JP2020110252A - Scanning ophthalmologic imaging device and ophthalmologic imaging program - Google Patents

Abstract

To provide a scanning ophthalmologic imaging device capable of acquiring a fine image, and an ophthalmologic imaging program.SOLUTION: A scanning ophthalmologic imaging device comprises: a light source for emitting photographic light; a projection optical system for projecting the photographic light emitted from the light source to a subject's eye; a reception optical system for receiving a reflectance of the photographic light reflected from the subject's eye; scanning means for scanning the photographic light projected by the projection optical system onto the subject's eye; a detector for detecting the reflectance received by the reception optical system at a detection period corresponding to scanning of the scanning means; and control means for changing an amount of the photographic light in synchronization with the detection period.SELECTED DRAWING: Figure 3

Description

The present disclosure relates to a scanning ophthalmologic imaging apparatus that captures an image of an eye by scanning light, and an ophthalmologic imaging program.

A scanning ophthalmologic imaging apparatus (for example, a scanning laser ophthalmoscope (SLO) for scanning laser light) that scans an eye by scanning light with a scanning unit (scanner or the like) is known (Patent Document 1). ). The scanning laser ophthalmoscope obtains an image of the eye to be inspected by scanning a spot, line, or slit-shaped light beam and receiving light from the eye to be inspected.

JP, 2017-46939, A

By the way, in the scanning type ophthalmologic imaging apparatus, when the imaging is performed while scanning the imaging light with respect to the eye, blurring may occur in the image. In order to suppress this, it is conceivable to stop the driving of the scanning unit only during the exposure of each frame, but since the scanning unit repeatedly drives and stops, acceleration is generated, which complicates the control of the scanning unit. ..

In view of the problems of the related art, the present disclosure has a technical problem to provide a scanning ophthalmologic imaging apparatus and an ophthalmologic imaging program that can obtain a good image.

In order to solve the above problems, the present disclosure is characterized by having the following configurations.

(1) A scanning ophthalmologic imaging apparatus, which is a light source that emits image-taking light, a projection optical system that projects the image-taking light emitted from the light source onto an eye to be examined, and the image-taking light reflected from the eye to be examined. A light receiving optical system for receiving reflected light, scanning means for scanning the photographing light projected by the light projecting optical system with respect to the eye to be inspected, and the reflected light received by the light receiving optical system, It is characterized by comprising a detector for detecting at a detection cycle according to the scanning of the scanning means, and a control means for changing the light quantity of the photographing light in synchronization with the detection cycle.
(2) An ophthalmologic imaging program executed by a scanning ophthalmologic imaging apparatus, which is executed by a processor of the scanning ophthalmologic imaging apparatus to project imaging light emitted from a light source onto an eye to be examined. A step, a light receiving step of receiving reflected light of the photographing light reflected from the eye to be examined, a scanning step of scanning the eye to be examined with the photographing light projected in the light projecting step, and the light receiving step A detection step of detecting the received reflected light at a detection cycle corresponding to scanning in the scanning step; a control step of controlling the light source, and changing the light amount of the photographing light in synchronization with the detection cycle; Is executed by the scanning ophthalmologic imaging apparatus.

According to the present disclosure, a good image of the subject's eye can be obtained.

It is the schematic which showed an example of the imaging optical system of a scanning ophthalmologic imaging device. It is a figure for explaining a photography method. It is a figure explaining operation|movement of a scanning part, exposure timing, and the light quantity of imaging|photography light. It is a figure explaining the example different from a present Example. It is a figure for explaining how to change a light quantity. It is a figure for demonstrating the modification of a present Example. It is a figure showing about scanning of photography light.

<Embodiment>
Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings. The scanning ophthalmologic imaging apparatus (for example, the scanning ophthalmologic imaging apparatus 1) of the present embodiment includes a light source (for example, the light source 2), a projection optical system (for example, the projection optical system 10), and a light receiving optical system (for example, The light receiving optical system 40), the scanning unit (for example, the scanning unit 20), the detector (for example, the detector 30), and the control unit (for example, the control unit 60) are mainly provided. The light source emits shooting light. The light projecting optical system projects the photographing light emitted from the light source onto the eye to be examined. The light receiving optical system receives the reflected light of the photographing light reflected from the subject's eye. The scanning unit scans the subject's eye with the imaging light projected by the projection optical system. The detector detects the reflected light received by the light receiving optical system. The control unit changes the light amount of the photographing light. The scanning ophthalmologic imaging apparatus according to the present embodiment, which has the above-described configuration, can capture a good image without blurring while suppressing mechanical blurring of the scanning unit.

The detector may detect the reflected light received by the light receiving optical system at a detection cycle according to the scanning of the scanning unit. In this case, the control unit may control the light source and change the light amount of the photographing light in synchronization with the detection cycle.

The control unit may adjust the exposure time of the detector by changing the light amount. Here, the exposure means, for example, a state in which the detector is exposed to the photographing light. For example, the control unit may adjust the length of time that the detector receives the photographing light by blinking the light amount.

The control unit may adjust the exposure time for each cycle of the detector. Here, the term “exposure” means a state in which the detector can detect light regardless of whether or not the photographing light is actually applied. The light projecting optical system may project, for example, wide slit-shaped photographing light to the subject's eye. Further, the scanning unit may scan the photographing light in the width direction of the slit-shaped photographing light. In this case, the control unit may set the exposure time of the detector to be shorter than the scanning time when the photographing light scans a distance half the width.

The processor (for example, the CPU 61) of the scanning ophthalmologic imaging apparatus may cause the scanning ophthalmologic imaging apparatus to execute the ophthalmologic imaging program stored in the storage unit (for example, the storage unit 62). The ophthalmology photographing program includes, for example, a light projecting step, a light receiving step, a scanning step, and a control step. The light projection step is, for example, a step of projecting the imaging light emitted from the light source onto the eye to be inspected. The light receiving step is, for example, a step of receiving the reflected light of the photographing light reflected from the subject's eye. The scanning step is a step of scanning the subject's eye with the imaging light projected in the light projecting step. The detection step is, for example, a step of detecting the reflected light received in the light receiving step at a detection cycle corresponding to the scanning in the scanning step. The control step is, for example, a step of controlling the light source and changing the light amount of the photographing light in synchronization with the detection cycle.

<Example>
Hereinafter, one of typical embodiments according to the present disclosure will be described. As an example, in this embodiment, a scanning type ophthalmologic imaging apparatus (hereinafter, also referred to as “SLO apparatus”) 1 including a laser treatment unit 70 will be described. That is, the scanning ophthalmologic imaging apparatus of the present embodiment is configured to scan light and capture an image of the tissue of the eye E, and to irradiate the tissue with therapeutic laser light based on the captured image. Together with the configuration. However, it is also possible to change the configuration of the SLO device 1. For example, the SLO device 1 may not include the laser treatment section 70. Further, a configuration for scanning light to capture an image of the tissue of the eye to be inspected and a configuration for irradiating the tissue with the treatment laser light may be provided in separate housings. Further, instead of the laser treatment section, a fixation projection optical system that projects a fixation target may be provided, or an OCT optical system that acquires OCT data of the fundus may be provided.

In this embodiment, the SLO device 1 for photographing the fundus of the eye E to be examined is exemplified. However, even when imaging a tissue other than the fundus (for example, the anterior segment of the eye), at least part of the technique illustrated in the present embodiment can be adopted.

With reference to FIG. 1, a schematic configuration of the SLO device 1 of the present embodiment will be described. The SLO device 1 includes a light source 2, a light projecting optical system 10, a scanning unit 20, a detector 30, a light receiving optical system 40, an optical path branching unit 50, a control unit 60, a laser treatment unit 70, and the like.

The light source 2 emits light for capturing an image of tissue (hereinafter, referred to as “imaging light”). As the light source 2, for example, at least one of a laser light source, an SLD (super luminescent diode) light source, an LED and the like can be used. A point light source may be used as the light source 2. The light source 2 of the present embodiment is arranged at a position conjugate with the tissue of the eye E to be examined (fundus in this embodiment). The light source 2 may be a light source that emits at least one of infrared light and visible light. When the light source 2 that emits infrared light is used, imaging in a non-mydriatic state is easily performed. When the light source 2 that emits white light is used, color photography is easily performed. In this embodiment, a laser light source is used as the light source 2. That is, the SLO device (scanning laser optometry device) 1 of the present embodiment is a type of scanning ophthalmologic imaging device that scans light to capture an image of the tissue of the subject's eye.

The light projecting optical system 10 projects the photographing light emitted from the light source 2 onto the fundus of the eye E to be examined. The projection optical system 10 includes a slit plate 11, an imaging lens 15, and an objective lens 18 in order from the upstream side of the optical path of the photographing light (that is, the light source 2 side). In this embodiment, the image forming lens 15 and the objective lens 18 are shared between the light projecting optical system 10 and the light receiving optical system 40. An optical path branching unit 50 is provided on the optical path between the slit plate 11 and the imaging lens 15. A scanning unit 20 and a half mirror 17 are provided on the optical path between the imaging lens 15 and the objective lens 18. The optical path branching unit 50 and the scanning unit 20 can be regarded as a part of the light projecting optical system 10.

The slit plate 11 shields a part of the photographing light emitted from the light source 2 to convert the photographing light into a slit-shaped light flux. That is, the slit plate 11 functions as a light beam conversion element that converts the photographing light into a slit light beam. The slit plate 11 is arranged, for example, on the fundus conjugate position. The slit plate 11 of the present embodiment has slits extending in a direction intersecting with (in the present embodiment, orthogonal to) the scanning direction of the slit-shaped light flux by the scanning unit 20, and has a slit width in the scanning direction. The light from the slit plate 11 passes through the optical path branching unit 50 and the imaging lens 15 and is incident on the scanning unit 20.

It is also possible to employ an optical element other than the slit plate 11 as the light beam conversion element. For example, a cylindrical lens arranged between the light source 2 and the fundus conjugation position may be employed as the light flux conversion element, and the photographing light may be linearly condensed at the fundus conjugation position. As a result, the illumination light is shaped into a line on the fundus Er.

The imaging lens 15 once forms an image of the photographing light emitted from the light source 2 at the front focus position of the objective lens 18. Further, the imaging lens 15 forms an image of the reflected light of the imaging light reflected by the fundus of the eye E on the detector 30. The imaging lens 15 may be composed of one lens or a group of lenses. The imaging lens 15 of the present embodiment is arranged on the downstream side of the slit plate 11 (specifically, on the downstream side of the optical path branching section 50) and on the upstream side of the scanning section 20 in the optical path of the photographing light. ing.

The objective lens 18 guides the imaging light incident from the scanning unit 20 to the fundus of the eye E to be inspected. Further, the objective lens 18 returns the reflected light of the imaging light reflected by the fundus of the eye E to be examined to the scanning unit 20. The objective lens 18 may be composed of one lens or a group of lenses. In this embodiment, the scanning unit 20 is arranged at a position conjugate with the pupil of the eye E by the objective lens 18. The objective lens 18 is arranged on the downstream side of the scanning unit 20 (specifically, on the downstream side of the half mirror 17) and on the upstream side of the eye E in the optical path of the photographing light.

The scanning unit 20 scans the imaging light projected by the projection optical system 10 on the tissue of the eye E to be examined (fundus in this embodiment). As described above, the scanning unit 20 is arranged in the common optical path of the light projecting optical system 10 and the light receiving optical system 40. The scanning unit of the present embodiment scans the slit-shaped light flux of the photographing light in a direction intersecting with the slit direction (orthogonal in the present embodiment). The scanning direction may be, for example, a vertical direction or a horizontal direction. At least one of a reflection mirror (for example, a galvano mirror, a polygon mirror, or a resonant scanner), an acousto-optic element that changes the traveling direction of light, or the like can be used as an element forming the scanning unit 20. In addition, the scanning unit 20 may include a plurality of elements (for example, an element that scans shooting light in the X direction and an element that scans shooting light in the Y direction).

The detector 30 detects the reflected light of the photographing light projected by the projection optical system 10 and reflected by the fundus, and outputs a detection signal. The detector 30 is arranged at a position conjugate with the fundus of the eye E to be inspected. The detector 30 of the present embodiment uses a two-dimensional light receiving element (for example, CCD camera) that receives slit-shaped reflected light. It is also possible to change the configuration of the detector 30. For example, in the case of a scanning type ophthalmologic imaging device that scans a spot of imaging light in a two-dimensional manner, a dot-shaped light receiving element may be used. Further, for example, in the case of a scanning type ophthalmologic imaging device that scans a line of imaging light in a one-dimensional manner, a one-dimensional light receiving element (for example, a line camera) may be used.

The light receiving optical system 40 guides the reflected light of the photographing light reflected by the fundus to the detector 30. The light receiving optical system 40 of the present embodiment includes an objective lens 18, an imaging lens 15, and a plane mirror 41 in order from the downstream side (that is, the eye E side) of the optical path of photographing light. As described above, in this embodiment, the imaging lens 15 and the objective lens 18 are shared between the light projecting optical system 10 and the light receiving optical system 40. An optical path branching section 50 is provided on the optical path between the imaging lens 15 and the plane mirror 41. A half mirror 17 and a scanning unit 20 are provided on the optical path between the objective lens 18 and the imaging lens 15. The optical path branching unit 50 and the scanning unit 20 can be regarded as a part of the light receiving optical system 40. The configuration of the light receiving optical system 40 can be changed. For example, the reflected light from the optical path branching unit 50 may be directly guided to the detector 30 without providing the plane mirror 41.

The imaging light is deflected by the scanning unit 20, and then is irradiated onto the eye E through the objective lens 18. The objective lens 18 guides the photographing light to the fundus of the eye through an exit pupil formed in the anterior segment of the eye. Although the objective lens 18 shown in FIG. 2 is a lens system, it may be a mirror system. The photographing light is rotated at the position of the exit pupil according to the driving of the scanning unit 20. The photographing light is reflected or scattered by the fundus. As a result, the return light (scattered/reflected light) from the fundus is emitted from the pupil as parallel light.

The optical path branching unit 50 passes (or transmits) the imaging light (in this embodiment, a slit-shaped light beam) emitted from the light source 2 and projected onto the fundus by the projection optical system 10. Further, the optical path branching unit 50 reflects the reflected light of the photographing light (slit-shaped light flux in this embodiment) reflected by the fundus and guides the reflected light to the independent optical path of the light receiving optical system 40. After that, the reflected light reflected by the plane mirror 41 is applied to the detector 30. The light is guided toward the detector 30. The optical path branching unit 50 may be any of various beam splitters such as a perforated mirror and a half mirror.

The configuration of the optical path branching unit 50 can be changed. For example, the optical path branching unit 50 reflects the shooting light projected onto the fundus by the projection optical system 10, transmits the reflected light of the shooting light reflected by the fundus, and guides it toward the detector 30. Good.

The control unit 60 performs various control processes in the SLO device (ophthalmologic apparatus) 1. The control unit 60 includes a CPU 61 that is a controller that controls the control, and a storage unit 62 that can store programs and data. The storage unit 62 stores an ophthalmologic imaging program and the like for executing imaging of the eye to be inspected. The number of control units and controllers is not limited to one. For example, a control unit for controlling image capturing and a control unit for controlling laser treatment by the laser treatment unit 70 may cooperate to perform processing.

The laser treatment unit 70 includes a treatment light source 71, an aiming light source 72, a focus adjustment unit 73, and a treatment light scanning unit 74. The treatment light source 71 emits treatment laser light. The aiming light source 72 emits aiming light that indicates the irradiation state of the treatment laser light that is applied to the fundus (for example, the spot size and focus of the treatment laser light). The optical axis of the treatment laser light and the optical axis of the aiming light are coaxial. The focus adjustment unit 73 adjusts the focus of the treatment laser light and the aiming light on the tissue of the eye E (the fundus in this embodiment). For the focus adjustment unit 73, for example, a configuration in which a focusing lens is moved in the optical axis direction can be adopted. The treatment light scanning unit 74 scans the treatment laser light and the aiming light on the fundus. In the present embodiment, the treatment laser light and the aiming light are reflected by the half mirror 17 and applied to the fundus. Further, a part of the aiming light reflected by the fundus of the eye passes through the half mirror 17 and is guided to the detector 30.

<Shooting operation>
The photographing operation of the SLO device 1 will be described. In the SLO device 1, the scanning unit 20 scans the slit-shaped photographing light on the fundus Er, and the detector 30 detects the reflected light of the photographing light reflected by the fundus Er. As a result, the SLO device 1 acquires a slit-shaped two-dimensional image. The detector 30 detects reflected light at a cycle corresponding to the scanning of the scanning unit 20 to acquire images of a plurality of frames in different shooting regions (see FIG. 2 ). The SLO device 1 creates one full-size image of the fundus by arranging the images of the plurality of frames.

FIG. 3 is a diagram showing the operation of the scanning unit 20, the light amount of the photographing light, and the exposure timing of the detector 30 when the SLO device 1 performs photographing. The control unit 60 of the present embodiment continuously changes the scanning angle of the scanning unit 20 over time. That is, the scanning unit 20 is driven smoothly. As a result, the mechanical shake of the scanning unit 20 is suppressed.

The control unit 60 also controls the exposure time of the detector 30 in a predetermined cycle according to the scanning of the scanning unit 20. For example, as shown in FIG. 3, the control unit 60 causes the detector 30 to repeat the exposure time required to acquire an image of one frame at a predetermined cycle according to the scanning speed of the scanning unit 20. As a result, the detector 30 acquires images of a plurality of frames with different shooting areas.

Further, as shown in FIG. 3, the control unit 60 changes the light amount of the light source 2. For example, the control unit 60 blinks the light source 2 in synchronization with the exposure timing of the detector 30. For example, the control unit 60 turns on the light source 2 for a moment during the exposure time of the detector 30 in each frame. For example, the control unit 60 turns on the power of the light source 2 after the exposure is started, and immediately (before the end of the exposure) turns off the power of the light source 2 to blink the photographing light.

In this way, the control unit 60 can prevent the scanning unit 20 from moving and the image being blurred during the exposure of the detector 30 by blinking the light source 2. In other words, the control unit 60 can reduce the amount of change in the shooting area while the detector 30 actually detects the shooting light by shortening the lighting time of the shooting light, and can suppress image blurring.

In general, the longer the exposure time for each frame in the detector 30, the more light can be captured for each frame, and a bright image can be obtained. However, in that case, since the scanning unit 20 continues to be driven even during the exposure of one frame, the image capturing region moves to form a blurred image, and the resolution deteriorates. This is because even when a single full-size image is created by shooting a plurality of two-dimensional images and arranging the two-dimensional images as in the present embodiment, the angle of view per frame is increased (one full-size image The smaller the number of frames per frame), the longer the scanning distance that the scanning unit 20 scans during the exposure for each frame, and the more noticeable the image blur.

In such a case, as shown in FIG. 4, it is conceivable to keep the scanning unit 20 stationary only while exposing each frame while continuously irradiating the photographing light, but since the scanning unit 20 repeatedly stops and drives, the acceleration is increased. As a result, mechanical blurring of the scanning unit 20 occurs, and control of the scanning unit 20 becomes complicated. On the other hand, in the SLO device 1 of the present embodiment, by blinking the light source 2, it is possible to smoothly drive the scanning unit 20 and obtain a clear image with less blur.

It should be noted that when the photographing light is blinked, the influence of the movement of the scanning unit 20 during the exposure of the detector 30 and the blurring of the image can be further suppressed by shortening only the lighting time without changing the blinking cycle of the light source 2. it can. At this time, if the lighting time is shortened, the amount of light becomes insufficient and a dark image is obtained. Therefore, it is preferable to increase the amount of light within a range satisfying the optical safety of the eye so that the continuous pulse light source has a high light amount and a short emission time.

The method of blinking the photographing light is not limited to turning on/off the power source of the light source 2 as described above. For example, the control unit 60 may blink the photographing light emitted from the light source that is continuously turned on by repeatedly blocking the photographing light with a mechanical shutter or the like. Further, the imaging light emitted to the eye E to be inspected may be blinked by repeatedly deflecting the imaging light emitted from the light source that is continuously turned on out of the optical path of the projection optical system 10 by the optical element.

The control unit 60 does not have to completely turn off the photographing light, and may reduce the amount of light to limit the photographing light received by the detector 30. Thereby, the control unit 60 may suppress the blurring of the image.

In addition, in the above-mentioned embodiment, as shown in FIG. 3, the light amount is changed in a rectangular wave pulse shape (abruptly), but the present invention is not limited to this. For example, the control unit 60 may change the light amount in a sinusoidal pulse shape (gradually) as shown in FIG. Further, the control unit 60 may change the light amount between frames as shown in FIG.

<Transformation example>
A modified example of this embodiment will be described. The SLO device 1 of the modified example differs from the above-described embodiment in the light amount at the time of shooting and the exposure time of the detector 30. Specifically, as shown in FIG. 6, the control unit 60 sets the light amount of the light source 2 constant and sets the exposure time of the detector 30 sufficiently short. As a result, it is possible to prevent the captured image from blurring due to the scanning of the scanning unit 20 during the exposure of the detector 30. Further, since the SLO device 1 of the modification does not need to periodically change the light amount of the light source 2, the device configuration can be simplified. As a method of shortening the exposure time of the detector 30, light may be blocked by a mechanical shutter, or exposure may be limited by an electronic shutter of the detector.

The exposure time is preferably shorter than the time required to scan the distance A (see FIG. 7) that is half the slit width. Thereby, the SLO device 1 can capture a good image with little blur. More preferably, the exposure time may be shorter than the time required to scan the distance of one pixel of the detector.

DESCRIPTION OF SYMBOLS 1 Scanning ophthalmologic imaging device 2 Light source 10 Projection optical system 20 Scanning unit 30 Detector 40 Light receiving optical system 50 Optical path branching unit

Claims (6)

A scanning ophthalmologic imaging device,
A light source that emits shooting light,
A projection optical system for projecting the photographing light emitted from the light source onto the eye to be inspected,
A light receiving optical system for receiving the reflected light of the photographing light reflected from the eye to be inspected,
Scanning means for scanning the imaging light projected by the projection optical system with respect to the eye to be inspected;
A detector for detecting the reflected light received by the light receiving optical system at a detection cycle corresponding to the scanning of the scanning means;
A scanning-type ophthalmologic imaging apparatus comprising: a control unit that changes the light amount of the imaging light in synchronization with the detection cycle. The scanning type ophthalmologic imaging apparatus according to claim 1, wherein the control unit adjusts the exposure time of the detector by changing the light amount. The scanning type ophthalmologic imaging apparatus according to claim 1, wherein the control unit blinks the light source. The scanning type ophthalmologic imaging apparatus according to claim 1, wherein the control unit adjusts an exposure time of the detector for each cycle. The light projecting optical system projects the photographing light in the shape of a slit having a width onto the eye to be inspected,
The scanning means scans the photographing light in the width direction,
5. The scanning ophthalmologic imaging apparatus according to claim 4, wherein the control unit makes the exposure time of the detector shorter than the scanning time when the imaging light is scanned at a distance half the width. An ophthalmologic imaging program executed in a scanning ophthalmologic imaging apparatus, by being executed by a processor of the scanning ophthalmologic imaging apparatus,
A light projecting step of projecting the photographing light emitted from the light source to the eye to be inspected,
A light receiving step of receiving the reflected light of the photographing light reflected from the eye to be inspected,
A scanning step of scanning the imaging light projected in the projecting step with respect to the eye to be inspected;
A detection step of detecting the reflected light received in the light receiving step at a detection cycle corresponding to the scanning in the scanning step;
A control step of controlling the light source to change the light amount of the photographing light in synchronization with the detection cycle, and causing the scanning ophthalmic photographing apparatus to execute the ophthalmologic photographing program.

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