JP2016042931A - Ophthalmologic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an adaptive optics scanning laser ophthalmoscopy which can cope with a difference in a pupil diameter and can satisfy various requirements.SOLUTION: There are provided: a light source 101 for emitting measurement light to irradiate an eyeground 301 of a subject's eye 300 therewith; a first scanner 117 and a second scanner 120 for scanning the measurement light for irradiating the eyeground 301 therewith; a pupil magnification change part 121 which is disposed between the second scanner 120 and the subject's eye 300 and can have different optical magnifications set thereto; and a selector which selects the optical magnification on the basis of the observation visual field of the eyeground 301 of the subject's eye 300 or the pupil diameter of the subject's eye 300.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an adaptive optical scanning laser ophthalmoscopy (AO-SLO).

  An adaptive optical scanning laser ophthalmoscope (AO-SLO) is known as an ophthalmologic apparatus used for clinical researches such as fundus diseases (see, for example, Patent Document 1). The scanning laser ophthalmoscope (SLO) observes the state of the fundus (retina) seen from the front by irradiating the fundus while scanning with laser light (SLO measurement light) and detecting the reflected light from the fundus. Device. AO-SLO is a system that adds a mechanism (AO = Adaptive Optics) that corrects the effects of eye aberrations to SLO. AO-SLO can observe photoreceptor cells with high resolution.

  The SLO measurement light is applied to the fundus through the pupil of the subject's eye, but the pupil diameter of the subject's eye is not a fixed value, and there are individual differences. The difference in pupil diameter affects various measurements. For example, Patent Document 2 describes a technique that focuses on a change in pupil diameter in relation to a technique that performs wavefront compensation of reflected light from the fundus.

Special table 2013-517842 gazette JP2013-52048A

  One factor that determines the optical performance in the AO-SLO optical system is the pupil diameter of the eye to be examined. In the AO-SLO optical system, the wavefront measurement system, wavefront compensation device, and scanning device are designed to have a conjugate relationship with the pupil. In general, in order to perform wavefront compensation corresponding to the pupil diameter, the effective diameters of the wavefront measurement system and the wavefront compensation system are set in consideration of the maximum possible pupil diameter. However, there is an individual difference in the pupil diameter of the eye to be examined, and it is not always an assumed value. Therefore, the compensation performance of the AO-SLO optical system changes depending on the eye to be examined (pupil diameter). For this reason, depending on the pupil diameter of the eye to be examined, the function of wavefront compensation is not sufficiently exhibited. In SLO, when a scanning device having an effective diameter D is selected, if the assumed maximum pupil diameter is d, the magnification β of the pupil imaging optical system is determined as β = d / D. Therefore, the observation viewing angle θ is naturally determined as θ = 2Θ / β from the maximum mechanical angle Θ of the scanning device and the magnification β. If a scanning device having a small effective diameter D is selected for high-speed scanning, the magnification β is increased, which is disadvantageous for the observation viewing angle θ. A scanning device having a large maximum mechanical angle Θ and an effective diameter D is subject to high speed. That is, the product of Θ and D is in a trade-off relationship with high speed. Therefore, in the SLO in which the observation magnification is enlarged / reduced by changing the scan width of the scanning device, there is a problem that the maximum observation viewing angle is sacrificed.

  In such a background, an object of the present invention is to obtain an adaptive optical scanning laser ophthalmoscope that can cope with a difference in pupil diameter and satisfy various requirements.

  The invention described in claim 1 includes a measurement light emitting unit that emits measurement light applied to the fundus of the eye to be examined, a scan unit that scans the measurement light applied to the fundus, the scan unit, and the subject. An optical system that is disposed between the optical examination and has a conjugate relationship between the optical surface of the scanning unit and the pupil of the eye to be examined, the optical magnification of which can be changed, and the pupil diameter of the eye to be examined or the fundus of the eye to be examined An ophthalmologic apparatus comprising: a processing unit that performs a process of changing the optical magnification based on an observation visual field.

  The invention according to claim 2 is the invention according to claim 1, wherein the processing unit selects a relatively small optical magnification when the pupil diameter of the eye to be examined is relatively small. . According to the second aspect of the present invention, when the pupil diameter of the eye to be examined is relatively small, the imaging magnification on the pupil of the scanning unit optical surface is changed to a small magnification, and the incident light at the pupil is reduced. Reduces kicking (component of incident light that cannot pass through the pupil). Further, according to this configuration, the reflected light from the fundus limited by the pupil diameter, that is, the detection light hits a wider area of the optical surface of the compensation optical device (deformable mirror) and further the wavefront sensor surface. Can be used more effectively.

  FIG. 1 shows the principle of an adaptive optical scanning laser ophthalmoscope (AO-SLO = Adaptive Optics Scanning Laser Ophthalmoscope). 1 is an illustration for explaining the principle, and the present invention is not limited to the configuration of the optical system of FIG. As shown in FIG. 1, in AO-SLO, an image is obtained from reflected light by condensing and irradiating laser light onto the fundus 301 of the eye 300 to be examined and scanning the condensing position. The reflected light from the fundus 301 is split by the beam splitters 302 and 303 and guided to the wavefront sensor 305 placed at the conjugate position with the pupil 304 of the eye to be examined and the detector 306 placed at the conjugate position with the fundus 301. Lighted. The wavefront sensor 305 measures the aberration of the eye 300 to be examined. Then, by changing the shape of the deformable mirror 307, which is a deformable mirror placed at another conjugate position of the pupil 304 of the eye 300 so as to cancel out the aberration of the eye 300 measured by the wavefront sensor 305, It is possible to resolve a fundus structure having a diffraction limit size determined by the measurement light wavelength and the pupil diameter.

  AO-SLO is often intended for observation of the fundus photoreceptors, but the photoreceptor cell size is said to be approximately 2 to 6 μm. In order to observe this, it is necessary to open the pupil diameter to about φ8 mm. However, since the maximum pupil diameter varies among individuals, the observation state of photoreceptor cells depends greatly on the eye to be examined.

  The difference in pupil diameter depending on the eye to be examined is related not only to the resolution limit size but also to the wavefront compensation performance of AO-SLO. The wavefront sensor 305 and the deformable mirror 307 are placed at a conjugate position with the pupil of the eye to be examined. When the imaging magnification is fixed, a change in the pupil diameter is applied to the wavefront sensor 305 and the deformable mirror 307. This leads to a change in the incident fundus reflected beam diameter. For example, when the diameters of the light beams incident on the wavefront sensor 305 and the deformable mirror 307 are reduced, information on the outer periphery of the aberration analysis diameter set by the wavefront sensor is insufficient, and the accuracy of wavefront aberration analysis is lacking. In addition, the correction capability set by the deformable mirror 307 that contributes to wavefront correction is left behind.

  Therefore, in the invention described in claim 2, the processing unit selects a relatively small optical magnification when the pupil diameter of the eye to be examined is relatively small. In this configuration, even if the pupil diameter of the subject's eye changes, the pupil imaging magnification is changed so that the beam diameter of the inspection light (reflected light from the fundus) incident on the wavefront sensor and the deformable mirror does not become as small as possible. Is done.

  According to a third aspect of the present invention, in the second aspect of the invention, a wavefront sensor that detects an aberration of a wavefront of the reflected light of the measurement light from the fundus, and a wavefront of the reflected light that is detected by the wavefront sensor A deformable mirror that deforms the reflecting surface in order to suppress the aberration, and the change in the optical magnification specifies the relationship between the beam diameter of the reflected light in the deformable mirror and the effective diameter of the deformable mirror It is characterized by being performed under conditions that satisfy the following conditions.

According to the third aspect of the present invention, the ratio (φ ₂ / φ ₁ ) of the beam diameter φ ₂ of the detection light (reflected light from the fundus) incident on the deformable mirror with respect to the effective diameter φ ₁ of the deformable mirror. The optical magnification is selected so as to satisfy a specific relationship, for example, (φ ₂ / φ ₁ ) ≧ 0.8. As (φ ₂ / φ ₁ ) decreases, the wavefront sensor in a conjugate relationship with the deformable mirror and the unused portion of the deformable mirror increase, so the accuracy of wavefront compensation decreases.

According to the third aspect of the present invention, since the optical magnification of the optical system is selected so that (φ ₂ / φ ₁ ) satisfies a specific condition, a decrease in the utilization efficiency of the deformable mirror can be suppressed, and the wavefront A decrease in correction accuracy can be suppressed.

  The invention according to claim 4 is the invention according to any one of claims 1 to 3, wherein the processing unit has a relatively large optical magnification when a high resolution is required for the observation image of the fundus. And a relatively small optical magnification is selected when a relatively large observation field is required.

  The observation viewing angle in the AO-SLO optical system is generally changed by changing the scan width of the scanning device as in the SLO optical system. The merit of this is that since the imaging magnification of the optical system does not change even if the observation viewing angle is changed, the resolution does not depend on the observation viewing angle as long as the pupil diameter of the eye to be examined is constant.

  However, in order to take advantage of this advantage at a wide viewing angle, it is necessary to reduce the scan pitch, that is, to reduce the frame rate. However, in the case of AO-SLO, the observation target is the fundus of the living body, and the eyeball is constantly moving by eye movement, so lowering the frame rate leads to lowering of image quality. In other words, it is difficult to take advantage of the above advantages with AO-SLO during wide-field observation.

  Therefore, in the invention according to claim 4, by changing the optical magnification to a relatively small value when changing from the narrow observation field to the wide observation field, the reduction in the frame rate is suppressed and the wide observation field angle is reduced. Make observations possible.

  According to the fourth aspect of the present invention, the resolution during narrow-field observation is not maintained during wide-field observation, but the frame rate can be maintained or further increased. The scanning device can be selected based on the optical conditions for narrow-field observation. In other words, it is possible to select a device with a small product of effective diameter and scan width, and device selection that pursues high-speed scanning. Is advantageous.

  ADVANTAGE OF THE INVENTION According to this invention, the adaptive optical scanning type laser ophthalmoscope which can respond to the difference in pupil diameter and can satisfy various requirements can be obtained.

It is a conceptual diagram explaining the principle of invention. It is a conceptual diagram of the optical system of embodiment. It is a block diagram of a control system of an embodiment. It is a flowchart which shows an example of the procedure of a process. It is a model figure which shows the state of the light beam of the fundus oculi reflection light on the optical surface of the deformable mirror system. It is a table | surface which shows the relationship between the effective diameter of a deformable mirror, and the light beam diameter of the detection light which strikes a deformable mirror. It is a flowchart which shows an example of the procedure of a process.

(Constitution)
FIG. 2 shows an ophthalmic apparatus 100 according to the embodiment. The ophthalmologic apparatus 100 is an adaptive optical scanning laser ophthalmoscope (AO-SLO). The ophthalmologic apparatus 100 includes a light source 101 that emits measurement light. For example, a light source 101 that emits light having high directivity selected from a wavelength range of 500 nm to 1500 nm, that is, light having a small divergence angle is used. Examples of the light source 101 include a solid-state laser, a gas laser, a laser diode (LD), a super luminescent diode (SLD), and a laser driven light source (LDLS).

  An optical fiber 102 that guides light is connected to the light source 101. A single mode optical fiber is employed as the optical fiber 102. A lens (collimator lens) 103 for collimating the laser light emitted from the optical fiber 102 is disposed at the tip of the optical fiber 102. The light from the light source 101 is converted into parallel light by the lens 103 and enters the half mirror 104. The half mirror 104 is a light quantity splitting mirror that branches the light projecting system and the wavefront detecting system. Here, the light projecting system is an optical system that irradiates light to the eye 300, and relays parallel light obtained by the configuration of the light source 101, the optical fiber 102, and the lens 103 through the relay lenses 115, 116, and the like. The whole optical system which radiate | emits to the eye 300 to be examined from the objective lens 131 is pointed out. The wavefront detection system is an optical system for detecting wavefront information from reflected light (detection light) from the fundus 301 of the eye 300 to be examined, and includes a wavefront detection unit 105 and an optical system 106.

  The half mirror 104 transmits part of the laser light (projection) from the light source 101 to the half mirror 110 side described later, and part of detection light incident from the half mirror 110 side of the wavefront detection unit 105. Reflect to the side. Note that the branching ratio (the ratio of the amount of light to be divided) of the half mirror 104 is not limited to 1: 1, and can be arbitrarily set as necessary. It is also possible to use a polarization beam splitter instead of the half mirror 104.

  The wavefront detection unit 105 includes a CCD 107 that is an imaging device and a lens array 108 in front of the CCD 107. The lens array 108 is a Hartmann plate and is arranged at the pupil conjugate position. The wavefront detection unit 105 functions as a Shack-Hartmann sensor. The lens array 108 is an array of small lenses arranged in a grid, and divides incident light into a number of light beams and condenses them. The light collected by the lens array 108 is imaged by the CCD 107, and the output of the CCD 107 is sent to the arithmetic unit 203 described later.

  An optical system 106 having a pair of lenses and a pinhole (optical aperture) between them is disposed between the half mirror 104 and the wavefront detection unit 105. Further, the optical system 106 reduces reflection noise from the optical system on the side of the eye 300 to be examined and the cornea of the eye 300 to be examined.

  Another half mirror 110 is arranged on the eye 300 side of the half mirror 104. The half mirror 110 is a light quantity splitting mirror that branches the light projecting system and the retinal imaging system (fundus imaging system). The retinal imaging system detects image information of the retina on the fundus 301 from the reflected light (detection light) from the fundus 301. The branching ratio (the ratio of the amount of light to be divided) of the half mirror 110 is not limited to 1: 1, and can be arbitrarily set as necessary. Note that a polarizing beam splitter may be used instead of the half mirror 110.

  The retinal imaging system includes a lens 111, a pinhole (optical aperture) 112, and a fundus reflection light detector 113. The fundus reflection light detector 113 is a light detection element that detects weak reflected light from the fundus 301, and includes, for example, an APD (avalanche photodiode) or a photomultiplier tube. A detection signal from the fundus reflection light detector 113 is sent to the arithmetic unit 203 via an ADC (A / D converter) 202 described later (see FIG. 3). By irradiating the fundus 301 with light from the light source 101 while scanning, scan data of reflected light from the fundus 301 is obtained from the fundus reflected light detector 113.

  A pinhole 112 that functions as an optical aperture is disposed in front of the fundus reflection light detector 113, and a light beam is emitted in front of the pinhole 112 so that the fundus conjugate position is located at the optical aperture of the pinhole 112. A lens 111 for squeezing is disposed.

  A deformable mirror 114, which is a wavefront correction device, is disposed on the eye side 300 of the half mirror 110. The deformable mirror 114 is a deformable mirror for performing wavefront correction. The deformable mirror 114 is a mirror whose surface shape can be deformed by a plurality of actuators. The deformable mirror 114 is controlled by the control unit 206 (see FIG. 3) based on the processing in the arithmetic unit 203, and corrects the wavefront of the reflected light by deforming the reflecting surface.

  The optical surface (reflection surface) of the deformable mirror 114 is placed at a position conjugate with the pupil of the eye 300 to be examined. For high compensation performance of eyeball aberration, it is desirable that more actuators be arranged in the portion of the deformable mirror 114 where the target light beam is hit. Therefore, the imaging magnification of the lens system described later is selected so that the size of the pupil image on the optical surface of the deformable mirror 114 is the same as the effective diameter of the deformable mirror. In this example, the effective diameter Dd of the deformable mirror is 13.5 mm, and the lens system described later is set so that the pupil image on the mirror surface of the deformable mirror 114 (the light beam diameter of the detection light) is as close as possible to Dd. The image magnification is selected. Note that a spatial phase modulator, a bimorph mirror, or the like can be used as the wavefront correction device.

A first scanner 117 is disposed on the side of the subject's eye 300 of the deformable mirror 114 via relay lenses 115 and 116. In this example, the relay magnification by the relay lenses 115 and 116 is 0.3. The first scanner 117 is arranged at a position conjugate with the pupil and performs scanning in the vertical direction (vertical direction). This scan is performed at a higher speed than the second scanner 120 described later. The first scanner 117 is constituted by a resonant scanner. A resonant scanner (resonance type scanner) is an optical element that scans reflected light by rotating a mirror back and forth by a resonance motion. Resonant scanners cannot move the scan center, but have the advantage of being able to scan at high speed. In this example, a first scanner 117 having a mirror diameter _DS1 of 4 mm is selected.

The second scanner 120 is disposed on the eye 300 side of the first scanner 117 via relay lenses 118 and 119. The second scanner 120 is also arranged at a position conjugate with the pupil, and is used to move the scan center of the first scanner 117 in the horizontal direction in addition to performing the horizontal (left-right) scan. Can do. The second scanner 120 is configured by a galvano scanner. The galvano scanner has a structure in which a mirror attached to a rotating shaft is driven by a motor. The galvano scanner cannot operate at a higher speed than the resonant scanner, but can set the scan center to a desired position. In this example, the mirror diameter _{D S2} of the second scanner 120 is 4 mm.

  A pupil magnification changing unit 121 is arranged on the eye 300 side of the second scanner 120. The pupil magnification changing unit 121 includes a plurality of optical systems having different optical magnifications, and has a function of positioning one of them on the optical axis. In this example, four optical systems of pupil relay systems 121a to 121d are prepared as a plurality of optical systems having different optical magnifications. The pupil relay systems 121a to 121d are lens systems that are set to a predetermined optical magnification by two lenses. The pupil magnification changing unit 121 includes a rotary container having a shape similar to a rotary magazine of a revolver handgun, and four pupil relay systems 121a to 121d are held in this container. By rotating this container, any one of the pupil relay systems 121a to 121d can be positioned on the optical axis. The pupil relay systems 121a to 121d are optically designed so that the optical surfaces (reflection surfaces) of the first scanner 117 and the second scanner 120 are conjugated with the pupil of the eye 300 to be examined. The pupil magnification changing unit 121 is a first scanning device for the purpose of making the measurement light beam diameter on the scanning device or wavefront compensation device surface arranged at the pupil conjugate position as constant as possible regardless of the pupil diameter. It is necessary to arrange between the scanner 117 and the second scanner 120 and the eye 300 to be examined. That is, the pupil magnification changing unit 121 needs to be disposed on the eye 300 side from the scanner.

  Here, the pupil relay system 121a has an optical magnification (imaging magnification) of 2.0 (β = 2.0), and the pupil relay system 121b has an optical magnification (imaging magnification) of 1.6 ( β = 1.6), the pupil relay system 121c has an optical magnification (imaging magnification) of 1.3 (β = 1.3), and the pupil relay system 121d has an optical magnification (imaging magnification). Is 1.05 times (β = 1.05).

  The pupil relay system 121a increases the light beam diameter of the measurement light incident from the light source 101 side and reflected from the second scanner 120 by 2.0, and emits it to the eye 300 to be examined. In other words, the pupil relay system 121a multiplies the light beam diameter of the detection light reflected from the fundus 301 by (1/2) and emits it to the second scanner 120 side. This optical function is the same in the pupil relay systems 121b to 121d except that the value of the optical magnification is different. In this case, the observation viewing angle corresponding to the pupil position beam diameter φ = 4 mm is set to 20 °. Therefore, when the pupil relay system 121a is selected, the pupil position light beam diameter φ = 8 mm and the observation viewing angle is 10 °. When the pupil relay system 121b is selected, the pupil position beam diameter φ = 6.4 mm and the observation viewing angle is 12.5 °. When the pupil relay system 121c is selected, the pupil position beam diameter φ = 5.2 mm and the observation viewing angle is 15.4 °. When the pupil relay system 121d is selected, the pupil position beam diameter φ = 4.2 mm and the observation viewing angle is 19 °.

  In addition, the structure which arrange | positions a desired pupil relay system on an optical axis is also possible by arrange | positioning several pupil relay systems in parallel and moving them in parallel. It is also possible to further increase or decrease the number of pupil relay systems. The pupil magnification changing unit 121 employs a mechanism that continuously changes the imaging magnification by changing the distance between the lenses of the pupil relay system in addition to a mechanism that switches the optical system with a fixed magnification. You can also.

  A mirror 122 is disposed on the eye 300 side of the pupil magnification changing unit 121, and a diopter correction system 125 is disposed on the eye 300 side of the mirror 122. The diopter correction mechanism 125 performs adjustment so that the observation point of the fundus 301 is the focal point of the optical system. That is, the diopter correction mechanism 125 performs adjustment so that the laser light from the light source 101 is irradiated onto the fundus 301 as a substantially point image. The diopter correction mechanism 125 includes diopter-shaped diopter correction mirrors 126 and 127.

  Adjustment is performed so that the fundus 301 is focused by moving the diopter correction mirror 126 relative to the diopter correction mirror 127. There are individual differences and individual differences in diopter. Even if there is a difference in diopter, by moving the position of the diopter correction mirror 126, the fundus 301 is focused, that is, on the fundus 301. Adjustment is performed so that the irradiation light is condensed and irradiated as a substantially point image. The diopter correction mechanism 125 can also be used for fine adjustment of the light collection position on a specific layer to be observed.

  Dichroic mirrors 129 and 130 are arranged on the side of the eye 300 to be examined of the diopter correction mechanism 125 via the lens system 128. The dichroic mirror 129 reflects light from the light source 101 and transmits near-infrared light emitted from the light source 134 and reflected from the anterior eye portion. For example, the dichroic mirror 129 reflects light having a wavelength of 840 nm from the light source 101 and transmits light having a wavelength of 950 nm that is illuminated by the light source 134 and reflected from the anterior segment.

  The dichroic mirror 130 reflects light from the light source 101 and near-infrared light irradiated from the light source 134 to the anterior eye part and reflected by the anterior eye part, and transmits light from a fixation target 132 to be described later. For example, the dichroic mirror 130 reflects light having a wavelength of 840 nm from the light source 101 and near-infrared light having a wavelength of 950 nm reflected by the anterior eye part, and transmits light having a wavelength of 550 nm from the fixation target 132 described later.

  An objective lens 131 is disposed in front of the eye 300 to be examined. The objective lens 131 has a structure in which a plurality of lenses are combined in order to suppress aberrations (of course, it may be composed of a single lens). The objective lens 131 is set so that the pupil of the optical system matches the position of the pupil 304 of the eye 300 to be examined.

  The eye 300 visually recognizes the fixation target 132 through the dichroic mirror 130. The fixation target 132 is a visual target for fixing the direction (line of sight) of the eye 300 to be examined. The fixation target 132 is composed of a film or an organic EL element that emits light having a wavelength that can be visually recognized by the eye 300 (about 400 nm to 600 nm), and is movable in a direction perpendicular to the optical axis. By moving the fixation target 132, the direction of the line of sight of the eye 300 to be examined can be guided in the direction intended by the observer.

  The anterior segment of the eye 300 is irradiated with near-infrared light (for example, a wavelength of 950 nm) from the light source 134, and the reflected light from the eye 300 is transmitted through the dichroic mirrors 130 and 129. The image is formed on the image sensor 133. Imaging by the near-infrared light of the anterior eye part (pupil) of the eye to be examined is performed by the imaging element 133. The imaging element 133 is configured by a CCD or a CMOS image sensor. The output of the image sensor 133 is sent to the calculation unit 203, and the calculation unit 203 detects the pupil diameter from the anterior eye image (image of the pupil viewed from the front) captured by the image sensor 133.

(basic action)
First, the basic operation will be described. The SLO measurement light from the light source 101 enters the eye 300 to be examined through the half mirror 110 → deformable mirror 114 → first scanner 117 → second scanner 120 → pupil magnification changing unit 121, diopter correction system 125 → objective lens 131. To do. The incident light beam is limited by the pupil diameter of the pupil 304, and is condensed on the fundus 301 by the lens action of the eyeball to illuminate the fundus 301 in a substantially dot shape. The SLO measurement light condensed on the fundus 301 is reflected and scattered at the condensing point of the fundus 301. The reflected and scattered light follows the reverse path as described above as SLO detection light, passes through the half mirror 110, and is detected by the fundus reflection light detector 113.

  A part of the SLO detection light is reflected by the half mirror 110 toward the half mirror 104, further reflected by the half mirror 104, and detected by the wavefront detection unit 105. In the wavefront detection unit 105, wavefront disturbance in the SLO detection light is detected, and the detection signal is sent to the calculation unit 203. The calculation unit 203 performs a process for controlling the deformable mirror 114 so as to suppress the disturbance of the wavefront detected by the wavefront detection unit 105. In this way, the wavefront of the detection light is corrected while detecting the reflected light from the fundus.

  In the above process, a two-dimensional region of the fundus 301 is scanned by a combination of the vertical scan of the first scanner 117 performed at a relatively high speed and the horizontal scan of the second scanner 120 performed at a relatively low speed. Is called.

(Control system)
Hereinafter, an example of the control system of the ophthalmologic apparatus shown in FIG. 1 will be described. FIG. 3A shows a block diagram of a control system of the ophthalmologic apparatus of FIG. In FIG. 3A, input operation information from an input device (not shown) is input to the input unit 220. As the input device, a keyboard device, a device using a GUI (graphical user interface), a device using a touch panel display, or the like can be used. In recent years, various portable information processing terminals that can use a GUI have been used, but it is also possible to perform various operations using these portable information processing terminals and receive the contents of operations by the input unit 220. It is.

  The arithmetic unit 203 includes a CPU and other hardware, and is configured by a microcomputer having various arithmetic functions and interface functions. FIG. 3B shows a configuration when the calculation unit 203 is grasped as a functional block. Each functional unit illustrated in FIG. 3B may be configured as software so that a predetermined function is exhibited by the calculation of the CPU, or at least a part thereof may be configured with dedicated hardware. .

  In FIG. 3B, the scanner control unit 311 performs processing for scanning irradiation light (measurement light) to the fundus 301 using the first scanner 117 and the second scanner 120. By changing the scanning range, the observation visual field (observation visual field angle) can be changed. For example, when the scan range is narrowed, the observation visual field is narrowed, and when the scan range is widened, the observation visual field is widened.

  The fundus image creation unit 316 creates a retina image based on the scan data of the reflected light detected by the fundus reflection light detector 113. The retina image is sent to the display unit 204 and displayed there. That is, the output of the fundus reflection light detector 113 is converted into a digital signal by an ADC (A / D converter) 202 and sent to the arithmetic unit 203. The fundus 301 (see FIG. 1) is irradiated with light from the light source 101 while being scanned. The irradiation point at this time is determined by the scanner control unit 311. The position of the irradiation point at a certain moment is This is known on the calculation unit 203 side. Therefore, the fundus image can be obtained by converting the output of the ADC 202 to the shade of the assigned image corresponding to the scan position. This process is performed in the fundus image creation unit 316.

  The pupil diameter detector 317 analyzes the anterior eye image captured by the image sensor 133 and detects the pupil diameter of the pupil 304. The pupil diameter determination unit 318 determines which of the predetermined determination conditions the pupil diameter detected by the pupil diameter detection unit 317 meets. The pupil relay system selection unit 319 performs a process of selecting any one of the four pupil relay systems 121a to 121d based on the determination in the pupil diameter determination unit 318.

  In the case of the pupil magnification changing unit configured to change the distance between the lenses and continuously change the pupil magnification, the pupil diameter determining unit 318 determines the necessary pupil magnification from the pupil diameter of the pupil 304 detected by the pupil diameter detecting unit 317. And the pupil relay system selection unit 319 performs a process of selecting an inter-lens distance according to the pupil magnification.

  The wavefront aberration detection unit 320 performs analysis (Zernike analysis) of the image captured by the Hartmann imaging device 107 and detects the state of aberration of the wavefront. The adaptive optics control unit 321 performs control to deform the deformable mirror 114 so as to suppress the wavefront aberration detected by the wavefront aberration detection unit 320. In addition, the calculation unit 203 performs processing for ON / OFF control of the light source 101, processing for diopter correction, and the like.

  The display unit 204 displays various displays necessary for operating the ophthalmologic apparatus of FIG. 2 and the fundus image obtained by the calculation unit 203. Note that a display function of an external device may be used as the display unit 204. In this case, a process related to image data desired to be displayed by a display control unit (not shown) is performed and transmitted to the external device. The memory 205 stores various information necessary for the calculation performed by the calculation unit 203 and a program for determining the procedure of the calculation performed by the calculation unit 203. The memory 205 stores various calculation results and image data of the obtained fundus image.

  The control unit 206 performs control of the scanning operation, control of the pupil magnification change unit 121, control of the light source 101, control of the deformable mirror 114, control of the diopter correction mirror 126, and the like based on the processing result in the calculation unit 203. A control signal for generating

  The first scanner driving unit 207 includes a motor for moving the first scanner 117 and its driving circuit. The second scanner drive unit 208 includes a motor for moving the second scanner 120 and its drive circuit. The pupil magnification changing unit driving unit 209 includes a motor that drives the pupil magnification changing unit 121 and its control circuit. The container of the pupil magnification changing unit 121 is rotated by the motor of the pupil magnification changing unit driving unit 209, and the pupil relay system selected by the pupil relay system selecting unit 319 moves on the optical axis. Alternatively, the pupil magnification changing unit driving unit 209 expands / contracts lens interval changing portions prepared at a plurality of locations of the pupil magnification changing unit 121 in the optical axis direction in accordance with the pupil magnification selected by the pupil relay system selection unit 319. The diopter correction mirror drive unit 210 includes a motor that determines the position of the diopter correction mirror 126 on the optical axis and a drive circuit therefor.

(Operation example 1)
In this example, the pupil diameter of the eye to be examined is measured, and the magnification of the pupil relay system is selected based on the result. FIG. 4 shows an example of processing. When the process is started, alignment of the eye to be examined (step S201) and fixation of the line of sight of the eye to be examined 300 using the fixation target 132 (step S202) are performed. Next, the image of the anterior segment imaged by the imaging element 133 is analyzed by the pupil diameter detection unit 317, and the pupil diameter of the pupil 304 is measured (step S203).

  When the pupil diameter is detected, it is determined which of the predetermined conditions the pupil diameter measured in step S203 is met (step S204). This process is performed in the pupil diameter determination unit 318. In this process, (1) pupil diameter is 6.4 mm or more, (2) pupil diameter is 5.2 mm or more and less than 6.4 mm, (3) pupil diameter is 4.2 mm or more and less than 5.2 mm, and (4) pupil diameter. Is determined to fall between 3.4 mm and less than 4.2 mm.

  After step S204, the process proceeds to step S206. In step S206, one of the four pupil relay systems 121a to 121d is selected based on the determination result in step S204. This processing is performed in the pupil relay system selection unit 319. In this process, the pupil relay system 121a (β = 2.0) is selected in the case of (1) in the above determination condition, and the pupil relay system 121b (β = 1.6) is selected in the case of (2). In the case of (3), the pupil relay system 121c (β = 1.3) is selected, and in the case of (4), the pupil relay diameter 121d (β = 1.05) is selected.

  In step S206, a magnification is selected such that the reflected light beam from the fundus limited by the pupil diameter can effectively fill the reflective surface of the deformable mirror 114. In other words, in the process of step S206, the reflected light beam from the fundus limited by the pupil diameter is reflected by the widest possible part of the reflecting surface of the deformable mirror 114, and the function as the deformable mirror can be used as effectively as possible. The optical magnification is selected by the pupil magnification changing unit 121 so that If the pupil diameter is much smaller than 3.4 mm, it can be dealt with by reducing the pupil relay diameter magnification. Therefore, a pupil relay system with a fixed magnification may be appropriately prepared.

  When the pupil relay system is selected, a fundus image is taken (step S207). At this time, wavefront compensation using the deformable mirror 114 is also performed at the same time. After step S207, it is determined whether or not there is an instruction for enlargement shooting (step S208). If enlargement shooting is instructed, the swing angle of the scanner is changed, and another shooting is performed (step S208). S209).

  At this time, the relationship between the mechanical angle Θ of the scanner and the observation viewing angle θ changes depending on the magnification of the selected pupil relay system. For example, when the pupil relay system has a magnification of 2 times, the observation viewing angle θ is 1 times the mechanical angle Θ of the scanner. When the pupil relay system has a magnification of 1.05, the mechanical angle Θ of the scanner is 0.525 times the observation viewing angle θ. Assuming that the selection magnification of the pupil relay system is β, the relationship θ = 2 / β × Θ is established, so that the fundus photographing is performed again by changing the swing angle of the scanner in accordance with this relationship (step S209). After step S208 or S209, the captured image data is stored (step S210), and the process ends.

In the process of FIG. 4, the magnification β of the pupil relay system is switched so that the reflected light beam diameter from the fundus at the position of the deformable mirror 114 is 80% or more of the effective diameter of the deformable mirror. In this example, the magnification β of the pupil magnification changing unit 121 between the eye 300 to be examined and the deformable mirror and the light beam diameter φ _{H at the} position of the pupil are the light beam diameter on the reflecting surface of the deformable mirror 114 as φ _d There is a relationship of φ _H = 0.3 × β × φ _d . Here, the diameter of the reflecting surface of the deformable mirror 114 is 13.5 mm. Therefore, when φ _H = 7.0 mm, that is, the pupil diameter is 7.0 mm, by selecting β = 2.0, the beam diameter φ _d of the reflected light from the fundus at the deformable mirror position becomes 11.7 mm. . In this case, φ _d (= 11.7 mm) is 86% of the effective diameter (= 13.5 mm) of the deformable mirror 114.

Also, if phi _H is a small value, that is, if the value of the pupil diameter is small, selecting a small value as the value of beta, phi _d is prevented from becoming a small value. That is, in this case, φ _d is 13.5 mm or less and is as close to 13.5 mm as possible.

  FIG. 5 shows an example of actuator arrangement in the deformable mirror. As the luminous flux diameter of the fundus reflection light returning to the deformable mirror surface position is closer to the effective diameter of the deformable mirror, the number of actuators existing in the luminous flux of the fundus reflection light increases, and the wavefront compensation performance is improved. Similarly to the deformable mirror, the wavefront sensor placed at the position of the pupil conjugate plane can effectively use the effective diameter of the wavefront sensor by changing the pupil magnification based on the pupil diameter. Wavefront analysis can be performed.

FIG. 6 shows the pupil diameter D _H , the effective diameter of the deformable mirror 114 (D _d = 13.5 mm), and the beam diameter (φ _d ) of the detection light impinging on the deformable mirror 114 when the processing of FIG. 4 is performed. A table showing the relationship is shown. (Φ _d / D _d ) in the table of FIG. 6 is the effective diameter D of the deformable mirror 114 corresponding to the difference in the pupil diameter D _H using the relational expression of D _H = 0.3 × β × φ _d. it is obtained by calculating the ratio of the beam diameter phi _d of the reflective surface of the deformable mirror 114 for _d.

  As shown in FIG. 6, when the processing of FIG. 4 is performed, the light beam diameter of the detection light hitting the reflecting surface of the deformable mirror 114 by changing the optical magnification of the pupil relay system regardless of the size of the pupil diameter. Can be in the range of 80% to 100% of the effective diameter of the deformable mirror 114. By doing so, the deformable mirror 114 can be used effectively, and wavefront compensation for the wavefront of the reflected light from the fundus can be effectively performed.

(Operation example 2)
FIG. 7 is a flowchart showing an example of an operation performed in the control system of FIG. FIG. 7 shows an example of processing for selecting the optical magnification of the pupil relay system in accordance with the observation viewing angle. When the process is started, first, eye alignment is performed (step S101). In this process, the eye to be examined 300 (see FIG. 2) and the optical axis of the apparatus are aligned. Next, the line of sight of the eye 300 to be examined is fixed using the fixation target 132 (step S102).

  Next, it is determined whether the observation viewing angle is less than 7.5 ° or 7.5 ° or more (step S103). In this example, the upper limit of the observation viewing angle is 20 °, and the observation viewing angle is specified in advance by the user. If the observation viewing angle is less than 7.5 ° (narrow observation viewing angle), the process proceeds to step S104, where the pupil relay system 121a (β = 2) is selected, that is, a relatively high magnification optical system is selected. This processing is performed in the pupil relay system selection unit 319. By selecting the pupil relay system 121a, the pupil relay system 121a is inserted on the optical axis.

  When the pupil relay system 121a is positioned on the optical axis, the measurement light is scanned under a predetermined condition to photograph the fundus 301, and the image is displayed on the display unit 204 (step S105). In this processing, laser light irradiation from the light source 101 is performed while scanning the fundus, and the reflected light is detected by the fundus reflection light detector 113. At this time, the fundus is imaged based on the reflected light from the fundus of the scan light, and an image of the fundus is obtained. Further, the wavefront correction of the detection light is performed simultaneously with the above scan. In this processing, the state of the wavefront of the detection light is detected by the wavefront detection system, and the surface shape of the deformable mirror 114 is deformed so as to suppress the aberration of the wavefront.

  If further magnification observation is instructed by the user, it is accepted by the input unit 220, and the process proceeds from step S106 to step S107. In step S107, the fundus photographing in a narrower region is performed again by changing the swing angle of the scanner. And the data of the image image | photographed by step S105 and step S107 are preserve | saved (step S111), and a process is complete | finished. If there is no instruction for magnification observation in step S106, the fundus image data captured in step S105 is stored (step S111), and the process is terminated.

  Returning to step S103, if the observation viewing angle is 7.5 ° or more, the process proceeds to step S108, and the pupil relay system 121d (β = 1.05) is selected. This process is performed by the pupil relay system selection unit 319. By selecting the pupil relay system 121d, the pupil relay system 121d is arranged on the optical axis. When the pupil relay system 121d is positioned on the optical axis, the measurement light is scanned under a predetermined condition to photograph the fundus 301, and the image is displayed on the display unit 204 (step S109). At this time, the wavefront correction of the detection light is performed as in step S105.

  Next, when an instruction for magnification observation is received from the user, it is accepted by the input unit 220, and the process proceeds from step S110 to step S104, and the processing from step S104 onward is executed. If there is no instruction for magnification observation, the fundus image data captured in step S109 is stored (step S111), and the process is terminated.

  According to the processing of FIG. 7, in the case of wide-angle observation, the optical magnification of the pupil relay system is set to a low magnification. When the optical magnification of the pupil relay system is set to a low magnification, the beam diameter φ at the pupil position is relatively small. For example, when the pupil relay system 121d (β = 1.05) is selected, the light beam diameter φ at the pupil position is φ4.2 mm. In the operation of this example, the purpose of changing the magnification of the pupil relay system is to change the observation viewing angle. Therefore, when the pupil diameter of the eye to be examined is smaller than this, the effectiveness of the wavefront compensation described in the operation example 1 Will be sacrificed. When the pupil diameter of the eye to be examined is larger than this, the measurement light is determined not by the pupil diameter but by the effective diameter of the optical system placed at the pupil conjugate position, and the resolution of the observation image is sacrificed. In this example, wide-angle observation with high-speed scanning is realized on the sacrifice.

(Superiority)
In the above example, by changing the optical magnification of the pupil relay system 121 according to the pupil diameter, the beam diameter of the detection light at the deformable mirror 114 at a conjugate position with the pupil (pupil) even if the pupil diameter varies. Is set to be equal to or larger than a specific ratio of the mirror diameter of the deformable mirror 114. Thereby, even if the pupil diameter is various, the function of correcting the aberration of the deformable mirror 114 can be used effectively, and the deterioration of the image quality of the obtained fundus image can be suppressed.

  In addition, it is possible to obtain high-resolution fundus images while obtaining high-speed scanning performance. Generally, the smaller the mirror diameter of a scanner, the smaller and lighter it is, so it is suitable for high-speed scanning. On the other hand, in pursuit of resolution, it is preferable to make the assumed pupil diameter as large as possible. This is because the spot diameter of the irradiation light on the fundus can be reduced as the pupil diameter increases. However, if the pupil diameter is large, the beam diameter of the detection light incident on the reflecting surface of the scanner at the pupil conjugate position becomes large, so the mirror diameter of the scanner needs to be increased. Alternatively, it is necessary to increase the pupil imaging magnification of the optical system. This is the reason why it is difficult to achieve both a wide observation viewing angle and high resolution with a single ophthalmic apparatus.

In this embodiment, high-speed scanning performance is pursued by selecting a first scanner 117 having a relatively small mirror diameter _DS1 of 4 mm. On the other hand, by making it possible to change the optical magnification of the optical system between the first scanner 117 and the eye to be examined 300, even if the mirror diameter of the scanner is small, high resolution is pursued and a wide-angle field of view is achieved. It is designed to support observation at high frame rates.

In the above example, the magnification of the pupil relay system is set to a high magnification in the observation of the narrow-angle visual field. When the magnification of the pupil relay system is set to a high magnification, the light beam diameter φ _H at the pupil position becomes relatively large, and the optical performance can be determined by the pupil diameter of the eye to be examined. Therefore, the diameter of the light beam (spot diameter) at the irradiation point of the fundus becomes relatively small by darkening the measurement environment or enlarging the pupil diameter of the eye to be examined by using a mydriatic agent. For this reason, the resolution of the optical system is relatively increased, and observation at the photoreceptor cell level becomes possible. That is, a high-resolution enlarged image can be taken. Specifically, when the mirror diameter of the first scanner 117 is 4 mm, it is possible to assume that the maximum pupil diameter is 8 mm if the optical magnification of the pupil relay system is set to 2 times. If the optical magnification of the pupil relay system is set to 1.6 times, the maximum pupil diameter can be assumed only up to 6.4 mm, but the observation viewing angle can be made larger than when the optical magnification is 2 times.

As described above, the mechanical angle Θ of the scanner, the viewing field angle θ, and the selection magnification β of the pupil relay system have a relation of θ = 2 / β × Θ. Therefore, when performing wide-angle observation, the pupil relay system By reducing the optical magnification, the observation viewing angle can be expanded without changing the mechanical angle of the scanner. At this time, the light beam diameter φ _H at the pupil position is relatively small, and in the case where it is smaller than the pupil diameter _{DH of the} eye to be examined, the resolution is determined by φ _H. Specifically, when the optical angle of the pupil relay system is set to 1.05 when the mechanical angle of the scanner 117 is 10 °, the observation viewing angle is 19 °. However, in that case, the light beam diameter φ _H at the pupil position is 4.2 mm, and even if the pupil diameter of the eye to be examined is 4.2 mm or more, the optical system accepts the reflected light beam from the fundus within 4.2 mm. Is limited to the luminous flux. In other words, resolution is sacrificed during wide-angle observation. However, since the observation viewing angle is optically changed without changing the scanner mechanical angle, the observation viewing angle can be widened without sacrificing the high speed of the scanner.

  Thus, an ophthalmologic apparatus capable of performing high-speed scanning at the time of observing a large observation viewing angle while using a scanning device (scanner) selected in pursuit of high-speed scanning and the maximum pupil diameter is obtained.

  DESCRIPTION OF SYMBOLS 100 ... Ophthalmology apparatus, 101 ... Light source, 102 ... Optical fiber, 103 ... Lens (collimator lens), 104 ... Half mirror, 105 ... Wavefront detection part, 106 ... Optical system, 107 ... CCD, 108 ... Lens array, 110 ... Half Mirror, 111 ... lens, 112 ... pinhole, 113 ... fundus reflection light detector, 114 ... deformable mirror, 115 ... relay lens, 116 ... relay lens, 117 ... first scanner, 118 ... relay lens, 119 ... relay lens 120 ... second scanner, 121 ... pupil magnification changing unit, 121a ... pupil relay system (lens system), 121b ... pupil relay system (lens system), 121c ... pupil relay system (lens system), 121d ... pupil relay system ( Lens system), 122 ... mirror, 125 ... diopter correction mechanism, 126 ... diopter correction mirror, 127 ... diopter correction 128, lens system, 129 ... dichroic mirror, 130 ... dichroic mirror, 132 ... fixation target, 133 ... imaging device, 134 ... light source, 300 ... eye to be examined, 301 ... fundus, 302 ... beam splitter, 303 ... beam splitter 304, pupil, 305, wavefront sensor, 306, detector, 307, deformable mirror.

Claims (4)

A measurement light emitting unit that emits measurement light irradiated to the fundus of the eye to be examined; and
A scan unit that scans the measurement light emitted to the fundus;
An optical system disposed between the scan unit and the eye to be examined, the scan unit optical surface in a conjugate relationship with the pupil of the eye to be examined, and an optical system capable of changing the optical magnification;
An ophthalmologic apparatus comprising: a processing unit that performs a process of changing the optical magnification based on a pupil diameter of the eye to be examined or an observation visual field of the fundus of the eye to be examined.   The ophthalmologic apparatus according to claim 1, wherein the processing unit selects a relatively small optical magnification when the pupil diameter of the eye to be examined is relatively small. A wavefront sensor for detecting an aberration of a wavefront of the reflected light of the measurement light from the fundus;
A deformable mirror that deforms the reflection surface to suppress aberration of the wavefront of the reflected light detected by the wavefront sensor,
The change in the optical magnification is performed under a condition in which a relationship between a light beam diameter of the reflected light in the deformable mirror and an effective diameter of the deformable mirror is a specific relationship. Ophthalmic equipment. The processing unit selects a relatively large optical magnification when a high resolution is required for the fundus observation image, and selects a relatively small optical magnification when a relatively large observation field is required. The ophthalmologic apparatus according to any one of claims 1 to 3.

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