JP2018143428A - Ophthalmologic apparatus and ophthalmologic apparatus control program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ophthalmologic apparatus and an ophthalmologic apparatus control program capable of acquiring a condition for an examination or a treatment suitable to a subject.SOLUTION: An ophthalmologic apparatus includes execution means for executing an examination or a treatment of an eye to be examined, information acquisition means for acquiring motion information on the eye to be examined, and condition acquisition means for acquiring an operation condition for the execution means based on the motion information. An ophthalmologic apparatus control program executed in the ophthalmologic apparatus causes the ophthalmologic apparatus to execute an information acquisition step for acquiring the motion information on the eye to be examined, and a condition acquisition step for acquiring the operation condition for the execution means for executing an examination or a treatment of the eye to be examined based on the motion information acquired in the information acquisition step, by being executed by a processor of the ophthalmologic apparatus.SELECTED DRAWING: Figure 5

Description

  The present disclosure relates to an ophthalmologic apparatus and an ophthalmologic apparatus control program for examining or treating an eye to be examined.

  Divides the light from the light source into measurement light and reference light, acquires the interference light of the measurement light and reference light irradiated to the test object, and processes the acquired interference signal to acquire the tomographic image of the test object An OCT apparatus is known (see Patent Document 1). In addition, an ophthalmic laser treatment apparatus for irradiating a subject eye with laser light to treat the subject eye is known (see Patent Document 2).

JP 2009-291252 A Japanese Patent Laying-Open No. 2015-006402

  In the ophthalmologic apparatus as described above, since the fixation state varies depending on the subject, the examination or treatment is not properly performed or takes time.

  In view of the above-described problems, an object of the present disclosure is to provide an ophthalmologic apparatus and an ophthalmologic apparatus control program that can acquire examination or treatment conditions suitable for a subject.

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

(1) An ophthalmologic apparatus, an execution means for examining or treating an eye to be examined, an information acquisition means for acquiring movement information of the eye to be examined, and an operating condition of the execution means based on the movement information And a condition acquisition means for acquiring.
(2) An ophthalmologic apparatus control program executed in an ophthalmologic apparatus, which is executed by a processor of the ophthalmologic apparatus, thereby obtaining an information acquisition step for acquiring movement information of the eye to be examined, and the information acquisition step. Based on the acquired movement information, the ophthalmologic apparatus is caused to execute a condition acquisition step of acquiring an operation condition of an execution means for examining or treating an eye to be examined.

It is the schematic which shows the internal structure of an OCT apparatus. It is a flowchart which shows the control operation of an OCT apparatus. It is a figure which shows an example of a fundus observation image. It is a figure which shows an example of a tomographic image. It is a figure which shows the operation timing of each part. It is a figure which shows the operation timing of each part. It is a figure which shows the operation timing of each part. It is the schematic which shows the internal structure of a laser treatment apparatus. It is a flowchart which shows the control operation of a laser treatment apparatus.

<Embodiment>
Hereinafter, embodiments according to the present disclosure will be described. The ophthalmologic apparatus (for example, the OCT apparatus 1 or the ophthalmic laser apparatus 900) of the present embodiment performs, for example, examination or treatment of the eye to be examined. The ophthalmologic apparatus includes, for example, an execution unit (for example, the OCT optical system 100 or the laser irradiation unit 400), an information acquisition unit (for example, the observation optical system 200, the control unit 70, etc.), and a condition acquisition unit (for example, a control unit). 70). The execution unit examines or treats the eye to be examined. The information acquisition unit acquires movement information of the eye to be examined. The condition acquisition unit acquires the operation condition of the execution unit based on the movement information of the eye to be examined acquired by the information acquisition unit. As a result, the ophthalmologic apparatus can acquire operating conditions for performing examination or treatment suitable for the subject.

  The ophthalmologic apparatus may further include a control unit (for example, the control unit 70). The control unit controls the execution unit based on the operation condition acquired by the condition acquisition unit. Thereby, the ophthalmologic apparatus can easily perform examination or treatment suitable for the subject.

  The movement information is information indicating the fixation state of the eye to be examined, for example. For example, the motion information may be a stable time. The stable time represents, for example, a time during which the fixation of the eye to be examined is stable. That is, the longer the stabilization time, the more stable the fixation state. Further, the movement information may be, for example, the amount of movement of the eye to be examined. The amount of movement represents the amount of movement of the eye to be examined. For example, the greater the amount of movement, the more unstable the fixation state.

  The information acquisition unit may include an imaging unit (for example, the observation optical system 200). The imaging unit captures an observation image of the eye to be examined, for example. In this case, the information acquisition unit may acquire motion information based on the observation image captured by the imaging unit. For example, the information acquisition unit may acquire the motion information based on a difference between at least two temporally different observation images captured by the imaging unit. The information acquisition unit may acquire motion information based on the SN ratio of the observation image captured by the imaging unit. The information acquisition unit may acquire motion information based on a correlation between at least two temporally different observation images captured by the imaging unit.

  Note that the imaging unit mainly captures an observation image used for alignment (alignment) between the ophthalmologic apparatus and the eye to be examined, for example. The imaging unit may be, for example, a scanning laser ophthalmoscope (SLO), a fundus camera, an anterior eye camera, or the like. An OCT optical system may be used as an imaging unit. Note that the information acquisition unit may include, for example, a laser displacement meter and acquire movement information of the eye to be examined.

  The execution unit may include an OCT optical system (for example, the OCT optical system 200). For example, the OCT optical system acquires a tomographic image of the eye to be inspected based on interference light between measurement light and reference light corresponding to the measurement light. In this case, the condition acquisition unit may acquire a tomographic image capturing condition (operation condition) based on the motion information. Since the degree of fixation stability varies depending on the subject, the control unit can acquire a good tomographic image by setting imaging conditions suitable for the subject.

  For example, the imaging condition may be a continuous imaging time for tomographic images. In this case, for example, as the imaging condition, the higher the fixation stability, the longer the continuous imaging time, and the lower the fixation stability, the shorter the continuous imaging time. By controlling the OCT optical system based on such imaging conditions, the imaging time can be shortened for a subject whose fixation is stable. In addition, the success rate of imaging can be increased for subjects with unstable fixation.

  The imaging condition may be the number of continuous tomographic images. In this case, for example, as the imaging condition, the higher the fixation stability, the larger the number of consecutive shots, and the lower the fixation stability, the smaller the number of consecutive shots.

  Further, the imaging condition may be a motion amount threshold value for determining whether to change the imaging position of the OCT optical system based on the motion amount of the eye to be examined. In this case, for example, in the shooting conditions, the higher the fixation stability, the smaller the movement amount threshold, and the lower the fixation stability, the larger the movement amount threshold. By controlling the OCT optical system according to such imaging conditions, a better image can be captured for a subject whose fixation is stable. In addition, for a subject with unstable fixation, imaging time can be shortened by roughly tracking.

  Further, the shooting condition may be the update frequency of the shooting parameter. For example, the imaging parameter is the focus or optical path length of the OCT optical system. In this case, for example, in the imaging conditions, the higher the fixation stability, the lower the imaging parameter update frequency, and the lower the fixation stability, the higher the imaging parameter update frequency. By controlling the OCT optical system under such imaging conditions, the imaging time can be shortened for a subject whose fixation is stable. In addition, the image quality can be improved for a subject whose fixation is unstable.

  Further, the shooting condition may be a shooting range of the observation image. In this case, for example, the condition acquisition unit acquires the imaging range of the observation image that matches the imaging time of the tomographic image. Thereby, the OCT optical system and the imaging unit can be easily synchronized.

  Note that the control unit may stop the tracking function based on the movement information of the eye to be examined. The tracking function is a function for causing the imaging position of the OCT optical system to follow the movement of the eye to be examined, for example. For example, when the stability of fixation is low, the control unit can suppress an increase in shooting time by stopping the tracking function.

  Note that the control unit may update the imaging conditions while imaging the eye to be examined by the OCT optical system. For example, the control unit may update the shooting condition to the shooting condition newly acquired by the condition acquisition unit. As a result, even when the fixation stability changes during shooting, shooting can be performed under appropriate conditions.

  The OCT optical system may photograph OCT Angiography. OCT Angiography is, for example, a blood vessel image based on motion contrast calculated from a plurality of tomographic images acquired by an OCT optical system. OCT Angiography takes time because it requires multiple tomographic images taken at different times. Therefore, the entire imaging time can be shortened by changing the imaging conditions based on the movement information of the eye to be examined. For example, the number of tomographic images acquired at one scanning position may be changed based on the movement information of the eye to be examined. In this case, for example, as the imaging condition, the higher the stability of fixation, the larger the number of images acquired at one scanning position, and the lower the stability of fixation, the smaller the number of images acquired at one scanning position. .

  The execution unit may include a laser irradiation unit (for example, the laser irradiation unit 400). A laser irradiation part irradiates a test subject with a laser beam, for example. In this case, the condition acquisition unit may acquire an irradiation condition (operation condition) when irradiating the eye to be examined with laser based on the motion information. For example, the irradiation condition may be a maximum laser irradiation time or a laser irradiable region. For example, the irradiation condition is such that the higher the fixation stability, the longer the maximum irradiation time is, and the lower the fixation stability, the shorter the maximum irradiation time. Further, for example, the irradiation condition is such that the higher the fixation stability, the wider the irradiable area is than the predetermined area, and the lower the fixation stability, the narrower the irradiable area is than the predetermined area. By controlling the laser irradiation unit under such irradiation conditions, appropriate and efficient treatment can be performed for each subject.

  The control unit may execute an ophthalmologic apparatus control program stored in the storage unit (storage unit 74) or the like. The ophthalmologic apparatus control program includes, for example, an information acquisition step and a condition acquisition step. The information acquisition step is a step of acquiring movement information of the eye to be examined. The condition acquisition step is a step of acquiring the operation condition of the execution unit based on the motion information acquired in the acquisition step.

<Example>
The OCT apparatus 1 of the present embodiment will be described. FIG. 1 is a schematic diagram showing the internal configuration of the OCT apparatus 1. As shown in FIG. 1, the OCT apparatus 1 includes an OCT optical system 100, an observation optical system 200, a fixation target projection unit 300, a control unit 70, and the like.

<OCT optical system>
For example, the OCT optical system 100 irradiates the eye E with measurement light and acquires an OCT signal acquired by the reflected light and the measurement light. For example, the OCT optical system 100 captures a tomographic image of the eye E by acquiring an OCT signal.

  The OCT optical system 100 is a so-called optical coherence tomography (OCT) optical system. The OCT optical system 100 splits the light emitted from the measurement light source 102 into measurement light (sample light) and reference light by a coupler (light splitter) 104. Then, the OCT optical system 100 guides the measurement light to the fundus oculi Ef of the eye E by the measurement optical system 106. The measurement optical system 106 includes, for example, a scanning unit (for example, an optical scanner) 108. For example, the scanning unit 108 changes the scanning position of the measurement light on the eye to be examined in order to change the imaging position on the eye to be examined. The OCT optical system 100 guides the reference light to the reference optical system 130. Thereafter, the detector 120 receives interference light obtained by combining the measurement light reflected by the eye E and the reference light.

  The detector 120 detects an interference state between the measurement light and the reference light. In the case of Fourier domain OCT, the spectral intensity of the interference light is detected by the detector 120, and a depth profile (A scan signal) in a predetermined range is obtained by Fourier transform on the spectral intensity data. Examples include Spectral-domain OCT (SD-OCT) and Swept-source OCT (SS-OCT). Moreover, Time-domain OCT (TD-OCT) may be used.

  In the case of SD-OCT, a low-coherent light source (broadband light source) is used as the light source 102, and the detector 120 is provided with a spectroscopic optical system (spectrometer) that separates interference light into each frequency component (each wavelength component). . The spectrometer includes, for example, a diffraction grating and a line sensor.

  In the case of SS-OCT, a wavelength scanning light source (wavelength variable light source) that changes the emission wavelength at a high speed in time is used as the light source 102, and a single light receiving element is provided as the detector 120, for example. The light source 102 includes, for example, a light source, a fiber ring resonator, and a wavelength selection filter. Examples of the wavelength selection filter include a combination of a diffraction grating and a polygon mirror, and a filter using a Fabry-Perot etalon.

  The light emitted from the light source 102 is split into a measurement light beam and a reference light beam by the coupler 104. Then, the measurement light flux passes through the optical fiber and is then emitted into the air. The light beam is condensed on the fundus oculi Ef via the optical member of the measurement optical system 106. Then, the light reflected by the fundus oculi Ef is returned to the optical fiber through a similar optical path.

  The scanning unit 108 scans the measurement light in the XY direction (transverse direction) on the fundus. The scanning unit 108 is disposed at a position substantially conjugate with the pupil. For example, the scanning unit 108 is a galvano scanner having two galvanometer mirrors, and the reflection angle thereof is arbitrarily adjusted by the drive mechanism 50.

  Thereby, the reflection (advance) direction of the light beam emitted from the light source 102 is changed and scanned in an arbitrary direction on the fundus. Note that scanning the measurement light in the optical axis direction of the measurement light is referred to as “A scan”, and scanning the measurement light in a direction intersecting the optical axis direction of the measurement light is referred to as “B scan”. The scanning unit 108 performs B scan. The scanning unit 108 may be configured to deflect light. For example, in addition to a reflective mirror (galvano mirror, polygon mirror, resonant scanner), an acousto-optic device (AOM) that changes the traveling (deflection) direction of light is used.

  The reference optical system 130 generates reference light that is combined with reflected light acquired by reflection of measurement light at the fundus oculi Ef. The reference optical system 110 may be a Michelson type or a Mach-Zehnder type. The reference optical system 130 is formed by, for example, a reflection optical system (for example, a reference mirror), and reflects light from the coupler 104 back to the coupler 104 by being reflected by the reflection optical system and guides it to the detector 120. As another example, the reference optical system 130 is formed by a transmission optical system (for example, an optical fiber), and guides the light from the coupler 104 to the detector 120 by transmitting the light without returning.

  The reference optical system 130 has a configuration that changes the optical path length difference between the measurement light and the reference light by moving an optical member in the reference light path. For example, the reference mirror is moved in the optical axis direction. The configuration for changing the optical path length difference may be arranged in the measurement optical path of the measurement optical system 106.

<Observation optics>
The observation optical system 200 captures an observation image of the eye to be examined. The observation image may be, for example, a front image of the fundus oculi Ef or an anterior ocular segment image. The observation optical system 200 of this embodiment is a so-called scanning laser ophthalmoscope (SLO). For example, the observation optical system 200 includes, for example, an SLO light source 61, a focusing lens 63, a scanning unit 64, a relay lens 65, and the like. The SLO light source 61 is a light source that emits highly coherent light. For example, a laser diode light source with λ = 780 nm is used. The focusing lens 63 is movable in the optical axis direction according to the refractive error of the eye to be examined. The scanning unit 64 includes a combination of a galvanometer mirror and a polygon mirror that can scan the measurement light in the XY directions at high speed on the fundus by driving the driving unit 52. The relay lens 65 relays the measurement light reflected by the scanning unit 64 to the objective lens 10.

  A beam splitter 62 is disposed between the SLO light source 61 and the focusing lens 63. In the reflection direction of the beam splitter 62, a condensing lens 66, a confocal aperture 67 placed at a conjugate position with the fundus, and a light receiving element 68 are provided.

  Laser light (measurement light) emitted from the SLO light source 61 passes through the beam splitter 62, then reaches the scanning unit 64 via the focusing lens 63, and the reflection direction is changed by driving a galvanometer mirror, a polygon mirror, or the like. . The laser light reflected by the scanning unit 64 is transmitted through the dichroic mirror 40 via the relay lens 65 and then condensed on the fundus of the eye to be examined via the objective lens 10.

  The laser light reflected from the fundus is reflected by the beam splitter 62 through the objective lens 10, the relay lens 65, the scanning unit 64, and the focusing lens 63. Thereafter, the light is condensed by the condenser lens 66 and then detected by the light receiving element 68 through the confocal aperture 67. Then, the light reception signal detected by the light receiving element 68 is input to the control unit 70. The control unit 70 acquires a front image of the fundus of the eye to be examined based on the light reception signal obtained by the light receiving element 68. The acquired front image is stored in the storage unit 74. The acquisition of the SLO image is performed by vertical scanning (sub-scanning) of laser light by a galvanometer mirror provided in the scanning unit 64 and horizontal scanning (main scanning) of laser light by a polygon mirror.

  Note that the configuration of the observation optical system 200 may be a so-called fundus camera type configuration. The OCT optical system 100 may also be used as the observation optical system 200. That is, the front image may be acquired using data forming a tomographic image obtained two-dimensionally (for example, an integrated image in the depth direction of the three-dimensional tomographic image, at each XY position). The integrated value of the spectrum data.

<Fixed target projection unit>
The fixation target projecting unit 300 includes an optical system for guiding the line-of-sight direction of the eye E. For example, the projection unit 300 presents a fixation target to the eye E. The fixation target projection unit 300 includes, for example, a visible light source that emits visible light. The fixation projection unit 300 may be an internal fixation lamp type or an external fixation lamp type.

<Control unit>
For example, the control unit 70 is realized by a general CPU (Central Processing Unit) 71, a ROM 72, a RAM 73, and the like. The ROM 72 of the control unit 70 has an OCT signal processing program for processing an OCT signal, various programs for controlling the operation of a device (for example, the OCT optical system 100) connected to the OCT signal processing apparatus 1, and an initial value. Values are stored. The RAM 73 temporarily stores various information. The control unit 70 may be configured by a plurality of control units (that is, a plurality of processors).

  As shown in FIG. 1, for example, a storage unit (for example, a non-volatile memory) 74, an operation unit 76, a display unit 75, and the like are electrically connected to the control unit 70. The storage unit 74 is a non-transitory storage medium that can retain stored contents even when power supply is interrupted. For example, a hard disk drive, a flash ROM, a removable USB memory, or the like can be used as the storage unit 74.

  Various operation instructions by the examiner are input to the operation unit 76. The operation unit 76 outputs a signal corresponding to the input operation instruction to the CPU 71. For the operation unit 76, for example, at least one of user interfaces such as a mouse, a joystick, a keyboard, and a touch panel may be used.

  The display unit 75 may be a display mounted on the apparatus main body or a display connected to the main body. A display of a personal computer (hereinafter referred to as “PC”) may be used. A plurality of displays may be used in combination. The display unit 75 may be a touch panel. When the display unit 75 is a touch panel, the display unit 75 functions as the operation unit 76. The display unit 75 displays, for example, image data obtained by processing the OCT signal acquired by the OCT optical system 100.

<Control action>
The control operation of the OCT apparatus 1 as described above will be described based on the flowchart of FIG. In the following description, a case where OCT angiography is performed will be described. OCT Angiography is a blood vessel image based on motion contrast calculated from a plurality of images taken of the same part. Note that the steps shown in FIG. 2 are not necessarily performed in the order described below.

(Step S1: Alignment)
The control unit 70 first aligns the optical system with respect to the eye to be examined. For example, the control unit 70 projects the fixation target onto the subject by the fixation target projection unit 300. Then, the control unit 70 automatically controls the driving unit (not shown) so that the measurement optical axis comes to the center of the eye E based on the anterior ocular segment observation image taken by the anterior eye imaging camera (not shown). Align with.

(Step S2: Preliminary shooting)
The control unit 70 performs preliminary photographing with the observation optical system 200 for a certain time (for example, 0.5 seconds) in order to observe the movement of the eye to be examined. For example, the observation optical system 200 scans the fundus of the subject's eye with measurement light and captures a fundus observation image 91 (see FIG. 3). The control unit 70 captures a plurality of fundus observation images 91 using the observation optical system 200. A fundus observation image 91 photographed by the observation optical system 200 is stored in the storage unit 74. Note that the tomographic image 92 (see FIG. 4) may be captured by the OCT optical system 100 while the fundus observation image 91 is captured. The tomographic image 92 photographed at this time is used for adjustment of photographing parameters of the OCT optical system 100, for example. For example, the control unit 70 adjusts imaging parameters such as the focus or optical path length of the OCT optical system 100 according to the position of the fundus in the tomographic image 92 or the brightness of the image.

(Step S3: Calculation of stabilization time)
The control unit 70 calculates the time during which the subject eye is stable (stable time) based on the captured image. The control unit 70 calculates the amount of movement of the subject's eye based on the deviation of the plurality of fundus observation images 91 photographed in step S2. In this case, the control unit 70 calculates a shift between images by image processing such as a phase-only correlation method or feature point matching. Then, the control unit 70 calculates a time during which the movement of the eye to be examined, which is converted from the image shift, is stable below a preset threshold (for example, 0.5 pixel or 10 μm). For example, the control unit 70 calculates the movement of the eye to be examined between the fundus observation images, and when the calculated value exceeds 0.5 pixel, from the start of the acquisition of the first image, the imaging of the image exceeding the threshold is started. The time until the previous time is regarded as a stable time. When comparing the images, the first image at the start of shooting may be compared as a reference, or an image shot before this shooting may be compared as a reference.

(Step S4: Setting of shooting conditions)
Subsequently, the control unit 70 acquires and sets the tomographic image capturing conditions based on the stabilization time calculated in step 32. The imaging conditions include, for example, a tracking function, a continuous imaging time of tomographic images, a continuous imaging number of tomographic images, and the like. For example, the tracking function is a function of correcting the imaging position of the tomographic image based on the amount of movement of the eye to be examined. The continuous imaging time is, for example, a time for continuously capturing tomographic images without performing tracking control. Similarly, the number of continuous shots is the number of tomographic images that are continuously shot without performing tracking control.

  When setting about a tracking function, the control part 70 may set the movement threshold value which a tracking function works according to the length of stable time, for example. In this case, when the stabilization time is short, the control unit 70 may set a large movement threshold value at which the tracking function works. That is, the tracking function is prevented from working only by a slight movement of the fundus. Further, the control unit 70 may switch the tracking function ON and OFF according to the length of the stable time, for example. For example, the control unit 70 may turn off the tracking function when the stabilization time is shorter than a predetermined value.

  Moreover, when setting the continuous imaging time of a tomographic image, the control part 70 sets continuous imaging time according to the length of stable time, for example. For example, the control unit 70 sets the continuous shooting time longer as the stabilization time is longer. For example, the control unit 70 may set 80% of the stable time as the continuous shooting time.

  Further, when setting the number of continuously shot images, the control unit 70 may set the number of continuously shot images according to the length of the stable time. For example, the longer the stabilization time, the larger the number of continuous shots. For example, when the stabilization time is longer than a predetermined value, the control unit 70 captures more images for a predetermined number of images. For example, when the stabilization time is 80 milliseconds or more, the control unit 70 changes the number of shots from 4 to 8.

(Step S5: Main shooting)
The control unit 70 performs shooting under the set shooting conditions. First, the control unit 70 captures a tracking fundus observation image 91 by the observation optical system 200. For example, as shown in FIG. 3, a fundus observation image 91 in a predetermined range including a predetermined tomographic image capturing position (for example, scan lines SL1 to SLn in FIG. 3) is captured. When the control unit 70 captures the fundus observation image 91 once, the control unit 70 captures the fundus observation image 91 in the same range again. In this manner, the control unit 70 repeatedly captures the fundus observation image 91 within a predetermined range and observes the eye to be examined.

  For example, the control unit 70 performs control to associate preset scanning positions (for example, the scan lines SL1 to SLn) with the fundus observation image 91 photographed for the first time. Then, the control unit 70 scans the associated scanning position and captures a tomographic image 92 as shown in FIG. The control unit 70 controls the observation optical system 200 and the OCT optical system 100 in synchronization, and captures a predetermined number of tomographic images 92 while capturing one fundus observation image 91. For example, while the OCT optical system 100 captures a plurality of tomographic images 92 on the scan line SL1, the control unit 70 performs the second capturing of the fundus observation image 91 by the observation optical system 200.

  Subsequently, the control unit 70 obtains the movement amount of the eye to be inspected based on the fundus observation image 91 photographed for the first time and the fundus observation image 91 photographed for the second time. The amount of movement is obtained from the amount of deviation of the fundus observation image 91, for example, as in step S3. The control unit 70 performs control (tracking control) for correcting the next scanning position (for example, the scan line SL2) based on the obtained amount of motion. Then, the control unit 70 captures a plurality of tomographic images at the corrected scanning position. Similarly, the control unit 70 performs tracking control of the OCT optical system 100 based on the latest fundus observation image 91, and takes a predetermined number of tomographic images 92 in each scan line. The captured image is stored in the storage unit 74.

  FIG. 5 is a diagram illustrating timings of operations of the observation optical system 200, the OCT optical system 100, and the control unit 70 (for example, tracking control by the CPU 71) in steps S2 to S5. FIG. 5A shows a case where the stabilization time is within a predetermined range, and FIG. 5B shows a case where the stabilization time is longer than the predetermined range. In the case of FIG. 5A, for example, the number of continuous shots is set to four. Therefore, the control unit 70 controls the OCT optical system 100 and the observation optical system 200 in synchronization, and captures four tomographic images 92 while capturing one fundus observation image 91.

  In the case of FIG. 5B, since the stabilization time is longer than the predetermined range, in step S4, for example, the control unit 70 sets the number of continuously shot images to 8. Therefore, in step S5, the control unit 70 controls the OCT optical system 100 and the observation optical system 200 in synchronization, and captures eight tomographic images 92 while capturing one fundus observation image 91. Take a picture. In this case, the control unit 70 may capture eight tomographic images 92 at one scanning position, or may capture several tomographic images 92 at a plurality of scanning positions. As shown in FIGS. 5A and 5B, by setting a large number of continuous shots when the stabilization time is long, the tracking control frequency is changed from once to four shots to eight shots. The total measurement time can be shortened by reducing to one time.

(Step S6: Calculation of motion contrast)
The control unit 70 acquires the motion contrast based on the plurality of OCT signals acquired in each scan line as described above. Motion contrast captures, for example, blood flow, object movement, or change. For example, the control unit 70 processes a plurality of OCT signals stored in the storage unit 74 and acquires a complex OCT signal. For example, the control unit 70 performs a Fourier transform on the OCT signal. For example, when the signal at the nth (x, z) position in N OCT images is represented by An (x, z), the control unit 70 converts the complex OCT signal An (x, z) by Fourier transform. obtain. The complex OCT signal An (x, z) includes a real component and an imaginary component.

  The control unit 70 processes the acquired complex OCT signal and acquires motion contrast. As a method of processing the complex OCT signal, for example, a method of calculating an intensity difference of the complex OCT signal, a method of calculating a phase difference of the complex OCT signal, a method of calculating a vector difference of the complex OCT signal, a level of the complex OCT signal, and the like. A method of multiplying a phase difference and a vector difference, a method of using signal correlation (correlation mapping), a method of calculating decorrelation of signal strength, a method of using a ratio between the maximum value and the minimum value of the strength, and the like are conceivable. In this embodiment, a method for calculating a phase difference will be described as an example.

First, the control unit 70 calculates a phase difference with respect to the complex OCT signal A (x, z) acquired at least at two different times at the same position. The CPU 71 calculates the change in phase using, for example, the following equation (2). For example, when different times T are measured N times, time T ₁ and time T ₂ , time T ₂ and time T ₃ ,..., Time T _(n−1) and time T _n total (n -1) calculation is performed, and (n-1) pieces of data are calculated. Of course, the combination of time is not limited to the above, and the combination may be changed as long as the time is different. Note that A _n in the equation represents a signal acquired at time T _n , and * represents a complex conjugate.

  In this manner, the control unit 70 acquires a phase difference profile in the depth direction (A scan direction) related to the phase difference of the complex OCT signal. For example, the control unit 70 acquires a luminance profile whose luminance is determined according to the size of the phase difference profile, and acquires a motion contrast image in which the luminance profiles are arranged in the B scan direction.

  As described above, the OCT apparatus of the present embodiment can shorten the measurement time by using the OCT image capturing condition based on the movement information (for example, the stabilization time) of the eye to be examined. For example, when the subject's fixation state is stable, the number of times of tracking control is reduced by increasing the number of continuous shots. As a result, the entire imaging time is shortened, and the burden on the subject can be reduced.

  When the subject's fixation state is stable, for example, the control unit 70 increases the resolution of the image by increasing the continuous imaging time and decreasing the scanning speed per one of the tomographic images 92. May be high. For example, FIG. 6 shows a case where the B-scan speed is slowed without changing the number of tomographic images continuously taken when the fixation state of the eye to be examined is stable. By slowing down the B scan speed, the A scan signal can be acquired more densely in one B scan, so that the resolution of the tomographic image 92 can be increased. Further, the control unit 70 may acquire a wide range of tomographic images 92 by expanding the imaging range instead of reducing the B scan speed. Thus, the tomographic image 92 can be imaged under imaging conditions suitable for the subject according to the fixation state.

  If the stabilization time is short, the control unit 70 may reduce the number of continuously captured tomographic images 92. For example, when the stabilization time is shorter than a predetermined range, the number of continuously shot tomographic images 92 may be reduced from four to two. Thereby, the frequency of tracking control can be increased and the shift of the scanning position can be suppressed.

  Further, when the stabilization time is short, the control unit 70 may turn off the tracking function. When the tracking function is turned on, for example, when the fixation time of the subject's fixation is shorter than the tracking control interval, the control cannot catch up, so that it may take time for imaging. Therefore, by turning off the tracking function, the tracking control time can be shortened, and the entire measurement time can be shortened.

  As shown in FIG. 6, the control unit 70 may synchronize the observation optical system 200 and the OCT optical system 100 by changing the photographing time of the fundus observation image 91. For example, the control unit 70 may match the continuous imaging time of the tomographic image 92 by increasing the time of one imaging of the fundus observation image 91. When the observation optical system 200 is SLO as in this embodiment, the imaging time is lengthened by slowing the scanning speed when capturing the fundus observation image 91.

  Note that the control unit 70 may adjust the imaging time of the fundus observation image 91 and the continuous imaging time of the tomographic image 92 by changing the imaging range of the fundus observation image 91. For example, as illustrated in FIG. 7, when the fundus observation image 91 is captured, the imaging time of the fundus observation image 91 may be adjusted by changing the scanning range without changing the scanning speed.

  Further, the control unit 70 may change the imaging condition of the tomographic image 92 set in step 4 during the imaging of the tomographic image 92 in step S5. In this case, for example, the control unit 70 may observe the movement of the eye to be inspected by the fundus observation image 91 continuously photographed in step S5 and update the photographing condition based on the observation result. For example, as shown in FIG. 7, the control unit 70 may change the number of continuously captured tomographic images 92 from 8 to 6 in the middle of step S5.

  Further, the control unit 70 may set the update frequency of the imaging parameters (focus, optical path length, etc.) of the OCT optical system 100 based on the stabilization time. For example, the control unit 70 may set the imaging parameter update frequency low because the eye to be examined does not move much when the stabilization time is long. As a result, the imaging time can be shortened for a subject whose fixation state is stable. Conversely, when the stabilization time is short, there is a lot of movement of the eye to be examined, and therefore the control unit 70 may set the imaging parameter update frequency high to suppress the deterioration of the image quality.

  Note that the control unit 70 may set an eye movement threshold value such that photographing is completed within a preset maximum photographing time based on a fundus observation image group at the time of preliminary photographing. For example, the control unit 70 calculates an imaging success rate for completing the imaging within the maximum imaging time based on the maximum imaging time, the time required for imaging one tomographic image, and the required number of tomographic images. And the control part 70 is the ratio of the image (image which does not exceed a movement threshold value) in which imaging | photography succeeded among the fundus observation image group at the time of preliminary imaging, and the image (image exceeding a movement threshold value) in which imaging | photography failed. A movement threshold is set so as to satisfy the calculated shooting success rate. As a result, it is expected that shooting will be completed within the maximum shooting time at the longest.

  Note that the control unit 70 may determine a feature point of the eye to be examined from the fundus observation image 91 photographed in Step 2 and use the feature point for motion detection. For example, the control unit 70 can appropriately adjust the shooting position by performing tracking control so that the feature point is at a constant position. For example, when the image of the macular region is unclear due to a disease such as cataract, the movement of the eye to be examined can be accurately detected regardless of the state of the eye to be examined by performing motion detection using the nipple as a feature point.

  In addition, the control unit 70 measures the transfer rate when capturing the tomographic image 92 during the preliminary photographing in step 2, and if the transfer rate of the system (such as the control unit 70 or an external computer) is low, the tomographic image is acquired. The imaging cycle (for example, continuous imaging time) of the 92 and the fundus observation image 91 may be extended. As a result, it is possible to prevent the image capturing speed from following the shooting cycle and prevent the image from being transferred, and it is possible to perform shooting under optimal conditions even when a plurality of applications are executed or the system is deteriorated.

  Note that, when the observation optical system 200 is an optical system that scans measurement light such as SLO as in the present embodiment, the control unit 70 displays the fundus observation image 91 because the photographing time varies depending on the position of the image. By dividing, eye movement may be measured in a finer time. As a result, the control unit 70 can increase the measurement accuracy of the stable time when calculating the stable time in Step 3. This can also be realized by reducing the number of lines on the slow axis (y axis in FIG. 3) of the SLO image.

  Note that the imaging condition may not be automatically set by the control unit 70. For example, the control unit 70 may present an appropriate imaging condition to the examiner according to the stabilization time. For example, the examiner may select recommended imaging conditions displayed on the display unit. The control unit 70 may change the OCT imaging conditions according to the selected imaging conditions. This makes it possible to set imaging conditions that suit the examiner's preference.

  In the above-described embodiment, the control unit 70 determines the movement of the eye to be examined based on the shift amount of the fundus observation image 91 when measuring the stabilization time. However, the present invention is not limited to this. For example, the control unit 70 may determine the movement of the eye to be examined based on the SN ratio of the photographed fundus observation image 91. If the eye to be examined moves due to blinking or the like, the signal is considered to be small. Therefore, the control unit 70 may determine that the eye to be examined has moved when the SN ratio has decreased. For example, the control unit 70 may calculate the time until the SN ratio of the fundus observation image 91 falls below a certain value as the stable time.

  Note that the OCT optical system 100 may be used as the observation optical system 200. At this time, the control unit 70 can determine that the eye is not moving when the correlation value between the tomographic images taken at the same scanning position exceeds a predetermined threshold, and when the correlation value does not exceed the threshold, Since it can be determined that is moving, the stabilization time can be calculated.

  For example, the control unit may determine the movement of the eye to be examined based on the correlation information of the OCT signal. For example, in the provisional imaging in step S1, a plurality of tomographic images may be captured at the same position, and when the correlation between them is low, it may be determined that the eye to be examined has moved, and the stabilization time may be measured. Note that, as an evaluation value for evaluating the correlation, for example, a degree of difference such as SSD (sum of squares of differences in luminance values), SAD (sum of absolute values of differences in luminance values), or the like is calculated. Good. In this case, the smaller the difference is, the more correlation is obtained. As the evaluation value, a similarity such as normalized cross-correlation (NCC, ZNCC, etc.) may be calculated. In this case, the closer the similarity is to 1, the more correlation is obtained.

<Second embodiment>
Subsequently, a second example according to the present disclosure will be described. The second embodiment is a laser treatment apparatus 900 that irradiates a subject's eye with laser light. For example, the laser irradiation unit 400, the observation optical system 200, and the control unit 70 are mainly provided. Since the observation optical system 200 and the control unit 70 are the same as those in the first embodiment, the description is omitted here and the laser irradiation unit 400 is described.

  For example, the laser irradiation unit 400 oscillates a therapeutic laser beam and irradiates the patient's eye E with the laser beam. For example, the laser irradiation unit 400 includes a laser light source 401, a focusing lens 402, a driving unit 403, a scanning unit 408, and the like. The laser light source 401 oscillates treatment laser light (for example, a wavelength of 532 nm). The focusing lens 402 is moved by the driving unit 403 to adjust the focus of the laser light. The scanning unit 408 includes, for example, a drive mirror 409, a drive unit 450, and the like. The drive unit 450 changes the angle of the reflection surface of the drive mirror 409.

  The light emitted from the laser light source 401 is reflected by the scanning unit 408 and the dichroic mirror 40 through the focusing lens 402 and is condensed on the fundus oculi Ef through the objective lens 10. At this time, the irradiation position of the laser beam on the fundus oculi Ef is changed by the scanning unit 408.

  The control operation of the laser treatment apparatus 900 will be described using the flowchart of FIG. First, in step S11, the control unit 70 adjusts the positional relationship of the laser treatment apparatus with respect to the eye to be examined by a drive unit (not shown). In step S <b> 12, the control unit 70 performs preliminary imaging of the eye to be examined for a certain period of time using the observation optical system 200. In step S <b> 13, the control unit 70 calculates a stabilization time based on the fundus observation image 91. Up to this point, the process is the same as in the first embodiment. In step S14, the control unit 70 acquires and sets the laser irradiation conditions such as the maximum irradiation time and the irradiation possible area according to the length of the stable time. In step S15, the control unit 70 irradiates the eye to be examined with a laser according to the set irradiation conditions.

  Thus, in the apparatus of the second embodiment, safe treatment can be performed regardless of the state of the patient's eye by using the laser irradiation condition according to the length of the stable time. For example, in the case of a patient with unstable fixation, there is a possibility that an unintended portion is irradiated with a laser because the eye moves during irradiation. When the macula is irradiated, the visual field may be lost. Therefore, for example, if the patient is unstable, the control unit 70 shortens the maximum irradiation time or narrows the irradiable area. In addition, if the patient has a stable fixation, the control unit 70 increases the maximum irradiation time or widens the irradiation possible area. Thereby, a safe and effective treatment for the patient can be performed.

  The OCT apparatus according to the first embodiment may be configured to include the laser irradiation unit 400 as in the second embodiment and to irradiate the eye to be examined with a laser. Further, the laser treatment apparatus of the second embodiment may be configured to include the OCT optical system 100 as in the first embodiment and to take a tomographic image.

1 OCT apparatus 70 Control unit 71 CPU
72 ROM
73 RAM
74 Memory 75 Monitor 76 Operation Unit 100 OCT Optical System 108 Scanning Unit 200 Observation Optical System 300 Fixation Target Projection Unit 400 Laser Irradiation Unit 900 Laser Therapy Device

Claims (20)

An ophthalmic device,
Execution means for examining or treating the eye;
Information acquisition means for acquiring movement information of the eye to be examined;
Condition acquisition means for acquiring an operation condition of the execution means based on the movement information;
An ophthalmologic apparatus comprising:   The ophthalmologic apparatus according to claim 1, further comprising a control unit that controls the execution unit based on the operation condition.   3. The ophthalmologic apparatus according to claim 1, wherein the movement information is a stable time indicating a time during which the fixation of the eye to be examined is stable.   The ophthalmologic apparatus according to claim 1, wherein the movement information is a movement amount of the eye to be examined.   The said information acquisition means is provided with the imaging | photography means which image | photographs the observation image of the said to-be-tested eye, The said movement information is acquired based on the observation image image | photographed by the said imaging | photography means. Any ophthalmic device.   The ophthalmologic apparatus according to claim 5, wherein the information acquisition unit acquires the motion information based on a shift between the observation images that are temporally different from each other imaged by the imaging unit.   The ophthalmic apparatus according to claim 5 or 6, wherein the information acquisition unit acquires the motion information based on an SN ratio of the observation image captured by the imaging unit. The execution means includes an OCT optical system that acquires a tomographic image of the eye based on interference light between measurement light and reference light corresponding to the measurement light,
The ophthalmologic apparatus according to claim 1, wherein the condition acquisition unit acquires an imaging condition of the tomographic image as the operation condition.   The ophthalmologic apparatus according to claim 8, wherein the imaging condition is a continuous imaging time of the tomographic image.   The ophthalmologic apparatus according to claim 8 or 9, wherein the imaging condition is the number of continuous imaging of the tomographic image.   11. The movement amount threshold value for determining whether or not to change the imaging position of the OCT optical system based on the movement amount of the eye to be examined. Ophthalmic equipment.   The ophthalmologic apparatus according to claim 8, wherein the imaging condition is an update frequency of imaging parameters.   The ophthalmologic apparatus according to claim 8, wherein the photographing condition is a photographing range of the observation image.   The ophthalmologic apparatus according to any one of 8 to 13, wherein the control unit stops a tracking function for causing the imaging position of the OCT optical system to follow the movement of the eye to be examined based on the imaging conditions.   15. The ophthalmologic apparatus according to claim 8, wherein the control unit updates the imaging condition while controlling the OCT optical system based on the imaging condition.   The ophthalmic apparatus according to claim 8, wherein the OCT optical system photographs OCT angiography. The execution means includes laser irradiation means for irradiating the eye to be examined with laser light,
The ophthalmic apparatus according to claim 1, wherein the condition acquisition unit acquires an irradiation condition when irradiating the eye to be examined with a laser based on the motion information. The ophthalmic apparatus according to claim 17, wherein the irradiation condition is a maximum laser irradiation time. 19. The ophthalmologic apparatus according to claim 17, wherein the irradiation condition is a laser irradiable region. An ophthalmologic apparatus control program executed in the ophthalmologic apparatus, being executed by a processor of the ophthalmologic apparatus,
An information acquisition step for acquiring movement information of the eye to be examined;
Based on the movement information acquired in the information acquisition step, a condition acquisition step of acquiring an operation condition of an execution unit that performs examination or treatment of the eye to be examined;
Is executed by the ophthalmologic apparatus.