Ophthalmologic apparatus and control program for ophthalmologic apparatus

Abstract

To suppress unnecessary reflected light from other than a fundus from being generated as flare in a fundus image.SOLUTION: An ophthalmologic apparatus of the present disclosure includes a light source unit including a light source configured to illuminate an eye to be inspected, a light receiving unit configured to convert reflection light reflected from the eye to be inspected by the illumination into an electric signal and output the electric signal, and a control unit configured to, based on an output timing of a first electric signal corresponding to reflection light from a first site of the eye to be inspected, output a second electric signal corresponding to reflection light from a second site different from the first site. A separation unit that separates a second electric signal output later than the first electric signal from the first electric signal, and a display control unit that displays at least one of an image based on the first electric signal separated by the separation unit or an image based on the second electric signal separated by the separation unit on a display unit.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to an ophthalmic apparatus and a control program for the ophthalmic apparatus. [Background technology]

[0002] Fundus cameras for photographing the fundus of a subject's eye have been put to practical use as ophthalmic devices. Fundus cameras use an optical system in which the optical axis of light incident on the subject's eye coincides with the optical axis of light reflected from the subject's eye. As a result, unwanted reflected light from sources other than the fundus (for example, reflected light from the cornea) can appear as flare in the fundus image.

[0003] Here, Patent Document 1 discloses a method for reducing flare occurring in a fundus image by using an optical system that separates an incident light beam from a reflected light beam. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 5-337087 Summary of the Invention [Problem to be solved by the invention]

[0005] Here, even if an optical system that separates the incident light beam from the reflected light beam is used, if the positional relationship (alignment) between the ophthalmic device and the subject's eye is misaligned, unnecessary reflected light from sources other than the fundus may appear as flare in the fundus image.

[0006] Therefore, an object of the present disclosure is to suppress unnecessary reflected light from sources other than the fundus from appearing as flare in a fundus image. [Means for solving the problem]

[0007] The ophthalmic device of the present disclosure includes a light source unit having a light source that illuminates the test eye; a light receiving unit that converts the light reflected by the test eye from the illumination into an electrical signal and outputs it; a separation unit that separates the first electrical signal from a second electrical signal corresponding to reflected light from a first portion of the test eye based on the output timing of the first electrical signal, the second electrical signal corresponding to reflected light from a second portion different from the first portion, and the second electrical signal being output after the first electrical signal; and a display control unit that displays at least one of an image based on the first electrical signal separated by the separation unit or an image based on the second electrical signal separated by the separation unit on a display unit. [Effects of the Invention]

[0008] According to the present disclosure, it is possible to prevent unnecessary reflected light from sources other than the fundus from appearing as flare in a fundus image. [Brief explanation of the drawings]

[0009] [Figure 1] 1 shows an example of a schematic configuration of a fundus camera device according to a first embodiment and its optical system. [Figure 2] 1 shows a schematic diagram for explaining the optical path of a fundus photographing system of a fundus camera device according to a first embodiment. [Figure 3] 2 shows a schematic configuration example of a control unit according to the first embodiment. [Figure 4] 10 shows an example of the operation of the signal separation unit 205 when the pulse width of the fundus illumination according to the first embodiment is very short. [Figure 5] 10 shows an example of the operation of the signal separation unit 205 when the pulse width of the fundus illumination according to the first embodiment is long. [Figure 6] 1 shows an example of a measurement screen display according to the first embodiment. [Figure 7] 10A and 10B are diagrams for explaining a method for determining the axial length and eyeball shape according to the second embodiment. [Figure 8] 10A and 10B are diagrams for explaining a fluorescence separation method according to a third embodiment. [Figure 9] 10 shows a diagram for explaining a method for calculating a fluorescence lifetime according to a third embodiment. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0010] Exemplary embodiments of the present disclosure will be described in detail below with reference to the drawings. However, the dimensions, materials, shapes, and relative positions of components described in the following embodiments are arbitrary and can be changed depending on the configuration of the device to which the present disclosure is applied or various conditions. In addition, the same reference numerals are used in the drawings to indicate identical or functionally similar elements.

[0011] [Embodiment 1] A fundus camera device and a control method thereof will be described below as an example of an ophthalmic device and a control method thereof according to Embodiment 1 of the present disclosure. The fundus camera device described in this embodiment separates only a specific structure, in particular a reflected signal from the fundus, from a received light signal of light reflected from the eye, and acquires information.

[0012] <Outline of the device configuration> First, the schematic configuration of the fundus camera device according to this embodiment will be described with reference to Fig. 1. Fig. 1 shows the schematic configuration of the fundus camera device according to this embodiment and an example of its optical system. In the following description, the direction that approximately coincides with the line of sight of the subject's eye E is referred to as the Z direction. Furthermore, the plane perpendicular to the Z direction is referred to as the XY plane, the horizontal direction is referred to as the X direction, and the vertical direction is referred to as the Y direction.

[0013] The fundus camera device is provided with an optical head unit 100 and a control unit 200. The control unit 200 is also provided with a display unit 210 and an input unit 220. The configurations of the optical head unit 100 and the control unit 200 will be described below in order.

[0014] <Configuration of the optical head unit 100> The optical head unit 100 is provided with a high-speed image sensor (light receiving unit) 130, a fundus illumination (light source unit) 140, and an optical system for capturing two-dimensional images of the anterior segment Ea and fundus Ef of the subject's eye E. Various optical systems arranged in the optical head unit 100 will be described below.

[0015] In the optical head unit 100, an objective lens 101 is disposed facing the subject's eye E. A first dichroic mirror 102, which functions as an optical path branching unit, is disposed on the optical axis L1 of the objective lens 101. The first dichroic mirror 102 branches the optical path (optical axis L2) of the anterior eye observation system and the optical path (optical axis L3) of the fundus photography system into separate optical paths for each wavelength band.

[0016] A lens 120, a prism 121, a diaphragm 122, a lens 123, and an image sensor 124 are arranged on an optical axis L2 in the reflection direction of the first dichroic mirror 102. The image sensor 124 is a monochrome sensor sensitive to infrared light. These optical members and the like arranged on the optical axis L2 constitute an anterior eye segment observation system for observing the anterior eye segment Ea.

[0017] The image sensor 124 is connected to the control unit 200. The image sensor 124 sends a signal corresponding to the detected light to the control unit 200. The control unit 200 can generate an anterior eye segment observation image based on the signal received from the image sensor 124 and display the image on the display unit 210. In addition, a light source 125 for anterior eye segment observation, which is arranged near the objective lens 101, illuminates the anterior eye segment Ea of the subject's eye E.

[0018] A beam splitter 131, a focus lens 132, an imaging lens 133, a half mirror 134, and a high-speed image sensor 130 are arranged on an optical axis L3 in the transmission direction of the first dichroic mirror 102. The focus lens 132 is held so as to be movable in the optical axis direction indicated by the arrow in the figure by a driving unit such as a motor (not shown) controlled by the control unit 200. The focus of the fundus photography system can be adjusted by moving the focus lens 132 on the optical axis L3. The optical path on the optical axis L3 is branched by the half mirror 134 into an optical path leading to the high-speed image sensor 130 and an optical path leading to a fixation lamp 135.

[0019] The fixation lamp 135 emits visible light to encourage the subject to fixate. The fixation lamp 135 may also be provided with a diaphragm (not shown) for cutting off the light beam necessary for fundus photography.

[0020] The high-speed image sensor 130 is a sensor for capturing fundus images. The high-speed image sensor 130 sends an electrical signal corresponding to the detected light to the control unit 200. The control unit 200 can generate a fundus image (frontal fundus image) based on the electrical signal received from the high-speed image sensor 130 and display it on the display unit 210.

[0021] In this embodiment, the high-speed image sensor 130 includes a two-dimensional imaging element. Furthermore, in this embodiment, it is necessary to separate only the reflection from the fundus Ef. FIG. 2 is a schematic diagram illustrating the optical path of the fundus imaging system according to this embodiment. As shown in FIG. 2, a reflection L1a from the anterior segment Ea, which is a highly reflective region other than the fundus Ef, and a reflection L1f from the fundus Ef arrive at the high-speed image sensor 130. To distinguish and detect the reflection L1a and the reflection L1f, the high-speed image sensor 130 needs a time resolution capable of detecting the time difference between the arrival time of the reflection L1a and the arrival time of the reflection L1f. Specifically, the reflection L1f from the fundus Ef arrives at the high-speed image sensor 130 later than the reflection L1a from the anterior segment Ea by a distance twice the diameter of the eyeball. The size of an adult eyeball is approximately 24 to 30 mm along its major axis. If the major axis is 24 mm, the time calculated from the speed of light, 299,792,458 (m / s), is approximately 160 picoseconds. Therefore, it is desirable for the high-speed image sensor 130 to have a time resolution higher than 160 picoseconds. The high-speed image sensor 130 is a sensor that has light-receiving sensitivity to the wavelength of light emitted by the fundus illumination 140. The anterior segment Ea is an example of a first portion of the subject's eye. The fundus Ef is an example of a second portion.

[0022] In this embodiment, a SPAD (Single Photon Avalanche Diode) sensor is used as the high-speed image sensor 130. The SPAD sensor uses avalanche multiplication and photon counting technology and has extremely fast time resolution at the picosecond level. In addition, the SPAD sensor has the advantage of being able to reduce read noise during digital signal conversion to zero, making it suitable for generating clearer images from the small amount of reflected light from the fundus Ef.

[0023] In this embodiment, the high-speed image sensor 130 is not limited to the above-mentioned SPAD sensor, as long as it is a sensor having a time resolution capable of separating the reflected signal from the fundus oculi Ef. For example, the high-speed image sensor 130 may be a high-speed CMOS sensor or a CCD sensor.

[0024] On the optical axis L4 in the reflection direction of the beam splitter 131, a relay lens 141, a focus target unit 142, and a lens 143 are arranged in this order.

[0025] The focus target unit 142 is an optical element that provides a target for focusing using the focus lens 133, and in this embodiment, a split bright line is projected as an example of the target. The focus target unit 142 according to this embodiment has a split target member that is movable along the optical axis L4 in conjunction with the focus lens 133. The split target member is configured to be inserted into and removed from the optical path of the optical axis L4 by a drive unit such as a motor (not shown) controlled by the control unit 200.

[0026] The split bright lines irradiated by the focus target unit 142 pass through the relay lens 141 and are reflected by the beam splitter 131 toward the first dichroic mirror 102. The split bright lines reflected by the beam splitter 131 are projected onto the fundus Ef of the subject's eye E via the first dichroic mirror 102 and the objective lens 101. The control unit 200 can calculate the amount of focus deviation by detecting the positions of the split bright lines from the fundus image.

[0027] The fundus illuminator 140 is a light source that emits modulated light to an illumination optical system that illuminates the eye E. Modulation refers to light whose light intensity changes over time, such as pulsed light including a single pulse or light modulated with a sine wave. The light emitting element may be, for example, a light emitting diode or a laser diode that emits light of a predetermined wavelength.

[0028] The fundus illuminator 140 receives an emission control signal transmitted from the control unit 200 and controls the light-emitting element to emit light with a predetermined pulse width and light intensity in accordance with the emission control signal. To more clearly separate the reflections of the anterior segment Ea and the fundus Ef of the subject's eye E, it is desirable that the fundus illuminator 140 have a steep fall and rise of the emitted light. It is particularly desirable that the fundus illuminator 140 be an ultrashort pulse light source, the fall and rise times of which are both shorter than 1 picosecond. The pulse width can be set to an appropriate value depending on the distance between the structures to be separated, the exposure time of the high-speed image sensor 130, and the like. For ease of explanation, the fundus illuminator 140 is assumed to project a pulse wave (rectangular wave) along the optical axis L4.

[0029] The wavelength of light emitted by the fundus illumination 140 is any wavelength for which the high-speed image sensor 130 has light sensitivity. It is preferable that the light emitted by the fundus illumination 140 be visible light when photographing the fundus, and infrared light when observing the fundus to suppress miosis and glare. However, since the miosis and glare vary depending on the light intensity and emission interval of the emitted light, and the optimal wavelength also varies depending on the structure of the fundus to be photographed, a monochromatic light source having any wavelength, such as white light or infrared light, may also be used. Here, the fundus illumination 140 is assumed to be able to arbitrarily switch between infrared light and visible light using a wavelength control signal transmitted from the control unit 200.

[0030] The objective lens 101, the lens 143, and the optical members between them constitute an illumination optical system that illuminates the fundus Ef. The fundus Ef of the subject's eye E can be illuminated with light from the fundus illumination 140 via the illumination optical system. In addition, the optical members on the optical axes L3 and L4 constitute a fundus photography system.

[0031] Furthermore, the optical head unit 100 is provided with a head drive unit (not shown). The head drive unit includes three motors (not shown). The control unit 200 controls the driving of the head drive unit to move the optical head unit 100 in three-dimensional (X, Y, Z) directions relative to the subject's eye E. This allows the control unit 200 to align the optical head unit 100 with the subject's eye E.

[0032] <Configuration of control unit 200> Next, a schematic configuration of the control unit 200 will be described with reference to Fig. 3. The control unit 200 includes an imaging control unit 201, a storage unit 202, an output control unit 203, an acquisition unit 204, a signal separation unit 205, and an image generation unit 206.

[0033] The imaging control unit 201 is connected to the storage unit 202, the acquisition unit 204, the optical head unit 100, and the input unit 220. The imaging control unit 201 controls each unit of the optical head unit 100 based on an input signal from the input unit 220.

[0034] Here, the control during capture of various images will be described. When capturing an anterior-segment observation image, the capture control unit 201 causes the anterior-segment observation light source 125 to emit light, and the image sensor 124 receives the light returning from the anterior segment Ea. The image sensor 124 sends a signal corresponding to the light received for each pixel to the acquisition unit 204. The image processing unit 206 uses the signal acquired by the acquisition unit 204 to generate an anterior-segment observation image.

[0035] Furthermore, the photographing control unit 201 can cause the fundus illumination unit 140 to emit infrared light at a predetermined pulse width one or more times to photograph a fundus observation image using the fundus camera. In photographing a fundus observation image, the photographing control unit 201 drives the focus target unit 142 to acquire diopter information of the subject's eye E, and then drives the focus lens 132 to match the acquired diopter information. The light returned from the fundus Ef is received by the high-speed image sensor 130. The high-speed image sensor 130 sends a signal corresponding to the received light returned for each pixel to the acquisition unit 204. The signal separation unit 205 separates, using the signal acquired by the acquisition unit 204, reflected light L1a from the anterior segment Ea and reflected light L1f from the fundus Ef, which are included in the light reflected from the eye E. The image generation unit 206 generates a fundus observation image using the signal separated by the signal separation unit 205. In photographing fundus observation images, the above operation is repeated at any given interval to generate a fundus observation video.

[0036] Furthermore, when photographing a fundus image using a fundus camera, the photographing control unit 201 changes the position of the focus lens 132 so that the position matches the diopter position obtained by applying aberration correction due to differences in the wavelength of the light source to the acquired diopter information of the subject's eye E. Thereafter, the photographing control unit 201 causes the fundus illumination unit 140 to emit visible light at a predetermined pulse width one or more times, and receives the returned light from the fundus Ef with the high-speed image sensor 130. The high-speed image sensor 130 sends a signal corresponding to the received returned light for each pixel to the acquisition unit 204. The signal separation unit 205 separates the reflected light from the eye E into reflected light L1a from the anterior segment Ea and reflected light L1f from the fundus Ef using the signal acquired by the acquisition unit 204. The image generation unit 206 generates a fundus image using the signal separated by the signal separation unit 205.

[0037] As described above, the acquisition unit 204 can acquire the signals output from the image sensor 124 and the high-speed image sensor 130. The acquisition unit 204 also outputs the signal output from the image sensor 124 to the image generation unit 206. The acquisition unit 204 also outputs the signal output from the high-speed image sensor 130 to the signal separation unit 205.

[0038] The signal separation unit 205 separates the reflected light L1a from the anterior segment Ea and the reflected light L1f from the fundus Ef, which are included in the reflected light from the eye E, using the signal acquired by the acquisition unit 204 and output from the high-speed image sensor 130. The signal separation unit 205 also outputs the separated signals to the image generation unit 206. A specific separation method will now be described with reference to Figs. 4 and 5. Figs. 4 and 5 are waveform diagrams for explaining an example of the operation of the signal separation unit 205.

[0039] 4 and 5 show, from the top, the pulsed light of the fundus illumination 140, the reflected light L1a from the anterior segment Ea, the reflected light L1f from the fundus Ef, the signal received by the high-speed image sensor 130, and the signal waveform after separation by the signal separation unit 205 (the signal waveform output to the image generation unit 206). Furthermore, Fig. 4 shows an example in which the pulse width W of the pulsed light of the fundus illumination 140 is shorter than the time difference Δt between the reflected light L1a from the anterior segment Ea and the reflected light L1f from the fundus Ef, while Fig. 5 shows an example in which the pulse width W of the pulsed light of the fundus illumination 140 is longer than the time difference Δt between the reflected light L1a from the anterior segment Ea and the reflected light L1f from the fundus Ef.

[0040] 4 and 5, the horizontal axis represents time and the vertical axis represents intensity. For example, in the waveform of the sensor light reception signal, the vertical axis represents the signal intensity (brightness, etc.) of the light received by the high-speed image sensor 130.

[0041] As shown in FIG. 4, when the pulse width of the fundus illumination 140 is very short, the high-speed image sensor 130 sequentially receives the reflected light L1a from the anterior segment Ea and the reflected light L1f from the fundus Ef and outputs electrical signals in the order of reception. The signal separation unit 205 detects the output timing of the electrical signal at an arbitrary trigger level (e.g., trg1 in FIG. 4). In FIG. 4, the signal separation unit 205 first detects the electrical signal corresponding to the reflected light L1a from the anterior segment Ea, and then detects the electrical signal corresponding to the reflected light L1f from the fundus Ef a second time. The signal separation unit 205 can separate the electrical signal corresponding to the reflected light L1a from the anterior segment Ea and the electrical signal corresponding to the reflected light L1f from the fundus Ef by using the rising edge of the second detected electrical signal as the starting point. The signal separation unit 205 outputs the separated electrical signal corresponding to the reflected light L1f from the fundus Ef as a separated signal to the image generation unit 206.

[0042] The method for detecting the output timing of the electrical signal is not limited to the above-described method. For example, the trigger level may be set to trg2, the falling edge of the electrical signal corresponding to the reflected light L1a from the anterior segment Ea may be detected, and the detected timing may be used as the starting point to similarly separate the electrical signal corresponding to the reflected light L1a from the anterior segment Ea and the electrical signal corresponding to the reflected light L1f from the fundus Ef. Alternatively, as in a runt trigger, the timing when a pulse enters or leaves between any two trigger levels (trg1-trg2 in Figure 4) may be detected and used as the starting point.

[0043] Next, the case of Fig. 5(a) will be described. When the pulse width of the fundus illumination 140 is long, the high-speed image sensor 130 receives reflected light in which reflected light L1a from the anterior segment Ea and reflected light L1f from the fundus Ef are superimposed during a certain time period. The signal separation unit 205 detects the falling edge of the signal at an arbitrary trigger level (for example, trg3 in Fig. 5(a)) and, by using the detected falling edge timing as a starting point, can separate the signal of only reflected light L1f from the fundus Ef.

[0044] The method for detecting the output timing of the electrical signal is not limited to the above-described method. As shown in FIG. 5(b), a signal containing only the reflected light L1a from the anterior segment Ea is detected at an arbitrary trigger level (e.g., trg4 in FIG. 5(b)). The detected rising edge (first trigger) is used as the starting point. A signal containing only the reflected light L1a from the anterior segment Ea is then detected at an arbitrary trigger level (e.g., trg3 in FIG. 5(b)). The detected rising edge (second trigger) is used as the end point. This separates the signal containing only the reflected light L1a from the anterior segment Ea as a separated signal 1. Subsequently, the intensity S of the signal separated as the separated signal 1 is subtracted from the signal containing the reflected light L1a from the anterior segment Ea and the reflected light L1f from the fundus Ef. Similarly, a signal containing only the reflected light L1f from the fundus Ef can be separated as a separated signal 2. Whether the signal contains the reflected light L1a from the anterior segment Ea and the reflected light L1f from the fundus Ef can be determined from the rising edge and falling edge of trg3.

[0045] In this embodiment, trigger events (optimal starting point detection methods), such as trigger methods (rising edge, falling edge, etc.) and trigger levels (detection voltages), are not limited to those described above. The trigger events may be changed depending on the light intensity and pulse width of the fundus illumination 140, the various optical systems arranged in the optical head unit 100, and the characteristics of the subject's eye E. For example, the signal separation unit 205 may switch the trigger events depending on the device, imaging conditions, and the state of the subject's eye. Furthermore, the trigger event settings may be recorded in the device in advance. Furthermore, as a method for reducing the influence of noise on the signal, the signal separation unit 205 may apply a low-pass filter to the signal acquired by the acquisition unit 204 before detecting the starting point.

[0046] Next, we will explain the components of the control unit 200 in Figure 3 that have not been described so far. The image generation unit 206 generates an anterior eye observation image based on the signal output from the acquisition unit 204. The image generation unit 206 can also generate a fundus observation image, a fundus image, etc. based on the signal output from the signal separation unit 205. In this embodiment, when generating one image, the fundus illumination 140 may be caused to emit light multiple times, and multiple signals may be superimposed. This operation makes it possible to generate an image with sufficient brightness and S / N even with low light intensity. Any known generation method may be used to generate these images.

[0047] The storage unit 202 stores an anterior segment observation image, a fundus observation image, a fundus image, etc. of the subject's eye E generated by the image generation unit 206. The storage unit 202 also stores, for example, an examination sequence that defines a series of control procedures for performing an examination multiple times, analysis results of various images, photographing conditions when acquiring images, so-called patient information about the subject's eye E, etc. The storage unit 202 also stores various programs and the like for controlling the above-mentioned photographing of an anterior segment observation image, photographing of a fundus observation image by a fundus camera, and photographing of a fundus image.

[0048] The output control unit 203 is connected to the storage unit 202, the image generation unit 206, and the display unit 210, and can control the display on the display unit 210. The output control unit 203 can display, for example, various images such as an anterior eye observation image, a fundus observation image, and a fundus image, as well as patient information, stored in the storage unit 202, on the display unit 210. The output control unit 203 can also receive various images generated from the image generation unit 206 and output them to the display unit 210. The output control unit 203 is an example of a display control unit.

[0049] Here, the control unit 200 can be configured by a computer provided with a processor and a memory. The control unit 200 may be configured by a general computer or a computer dedicated to the ophthalmologic apparatus. The control unit 200 may be, for example, a personal computer, such as a desktop PC, a notebook PC, or a tablet PC (portable information terminal). Furthermore, the control unit 200 may be configured as a cloud-based computer in which some of the components are located in an external device.

[0050] Furthermore, each component of the control unit 200 other than the storage unit 202 may be configured by a software module executed by a processor such as a CPU (Central Processing Unit) or an MPU (Micro Processing Unit). The processor may be, for example, a GPU (Graphical Processing Unit) or an FPGA (Field-Programmable Gate Array). Each component may be configured by a circuit that performs a specific function, such as an ASIC. The storage unit 202 may be configured using any memory or storage medium, such as an optical disk.

[0051] The display unit 210 is configured with any display, and displays various information such as patient information, various images, a mouse cursor, etc. in accordance with the operation of the input unit 220, under the control of the output control unit 203. The input unit 220 is an input device that issues instructions to the control unit 200, and specifically includes a keyboard and a mouse. Note that the display unit 210 may be configured with a touch panel display, in which case the display unit 210 can also be used as the input unit 220.

[0052] <Inspection operation flow> Next, the measurement screen and operation flow of this embodiment will be described with reference to Fig. 6. Fig. 6(a) shows an example of the measurement screen displayed on the display unit 210. A measurement screen 1000 according to this embodiment displays a left / right eye switching button 1001, a Capture button 1003, a Start button 1004, an anterior eye observation image 1101, a fundus observation image 1201, and a Mode button 1401. The measurement screen 1000 also displays sliders 1102 and 1202 for controlling various adjustments, an imaging light intensity adjustment button 1203, and an index 1204 indicating the fixation position. Note that although the index 1204 indicating the fixation position is shown as a cross in the figure, it may also be a dot, a cross, or the like as long as the position is clear.

[0053] To start the examination according to this embodiment, the operator moves the cursor 1002 on the measurement screen 1000 shown in FIG. 6(a) via the input unit 220, selects the left or right eye with the left or right eye switch button 1001, and selects the imaging mode with the Mode button 1401. The imaging mode includes a fundus imaging mode and may also include other imaging modes such as a fundus fluorescence imaging mode and an axial length measurement mode. The operator can also manually move the index 1204 indicating the fixation position to adjust the fixation position of the subject's eye.

[0054] Next, when the operator presses the Start button 1004 via the input unit 220, the control unit 200 automatically performs alignment adjustment and focus adjustment, and preparations for imaging are made. Here, alignment adjustment is an adjustment to align the optical head unit 100 with respect to the subject's eye E. Focus adjustment is an adjustment to move the focus lens 132 in the optical axis direction in order to perform focusing adjustment on the fundus oculi Ef. Note that focus adjustment and alignment adjustment may be performed by any known method.

[0055] For example, the imaging control unit 201 may use the anterior eye observation image to determine the amount of misalignment of the optical head unit 100 with respect to the subject's eye E, and adjust the alignment of the optical head unit 100 with respect to the subject's eye E. Note that the imaging control unit 201 can detect the distance in the Z-axis direction (optical axis direction) of the optical head unit 100 with respect to the subject's eye E, using an image of the anterior eye segment Ea divided into upper and lower parts based on light that has passed through the prism 121.

[0056] The imaging control unit 201 may also adjust the focus of the fundus imaging system using a fundus observation image. For example, the imaging control unit 201 can adjust the focus by moving the focus lens 132 so as to eliminate the vertical deviation of split bright lines in the fundus observation image as targets. In this embodiment, as described above, the split target member of the focus target unit 142 is driven along the optical axis L4 in conjunction with the focus lens 132.

[0057] Furthermore, the operator can perform fine adjustments of the alignment and focus by operating the sliders 1102, 1202, etc. via the input unit 220. When performing fine adjustments of the alignment, the operator can adjust the alignment by operating the slider 1102 or a button (not shown) to move the Z-direction position and the XY position of the optical head unit 100 relative to the eye E while viewing the anterior eye observation image 1101. Furthermore, the operator can adjust the focus of the fundus imaging system by operating the slider 1202 while viewing the brightness, etc., of the fundus observation image 1201.

[0058] Furthermore, the operator can adjust the amount of imaging light by clicking the imaging light amount adjustment button 1203 via the input unit 220. Furthermore, the signal separation unit 205 may switch the method of detecting the starting point (trigger event) based on the selected imaging light amount. Furthermore, the imaging control unit 201 may switch the light amount, pulse width, or number of emissions of the fundus illumination 140 based on the selected imaging light amount.

[0059] The operator can start photographing by pressing the Capture button 1003. When photographing of a frontal fundus image starts, the photographing control unit 201 changes the position of the focus lens 132 to match the diopter position corrected for aberration due to differences in wavelength of the light source, and then causes the fundus illumination 140 to emit visible light.

[0060] Furthermore, an operating method for changing the frame rate of the high-speed image sensor 130 may be used. For example, the frame rate of the high-speed image sensor 130 may be set low during adjustment, and the frame rate may be increased during fundus imaging control when the operator presses the Capture button 1003. Because a low frame rate makes it difficult to separate the signals described in FIGS. 4 and 5, it is desirable to separate the signals using a different method during adjustment. For example, a different method may involve using an optical element (not shown) to split the optical path during adjustment, as described in Patent Document 1, to remove reflected light from the anterior segment. While this may result in issues such as flare, as described above, some flare is acceptable since various adjustments can be performed during adjustment.

[0061] The various images generated by the acquisition unit 204 , the signal separation unit 205 , and the image generation unit 206 are stored in the storage unit 202 .

[0062] The output control unit 203 displays the frontal fundus image on the fundus image display unit 1301. Furthermore, it can also display on the display unit 210 various images stored in the storage unit 202 and various information such as patient information.

[0063] Next, the operation flow in this embodiment will be described with reference to FIG. 6(b).

[0064] When an examination is started in S601, an imaging mode is selected by the operator in S602. The Mode button 1401 is used to select the imaging mode.

[0065] When a photography mode is selected, in S603, the signal separation unit 205 sets a trigger method and a trigger level according to the photography mode.

[0066] Next, in S604, when the operator presses the Start button 1004, the control unit 200 executes alignment adjustment (S605), and then the control unit 200 executes focus adjustment (S606).

[0067] Next, in S607, when the operator presses the Capture button 1003, the imaging control unit 201 images the subject's eye (S608). A signal obtained by imaging is acquired by the acquisition unit 204. The signal acquired by the acquisition unit 204 is separated by the signal separation unit 205 into a signal corresponding to the reflected light L1a from the anterior segment Ea and a signal corresponding to the reflected light L1f from the fundus Ef (S609).

[0068] Subsequently, the image generating unit 206 generates a front image of the fundus oculi (S610). The front image of the fundus oculi is generated using a signal corresponding to the reflected light L1f from the fundus oculi Ef separated by the signal separating unit 205.

[0069] Next, the output control unit 203 displays the front fundus image on the fundus image display unit 1301 (S610). When the front fundus image is displayed on the fundus image display unit 1301, the examination ends (S611).

[0070] With the above configuration, it is possible to separate only the signal corresponding to the light reflected from the fundus from the light receiving signal including the light reflected from the anterior segment and the light reflected from the fundus. Then, by generating and displaying an image based on the signal corresponding to the light reflected from the fundus, it is possible to prevent unnecessary reflected light from sources other than the fundus from appearing as flare in the fundus image.

[0071] In this embodiment, a method for separating reflected light L1f from the fundus Ef and generating a frontal fundus image has been described. However, it is also possible to separate reflected light L1a from the anterior segment Ea and generate and display a frontal anterior eye image using a similar method. Furthermore, the focus of the fundus imaging system may be adjusted to the anterior segment and the fundus between the arrival of reflected light L1a from the anterior segment and the arrival of reflected light L1f from the fundus. Alternatively, it is also possible to simultaneously acquire and display a frontal anterior eye image and a frontal fundus image in a single light emission sequence by inserting or removing a focus adjustment lens or using a multifocal optical system between the arrival of reflected light L1a from the anterior segment and the arrival of reflected light L1f from the fundus.

[0072] [Embodiment 2] In the first embodiment, a method for obtaining a fundus image by separating only the reflected signal from the fundus from the received signal of light reflected from the eye and removing the reflected signal from the anterior segment, etc., was described. In contrast, in the second embodiment, a method for obtaining the axial length and eyeball shape by separating the reflected signal from the anterior segment and the reflected signal from the fundus from the received signal of light reflected from the eye and calculating the distance from the time difference between the signals is described. Note that the configuration of the ophthalmic apparatus according to this embodiment is the same as that of the ophthalmic apparatus according to the first embodiment. Therefore, the components according to this embodiment are designated by the same reference numerals as those according to the first embodiment, and their description will be omitted. The following description of the ophthalmic apparatus according to this embodiment will focus on the differences from the ophthalmic apparatus according to the first embodiment.

[0073] <Configuration of control unit 200> The imaging control unit 201 causes the fundus illumination 140 to emit infrared light, white light, or the like at least once with a predetermined pulse width, and receives the light returning from the fundus Ef with the high-speed image sensor 130 .

[0074] The high-speed image sensor 130 sends a signal corresponding to the returned light received for each pixel to the acquisition unit 204. The signal separation unit 205 uses the signal acquired by the acquisition unit 204 to separate the reflected light from the eye E into reflected light L1a from the anterior segment Ea and reflected light L1f from the fundus Ef.

[0075] Then, the signal separation unit 205 uses the separated signals to determine the arrival times of the reflected signals from the anterior segment Ea and the fundus Ef, and can calculate the distance between the anterior segment Ea and the fundus Ef based on the time difference between the signals.

[0076] Furthermore, the signal separation unit 205 outputs the calculated distance between the anterior eye segment Ea and the fundus Ef at each pixel to the storage unit 202 and the image generation unit 206 .

[0077] Here, a method for determining the axial length and eyeball shape of the subject's eye E will be described with reference to Fig. 7. Fig. 7 is a waveform diagram for explaining an example of the operation of the signal separating unit 205.

[0078] Fig. 7 shows a signal waveform after the reflected light L1a from the anterior segment Ea and the reflected light L1f from the fundus Ef are separated by the signal separation unit 205. Fig. 7 also shows an example in which the pulse width of the pulsed light of the fundus illumination 140 is shorter than the time difference between the reflected light L1a from the anterior segment Ea and the reflected light L1f from the fundus Ef.

[0079] 7, the horizontal axis represents time, and the vertical axis represents the signal intensity (brightness, etc.) of the light received by the high-speed image sensor 130.

[0080] As shown in FIG. 7, the signal separation unit 205 can detect the starting point (e.g., rising timing) of reflected light L1a from the anterior segment Ea using the same separation method as in the first embodiment. That is, the time Ta of the starting point can be obtained. Similarly, the signal separation unit 205 can determine the starting point of reflected light L1f from the fundus Ef, and can obtain the time Tf of the starting point. Then, the signal separation unit 205 can obtain the time difference between the anterior segment reflection and the fundus reflection by subtracting (Tf-Ta). The time difference obtained by subtraction is the time required for light to travel back and forth between the anterior segment and the fundus. Then, the distance between the anterior segment and the fundus can be calculated by dividing half of the calculated time difference (one way) by the speed of light, 299,792,458 (m / s).

[0081] The signal separation unit 205 can calculate the axial length based on the calculated distance between the anterior segment and the fundus of each pixel. The axial length can be obtained from the distance between the anterior segment and the fundus of a pixel near the fovea, for example.

[0082] The image generating unit 206 can generate an eyeball shape image by constructing a three-dimensional matrix based on the distance between the anterior eye segment and the fundus of each pixel calculated by the signal separating unit 205. When generating an eyeball shape image, it is necessary to be able to detect slight differences in distance from each position on the fundus due to the curvature of the eyeball, and therefore the high-speed image sensor 130 preferably requires a time resolution on the order of femtoseconds.

[0083] The storage unit 202 stores the axial length of the subject's eye E calculated by the signal separation unit 205, an eyeball shape image of the subject's eye E generated by the image generation unit 206, and the like. The storage unit 202 also stores, for example, an examination sequence that defines a series of control procedures for performing an examination multiple times, analysis results of various images, photographing conditions when acquiring images, so-called patient information about the subject's eye E, and the like. The storage unit 202 also stores various programs and the like for controlling the above-mentioned axial length photographing and eyeball shape photographing.

[0084] The output control unit 203 is connected to the storage unit 202, the image generation unit 206, and the display unit 210, and can control the display on the display unit 210. The output control unit 203 can display, for example, various images such as an eyeball shape image and axial length information of the subject's eye E, which are stored in the storage unit 202, on the display unit 210. The output control unit 203 can also receive various images generated from the image generation unit 206 and output them to the display unit 210.

[0085] With the above configuration, it is possible to provide an ophthalmologic device that can obtain the axial length and eyeball shape by separating the signal reflected from the anterior segment and the signal reflected from the fundus from the received light signal of light reflected from the eye and calculating the distance from the time difference of the signals, which can be used to determine the intraocular lens for cataract surgery, evaluate the progression of myopia, detect macular diseases, etc.

[0086] [Embodiment 3] In the third embodiment, an application example of this ophthalmologic device in fundus fluorescence photography will be described. In the third embodiment, only the fluorescent signal is separated from the light reception signal of light reflected from the eye, and a fluorescent fundus image is acquired. Furthermore, fundus fluorescence lifetime measurement is performed by utilizing the high time resolution of the high-speed sensor.

[0087] The device configuration of the ophthalmic apparatus according to this embodiment is the same as that of the ophthalmic apparatus according to embodiment 1. Therefore, the components according to this embodiment will be assigned the same reference numerals as those of embodiment 1, and their description will be omitted. The following description will focus on the differences between the ophthalmic apparatus according to this embodiment and the ophthalmic apparatus according to embodiment 1.

[0088] <Configuration of control unit 200> In fluorescent fundus image capture, the capture control unit 201 causes the fundus illumination 140 to emit excitation light at least once with a predetermined pulse width, and the high-speed image sensor 130 receives the light returning from the fundus Ef.

[0089] Regarding the wavelength of the excitation light, the imaging control unit 201 can switch the wavelength of the output light of the fundus illumination 140 depending on the fluorescence imaging mode. For example, blue light is used for fluorescein fundus angiography (FA), infrared light is used for indocyanine green fundus angiography (IA), and green light is used for autofluorescence imaging (FAF). Instead of switching the wavelength of the light emitted by the fundus illumination 140, the imaging control unit 201 may be configured to irradiate the subject's eye E with light of any wavelength by inserting an excitation filter (not shown) on the optical axis L4 of the fundus illumination optical system of the optical head unit 100.

[0090] The high-speed image sensor 130 sends a signal corresponding to the returned light received for each pixel to the acquisition unit 204. The signal separation unit 205 uses the signal acquired by the acquisition unit 204 to separate only the signal corresponding to the fluorescence from the fluorescent material in the fundus from the reflected light from the eye E. Furthermore, the signal separation unit 205 can calculate the fundus fluorescence lifetime using the separated signal.

[0091] The image generating unit 206 generates a fluorescent fundus image using the signals separated by the signal separating unit 205. Furthermore, the image generating unit 206 can generate a fundus fluorescence lifetime image using the fundus fluorescence lifetime value calculated by the signal separating unit 205.

[0092] A specific method for separating fluorescence will now be described with reference to Fig. 8. Fig. 8 is a waveform diagram for explaining an example of the operation of the signal separating section 205.

[0093] Figure 8 shows, from top to bottom, the fundus illumination 140, reflected light L1a from the anterior segment Ea, reflected light L1f from the fundus Ef, fluorescence from the fundus, a signal received by the high-speed image sensor 130, and a signal waveform after separation by the signal separation unit 205.

[0094] FIG. 8 shows an example in which the pulse width of the pulsed light of the fundus illumination 140 is sufficiently short compared to the fluorescence.

[0095] 8, the horizontal axis represents time, and the vertical axis represents the signal intensity (brightness, etc.) of the light received by the high-speed image sensor 130.

[0096] As shown in FIG. 8, when the pulse width of the fundus illumination 140 is sufficiently short, the high-speed image sensor 130 sequentially receives reflected light L1a from the anterior segment Ea, reflected light L1f from the fundus Ef, and fluorescence. The signal separation unit 205 detects the rising edge of a signal at an arbitrary trigger level (trg5 in FIG. 8). The signal separation unit 205 detects a trigger (first trigger) corresponding to the reflected light L1a, followed by a trigger (second trigger) corresponding to the reflected light L1f. After that, it detects a trigger (third trigger) corresponding to the fluorescence from the fundus. By using the third trigger as a starting point, the signal separation unit 205 can separate only the signal corresponding to the fluorescence from the fundus. Even if the pulse width of the fundus illumination 140 is long and the reflected light L1f and fluorescence from the fundus Ef overlap, it is possible to separate only the attenuation signal of the fluorescence by, for example, detecting the falling edge of the signal at an arbitrary trigger level (trg5 in FIG. 8) as a starting point.

[0097] In this embodiment, trigger events (optimal starting point detection methods), such as trigger methods and trigger levels, are not limited to those described above. The trigger event may be changed depending on the light intensity and pulse width of the fundus illumination 140, various optical systems arranged in the optical head unit 100, characteristics of the subject's eye E, and the target fluorescent material. For example, the signal separation unit 205 may switch the trigger event depending on the device and imaging conditions, the state of the subject's eye, and the type of fluorescence imaging. The trigger event settings may also be pre-recorded in the device. Furthermore, as a method for reducing the influence of noise on the signal, the signal separation unit 205 may apply a low-pass filter to the signal acquired by the acquisition unit 204 before detecting the starting point. Alternatively, as in conventional fluorescence imaging methods, the imaging control unit 201 may be configured to insert a filter into the optical path (optical axis L3) of the fundus imaging system of the optical head unit 100 to remove light other than the fluorescent wavelength in advance.

[0098] Furthermore, the signal separation unit 205 may calculate a fluorescence lifetime from the separated fluorescence signals. The fluorescence lifetime is the time it takes for the fluorescence generated after excitation to decay. The fluorescence lifetime is usually in the range of several hundred picoseconds to several hundred nanoseconds. Therefore, the high-speed image sensor 130 must have a time resolution of at least several hundred nanoseconds.

[0099] A specific method for calculating the fluorescence lifetime will now be described with reference to Fig. 9. Fig. 9 is a waveform diagram for explaining an example of the operation of the signal separation unit 205, showing the separated fluorescence signals.

[0100] 9, in this embodiment, the signal separation unit 205 calculates the time it takes for the intensity of the fluorescent signal to decay from its peak value to 1 / e (=36.8%) as the fluorescent lifetime. The signal separation unit 205 outputs the calculated value of the fundus fluorescent lifetime to the image generation unit 206.

[0101] The image generating unit 206 can generate a fundus fluorescence image, etc., based on the signal of each pixel output from the signal separating unit 205. Furthermore, the image generating unit 206 can perform pseudo-color mapping, etc., by constructing a two-dimensional matrix of fluorescence lifetimes based on the fluorescence lifetime values ​​of each pixel output from the signal separating unit 205, and generate a fundus fluorescence lifetime image.

[0102] Fundus fluorescence lifetime imaging allows observation of the fluorescence lifetime at each site of the fundus. It has been shown that the retinal fluorescence lifetime can change not only in macular diseases, but also in other retinal diseases and systemic diseases without obvious ophthalmological findings. Fundus fluorescence lifetime imaging may be able to clarify the state of these diseases.

[0103] The storage unit 202 stores fundus fluorescence images, fundus fluorescence lifetime images, etc. of the subject's eye E generated by the image generation unit 206. The storage unit 202 also stores, for example, an examination sequence that defines a series of control procedures for performing an examination multiple times, analysis results of various images, photographing conditions when acquiring images, so-called patient information about the subject's eye E, etc. The storage unit 202 also stores the various programs, etc., described above, used to control fluorescent fundus photography.

[0104] The output control unit 203 is connected to the storage unit 202, the image generation unit 206, and the display unit 210, and can control the display on the display unit 210. The output control unit 203 can display, for example, various images such as fundus fluorescence images and fundus fluorescence lifetime images, as well as patient information, stored in the storage unit 202, on the display unit 210. The output control unit 203 can also receive various images generated from the image generation unit 206 and output them to the display unit 210.

[0105] With the above configuration, it is possible to separate only the fluorescence signal from the received light signal that includes light reflected from the anterior segment and light reflected from the fundus. Furthermore, by acquiring a fundus fluorescence lifetime image from the fluorescence signal, it may be possible to understand the condition of macular disease, other retinal diseases, and systemic diseases that do not show clear ophthalmological findings.

[0106] (Configuration 1) a light source unit having a light source that illuminates the eye to be examined; a light receiving unit that converts light reflected by the eye to an electrical signal and outputs the electrical signal; a separation unit that separates, based on an output timing of a first electrical signal corresponding to reflected light from a first region of the subject's eye, a second electrical signal corresponding to reflected light from a second region different from the first region, the second electrical signal being output after the first electrical signal; and a display control unit that displays, on a display unit, at least one of an image based on the first electrical signal separated by the separation unit and an image based on the second electrical signal separated by the separation unit; An ophthalmic device having

[0107] (Configuration 2) the reflected light from the first site is reflected light from an anterior segment of the subject's eye, 2. The ophthalmologic apparatus according to configuration 1, wherein the light reflected from the second portion is light reflected from a fundus of the subject's eye.

[0108] (Configuration 3) 3. The ophthalmologic apparatus according to configuration 1 or 2, wherein the output timing of the first electrical signal is at least one of a rising timing and a falling timing of the first electrical signal.

[0109] (Configuration 4) 4. The ophthalmologic apparatus according to any one of configurations 1 to 3, wherein the separation unit separates the second electrical signal and the first electrical signal at a falling edge timing of the first electrical signal.

[0110] (Configuration 5) An ophthalmic device according to any one of configurations 1 to 4, wherein the separation unit separates the second electrical signal and the first electrical signal at the rising timing of the second electrical signal that is detected after detecting the output timing of the first electrical signal.

[0111] (Configuration 6) 6. The ophthalmologic apparatus according to any one of configurations 1 to 5, wherein the separation unit changes the timing at which the second electrical signal and the first electrical signal are separated in accordance with an imaging mode selected by an operator.

[0112] (Configuration 7) When the fundus photography mode is selected as the photography mode, the separation unit separates the second electrical signal and the first electrical signal at a rising timing of the second electrical signal corresponding to the reflected light from a fundus of the subject's eye, which is detected after detecting an output timing of the first electrical signal corresponding to the reflected light from an anterior segment of the subject's eye; 7. The ophthalmologic apparatus according to configuration 6, wherein the display control unit displays, on a display unit, an image based on the second electrical signal separated by the separation unit.

[0113] (Configuration 8) When the fundus fluorescence photography mode is selected as the photography mode, the separation unit separates the second electrical signal and the first electrical signal at a rising edge of the second electrical signal corresponding to a fluorescent substance in a fundus of the subject's eye, the rising edge of the second electrical signal being detected after detecting an output timing of the first electrical signal corresponding to reflected light from an anterior segment of the subject's eye, and calculates a fluorescence lifetime using the second electrical signal; 8. The ophthalmologic apparatus according to configuration 6 or 7, wherein the display control unit displays, on a display unit, an image based on the second electrical signal separated by the separation unit and the fluorescence lifetime.

[0114] (Configuration 9) When the axial length measurement mode is selected as the imaging mode, the separation unit calculates an axial length using an output timing of a first electrical signal corresponding to reflected light from an anterior segment of the subject's eye and an output timing of a second electrical signal corresponding to reflected light from a fundus of the subject's eye; 9. The ophthalmologic apparatus according to any one of configurations 6 to 8, wherein the display control unit displays the axial length on a display unit.

[0115] (Configuration 10) 10. The ophthalmologic apparatus according to any one of configurations 1 to 9, wherein the light receiving unit has a time resolution higher than 160 picoseconds.

[0116] (Configuration 11) 11. The ophthalmologic apparatus according to any one of configurations 1 to 10, wherein the light receiving unit includes a SPAD.

[0117] (Configuration 12) 12. The ophthalmologic apparatus according to any one of configurations 1 to 11, wherein the light source unit includes a short-pulse light source that generates pulsed light whose fall time and rise time of light emission are both shorter than 1 picosecond.

[0118] (Program 1) 13. A program for operating the ophthalmologic apparatus according to any one of configurations 1 to 12.

[0119] (Other embodiments) The disclosed technology can also be realized by executing the following process. That is, the disclosed technology can also be realized by supplying software (programs) that realize one or more functions of the various embodiments described above to a system or device via a network or a storage medium, and having a computer (or a CPU, MPU, or the like) of the system or device read and execute the programs. The computer has one or more processors or circuits, and may include multiple separate computers or a network of multiple separate processors or circuits to read and execute computer-executable instructions. In this case, the processor or circuit may include a central processing unit (CPU), a microprocessing unit (MPU), a graphics processing unit (GPU), an application-specific integrated circuit (ASIC), or a field-programmable gateway (FPGA). The processor or circuit may also include a digital signal processor (DSP), a data flow processor (DFP), or a neural processing unit (NPU). [Explanation of symbols]

[0120] 100 Optical head unit 200 control section 210 Display section 220 Input section

Claims

1. a light source unit having a light source that illuminates the eye to be examined; a light receiving unit that converts light reflected by the eye to an electrical signal and outputs the electrical signal; a separation unit that separates, based on an output timing of a first electrical signal corresponding to reflected light from a first portion of the subject's eye, a second electrical signal corresponding to reflected light from a second portion different from the first portion, the second electrical signal being output after the first electrical signal; and a display control unit that displays, on a display unit, at least one of an image based on the first electrical signal separated by the separation unit and an image based on the second electrical signal separated by the separation unit; An ophthalmic device having

2. the reflected light from the first portion is reflected light from an anterior segment of the subject's eye, 2. The ophthalmologic apparatus according to claim 1, wherein the light reflected from the second portion is light reflected from a fundus of the subject's eye.

3. The ophthalmologic apparatus according to claim 1 , wherein the output timing of the first electrical signal is at least one of a rising timing and a falling timing of the first electrical signal.

4. The ophthalmologic apparatus according to claim 1 , wherein the separator separates the second electrical signal from the first electrical signal at a falling edge of the first electrical signal.

5. The ophthalmologic apparatus according to claim 1 , wherein the separation unit separates the second electrical signal from the first electrical signal at a rising edge of the second electrical signal that is detected after detecting an output timing of the first electrical signal.

6. The ophthalmologic apparatus according to claim 1 , wherein the separation unit changes the timing at which the second electrical signal and the first electrical signal are separated in accordance with an imaging mode selected by an operator.

7. When the fundus photography mode is selected as the photography mode, the separation unit separates the second electrical signal and the first electrical signal at a rising timing of the second electrical signal corresponding to the reflected light from a fundus of the subject's eye, which is detected after detecting an output timing of the first electrical signal corresponding to the reflected light from an anterior segment of the subject's eye; The ophthalmologic apparatus according to claim 6 , wherein the display control unit displays an image based on the second electrical signal separated by the separation unit on a display unit.

8. When the fundus fluorescence photography mode is selected as the photography mode, the separation unit separates the second electrical signal and the first electrical signal at a rising edge of the second electrical signal corresponding to a fluorescent substance in a fundus of the subject's eye, the rising edge being detected after detecting an output timing of the first electrical signal corresponding to reflected light from an anterior segment of the subject's eye, and calculates a fluorescence lifetime using the second electrical signal; The ophthalmologic apparatus according to claim 6 , wherein the display control unit displays an image based on the second electrical signal separated by the separation unit and the fluorescence lifetime on a display unit.

9. When the axial length measurement mode is selected as the imaging mode, the separation unit calculates an axial length using an output timing of a first electrical signal corresponding to light reflected from an anterior segment of the subject's eye and an output timing of a second electrical signal corresponding to light reflected from a fundus of the subject's eye; The ophthalmologic apparatus according to claim 6 , wherein the display control unit displays the axial length on a display unit.

10. The ophthalmic apparatus according to claim 1 , wherein the light receiving unit has a time resolution higher than 160 picoseconds.

11. The ophthalmic apparatus according to claim 1 , wherein the light receiving unit includes a SPAD.

12. 2. The ophthalmic apparatus according to claim 1, wherein the light source unit includes a short-pulse light source that generates pulsed light whose fall time and rise time of emitted light are both shorter than 1 picosecond.

13. A program for operating the ophthalmologic apparatus according to any one of claims 1 to 12.

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