solve the above problems, the present invention is characterized by having the following configuration.

(1) A fundus imaging optical system that receives reflected light from the fundus of the subject's eye and picks up a fundus image, and a wavefront aberration of the eye to be examined by controlling the wavefront of incident light that is disposed in the optical path of the fundus imaging optical system. A wavefront compensation device that compensates for the above, a wavefront aberration detection optical system that projects measurement light toward the fundus of the subject's eye, and detects the reflected light from the fundus using a wavefront sensor, and acquires and acquires pupil information of the eye to be examined Control means for changing the size of an effective region in which aberration correction control is effective by controlling the wavefront compensation device according to the pupil information.
(2) light receiving means for receiving reflected light from the eye to be examined, and detection means for detecting pupil information of the eye to be examined based on a light reception signal from the light receiving means, the control means from the detection means to the eye of the eye to be examined The fundus imaging apparatus with wavefront compensation of (1) for acquiring pupil information.
(3) comprising an anterior ocular segment observation unit that captures an anterior ocular segment image of the eye to be examined, wherein the detection means extracts an outer edge of the pupil from the anterior segment image captured by the anterior ocular segment observation unit by image processing; The detection means for detecting a pupil diameter, wherein the control means changes the size of the effective region in accordance with the pupil diameter detected by the detection means (2).
(4) The detection unit is a detection unit that detects an outer edge portion of a light receiving region of the index pattern image by the wavefront sensor, and the control unit is configured to detect a size of the outer edge portion detected by the detection unit. The fundus imaging apparatus with wavefront compensation according to (2), wherein the size of the effective area is changed.
(5) The detection means calculates a center position of the light receiving region of the index pattern image from the detected outer edge portion, detects a diameter from the center coordinate to the outer edge portion, and the control means is operated by the detection means. The fundus imaging apparatus with wavefront compensation according to (2), wherein the size of the effective area is changed according to the detected diameter from the center coordinate to the outer edge.
(6) The control means obtains pupil information of the eye to be examined, and performs first feedback control for changing the size of the effective region in accordance with changes in the obtained pupil information (1) to (5) ) Fundus imaging device with wavefront compensation.
(7) The control means detects a wavefront aberration of the subject's eye based on a detection signal from the wavefront sensor, and performs a second feedback control for controlling the wavefront compensation device based on the detection result. (1)-(6) fundus imaging apparatus with wavefront compensation.

  In view of the above problems, the present invention can capture a good fundus image in a state where wavefront aberration is corrected.

  An embodiment of the present invention will be described. FIG. 1 is an external view of a fundus imaging apparatus according to this embodiment, and the apparatus includes a base 510, a face support unit 600, and an imaging unit 500. The face support unit 600 is attached to the base 510. The imaging unit 500 houses an optical system described later, and is provided on the base 510. The face support unit 600 is provided with a chin rest 610. The chin rest 610 is moved in the left / right direction (X direction), the up / down direction (Y direction), and the front / rear direction (Z direction) with respect to the base of the face indicating unit 600 by operating a chin rest driving means (not shown).

  FIG. 2 is a schematic diagram showing an optical system of the fundus imaging apparatus of the present embodiment. The fundus imaging apparatus of the present embodiment is broadly divided into a fundus imaging optical system 100, a wavefront aberration detection optical system (hereinafter referred to as an aberration detection optical system) 110, aberration compensation units 10 and 72, and a second imaging. A unit 200, a tracking unit (position detection unit) 300, and an anterior ocular segment observation unit 700 are provided.

  The fundus imaging optical system 100 receives reflected light from the fundus of the eye E and captures a fundus image of the eye. The aberration detection optical system 110 includes a wavefront sensor 73, projects measurement light onto the fundus of the eye to be examined, and receives (detects) reflected light from the fundus as an index pattern image. The aberration compensation units 10 and 72 are disposed in the fundus imaging optical system 100 in order to correct the aberration of the eye to be examined. The second photographing unit 200 displays a fundus observation image (hereinafter referred to as a second fundus image) for designating a photographing position of a fundus image obtained by the fundus imaging optical system 100 (hereinafter referred to as a first fundus image). obtain.

  Here, the fundus imaging optical system 100 captures the fundus of the eye E with high resolution (high resolution) and high magnification. The aberration compensation unit includes a diopter correction unit 10 for correcting low-order aberrations (diopter: for example, spherical power) of the eye to be examined, and a high-order aberration compensation unit for correcting high-order aberrations of the eye to be examined. (Wavefront compensation device) 72.

  The fundus imaging optical system 100 includes a first illumination optical system 100a that irradiates the eye E with illumination light (illumination light beam) to illuminate the fundus two-dimensionally, and reflected light (reflected light beam) of the illumination light irradiated on the fundus. And a first compensation optical system 100b for obtaining a first fundus image and an aberration compensator 72. The fundus imaging optical system 100 has, for example, a scanning laser ophthalmoscope configuration using a confocal optical system.

  The first illumination optical system 100 a includes a light source 1 (first light source) and a scanning unit 15. The light source 1 uses near-infrared illumination light that is difficult to be visually recognized by the eye to be examined, and emits illumination light for illuminating the fundus. In the present embodiment, the light source 1 is an SLD (Super Luminescent Diode) light source having a wavelength of 840 nm. The light source may be any light source that emits spot light having a high convergence property, and may be, for example, a semiconductor laser. The scanning unit 15 scans illumination light (spot light) in the horizontal direction (X direction) on the fundus.

  First, the first illumination optical system 100a will be described. The first illumination optical system 100a includes a lens 2, a polarizing beam splitter (PBS) 4, a concave mirror 6, a concave mirror 7, a plane mirror 8, a wavefront compensation device 72, and a concave mirror in the optical path from the light source 1 to the fundus. 11, a concave mirror 12, a scanning unit 15, a concave mirror 16, and a concave mirror 17. Further, the plane mirror 21, lens 22, plane mirror 23, diopter correction unit 10, plane mirror 25, concave mirror 26, deflection unit 400, dichroic mirror 90, concave mirror 31, plane mirror 32, plane mirror 33, concave surface A mirror 35 is arranged. The diopter correction unit 10 includes a plane mirror and a lens. The deflecting unit 400 scans the illumination light emitted from the light source 1 in the vertical direction (Y direction) on the fundus. Further, the deflecting unit 400 corrects the scanning position of the illumination light scanned in a two-dimensional manner. The dichroic mirror 90 makes the optical path of the second imaging unit 200 and the like substantially coaxial with the first illumination optical system 100a.

  The illumination light emitted from the light source 1 is converted into parallel light by the lens 2 and then passes through the PBS 4. In the present embodiment, the illumination light is changed to a light beam having only an S-polarized component by the PBS 4 in this embodiment. The illumination light that has passed through the PBS 4 is reflected by the concave mirror 6, the concave mirror 7, and the plane mirror 8 via the beam splitter (BS) 71, and enters the wavefront compensation device 72. The illumination light reflected by the wavefront compensation device 72 is reflected by the concave mirror 11 and the concave mirror 12 via the BS 75 and travels toward the scanning unit 15.

  Here, the scanning unit 15 scans illumination light in the X direction on the fundus. In the present embodiment, a resonant mirror serving as a deflecting member for deflecting and scanning illumination light in the horizontal direction (X direction) at the fundus and a drive unit for driving the mirror are provided. The illumination light that has passed through the scanning unit 15 is reflected by the concave mirror 16, the concave mirror 17, and the flat mirror 21 and is collected by the lens 22. The illumination light is reflected by the plane mirror 23. The illumination light is reflected by the plane mirror 25 and the concave mirror 26 via the diopter correction unit 10 and travels toward the deflection unit 400. The diopter correction unit 10 includes a driving unit 10a, and the optical path length can be changed by moving the plane mirror and the lens in the direction of the arrow shown in the drawing, and plays a role in diopter correction. The diopter correction unit 10 may be configured by a driving unit and a prism that can move in the optical axis direction by driving the driving unit.

  The deflecting unit 400 scans illumination light in the XY directions at the fundus. In this embodiment, the galvano mirror for X scanning and the galvano mirror for Y scanning are constituted by two galvano mirrors. Further, the deflecting unit 400 has a function of further deflecting the illumination light having passed through the scanning unit 15 by a predetermined amount with respect to the X direction and the Y direction. The illumination light that has passed through the deflecting unit 400 is reflected by the dichroic mirror 90, the concave mirror 31, the flat mirror 32, the flat mirror 33, and the concave mirror 35, and is condensed on the fundus of the eye E to be scanned, and the scanning unit 15 and the deflecting unit. By 400, the fundus is scanned two-dimensionally.

  Further, the dichroic mirror 90 has a characteristic of transmitting a light beam from a second imaging unit 200, a tracking unit 300, and an anterior ocular segment observation unit 700, which will be described later, and reflecting a light beam from the light source 1 and a light source 76, which will be described later. . Note that the emission ends of the light sources 1 and 76 and the fundus of the eye E are conjugate. Thus, the 1st illumination optical system 100a which irradiates illumination light to a fundus two-dimensionally is formed.

  The tracking unit 300 detects a time-dependent change in positional deviation due to fixation eye movement of the eye E to be photographed, and obtains movement position information. In the tracking unit 300, the light reception result obtained at the start of tracking is sent as reference information to the control unit 80, and thereafter, the light reception result (light reception information) obtained for each scan is sequentially transmitted to the control unit 80. The control unit 80 compares the received light information obtained thereafter with the reference information, and obtains the movement position information by calculation so that the same received light information as the reference information is obtained. The control unit 80 drives the deflection unit 400 based on the obtained movement position information. By performing such tracking, the deflection unit 400 is driven so that even if the eye E moves slightly, the movement of the eye E is offset, so that the movement of the fundus image displayed on the monitor 70 is suppressed. It becomes. The dichroic mirror 91 has a characteristic of transmitting the light beam from the second photographing unit 200 and reflecting the light beam from the tracking unit 300.

  The anterior ocular segment observation unit 700 illuminates the anterior ocular segment to be examined with visible light and captures an anterior ocular segment front image. The dichroic mirror 95 has a characteristic of transmitting the light flux from the second imaging unit 200 and the tracking unit 300 and reflecting the light flux from the anterior ocular segment observation unit 700.

  Next, the first photographing optical system 100b will be described. The first photographing optical system 100 has a common optical path from the dichroic mirror 90 to the BS 71 described in the first illumination optical system 100a, and further includes a plane mirror 51, a PBS 52, a lens 53, a pinhole plate 54, a lens 55, and a light receiving element. 56. In this embodiment, the light receiving element 56 is an APD (avalanche photodiode). The pinhole plate 54 is placed at a position conjugate with the fundus.

  The reflected light from the fundus of the illumination light emitted from the light source 1 traces the first illumination optical system 100a in the reverse direction, is reflected by the BS 71 and the plane mirror 51, and only the S-polarized light is transmitted by the PBS 52. This transmitted light is focused on the pinhole of the pinhole plate 54 via the lens 53. The reflected light focused at the pinhole is received by the light receiving element 56 through the lens 55. Although a part of the illumination light is reflected on the cornea, most of the illumination light is removed by the pinhole plate 54, and the adverse effect of the corneal reflection on the image is reduced. For this reason, the light receiving element 56 can receive the reflected light from the fundus while suppressing the influence of corneal reflection.

  In this way, the first photographing optical system 100b is formed. The processed image received by the first imaging optical system 100b becomes the first fundus image. One frame of the first fundus image is formed by the main scanning of the scanning unit 15 and the sub scanning of the Y scanning galvanometer mirror provided in the deflection unit 400. Note that the deflection angle (swing angle) of the mirror in the scanning unit 15 and the deflection unit 400 is determined so that the angle of view of the fundus image (fundus image) acquired by the first imaging unit 100 becomes a predetermined angle. Here, in order to observe and photograph a predetermined range of the fundus at a high magnification (here, observation at a cell level or the like), the angle of view is set to about 1 to 5 degrees. In this embodiment, the angle is 1.5 degrees. Although depending on the diopter of the eye to be examined, the imaging range of the first fundus image is about 500 μm square.

  Further, the reflection angle of the X-scanning galvanometer mirror and the Y-scanning galvanometer mirror provided in the deflecting unit 400 is moved larger than the imaging field angle of the first fundus fundus image, so that the first fundus image on the fundus The imaging position is changed.

  Next, the second photographing unit 200 will be described. The second imaging unit is a unit for acquiring a fundus image (second fundus image) having a wider angle of view than the angle of view of the first imaging unit, and the acquired second fundus image has the narrow angle of view described above. Used for position designation and position confirmation for obtaining the first fundus image. The second imaging unit 200 for acquiring such a second fundus image only needs to be able to acquire the fundus image of the eye E to be examined in real time with a wide angle of view (for example, about 20 to 60 degrees). Therefore, the second imaging unit 200 can use an observation / imaging optical system of an existing fundus camera, an optical system of a scanning laser ophthalmoscope (SLO), and a control system.

  Next, the aberration detection optical system 110 will be described. As described above, the aberration detection optical system 110 has some optical elements on the optical path of the first illumination optical system 100a, and shares a part of the optical path with the first illumination optical system 100a. The aberration detection optical system 110 includes a light source 76, a lens 77, PBS 78, BS75, BS71, a dichroic mirror 86, PBS85, a lens 84, a plane mirror 83, a lens 82, and a wavefront sensor 73. The aberration detection optical system 110 is configured by sharing the optical members from the BS 71 to the concave mirror 35 placed on the optical path of the first illumination optical system 100a. The wavefront sensor 73 includes, for example, a microlens array composed of a number of microlenses and a two-dimensional imaging element 73a (two-dimensional light receiving element) for receiving a light beam that has passed through the microlens array. A light source 76 that is an aberration detection light source (third light source) is a light source that emits light in an infrared region different from that of the light source 1. In the present embodiment, the light source 76 uses a laser diode that emits laser light having a wavelength of 780 nm.

  The laser light emitted from the light source 76 is converted into a parallel light beam by the lens 77, and the polarization direction (P-polarized light) is orthogonal to the illumination light from the light source 1 by the PBS 78, and is guided to the optical path of the first illumination optical system by the BS 75. Note that the emission end of the light source 76 has a conjugate relationship with the fundus conjugate position. The PBS 78 has a role of making the light emitted from the light source 76 a predetermined polarization direction, and has a role of a first polarization means provided in the wavefront compensation unit.

  The laser light reflected by the BS 75 is condensed on the fundus of the eye E through the optical path of the first illumination optical system 100a. The laser light reflected from the fundus is reflected by the wavefront compensation device 72 through each optical member of the first illumination optical system 100a, deviated from the optical path of the first illumination optical system 100a by the BS 71, and reflected by the dichroic mirror 86. The light is guided to the wavefront sensor 73 through the PBS 85, the lens 84, the flat mirror 83, and the lens 82.

  The PBS 85 is a second polarization unit provided in the wavefront compensation unit, blocks the polarization direction (P-polarized light) of the light emitted from the light source 76 to the eye E, and is orthogonal to the polarization direction (S-polarized light). Light) and guides it to the wavefront sensor 73. The dichroic mirror 86 has a characteristic of transmitting light (840 nm) having the wavelength of the light source 1 and reflecting light (780 nm) having the wavelength of the light source 76 for detecting aberration. Accordingly, the wavefront sensor 73 detects light having an S-polarized component from the scattered light on the fundus of the irradiated laser light. In this way, light reflected by the cornea and the optical element is suppressed from being detected by the wavefront sensor 73. The scanning unit 15, the reflection surface of the wavefront compensation device 72, and the microlens array of the wavefront sensor 73 are substantially conjugate with the pupil of the eye to be examined. The light receiving surface of the wavefront sensor 73 is substantially conjugate with the fundus of the eye E. As the wavefront sensor 73, an element capable of detecting wavefront aberration including low-order aberration and high-order aberration, for example, a Hartmann Shack detector, a wavefront curvature sensor that detects a change in light intensity, or the like is used.

  The wavefront compensation device 72 is, for example, a liquid crystal spatial light modulator and uses a reflective LCOS (Liquid Crystal On Silicon) or the like. The wavefront compensation device 72 is disposed in the optical path of the fundus imaging optical system 100 and controls the wavefront of incident light to compensate for the wavefront aberration of the eye to be examined. The wavefront compensation device 72 is a predetermined unit such as illumination light from the light source 1 (S-polarized light), reflected light from the fundus of the illumination light (S-polarized light), reflected light from wavefront aberration detection light (S-polarized light component), or the like. Are arranged in a direction capable of compensating the aberration with respect to the linearly polarized light (S-polarized light). As a result, the wavefront compensation device 72 can modulate the S-polarized component of the incident light. Further, the wavefront compensation device 72 has a liquid crystal molecule arrangement direction in the liquid crystal layer substantially parallel to the polarization plane of the incident reflected light, and the liquid crystal molecules rotate in accordance with a change in voltage applied to the liquid crystal layer. The predetermined surface is substantially parallel to a plane including the incident optical axis and the reflected optical axis of the reflected light from the fundus to the wavefront compensation device 72, and the normal of the mirror layer of the wavefront compensation device 72. Have been placed.

  In this embodiment, the wavefront compensation device 72 is a liquid crystal modulation element and uses a reflective LCOS (Liquid Crystal On Silicon) or the like, but is not limited thereto. Any reflective wavefront compensation device may be used. For example, a deformable mirror that is a form of MEMS (Micro Electro Mechanical Systems) may be used. Further, instead of a reflection type wavefront compensation device, a transmission type wavefront compensation device that transmits reflected light from the fundus and compensates for wavefront aberration can also be used.

  In the above description, a light source that emits illumination light having a wavelength different from that of the first light source is used as the aberration detection light source. However, the first light source may be used as the aberration detection light source.

  In the present embodiment described above, the wavefront sensor and the wavefront compensation device are the pupil conjugate of the eye to be examined. However, the position may be a position that is substantially conjugate with a predetermined part of the anterior eye portion of the eye to be examined. There may be.

  Next, a control system of the fundus imaging apparatus will be described. FIG. 3 is a block diagram showing a control system of the fundus imaging apparatus of the present embodiment. The control unit 80 that controls the entire apparatus includes a light source 1, a driving mechanism 505, a scanning unit 15, a light receiving element 56, a wavefront compensation device 72, a wavefront sensor 73, a light source 76, a second photographing unit 200, a tracking unit 300, The deflection unit 400, the anterior ocular segment observation unit 700, and the drive unit 10a are connected. Further, a storage unit 81, a control unit 92, an image processing unit 93, and a monitor 70 are connected.

  Based on signals received by the light receiving element 56 and the second imaging unit 200, the image processing unit 93 forms on the monitor 70 images of the fundus of the subject's eye with different angles of view, that is, a first fundus image and a second fundus image. The storage unit 81 stores various setting information (a program for changing the size of an effective area, which will be described later) and a captured image. As the monitor 70, for example, a monitor of an external personal computer or a monitor provided in an apparatus can be considered. The monitor 70 displays fundus images (first fundus image and second fundus image) that are updated at a predetermined frame rate. The frame rate is, for example, 10 to 100 Hz. In this way, the fundus image is displayed as a moving image. In the present embodiment, the control unit 80 also functions as the display control unit 80 of the monitor 70, the drive control unit 80 of the deflection unit 400, and the emission control unit 80 such as the light sources 1 and 76.

  When the wavefront compensation device 72 is controlled, the wavefront compensation device 72 is controlled based on the wavefront aberration detected by the wavefront sensor 73, and the illumination emitted from the light source 1 together with the S-polarized component of the reflected light of the light source 76. Higher order aberrations of the light and its reflected light are removed. In this way, the aberration of the illumination light emitted from the light source 1 and the reflected light is removed. In other words, a high-resolution first fundus image from which the high-order aberration of the eye E is removed (wavefront compensated) is obtained. In this case, the low-order aberration is corrected by the diopter correction unit 10.

  FIG. 4 is a diagram for explaining a compensable region and an effective region of the wavefront sensor. The compensable region 40 indicates a region where the wavefront of the incident light can be controlled in the wavefront compensation device 72. An effective area 41 indicates an area in which aberration correction is effective by controlling the wavefront compensation device 72 based on the detection signal from the wavefront sensor 73 in the compensable area 40. In the present embodiment, the compensable region 40 has a size of 16 × 12 mm, and the effective region 41 has a size of φ8.64 mm. Since the size of the compensable region 40 is a size that is sufficiently larger than the size of the effective region 41, at least one of the position, size, and shape of the effective region 41 can be changed in the compensable region 40 (details will be described later). To do).

  FIG. 5 is a diagram for explaining a specific example of an index pattern image and an effective area on a compensable area of the wavefront sensor. FIG. 6 is a diagram showing an aberration correction screen 60 displayed on the screen of the monitor 70. The aberration correction screen 60 includes an index pattern image (in this embodiment, a Hartmann image, hereinafter referred to as a Hartmann image) 61 received by the two-dimensional imaging element 73a of the wavefront sensor 73, and a correction degree of aberration correction. An aberration correction graphic 65 that graphically displays (residual aberration) and a cell image image 66 of the fundus that is actually captured are displayed.

  A Hartmann image (dot pattern image) 61 represents a group of a plurality of point images 61 a received on the wavefront sensor 73. The fundus reflection light that has passed through the lens array is received by the two-dimensional imaging device 73a of the wavefront sensor 73 and captured as a Hartmann image. The Hartmann image 61 is displayed on the monitor 70. In the area where the point image 61a is detected by the wavefront sensor 73, aberration detection is possible.

  A circle 62 virtually indicates an effective region in which the wavefront of the wavefront compensation device 72 can be controlled on the two-dimensional image sensor 73a, and aberration correction is effective (possible) by controlling the wavefront. It is. The graphic corresponding to the circle 62 is superimposed on the Hartmann image on the monitor 70 and displayed. The mark located at the center of the circle 62 is a graphic indicating the center position of the effective area on the wavefront sensor 73.

  The outer circumference of the circle 62, the area, and the position information on the wavefront sensor 73 are set in the storage unit 81 in advance. These may be obtained in advance by calibration or simulation. In the wavefront compensation device 72, the effective region is limited to a light beam in a certain partial region (for example, a region having a diameter of 6 mm on the pupil) in the entire incident light. For this reason, other incident light is reflected toward the light receiving element 54, but the wavefront is not compensated.

  Here, the aberration correction is performed based on the aberration detection result by the wavefront sensor 73. In order to correct aberrations appropriately, it is necessary to detect aberrations appropriately. Hereinafter, the relationship between the Hartmann image and the effective area when performing aberration detection will be described.

  For example, in the aberration detection, if the size of the area where the Hartmann image 61 is formed (Hartmann image outer periphery 61b) is substantially the same as the area of the circle 62 (effective area), the wavefront state can be detected appropriately. For this reason, optimal aberration correction can be performed (see FIG. 5A).

  When the size of the area where the Hartmann image 61 is formed is smaller than the area (effective area) of the circle 62, an area S1 where the Hartmann image 61 is not formed in the effective area is generated. In the region of the circle 62, the wavefront state is not detected in the region S1 in which the Hartmann image 61 is not formed. Here, when a part of the wavefront data is missing, information on the entire wavefront cannot be obtained, so that the wavefront aberration in the wavefront correction region is not properly measured (see FIG. 5B). Therefore, as shown in FIG. 6A, even when the aberration correction is performed, the aberration is not properly removed as shown in the aberration correction graphic 65. In addition, as shown in the cell image 66, it becomes difficult to capture.

  When the size of the area where the Hartmann image 61 is formed is larger than the area (effective area) of the circle 62, in the area S2 where the area of the Hartmann image 61 is larger than the area of the circle 62, the reflected light flux in that area can be received. The wavefront by the wavefront compensation device 72 is not compensated (see FIG. 5C). For this reason, although the aberration information in the region S2 can be detected, the aberration information cannot be reflected (contributed) to the wavefront compensation device 72. Therefore, when imaging an image, a high-resolution image can be captured. It becomes difficult.

  As described above, in order to perform proper aberration detection, it is desirable that the size of the Hartmann image and the size of the effective region are substantially the same. Therefore, in the present embodiment, the pupil information of the eye to be examined is acquired, and the wavefront compensation device 72 is controlled according to the acquired pupil information, thereby changing the size of the effective region in which the aberration correction control is effective. For example, the size of the effective area is changed according to the size of the Hartmann image. As a result, as shown in FIG. 5A, the size of the area of the circle 62 becomes the size of the Hartmann image 61, and appropriate aberration detection and aberration correction can be performed (details will be described later). As shown in FIG. 6B, the aberration is removed as shown in the aberration correction graphic 65, and a high-resolution image from which aberration is removed is also displayed in the cell image 66.

  In the fundus imaging apparatus having the above-described configuration, a control operation until acquiring a good fundus image in a state where the wavefront aberration is corrected will be described with reference to a flowchart shown in FIG.

  First, the examiner adjusts the position of the chin rest 610 manually or automatically while observing the anterior ocular segment image displayed on the screen of the monitor 70 to perform rough alignment. Further, the examiner instructs the subject to fixate a fixation target (not shown). When the rough alignment by the chin rest 610 is completed and the measurement switch (not shown) is selected by the examiner, the diopter correction is performed by the control unit 80 using the diopter correction unit 10.

  Next, the control unit 80 receives reflected light from the eye to be examined by the anterior segment imaging unit 700 and detects a pupil portion (for example, pupil diameter) from the acquired anterior segment image. Hereinafter, a method for obtaining the edge position of the pupil from the anterior eye image and detecting the pupil diameter will be described with reference to FIG.

  FIG. 8A shows the captured anterior segment image, and FIG. 8B shows the video signal on the scanning line L. FIG. In order to know the boundary (edge) between the pupil (dark part) and the iris (bright part), first, the signal waveform in FIG. The signal waveform at this time is as shown in FIG. Since this signal is a positive / negative signal, when it is squared, it becomes a positive numerical signal shown in FIG. In FIG. 8D, for example, if the edges of the first waveform signal at the height e1 and the last waveform signal at the height e2 are defined as the half points of the respective heights (amplitudes), the pixel position n1 , N2 is the coordinate position of the edge on the scanning line L.

Further, the number of pixels n between the pixel positions n1 and n2 is obtained. Here, if the length of one pixel is K and the optical magnification is P, the distance between the pixel positions n1 and n2 (pupil diameter PS ′) is
PS '= n * K / P
It can be obtained from the following formula. That is, since the values of K and P are known values unique to the apparatus, the pupil diameter can be obtained by obtaining the number n of pixels.

  At this time, the position of the pupil center is detected based on the outline information of the pupil, and the pupil diameter in each meridian direction is calculated based on the pupil center.

  When the pupil diameter is detected, the control unit 80 changes the size of the effective region 41 in the wavefront compensation device 72 set at the time of aberration correction based on the detected pupil diameter. Further, in the Hartmann image received by the wavefront sensor 73, the size of the index region used for aberration detection is changed so as to correspond to the changed effective region 41 size. In the present embodiment, φ4.0 mm is set as the initial effective area before detection of the pupil diameter. Of course, a different size may be used as the initial effective area, or a configuration that can be arbitrarily set by the examiner.

  Hereinafter, the operation for changing the effective area will be described. The storage unit 81 stores a correlation between the pupil diameter and the effective area as a table. That is, an optimum effective area is set according to each pupil diameter. For example, the effective area when the pupil diameter is φ5.0 mm is set so that the effective area on the pupil is φ5.0 mm. The control unit 80 acquires an effective region corresponding to the detected pupil diameter from the storage unit 81 and changes the initial effective region to the acquired effective region. When creating a correlation table between the pupil diameter and the effective area, for example, the Hartmann image at a predetermined pupil diameter is detected in advance by the present apparatus, and the size of the Hartmann image and the effective area matches or substantially matches. The effective area to be determined is obtained. Then, by calculating this effective area for each model eye having a different pupil diameter, a correlation table between the pupil diameter and the effective area is created. As described above, the effective area is changed based on the pupil diameter.

  In the present embodiment, the effective area is changed based on the correlation between the pupil diameter and the effective area stored in the storage unit 81, but the present invention is not limited to this. For example, when the pupil diameter is detected, the effective area may be calculated by a predetermined arithmetic expression based on the detected pupil diameter, and changed to the calculated effective area.

  Next, the control unit 80 receives the effective area (for example, circle 62) of the wavefront compensation device 72 set on the wavefront sensor 73 and the light receiving area (wavefront measurement) of the index pattern image (for example, Hartmann image 61) by the wavefront sensor 73. The deviation of the center of gravity position from the area) is detected. Then, the controller 80 manually or automatically adjusts the position of the chin rest 610. As another configuration, when the photographing unit 500 is configured to be movable with respect to the eye E, the control unit 80 may move the photographing unit 500 so that the deviation information is within an allowable range. In addition, a light deflection unit that changes the traveling direction of the measurement light beam may be provided in the optical path of the detection optical system 110, and the positional relationship may be optically adjusted by driving the light deflection unit. Such an operation is for correcting a shift between the circle 62 and the Hartmann image 61 due to a positional shift between the eye E and the photographing unit 500.

  The control unit 80 determines whether the region formed by the circle 62 is within the region formed by the Hartmann image outer periphery 61b. And the control part 80 adjusts the relative position of the eye E and the imaging | photography part 500, when the area | region which the circle | round | yen 62 comprises has remove | deviated from the area | region which the Hartmann image outer periphery 61b comprises. On the other hand, when the region formed by the circle 62 is within the region formed by the Hartmann image outer periphery 61b, the control unit 80 detects the wavefront aberration of the eye E based on the detection result of the wavefront sensor 73, and performs fundus imaging. Fundus photographing with the optical system 100 is started.

  The controller 80 calculates an aberration compensation amount based on the detection result of the aberration, and controls the aberration correction amount in the effective region 41 of the wavefront compensation device 72 using the calculation result to compensate the wavefront aberration.

  Then, the control unit 80 detects the pupil diameter from the anterior eye image and changes the size of the effective area 41. Then, the control unit 80 newly acquires a Hartmann image output from the wavefront sensor 73, and detects wavefront aberration. Thereafter, an aberration compensation amount is calculated based on the aberration detection result, and the aberration correction amount in the effective region 41 of the wavefront compensation device 72 is controlled using the calculation result to compensate the wavefront aberration.

  The controller 80 detects the wavefront aberration of the subject's eye based on the detection signal from the wavefront sensor 73, and performs second feedback control that repeats the control of the wavefront compensation device 72 based on the detection result. The second feedback control is reflected on the fundus moving image acquired simultaneously while the wavefront aberration is compensated. That is, as described above, by performing the second feedback control, the wavefront of the fundus reflection light is compensated, so that the blur of the fundus moving image can be reduced. Therefore, a clear fundus image can be obtained even if the aberration state of the eye to be examined with respect to the fundus imaging apparatus changes due to a change in the pupil diameter of the eye to be examined.

  Note that the second feedback control is performed until the end of shooting. Further, when a predetermined trigger signal is output while the second feedback control is performed and the fundus moving image is acquired, the cell image of the fundus acquired at that time is stored as a moving image or a still image. Stored in the unit 81.

  Since the pupil diameter of the eye E may change during the second feedback control, the control unit 80 further acquires the pupil information of the eye to be examined, and according to the change of the acquired pupil information, You may make it perform the 1st feedback control which repeats the change of the size of the effective area | region 41. FIG.

  As described above, by changing the size of the effective region 41 of the wavefront compensation device 72 according to the size of the pupil diameter, a favorable aberration correction result can be obtained regardless of the difference in the pupil diameter of the eye to be examined. . As a result, a good fundus image with high resolution can be taken regardless of individual differences in the eye to be examined.

  In the present embodiment, the present invention can also be applied to an eye to be examined whose shape of the pupil (Hartmann image) is irregular. For example, in the case of an eye to be examined having a pupil that has a waveform shape or an elliptical pupil, an inscribed circle that includes the pupil region is changed as an effective region inside the irregular pupil region. Is mentioned.

  In the case of an eye to be examined having a pupil including a waveform shape or an elliptical pupil, a circumscribed circle including an irregular pupil region may be changed as an effective region. In this case, since an area where no aberration is detected is generated between the circumscribed circle and the pupil area, it is necessary to detect the aberration by estimating a case where the irregular pupil area is a circular pupil area.

  In the present embodiment, in the first feedback control, the pupil diameter is detected at any time and the size of the effective region 41 of the wavefront compensation device 72 is changed. However, the present invention is not limited to this. For example, when the pupil diameter change (for example, φ ± 0.3 mm) is within a predetermined allowable range, the size of the effective area 41 may not be changed. Alternatively, the size of the effective area 41 may be changed only at the start of shooting.

  In this embodiment, the control unit 80 extracts the outer edge of the pupil from the anterior segment image captured by the anterior segment observation unit 700 by image processing, detects the pupil diameter, and responds to the detected pupil diameter. Thus, the size of the effective area is changed, but the present invention is not limited to this. The apparatus includes a light receiving unit that receives reflected light from the eye to be detected, detects pupil information of the eye based on a light reception signal from the light receiving unit, and controls the wavefront compensation device 72 according to the detected pupil information. Thus, the size of the effective area where the aberration correction control is effective is changed. For example, the control unit 80 may be configured to change the size of the effective area based on the detection result of the wavefront sensor 73.

  As a first example, the control unit 80 detects the outer edge portion of the light receiving region of the index pattern image by the wavefront sensor 73 and changes the size of the effective region according to the detected size of the outer edge portion. More specifically, the control unit 80 sequentially detects the position of the point image received at the outermost side among the Hartmann images 61 received by the wavefront sensor 73, and detects the position information of the Hartmann image outer periphery 61b. Then, the control unit 80 compares the Hartmann image outer periphery 61 b with the circle 62. For example, the control unit 80 is configured to change the size of the effective region 41 of the wavefront compensation device 72 if the difference region between the region formed by the circle 62 and the region formed by the Hartmann image outer periphery 61b exceeds a predetermined threshold. Can be mentioned.

  As a second example, the control unit 80 calculates the center position of the light receiving region of the index pattern image from the detected outer edge, detects the diameter from the center coordinate to the outer edge, and detects the outer edge from the detected center coordinate. The size of the effective area 41 is changed according to the diameter up to the part. More specifically, the center coordinate position of the Hartmann image 61 is detected, and the distance in each meridian direction to the Hartmann image outer periphery 61b is calculated based on the center coordinate. Then, the minimum value of the calculated distances is detected, and based on the minimum value, the size of the effective area 41 of the wavefront compensation device 72 is changed so that the minimum distance value and the radius of the circle 62 match or substantially match. To do.

  In the present embodiment, the radius of the circular effective area is changed. However, the present invention is not limited to this. Any configuration in which the size of the effective area is changed based on the pupil information may be used. For example, the effective area may be an elliptical shape, a triangular shape, or a quadrangular shape, or a configuration in which the size thereof is changed. The control unit 80 may detect the outer periphery of the Hartmann image and change the size of the effective region 41 of the wavefront compensation device 72 so that the size of the outer edge of the Hartman image matches the size. The effective area shape may be set arbitrarily by the examiner.

  In the above embodiment, a sensor for detecting pupil information is provided, but the present invention is not limited to this. For example, the size of the effective area may be changed according to pupil information obtained by another pupil diameter measuring device.

  When changing the size of the effective region, the size of the effective region 41 does not necessarily need to match the pupil size of the eye to be examined, as long as a satisfactory aberration correction result can be obtained. For example, the size of the effective area 41 can be changed stepwise (for example, 1 mm step at φ = 3.0 to 8.0 mm), and the size of the effective area 41 close to the detected pupil size is selected / set. It may be a configuration.

  In the above embodiment, the size of the index region used for aberration detection is changed according to the change of the effective region 41, but the present invention is not limited to this. The control unit 80 may change the size of the index region used for aberration detection in the Hartmann image received by the wavefront sensor 73 in accordance with the acquired pupil information of the eye E. Further, the control unit 80 may detect the Hartmann image outer periphery 61 b and measure the wavefront aberration based on the entire index pattern image received by the wavefront sensor 73.

  In the above description, the fundus imaging optical system 100 receives the light beam reflected from the fundus of the eye to be examined through the confocal aperture disposed at a position substantially conjugate to the fundus of the eye to be examined, and confocals the fundus of the eye to be examined. Although a confocal optical system (SLO optical system) that captures a front image is used, the present invention is not limited to this (see, for example, JP 2001-507258 A).

  For example, a fundus camera optical system that captures a frontal image of the fundus of the subject's eye by receiving a light beam reflected from the fundus of the subject's eye with a two-dimensional image sensor. Further, it may be an optical tomographic interference optical system (OCT optical system) that receives a light beam reflected from the fundus of the eye to be examined and interference light from the reference light and takes a tomographic image of the eye to be examined.

It is the figure which showed the external view of the fundus imaging apparatus of this embodiment. It is the schematic diagram which showed the optical system of the fundus imaging apparatus of this embodiment. It is the block diagram which showed the control system of the fundus imaging apparatus of this embodiment. It is a figure explaining the compensation area | region and effective area | region of a wavefront sensor. It is a figure explaining the specific example of the index pattern image and effective area on the compensation possible area | region of a wavefront sensor. It is the figure which showed the aberration correction screen displayed on the screen of a monitor. It is a flowchart explaining the control operation | movement until it acquires the favorable fundus image of the state by which the wavefront aberration was correct | amended. It is a figure explaining the method to detect a pupil diameter.

DESCRIPTION OF SYMBOLS 1 Light source 10 Diopter correction part 15 Scan part 56 Light receiving element 72 Wavefront compensation device 73 Wavefront sensor 76 Light source 70 Monitor 80 Control part 81 Memory | storage part 100 Fundus imaging optical system 110 Wavefront aberration detection optical system 200 2nd imaging | photography unit 300 Tracking unit 400 Deflection unit 500 Imaging unit 700 Anterior segment observation unit

Claims (7)

A fundus imaging optical system that receives reflected light from the fundus of the subject's eye and captures a fundus image;
A wavefront compensation device that is disposed in the optical path of the fundus imaging optical system and that controls the wavefront of incident light to compensate the wavefront aberration of the eye to be examined;
A wavefront aberration detection optical system that projects measurement light toward the fundus of the subject's eye and detects reflected light from the fundus by a wavefront sensor;
Control means for acquiring pupil information of the eye to be examined and changing the size of an effective region in which aberration correction control is effective by controlling the wavefront compensation device according to the acquired pupil information;
A fundus imaging apparatus with wavefront compensation, comprising: A light receiving means for receiving reflected light from the eye to be examined, and a detecting means for detecting pupil information of the eye to be examined based on a light reception signal from the light receiving means,
The fundus imaging apparatus with wavefront compensation according to claim 1, wherein the control means acquires pupil information of the eye to be examined from the detection means. An anterior ocular segment observation unit that captures an anterior segment image of the eye to be examined;
The detection means is a detection means for extracting a pupil outer edge from an anterior eye image captured by the anterior eye observation unit by image processing and detecting a pupil diameter,
The fundus imaging apparatus with wavefront compensation according to claim 2, wherein the control unit changes the size of the effective region in accordance with a pupil diameter detected by the detection unit. The detection means is a detection means for detecting an outer edge portion of a light receiving region of the index pattern image by the wavefront sensor,
The fundus imaging apparatus with wavefront compensation according to claim 2, wherein the control unit changes the size of the effective region according to the size of the outer edge detected by the detection unit. The detection means calculates the center position of the light receiving region of the index pattern image from the detected outer edge, detects the diameter from the center coordinate to the outer edge,
The fundus imaging apparatus with wavefront compensation according to claim 2, wherein the control unit changes the size of the effective region in accordance with a diameter from the central coordinate to the outer edge detected by the detection unit.   The said control means acquires the pupil information of a to-be-tested eye, and performs the 1st feedback control which changes the size of the said effective area | region according to the change of the acquired pupil information, Wavefront compensation attached | subject of Claims 1-5 Fundus photographing device.   The control means includes control means for detecting a wavefront aberration of a subject's eye based on a detection signal from the wavefront sensor and performing second feedback control for controlling the wavefront compensation device based on the detection result. Item 9. A fundus photographing apparatus with wavefront compensation.