JP2016067764A - Fundus photographing apparatus with wavefront compensation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fundus photographing apparatus with wavefront compensation for surely and easily photographing a fundus image in a state where wavefront aberration is corrected.SOLUTION: A photographing apparatus includes a fundus imaging optical system 100 for receiving reflected light from a fundus to be examined to image a fundus image, a wavefront compensation device 72 arranged in the optical path of the fundus imaging optical system 100 to control a wavefront of incident light and compensate wavefront aberration of an eye E to be examined, and a wavefront sensor 73 for measuring the wavefront aberration of the eye E to be examined on the basis of reflected light from the fundus. A control part of the photographing apparatus performs control for driving the wavefront compensation device 72 on the basis of wavefront aberration to be measured by using the wavefront sensor 73. Further, the control part calculates a result of aberration correction by the wavefront compensation device 72 on the basis of a measurement result by the wavefront sensor 73, and changes an effective region where aberration correction control is effective in the wavefront compensation device 72 to a wavefront measurement area where the wavefront sensor 73 measures wavefront aberration in accordance with a change in the result of the aberration correction.SELECTED DRAWING: Figure 2

Description

  The present disclosure 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 is known that detects wavefront aberration of an eye using a wavefront sensor such as a Shack-Hartmann sensor, controls a wavefront compensation device based on the detection result, and takes a fundus image after wavefront compensation at a cellular level ( For example, see Patent Document 1). Such an apparatus repeatedly performs detection of wavefront aberration of the eye and wavefront compensation control based on the detection result.

JP 2013-52047 A

  The wavefront compensation control needs to be performed based on the result of wavefront aberration detection with sufficient reliability. For example, when the wavefront aberration detection range includes a turbid portion of a translucent body such as a cataract, the wavefront aberration of the eye to be examined cannot be accurately detected by the wavefront sensor. In this case, the wavefront compensation device is controlled based on an inaccurate detection result. As a result, the wavefront aberration is not properly corrected, and it may be difficult to capture a good fundus image.

  In view of the above problems, it is an object of the present disclosure to provide a fundus imaging apparatus with wavefront compensation that can easily capture a fundus image in a state in which wavefront aberration is corrected.

  In order to solve the above problems, a fundus imaging apparatus with wavefront compensation according to the present disclosure includes a fundus imaging optical system that receives reflected light from the fundus of a subject's eye and captures a fundus image, and an optical path of the fundus imaging optical system. A wavefront compensation device that is disposed and controls the wavefront aberration of the subject eye by controlling the wavefront of the incident light; and wavefront aberration measuring means for measuring the wavefront aberration of the subject eye based on the reflected light from the fundus; Wavefront compensation device control means for driving the wavefront compensation device based on the wavefront aberration, and a result of aberration correction by the wavefront compensation device is calculated based on a measurement result of the wavefront aberration measurement means, and the wavefront aberration measurement means The effective area where the aberration correction control is effective in the wavefront compensation device is changed according to the change in the aberration correction result with respect to the wavefront measurement area where the wavefront aberration is measured by And a control unit that, the.

  According to the fundus photographing apparatus with wavefront compensation of the present disclosure, there is an effect that it is easy to reliably photograph a fundus image in a state where the wavefront aberration is corrected.

It is the figure which showed the external view of the imaging device 1 of this embodiment. 2 is a schematic diagram illustrating an optical system of the photographing apparatus 1. FIG. It is the block diagram which showed the control system of the imaging device 1 of this embodiment. It is the figure which showed the compensation possible area | region and effective area | region on a wavefront compensation device. It is a figure explaining the example of an index pattern image and an effective field. It is the figure which showed the aberration correction screen displayed on the screen of a monitor. 5 is a flowchart illustrating main processing executed by a control unit 800. It is a figure explaining the specific example of a change of an effective area | region. It is a figure explaining the case where the change of an effective area is performed by the displacement of the setting position of an effective area. It is a figure explaining the case where the change of an effective area is performed by the change of the shape of an effective area.

  Hereinafter, exemplary embodiments of the present disclosure will be described with reference to the drawings. The imaging apparatus 1 is a fundus imaging apparatus with wavefront aberration compensation that captures a fundus image of the eye to be examined while correcting the wavefront aberration of the eye to be examined.

  First, a schematic configuration of the photographing apparatus 1 will be described with reference to FIG. The photographing apparatus 1 includes a base 510, a face support unit 600, and a photographing 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 and right direction (X direction), the up and down direction (Y direction), and the front and rear direction (Z direction) with respect to the base of the face indicating unit 600 by operation of a chin rest driving means (not shown).

  Next, the optical system of the photographing apparatus 1 will be described with reference to FIG. The imaging apparatus 1 of the present embodiment includes 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 20, 72, and a second imaging unit 200. A tracking unit (position detection unit) 300 and an anterior ocular segment observation unit 700.

  The fundus imaging optical system 100 projects laser light (illumination light) on the eye E and receives reflected light from the fundus of the laser light to capture a fundus image of the eye E. The fundus of the eye E is photographed by the fundus imaging optical system 100 with high resolution (high resolution) and high magnification. As described below, the fundus imaging optical system 100 may have a configuration of a scanning laser ophthalmoscope using a confocal optical system, for example. The fundus imaging optical system 100 includes a first illumination optical system 100a and a first imaging optical system 100b. In the present embodiment, the aberration compensation units 20 and 72 are arranged in the fundus imaging optical system 100 in order to correct the aberration of the eye to be examined. The aberration compensation unit includes a diopter correction unit 20 for correcting low-order aberrations (diopter: for example, spherical power) of the eye to be examined and high-order aberration compensation for correcting high-order aberrations of the eye to be examined. Part (wavefront compensation device) 72.

  The first illumination optical system 100a illuminates the fundus two-dimensionally by irradiating the eye E with laser light and scanning the laser light on the fundus. The first illumination optical system 100a includes a light source 11, a lens 12, a polarization beam splitter (PBS) 14, a beam splitter (BS) 71, a concave mirror 16, in an optical path from the light source 11 (first light source) to the fundus. Concave mirror 17, flat mirror 18, aberration compensation unit 72 (wavefront compensation device 72), beam splitter (BS) 75, concave mirror 21, concave mirror 22, scanning unit 25, concave mirror 26, concave mirror 27, flat mirror 31, Lens 32, plane mirror 33, aberration compensation unit 20 (diopter correction unit 20), plane mirror 35, concave mirror 36, deflection unit 400, dichroic mirror 90, concave mirror 41, plane mirror 42, plane mirror 43, and concave surface A mirror 45.

  The light source 11 emits laser light. In the present embodiment, the laser light has a near-infrared wavelength that is difficult to be visually recognized by the eye to be examined. For example, in the present embodiment, the light source 11 is an SLD (Super Luminescent Diode) having a wavelength of 840 nm. The light source 11 may be any light source that emits spot light having a high convergence property, and may be, for example, a semiconductor laser.

  The laser light emitted from the light source 11 is converted into parallel light by the lens 12 and then enters the wavefront compensation device 72 via the PBS 14, BS 71, concave mirrors 16 and 17, and the flat mirror 18. In the present embodiment, the laser light passes through the PBS 14 and becomes a light beam having only an S-polarized component. The wavefront compensation device 72 corrects higher-order aberrations of the eye to be examined by controlling the wavefront of the incident light. The detailed configuration of the wavefront compensation device 72 will be described later. In the present embodiment, the laser beam is guided from the wavefront compensation device 72 to the BS 75, reflected by the concave mirror 21 and the concave mirror 22, and travels toward the scanning unit 25.

  In the present embodiment, the scanning unit 25 is used together with the deflecting unit 400 in order to scan laser light two-dimensionally on the fundus. The scanning unit 25 is a resonant mirror used for main scanning of laser light. The laser light is scanned in the X direction on the fundus by the scanning unit 25.

  The light that has passed through the scanning unit 25 enters the diopter correction unit 20 via the concave mirrors 26 and 27, the plane mirror 31, the lens 32, and the plane mirror 33.

  The diopter correction unit 20 is a unit for performing diopter correction. The diopter correction unit 20 includes a pair of lenses and plane mirrors in addition to the drive unit 20a. The optical path length is adjusted by moving the plane mirror and lens of the diopter correction unit 20 in a predetermined direction by the drive unit 20a. As a result, the diopter error of the eye E is corrected.

  The illumination light guided from the diopter correction unit 20 to the plane mirror 35 is reflected by the concave mirror 36 and travels toward the deflection unit 400.

  The deflection unit 400 scans the laser light emitted from the light source 11 in the vertical direction (Y direction) on the fundus. Furthermore, the deflecting unit 400 is also used to move the scanning range of the laser light on the fundus. For example, in the present embodiment, the deflecting unit 400 may include two optical scanners (specifically, an X galvanometer mirror and a Y galvanometer mirror) having different directions of deflecting laser light.

  The light that has passed through the deflecting unit 400 is guided into the pupil of the eye E through the dichroic mirror 90, the concave mirror 41, the plane mirrors 42 and 43, and the concave mirror 45. The laser light is collected on the fundus of the eye E. As described above, the laser beam is two-dimensionally scanned on the fundus by the operations of the scanning unit 25 and the deflecting unit 400.

  Further, the dichroic mirror 90 has a characteristic of transmitting light beams from the second photographing unit 200 and tracking unit 300 described later and reflecting light beams from the light source 11 and the light source 76 described later. Note that the emission ends of the light sources 11 and 76 and the fundus of the eye E are conjugate. In this way, the first illumination optical system 100a is formed.

  Next, the first photographing optical system 100b will be described. The first imaging optical system 100 b receives the reflected light of the laser light irradiated on the fundus by the light receiving element 56. The imaging apparatus 1 acquires a first fundus image (in this embodiment, an AO-SLO image) based on a signal from the light receiving element 56. The first imaging optical system 100b shares the optical path from the eye E to the BS 71 with the first illumination optical system 100a. The first imaging optical system 100 includes elements arranged in the reflection side optical path of the BS 71, that is, 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). Further, the pinhole plate 54 is placed at a position conjugate with the fundus.

  The fundus reflection light of the laser light from the light source 11 traces the first illumination optical system 100 a in the reverse direction, is reflected by the BS 71 and the flat 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. A part of the illumination light is reflected on the cornea, but most of the illumination light is removed by the pinhole plate 54. Therefore, the light receiving element 56 can receive the reflected light from the fundus while suppressing the influence of corneal reflection.

  The first fundus image is acquired by processing the light reception signal of the light receiving element 56 by an image processing unit (for example, the control unit 800). In this embodiment, a fundus image of one frame is formed by main scanning of the scanning unit 25 and sub-scanning of a Y-scan galvanometer mirror provided in the deflection unit 400. Note that the deflection angle (swing angle) of the mirror in the scanning unit 25 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, when the reflection angle of the X-scanning galvanometer mirror and the Y-scanning galvanometer mirror provided in the deflection unit 400 is moved larger than the imaging field angle of the first fundus image, the first fundus image is captured on the fundus. The position (that is, the scanning range of the laser beam) is changed.

  The second photographing unit 200 is a unit for obtaining a fundus image (second fundus image) having a wider angle of view than the angle of view of the first photographing unit 100. The second fundus image is used, for example, as an image for position designation and position confirmation for obtaining the first fundus image. The second imaging unit 200 of the present embodiment preferably has a configuration capable of acquiring and observing a 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). For example, as the second imaging unit 200, an observation / imaging optical system of an existing fundus camera and an optical system and a control system of a scanning laser ophthalmoscope (SLO) may be used.

  The tracking unit 300 detects a temporal change in positional deviation due to fixation eye movement of the eye E and obtains movement position information. The tracking unit 300 sends the light reception result obtained at the start of tracking as reference information to the control unit 800, and then sequentially transmits the light reception result (light reception information) obtained for each scan to the control unit 800. The control unit 800 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 800 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 subject eye E moves slightly, the movement of the deflection unit 400 is performed, and thus the movement of the fundus image displayed on the monitor 850 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 segment observation unit 700 is a unit that illuminates the anterior segment of the eye E with visible light and captures a front image of the anterior segment. An image captured by the anterior segment observation unit 700 is output to the monitor 850. The anterior ocular segment image acquired by the anterior ocular segment observation unit 700 is used for alignment between the imaging unit 500 and the eye E to be examined. 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 aberration detection optical system 110 will be described. The aberration detection optical system 110 includes a wavefront sensor 73. The aberration detection optical system 110 projects measurement light onto the fundus of the eye E, and receives (detects) the fundus reflection light of the measurement light as an index pattern image with the wavefront sensor 73. The aberration detection optical system 110 has a part of optical elements on the optical path of the first illumination optical system 100a and the first photographing optical system 100b (in the present embodiment, on the common optical path), and the optical paths of the optical systems 100a and 100b. Some are shared. That is, the aberration detection optical system 110 of the present embodiment shares the BS 71 to the concave mirror 45 arranged on the optical path of the optical systems 100a and 100b with the optical systems 100a and 100b. Further, the aberration detection optical system 110 includes a light source 76, a lens 77, PBS 78, BS 75, BS 71, a dichroic mirror 86, a PBS 85, a lens 84, a plane mirror 83, and a lens 82.

  The light source 76 is used for detecting the aberration of the eye E. In the present embodiment, the light source 76 emits light having a wavelength different from that of the light source 11. As an example, in this embodiment, a laser diode that emits laser light having a wavelength of 780 nm is used as the light source 76 as measurement light. The measurement light emitted from the light source 76 is converted into a parallel light beam by the lens 77 and then incident on the PBS 78.

  The PBS 78 is an example of first polarization means provided in the wavefront compensation unit. The PBS 78 polarizes the light emitted from the light source 76 in a predetermined direction. More specifically, the PBS 78 is polarized in a direction (ie, P-polarized light) orthogonal to the polarization direction (ie, S-polarized light) of the PBS 14. The light that has passed through the PBS 78 is reflected by the BS 75 and guided to the optical path of the first illumination optical system 100a. As a result, the measurement light is condensed on the fundus of the eye E through the optical path of the first illumination optical system 100a.

  The measurement light is reflected at the condensing position of the fundus (for example, the retina surface). The fundus reflection light of the measurement light follows the optical path of the first illumination optical system 100a (that is, the optical path of the first photographing optical system 100b) in the opposite direction to that during projection. On the way, the measurement light is reflected by the wavefront compensation device 72. Thereafter, the measurement light is reflected by the BS 71, thereby deviating from the optical path of the first illumination optical system 100a. Thereafter, the measurement light is reflected by the dichroic mirror 86 and guided to the wavefront sensor 73 through the PBS 85, the lens 84, the plane mirror 83, and the lens 82.

  The PBS 85 is a second polarization unit provided in the wavefront compensation unit. The PBS 85 is used to guide light to the wavefront sensor 73 by transmitting light polarized in one direction (here, S-polarized light) out of the light irradiated to the eye E from the light source 76. The The PBS 85 blocks a component polarized in a direction orthogonal to the transmitted component (P-polarized light). The dichroic mirror 86 has a characteristic of transmitting light (840 nm) having the wavelength of the light source 11 and reflecting light (780 nm) having the wavelength of the light source 76 for detecting aberration. Therefore, the wavefront sensor 73 detects light having an S-polarized component from the fundus reflection light of the measurement light. In this way, light reflected by the cornea and the optical element is suppressed from being detected by the wavefront sensor 73.

  The wavefront sensor 73 receives fundus reflection light of measurement light for aberration measurement in order to detect wavefront aberration of the eye E. As the wavefront sensor 73, an element that can detect wavefront aberration including low-order aberration and high-order aberration (more specifically, a Hartmann Shack detector, a wavefront curvature sensor that detects a change in light intensity, and the like) is used. May be. In the present embodiment, the wavefront sensor 73 includes, for example, a microlens array composed of a number of microlenses, a two-dimensional imaging element 73a (or a two-dimensional light receiving element) for receiving a light beam that has passed through the microlens array, Have The microlens array of the wavefront sensor 73 is disposed at a position substantially conjugate with the pupil of the eye E to be examined. Further, the imaging surface (light receiving surface) of the two-dimensional imaging element 73a is disposed at a position substantially conjugate with the fundus of the eye E to be examined.

  An index pattern image 61 (Hartmann image in this embodiment) is formed on the imaging surface of the two-dimensional imaging element 73a by the light beam that has passed through the microlens array (not shown). Therefore, the fundus reflection light passes through the microlens array and is received by the two-dimensional imaging element 73a, thereby being imaged as a Hartmann image (dot pattern image). In the present embodiment, the aberration information of the eye to be examined is acquired from the Hartmann image, and the wavefront compensation device 72 is controlled based on the aberration information. Details of the Hartmann image will be described later.

  The wavefront compensation device 72 is disposed in the optical path of the fundus imaging optical system 100, and compensates the wavefront aberration of the eye E by controlling the wavefront of the incident light. In the present embodiment, a liquid crystal spatial light modulator may be used for the wavefront compensation device 72. As an example, a description will be given below assuming that a reflective LCOS (Liquid Crystal On Silicon) or the like is used. In this case, the wavefront compensation device 72 has predetermined laser light (S-polarized light) from the light source 11, fundus reflected light (S-polarized light) of the laser light, reflected light (S-polarized component) of wavefront aberration detection light, and the like. Are arranged in a direction capable of correcting 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. In the present embodiment, the reflection surface of the wavefront compensation device 72 is arranged at a position that is substantially conjugate with the pupil of the eye to be examined.

  In the wavefront compensation device 72 of the present embodiment, the alignment direction of the liquid crystal molecules in the liquid crystal layer is substantially parallel to the polarization plane of incident reflected light. The predetermined plane on which the liquid crystal molecules rotate according to the change in the voltage applied to the liquid crystal layer includes the incident optical axis and the reflected optical axis of the fundus reflection light with respect to the wavefront compensation device 72, and the mirror layer of the wavefront compensation device 72. And a plane that includes the normal line.

  In this embodiment, the wavefront compensation device 72 is a liquid crystal modulation element, and in particular, a reflective LCOS or the like is used, but the present invention is not limited to this. Other reflective wavefront compensation devices may be used. For example, a deformable mirror that is a form of MEMS (Micro Electro Mechanical Systems) may be used. Further, a transmissive wavefront compensation device may be used instead of the reflective wavefront compensation device. In the transmission type device, the wavefront aberration is compensated by transmitting the reflected light from the fundus.

  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 also serve 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, with reference to FIG. 3, a control system of the photographing apparatus 1 in the present embodiment will be described. The photographing apparatus 1 has a control unit 800. The control unit 800 is a processor (for example, a CPU) that controls the entire apparatus of the photographing apparatus 1. In the present embodiment, a storage unit 801, an operation unit 802, an image processing unit 803, and a monitor 850 are electrically connected to the control unit 800. The control unit 800 includes a light source 11, a drive unit 10a, a scanning unit 15, a light receiving element 56, a wavefront compensation device 72, a wavefront sensor 73, a light source 76, a second imaging unit 200, a tracking unit 300, a deflection unit 400, Are electrically connected.

  The storage unit 801 stores various control programs and fixed data. Further, the storage unit 801 may store an image captured by the imaging device 1, temporary data, and the like.

  The control unit 800 controls each member described above such as the first imaging unit 100 based on the operation signal output from the operation unit 802. The operation unit 802 is connected to a mouse or the like (not shown) as an operation member operated by the examiner.

  The image processing unit 803 forms, on the monitor 850, images of the fundus oculi having different angles of view, that is, a first fundus image and a second fundus image, based on signals received by the light receiving element 56 and the second imaging unit 200.

  The monitor 850 may be a display monitor mounted on the photographing apparatus 1 or a general-purpose display monitor that is separate from the photographing apparatus 1. Moreover, the structure in which these were used together may be sufficient. The monitor 850 can display fundus images (first fundus image and second fundus image) captured by the imaging apparatus 1 as moving images and still images.

  The control of the wavefront compensation device 72 by the controller 800 is executed based on the wavefront aberration detected by the wavefront sensor 73. In the present embodiment, feedback control of the wavefront compensation device 72 based on the detection signal from the wavefront sensor 73 is performed. By controlling the wavefront compensation device 72, the high-order aberrations of the laser light emitted from the light source 11 and the fundus reflection light of the laser light are removed together with the S-polarized component of the reflected light of the light source 76. In this way, the aberrations of the laser light emitted from the light source 11 and the fundus reflection light of the laser light are removed. As a result, the imaging apparatus 1 acquires a high-resolution first fundus image from which higher-order aberrations of the eye E have been removed (wavefront compensated). At this time, the low-order aberration is corrected by the diopter correction unit 10.

  Here, an overview of wavefront compensation control using the wavefront compensation device 72 and the wavefront sensor 73 will be described with reference to FIGS. As shown in FIG. 4, the wavefront compensation device 72 can control the wavefront of incident light in a range where the compensable region 40 is formed. In FIG. 4, a region 41 on the compensable region 40 indicates an effective region on the wavefront compensation device 72. The effective area 41 is an area where aberration correction based on a detection signal from the wavefront sensor 73 is effective. In the present embodiment, the compensable region 40 has a size of 16 × 12 mm. As an example, the effective area 41 shown in FIG. 4 has a size of φ8.64 mm. Since the compensable region 40 has a sufficient size compared to the effective region 41, the effective region 41 can be changed within the compensable region 40 in at least one of position, size, and shape (details will be described later). To do). In the wavefront compensation device 72, the effective region 41 may be limited to a light beam in a certain region (for example, a 6 mm diameter region on the pupil) of the entire incident light. In this case, the wavefront compensation device 72 of the present embodiment also reflects the light incident on the outside of the effective region 41 toward the light receiving element 54 in the same manner as the light incident on the effective region 41, but enters the outside. The wavefront of the emitted light cannot be compensated.

  On the other hand, as shown in FIG. 5, as described above, the Hartmann image 61 is captured by the two-dimensional imaging element 73 a of the wavefront sensor 73. The Hartmann image 61 shows a group of a plurality of point images 61 a received on the wavefront sensor 73. A light beam that has passed through one lens array forms one point image 61. In the area where the point image 61a is detected by the wavefront sensor 73, aberration detection is possible.

  Further, in FIG. 5, an effective region in which aberration correction is effective by the wavefront compensation device 72 (that is, the circle 62 corresponds to the outer periphery of the effective region 41) is virtually indicated by a circle 62. In the present embodiment, the wavefront aberration used for controlling the wavefront compensation device 72 is detected from the Hartmann image 61 included in the circle 62. The positional relationship between the circle 62 (effective region 41) and the Hartmann image 61 can be adjusted by displacing the position of the effective region 41 on the wavefront compensation device 72, for example. Further, the positional relationship between the circle 62 and the Hartmann image 61 is also displaced according to the positional relationship between the imaging optical axis and the pupil position of the eye to be examined. In the present embodiment, the Hartmann image 61 and the circle 62 are displayed on the monitor 850 as a part of the aberration correction screen 60.

  Here, the aberration correction screen 60 will be described with reference to FIG. The aberration correction screen 60 is generated based on signals from the light receiving element 56, the wavefront sensor 73, and the like. The aberration correction screen 60 includes a Hartmann image display screen 64, an aberration correction graphic display screen 65, and a cell display screen 66.

  On the Hartmann image display screen 64, the Hartmann image 61 and the circle 62 are shown superimposed on the same plane (for example, on the light receiving surface of the wavefront sensor 73). The position and size of the circle 62 are set by the control unit 800. For example, the control unit 800 sets a circle 62 in an area corresponding to the position and size of the effective area 41 on the wavefront compensation device 72. Information defining the outer circumference, region, etc. of the circle 62 on the Hartmann image display screen 64 can be obtained in advance from the result of calibration or simulation, for example.

  In FIG. 6, the mark 62 a positioned at the center of the circle 62 is a graphic indicating the center position of the effective area on the wavefront sensor 73. On the aberration correction graphic display screen 65, an aberration correction graphic 65a indicating the correction degree (residual aberration) of the aberration correction is displayed.

  The aberration correction graphic 65a represents the distribution of wavefront aberration of the light beam incident on the wavefront sensor 73 by contour lines. The aberration correction graphic is generated when the control unit 800 processes the Hartmann image 61 captured through the wavefront sensor 73, for example. As a specific example, it may be generated using the RMS value (average square root) of the wavefront aberration for each position obtained as the processing result of the Hartmann image 61. In this case, it may be evaluated that the wavefront aberration is larger as the contour lines in the aberration correction graphic are denser.

  The cell display screen 66 displays a cell image image 66a of the fundus that is actually photographed.

  Here, the aberration correction is performed based on the aberration detection result by the wavefront sensor 73. That is, in the region where the Hartmann image 61 is formed inside the circle 62, the wavefront state can be detected (see FIG. 5B). In the region S where the Hartmann image 61 is not formed inside the circle 62, the wavefront state is not detected. Here, when part of the wavefront data is missing (see, for example, FIG. 6A), information on the entire wavefront cannot be obtained, and therefore the wavefront aberration in the effective region is not properly measured. Therefore, even if the aberration correction is executed, the aberration is not properly removed as shown in the aberration correction graphic 65 of FIG. In this case, the cell image 66a is not displayed well. In addition, it is difficult to take a good image of the cell image 66a.

  The operation of the present apparatus having the above configuration will be described with reference to the flowchart shown in FIG.

  When the power of the photographing apparatus 1 is turned on, the main process is executed by the control unit 800 according to the control program stored in the storage unit 801. The photographing apparatus 1 is operated according to the main process.

  First, the imaging unit 500 is aligned with the eye to be examined (S1). For example, the control unit 800 acquires a real-time anterior segment image using the anterior segment observation unit 700 and causes the monitor 850 to display the front image. The examiner manually or automatically adjusts the position of the chin rest 610 while observing the anterior ocular segment image on the monitor 850 to perform rough alignment. Further, the examiner instructs the subject to fixate a fixation target (not shown).

  In this embodiment, when the measurement switch is operated by the examiner after the rough alignment is completed, acquisition of the fundus image using the first imaging unit 100 and the second imaging unit 200 is started (S2).

  In this case, first, the diopter correction of each of the photographing units 100 and 200 may be performed by the control unit 800 (S3). For example, diopter correction in the first photographing unit 100 is performed using the diopter correction unit 10.

  Further, the photographing position on the fundus (that is, the photographing position of the AOSLO image) by the first photographing unit 100 may be set (S4). In this case, the imaging position may be set to a position desired by the examiner. For example, the control unit 800 displays a wide-area second fundus image acquired by the second imaging unit 200 on the monitor 850 and displays an enlarged image (that is, the first fundus image) in the second fundus image. A location to be acquired is received via the operation unit 802. The control unit 800 sets the shooting position of the first fundus image by driving the deflection unit 400 based on the signal from the operation unit 802.

  Next, the control unit 800 performs initial setting of the effective region 41 in which the aberration correction is effective in the wavefront compensation device 72 (S5). In the initial setting, for example, at least one of the position, size (diameter), and shape of the effective area 41 may be set. Here, it is assumed that the effective area 41 is set at a predetermined position, size, and shape. For example, it is assumed that a circular area is set at a predetermined position of the wavefront compensation device 72 with a maximum settable size (for example, φ6 mm). The inner area of the circle is the effective area.

  The control unit 800 detects the Hartmann image 61 using the wavefront sensor 73 (S6). Next, the control unit 800 acquires deviation information between the light receiving area of the Hartmann image 61 and the effective area (S7). For example, the deviation information includes deviation information between the light receiving area (that is, the wavefront measurement area) of the Hartmann image 61 in the wavefront sensor 73 and the effective area (for example, circle 62) of the wavefront compensation device 72 set on the wavefront sensor 73. It may be.

  Next, the control unit 800 determines whether or not the wavefront measurement region satisfies the effective region (S8). More specifically, it is determined whether or not the region formed by the circle 62 is within the region formed by the Hartmann image outer periphery 61b. When the circle 62 is within the region formed by the Hartmann image outer periphery 61b, the wavefront measurement region satisfies the effective region (S8: Yes). In this case, the wavefront aberration is compensated by executing the steps after S10.

  On the other hand, if the region formed by the circle 62 does not fall within the region formed by the Hartmann image outer periphery 61b, it is determined that the wavefront measurement region does not satisfy the effective region (S8: No). In this case, the effective area changing process is executed by the control unit 800 (S9). Here, the effective area changing process in S <b> 9 may be, for example, a process of adjusting the relative position between the eye E and the imaging unit 500, or the set position of the effective area 41 on the wavefront compensation device 72. The process to change may be sufficient. For example, in the present embodiment, when the region formed by the circle 62 deviates from the region formed by the Hartmann image outer periphery 61b (for example, when part or all protrudes) (S9: No), the eye E and the imaging unit The relative position with respect to 500 is adjusted. The adjustment of the relative position between the eye E and the imaging unit 500 may be performed by adjusting the position of the chin rest 610 manually or automatically, for example. Further, if the imaging apparatus 1 includes a unit that moves the imaging unit 500 with respect to the eye E, the control unit 800 may move the imaging unit 500 so that the deviation information is within the allowable range. Good.

  In the present embodiment, after changing the effective area, each process of S6 to S8 is executed again. Therefore, the processing of S6 to S9 is repeated until it is determined that the wavefront measurement region satisfies the effective region (S8: Yes).

  In the process of S10, wavefront aberration is detected based on the signal from the wavefront sensor 73 (first wavefront aberration detection). For example, wavefront aberration is detected from a Hartmann image newly acquired in a state where the wavefront measurement region satisfies the effective region.

  Next, the control unit 800 controls the effective area 41 of the wavefront compensation device 72 based on the detection result of the wavefront aberration, and compensates for the wavefront aberration (S11). The control of the effective area 41 may be performed based on the aberration compensation amount calculated based on the detection result of the wavefront aberration, for example. As described above, the control unit 800 of the present embodiment performs feedback control that repeats aberration detection and wavefront compensation control (that is, aberration correction control) based on the result.

  For example, in the case of LCOS, compensation is performed in a loop process including detection of wavefront aberration by the wavefront sensor 73, calculation of an LCOS phase pattern based on the detection result, and application of a voltage to each pixel of the LCOS based on the calculation result. The phase pattern for use is feedback controlled. Accordingly, the refractive index of the LCOS liquid crystal layer is changed as needed based on the detection of the wavefront aberration, and the distortion of the wavefront of the fundus reflection light is corrected.

  In the case of a deformable mirror, a loop including wavefront aberration detection by the wavefront sensor 73, calculation of a mirror shape based on the detection result, and voltage application to each drive unit of the deformable mirror based on the calculation result. In the processing, the shape of the entire mirror is feedback controlled. Thereby, based on the detection of wavefront aberration, the shape of the entire mirror is changed as needed, and the distortion of the wavefront of the fundus reflection light is corrected.

  The above feedback control is reflected on the fundus moving image acquired via the fundus imaging optical system 100 in parallel with the compensation of the wavefront aberration. Therefore, when the wavefront of the fundus reflection light is appropriately compensated as a result of the feedback control, the blur of the fundus moving image is reduced.

  Next, the control unit 800 performs wavefront aberration detection (second wavefront aberration detection) based on the signal from the wavefront sensor 73 even after compensation of the wavefront aberration by the process of S11 (S12).

  As a result of the study by the present inventors, it is confirmed that the wavefront aberration detected by the wavefront sensor 73 may increase when the aberration correction control is executed under the condition that the reliability of wavefront detection is low. It was. That is, under conditions where the reliability of wavefront detection is low, the wavefront aberration (that is, residual aberration) measured after wavefront aberration compensation may be larger than before compensation. In the above phenomenon, for example, the turbidity K existing in the intermediate translucent body overlaps the effective region, and the wavefront data is lost due to the turbidity K (that is, the point image 61a in the Shack-Hartmann image 61) and the point image 61a. (That is, the received light intensity of fundus reflected light by the wavefront sensor 73) is reduced (see FIG. 8). In FIG. 8, for the sake of convenience, the turbidity K is superimposed on the Shack-Hartmann image 61.

  On the other hand, in the present embodiment, the control unit 800 changes the effective area of the wavefront compensation device 73 according to a change in the result of aberration correction by the wavefront compensation device 73. Here, as a result of the aberration correction, a residual aberration measurement result by the wavefront sensor 73 is used. For example, when the residual aberration detected using the wavefront sensor 73 increases with the execution of the aberration correction control, the control unit 800 changes the effective area. In the present embodiment, the effective region is maintained when the residual aberration decreases as the aberration correction control is executed.

  Note that the magnitude of the residual aberration may be detected (measured) as the above-described RMS value, for example. When the RMS value is used, for example, a value for the entire wavefront measurement region can be used. The magnitude of the residual aberration may be detected as at least one of the number of contour lines and the density (that is, PV value; Peak-Valley value) in the above-described aberration correction graphic 62a.

  Hereinafter, the operation content after S13 will be described more specifically. First, the first and second wavefront aberration detection results are compared, and it is determined whether or not the wavefront aberration (mainly residual aberration) has increased due to the wavefront compensation (S13). When it is determined that the wavefront aberration is not increased in the process of S13 (S13: No), it is considered that the wavefront compensation has been appropriately performed in the process of S11. In this case, a good fundus image (for example, fundus moving image) with high resolution is acquired via the fundus imaging optical system 100 and displayed on the monitor 850. In this case, the photographing operation is performed by the processing after S15 (details will be described later).

  On the other hand, in the process of S13, when it is determined that the wavefront aberration is increased by the wavefront compensation control (S13: Yes), it is considered that the wavefront compensation is not properly performed. In this case, the second effective area changing process (S14) is executed. Hereinafter, an example of the operation of changing the effective area in the process of S14 will be described.

  The process of changing the second effective area (S14) may be a process of changing the size (for example, the diameter) of the effective area 41. More specifically, as shown in FIG. 8, a process for reducing the size of the effective area 41 may be performed (FIG. 8 (a) → FIG. 8 (b)). In this case, the storage unit 801 may store diameter information indicating the diameter of the effective area that can be set. For example, in the present embodiment, based on the diameter information stored in the storage unit 801, the effective area can be set in a range of φ6.0 mm at the maximum and φ1.5 mm at the minimum on the pupil. As specific examples, φ6.0 mm, φ4.5 mm, φ3.0 mm, and φ1.5 mm can be set. In the process of S14, the control unit 800 changes the effective area to be smaller (more specifically, one step smaller) than the current effective area. Thereafter, the processing from S6 to S13 is executed again. Therefore, after the effective region is changed, wavefront compensation and wavefront aberration detection before and after the wavefront compensation are performed again. Then, it is determined whether or not the wavefront aberration is increased by the wavefront compensation. If the wavefront aberration increases, the effective area is further changed (S14), and the processes from S6 to S13 are repeated. That is, in the present embodiment, the size of the effective area is changed in the order of φ6.0 mm → φ4.5 mm → φ3.0 mm → φ1.5 mm.

  Note that the threshold value used in the comparison process of S13 may be set based on the wavefront aberration obtained in the most recent first wavefront aberration detection (S10). Further, the wavefront aberration obtained in the past first wavefront aberration detection (S10) including the latest and before may be set based on the smallest aberration.

  As shown in FIG. 8, the distribution in the effective area of the point image 61a affected by the turbidity (in this embodiment, the distribution in the inner area of the circle 62) is changed by changing the effective area (FIG. 8 ( a) → FIG. 8B). As described above, in the present embodiment, wavefront aberration is detected in the effective region. Therefore, the reliability of wavefront detection changes according to the change of the effective area. In this embodiment, until it is determined that the measured value of the wavefront aberration has not increased before and after the wavefront compensation based on the effective area after the change (that is, until it is determined that the residual aberration has not increased). The effective area is changed. As a result, the ophthalmologic apparatus 1 is guided to a state where the wavefront compensation is satisfactorily performed by so-called trial and error. Therefore, in the imaging device 1 of the present embodiment, it is possible to improve the certainty that appropriate wavefront compensation is performed even for the eye E to be examined whose opacity exists.

  In the present embodiment, the size of the effective area is set to be the largest in the initial setting, and the size of the effective area is gradually reduced until the wavefront compensation is appropriately performed. Therefore, it is easy to set the largest effective region within a range where the wavefront compensation is appropriately performed. Accordingly, it is easy to obtain a good fundus image with high resolution.

  As described above, the imaging apparatus 1 is likely to perform appropriate wavefront compensation for the eye E to be examined whose opacity includes turbidity. Therefore, in the photographing apparatus 1, a good fundus image with high resolution can be acquired more reliably.

  After it is determined that the wavefront aberration has not increased in the process of S13 after the effective area size is changed, the following photographing operation is performed by executing the processes after S15.

  The controller 800 determines whether or not an imaging trigger signal has been input (S15). When a shooting trigger signal is input (S15: Yes), image shooting is executed (S16). For example, the control unit 800 stores a fundus cell image moving image or a still image acquired at the trigger signal input timing in the storage unit 801. As described above, in the photographing apparatus 1, since appropriate wavefront compensation is performed, a good fundus image with high resolution is photographed.

  As mentioned above, although demonstrated based on embodiment, this indication is not limited to the said embodiment, A various deformation | transformation is possible.

  For example, in the above-described embodiment, the case has been described in which the effective area having the maximum settable size is set in the initial setting of the effective area, but the present invention is not necessarily limited thereto. For example, in the initial setting, an effective area having a minimum settable size may be set, or an effective area having an intermediate size may be set. In this case, when the change of the effective area based on the wavefront aberration before and after the wavefront compensation is performed by changing the size of the effective area, a process for increasing the size of the effective area may be performed. The enlargement of the size may be performed, for example, when the wavefront aberration is reduced before and after the wavefront compensation.

  Further, the diameter of the effective area set in the initial setting of the effective area may be a value corresponding to the individual difference of the eye E to be examined. For example, it may be a value set according to the pupil diameter of the eye E. In this case, for example, the control unit 80 acquires the pupil diameter data of the eye E using the anterior segment image acquired by the anterior segment observation unit 700. Further, the diameter of the effective area is set based on the pupil diameter data so that the diameter of the effective area on the pupil and the pupil diameter have the same length. For details, refer to, for example, JP 2013-52048 A.

  In the embodiment described above, the case where the effective area is changed based on the amount of aberration before and after wavefront compensation is performed by changing the size of the effective area has been described. However, the change of the effective region may be a change of at least one of the size, position, and shape (that is, the shape of the outer periphery) of the effective region.

  When the position of the effective area is changed, the effective area may be changed in a preset position or may be changed to an arbitrary position. When the position is set in advance, the position information of each position where the effective area is set is stored in advance in the storage unit 801. The position information may be, for example, coordinate information of the center position of the effective area, or relative coordinates based on the center of the Hartmann image. In the example of FIG. 9, coordinate information of the center of the Hartmann image and a plurality of locations (here, a total of 9 locations) around the center is prepared in advance. In this case, the control unit 80 may displace the effective area to a preset position every time the second effective area is changed. Note that the order of displacement of the effective area may be determined in advance. In the case of FIG. 9, FIG. 9 (a) → FIG. 9 (b) → FIG. 9 (c) → FIG. 9 (d) → FIG. 9 (e) → FIG. 9 (f) → FIG. h) The center position of the effective area is displaced in the order of FIG. 9 (i). Further, when the effective area is displaced to an arbitrary position, the effective area may be changed to a position instructed by the examiner via the operation unit 802.

  When the shape of the effective area is changed, the shape of the effective area may be changed by selecting one of a plurality of types of shape patterns prepared in advance. In this case, the shape pattern of the effective area may be stored in advance in the storage unit 801. For example, the outer periphery of the effective area may be changed to various geometric shapes such as a circle, an ellipse, and a polygon. Further, for example, the effective area of the wavefront compensation device 72 may be formed by a combination of several unit areas (9 divisions in FIG. 10) as shown in FIG. Each time the second effective area changing process is performed, the control unit 800 changes the combination of unit areas used as the effective area, thereby changing the shape of the effective area. The unit area is not limited to the mode shown in FIG. 10, and can be set to an arbitrary shape. For example, the unit region may be a ring-shaped region having an outer periphery formed by concentric circles.

  Moreover, when the shape of an effective area | region is changed, you may change to arbitrary shapes. When the shape is changed to an arbitrary shape, the effective area may be changed to a shape instructed by the examiner via the operation unit 802, or may be changed to a shape automatically set by the control unit 800. . In this case, for example, the effective area may be changed to a shape in which only a portion overlapping with turbidity is removed from a reference shape (for example, a circle).

  The control unit 80 is an image of the eye E (for example, a transillumination image, a three-dimensional cross-sectional image of the anterior eye part (for example, an image based on a Shine-Pluke image or an OCT image)) showing the turbid position of the transparent body May be displayed on the monitor 850 to allow the examiner to know the position of the turbidity of the transparent body.

  In addition, the change of the effective area as described above is based on an anterior eye image (for example, a transillumination image, an anterior eye 3D cross-sectional image, etc.) of the eye E including information on the turbid position of the transparent body. It may be done. For example, when the change of the effective area is automatically performed by the control unit 800, the control unit 80 identifies the turbid position by analyzing the anterior segment image, and avoids the identified turbid position (in more detail). The control unit 80 may change the effective area (so as to avoid a cloudy position in a range overlapping with the Hartmann image). In addition, for example, when an effective area after change is instructed by the examiner, by displaying the anterior ocular segment image on the monitor 850, the examiner previously grasped the position of the turbidity of the transparent body. In addition, the imaging apparatus 1 may receive an instruction from the examiner.

  In the above embodiment, the light beam diameter of the light for photographing the fundus image (that is, either the laser light from the light source 11 or the fundus reflected light of the laser light) is changed according to the size of the effective region. Also good. In this case, the wavefront may be compensated for the total luminous flux of the fundus reflection light. In that case, the fundus image in which the blur due to aberration is further reduced can be acquired by the photographing apparatus 1. In this case, the light beam diameter can be changed using, for example, a plurality of lenses and a mechanism for adjusting the distance between the lenses.

  In the above embodiment, the case where the wavefront aberration is calculated by analyzing the Hartmann image included in the effective region has been described. In this case, information on wavefront aberration (residual aberration) may be obtained based on the PSF (point spread function) of the eye to be examined. The PSF can be obtained from, for example, a Zernike coefficient calculated by analyzing a Hartmann image. As the magnitude of the PSF, a width (for example, a half width, a standard deviation, etc.) relating to a curve fitted to the intensity distribution of the PSF may be used. PSF can directly observe the state of blur. For example, even when the measurement accuracy is low due to the missing point image of the Hartmann image, the control unit 800 or the examiner can obtain information about the blur favorably from the PSF.

  In the above-described embodiment, the first effective area changing process and the second effective area changing process are described as processes having different contents. However, the processes having the same contents may be executed.

  In the above embodiment, the case where the wavefront sensor 73 is provided in the optical system of the ophthalmologic photographing apparatus 1 in order to measure the wavefront aberration of the eye E is not limited to this. What is necessary is just to have the structure which measures the wavefront aberration of an optometry based on the reflected light from a fundus. For example, a case where the wavefront aberration is measured using the Phase Diversity method is conceivable. This method performs image processing using an image obtained when a measurement light having a known wavefront aberration called Phase Diversity is intentionally applied to the target optical system (here, the eye to be examined). The wavefront aberration in the wavefront aberration of the optical system is estimated. Measurement light having Phase Diversity can be generated by controlling the wavefront compensation device 73 to a predetermined state, for example. Of course, it may be generated by other methods.

  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.

DESCRIPTION OF SYMBOLS 10 Diopter correction part 40 Compensable area | region 41 Effective area | region 72 Wavefront compensation device 73 Wavefront sensor 100 Fundus imaging optical system 110 Wavefront aberration detection optical system E Eye to be examined

Claims (5)

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 controls the wavefront aberration of the subject's eye by controlling the wavefront of incident light;
Wavefront aberration measuring means for measuring the wavefront aberration of the eye to be examined based on reflected light from the fundus;
Wavefront compensation device control means for driving the wavefront compensation device based on the wavefront aberration;
The result of aberration correction by the wavefront compensation device is calculated based on the measurement result of the wavefront aberration measuring means, and the wavefront compensation device is used for the wavefront measurement region in which the wavefront aberration is measured by the wavefront aberration measuring means. A fundus photographing apparatus with wavefront compensation, comprising: a control unit that changes the effective region in which aberration correction control is effective according to a change in the result of the aberration correction.   The effective area control means changes the effective area when the residual aberration measured by the wavefront aberration measuring means as a result of the aberration correction increases with the execution of the aberration correction control, and changes the residual aberration. 2. The fundus imaging apparatus with wavefront compensation according to claim 1, wherein the effective area is maintained when the aberration decreases with execution of the aberration correction control.   3. The wavefront compensation according to claim 2, wherein the effective area control unit changes the effective area in accordance with a change in one of an RMS value of the residual aberration and a PV value of the residual aberration in the entire wavefront measurement area. Fundus photography device   4. The wavefront according to claim 1, wherein the effective area control unit changes the effective area by changing at least one of a size, a position, and a shape of the effective area. 5. A fundus imaging device with compensation.   The fundus imaging apparatus with wavefront compensation according to claim 4, wherein the control means changes the effective area by reducing the size of the effective area.

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