JP7476693B2 - Fundus photography device - Google Patents

Description

This disclosure relates to a fundus imaging device that acquires OCT data of the fundus of a test eye.

A combined fundus imaging device that combines an optical coherence tomography (OCT) system and a fundus camera optical system is known. For example, in Patent Document 1, it is possible to obtain wide-area OCT data that captures both the macula and optic disc of the fundus.

JP 2015-104581 A

However, such wide-area OCT data can sometimes be obtained as images that do not include (or are partially missing from) at least one of the macula and the optic nerve. As these are unsuitable for analysis or diagnosis, it is necessary to take the images again.

In view of the above-mentioned conventional techniques, the technical objective of the present disclosure is to provide a fundus imaging device that can efficiently photograph the subject's eye.

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

(1) A fundus imaging apparatus having an OCT optical system that detects an interference signal between a measurement light and a reference light irradiated onto a fundus of a test eye, and acquires OCT data of the fundus based on the interference signal,
an observation image acquisition means for acquiring an observation image of the fundus;
A control means for executing a guidance process for guiding a macular region and an optic nerve disc included in the observation image into an imaging range of the OCT data captured by the OCT optical system, the guidance process being for aligning an analysis target including both the macular region and the optic nerve disc with an appropriate position set within the imaging range in consideration of a region size required for analysis of the analysis target;
and an analysis processing means for analyzing the OCT data including both the macular region and the optic nerve disc as analysis targets to obtain an analysis result for the macular region and the optic nerve disc,
The control means is characterized by performing the guidance process so that the measurement optical axis of the OCT optical system is positioned on the macular side of the center of the macular area and the optic disc of the test eye, but away from the macular area.

FIG. 1 is an external view of an OCT apparatus. FIG. 2 is a schematic diagram of the inside of an imaging section. 1 is an example of a front observation image. 13 is an example of an appropriate position in a front observation image. 13 is an example of a front observation image. 13 is an example of a front observation image. 1 is an example of an OCT tomographic image.

＜Overview＞
An embodiment of an ophthalmologic imaging apparatus according to the present disclosure will be described. The items grouped in <> below can be used independently or in conjunction with each other.

The fundus imaging device of this embodiment is an OCT device having the configuration of an optical coherence tomography. For example, the fundus imaging device has an OCT optical system that detects an interference signal caused by measurement light and reference light irradiated onto the fundus of the subject eye, and acquires OCT data of the fundus based on the interference signal. The fundus imaging device may further have a fundus camera configuration (fundus camera optical system) and acquire a fundus image. The fundus imaging device may further have a scanning laser ophthalmoscope configuration (SLO optical system) and acquire an SLO front image.

<Means for Obtaining Observed Images>
The fundus photographing device of the present embodiment may include an observation image acquiring means (e.g., the control unit 300). The observation image acquiring means acquires an observation image of the fundus of the subject eye (fundus observation image). The observation image acquiring means may acquire OCT data captured by an OCT optical system as the fundus observation image. In this case, the OCT data may be a two-dimensional OCT tomographic image, a three-dimensional OCT tomographic image, or an OCT front image based on the three-dimensional OCT tomographic image. The observation image acquiring means may also acquire a fundus observation image captured by a fundus camera optical system. In this case, an infrared fundus image by infrared light may also be acquired. The observation image acquiring means may also acquire a fundus observation image captured by an SLO optical system (i.e., an SLO front image).

<Detection Means>
The fundus imaging device of this embodiment may include a detection means (e.g., the control unit 300). The detection means detects an analysis target including at least one of the macular region and the optic disc from a fundus observation image acquired by the observation image acquisition means. The detection means may detect the analysis target using various image processing methods. As an example, a feature point extraction method, a method using a correlation function, a method using a Fourier transform, etc. may be used.

The detection means may directly detect the analysis target, such as the macula, the optic disc, etc. For example, the detection means may detect the analysis target by using the tissue characteristics (e.g., shape, brightness, etc.) of the analysis target stored in advance in the storage unit. Also, for example, the detection means may detect blood vessels, etc., and indirectly detect the analysis target, such as the macula, the optic disc, etc., based on the detection results. As an example, the position of the macula or the optic disc may be predicted and detected from the extension direction of the blood vessels. Also, for example, the detection means may predict and detect the position of the macula or the optic disc by using left/right eye information.

<Adjustment Means>
The fundus photographing apparatus of the present embodiment may include an adjustment means. The adjustment means adjusts the photographing range of the OCT data photographed by the OCT optical system. For example, the adjustment means may be a scanning means (e.g., the optical scanner 234) that scans the measurement light in the OCT optical system. Also, for example, the adjustment means may be a light source (e.g., a fixation lamp) for gazing at the line of sight of the subject's eye. Also, for example, the adjustment means may be a driving means for driving the photographing means (e.g., the photographing unit 200) with respect to the subject's eye. As an example, the adjustment means may be a driving means (e.g., the driving unit 105) for moving the photographing means in the left-right direction, the up-down direction, and the front-back direction with respect to the subject's eye. Also, as an example, the adjustment means may be a driving means for tilting (rotating) the photographing means in the left-right direction and the up-down direction with respect to the subject's eye.

<Setting method>
The fundus imaging device of the present embodiment may include a setting means (e.g., the control unit 300). The setting means can set a first imaging mode for acquiring first OCT data in which either the macular region or the optic nerve is imaged, and a second imaging mode for acquiring second OCT data in which both the macular region and the optic nerve are imaged. For example, the setting means may set either the first imaging mode or the second imaging mode based on a signal input by an operator operating an operating means (e.g., the monitor 104). Also, for example, the setting means may set either the first imaging mode or the second imaging mode based on an imaging program for imaging the subject's eye.

<Control Means>
The fundus imaging device of the present embodiment may include a control unit (for example, the control unit 300). The control unit executes a guidance process for guiding the macular area and the optic nerve optic nerve included in the fundus observation image into the imaging range of the OCT data captured by the OCT optical system, and for matching the analysis target with the appropriate position. The analysis target may be at least one of the macular area and the optic nerve optic nerve. The appropriate position may be a position set within the imaging range in consideration of the area size required for analyzing the analysis target. This allows imaging of the subject's eye to proceed efficiently, and reduces the possibility of re-imaging due to the macular area or the optic nerve optic nerve not being included in the imaging range.

The size of the area required for the analysis of the analysis target may be changed depending on the analysis content of the OCT data. That is, the appropriate position may be changed depending on the analysis content of the OCT data. For example, the appropriate position may be set to a position where the macular region or the optic nerve papilla is predicted to be located. In this case, the appropriate position may be set to a position predicted (stored) based on the results of an experiment, a simulation, or the like. In this case, the appropriate position may be set to a position predicted based on the axial length that differs for each subject eye that is previously acquired. In addition, for example, the appropriate position may be set based on the detection result of the detection means. In this case, the appropriate position may be set to the position of the macular region or the optic nerve papilla detected from the fundus observation image. In this case, the appropriate position may be set to a position a predetermined distance away from the macular region or the optic nerve papilla detected from the fundus observation image.

As a guidance process, the control unit may output guide information for guiding the analysis target to an appropriate position. For example, by using the guide information, the misalignment between the analysis target and the target position can be eliminated, and the analysis target can be easily aligned to the appropriate position.

For example, the control unit may control the display means and cause the display means to display the guide information. Also, for example, the control unit may control the sound generation means (for example, a speaker) and cause the sound generation means to generate the guide information as sound. Also, for example, the control unit may control the notification means (for example, a lamp) and display the guide information by lighting or blinking the notification means. Note that the control unit may execute a combination of these controls, or may execute a different control from these.

The guide information may be information for guiding the examiner's actions. For example, the guide information may be information for prompting the examiner to change the position of a fixation light to focus the gaze of the subject's eye, to move the imaging means (e.g., the imaging unit 200) relative to the subject's eye, to adjust the inclination or position of the subject's face, etc. The guide information may be information for guiding the examiner's actions. For example, the guide information may be information for prompting the subject to move his or her gaze (one example is the generation of a sound indicating that the gaze should be moved). The guide information may be information indicating at least one of the amount of movement and the direction of movement of the fixation light. The guide information may be information indicating at least one of the amount of movement and the direction of movement of the imaging means. Of course, the guide information may be a combination of these pieces of information, or may be information different from these pieces of information.

The control unit may output guide information for guiding the analysis target including at least one of the macular region and the optic disc to an appropriate position based on the detection result of the detection means as a guidance process. That is, the control unit may output guide information by controlling at least one of the display means, the sound generation means, the notification means, etc. based on the detection result of the detection means. This makes it possible to easily eliminate deviations between the macular region or the optic disc and the appropriate positions, and to easily align the macular region or the optic disc to the appropriate positions.

As a guidance process, the control unit may superimpose an index representing a target position for matching the analysis target with the appropriate position on the fundus observation image. In this case, the control unit may control the display of the display means (e.g., monitor 104) to display an index representing the target position of the macular at a predetermined position corresponding to the appropriate position of the macular. In addition, in this case, the control unit may control the display of the display means to display an index representing the target position of the optic nerve at a predetermined position corresponding to the appropriate position of the optic nerve. In other words, such an index may be used as the aforementioned guide information. Of course, the control unit may display such an index and output the aforementioned guide information. This allows the deviation between the macular or optic nerve and the target position to be grasped, and the macular or optic nerve can be easily aligned to the appropriate position.

The size of the index displayed on the display means may be changed depending on the analysis content of the OCT data. For example, the larger the display size of the index, the wider the tolerance range is set when matching the analysis target with the appropriate position. Also, for example, the smaller the display size of the index, the narrower the tolerance range is set when matching the analysis target with the appropriate position. In other words, an index corresponding to a different tolerance range may be displayed for each analysis content of the OCT data.

The control unit may control the adjustment means and adjust the imaging range as a guidance process in order to guide the analysis target into the imaging range of the OCT data captured by the OCT optical system. For example, the control unit may control a scanning means that scans the measurement light in the OCT optical system, and adjust the imaging range of the OCT data by automatically adjusting the scanning conditions of the measurement light. Also, for example, the control unit may control a light source (fixation light) to automatically change the on/off and on position of the light source to change the line of sight of the subject's eye and adjust the imaging range of the OCT data. Also, for example, the control unit may control a driving means for moving or tilting the imaging means with respect to the subject's eye, and adjust the imaging range of the OCT data by automatically adjusting the relative positional relationship between the subject's eye and the imaging means. By controlling at least one of these, the analysis target is automatically positioned within the imaging range of the OCT data, and as a result, the deviation between the analysis target and the target position is eliminated, and each part is appropriately positioned within the imaging range.

The control unit may execute each guidance process to align the optic disc as the analysis target with the appropriate position taking into account the area size required for analyzing the optic disc. That is, the control unit may output guide information for guiding the optic disc to the appropriate position. The control unit may also superimpose an indicator representing a target position for matching the optic disc with the appropriate position on the fundus observation image. The control unit may also control the adjustment means to guide the optic disc into the imaging range of the OCT data captured by the OCT optical system.

When the second imaging mode is set by the setting means, the control unit may execute a guidance process for aligning the analysis target with the appropriate position. For example, in the second imaging mode in which the macular region and the optic disc are imaged at the same time, both the macular region and the optic disc must be within a specified imaging range, and it is easy for these areas to not be included (or to be missing in part). For this reason, particularly in the second imaging mode, a guidance process for aligning the analysis target with the appropriate position is effective in improving the efficiency of imaging the subject's eye.

Of course, even when the first imaging mode is set by the setting means, the control unit may execute a guidance process to align the analysis target with the appropriate position. More specifically, when the macular region is imaged in the first imaging mode, the control unit may execute a guidance process to align the macular region with the appropriate position. Also, when the optic disc region is imaged in the first imaging mode, the control unit may execute a guidance process to align the optic disc region with the appropriate position.

The fundus imaging device of this embodiment may be a hybrid device equipped with an OCT optical system and a fundus camera optical system. In a hybrid device, the scanning range of the measurement light in the OCT optical system (i.e., the imaging range) is limited to the imaging range of the fundus camera optical system. In general, the angle of view is limited to 40° to 45°. Therefore, when the line of sight of the examined eye is directed forward, the macula is located in the center of the fundus observation image, and the optic disc is located on the periphery of the fundus observation image. Note that the positional relationship between the macula and the optic disc differs for each examined eye, so part of the optic disc may be missing from the image.

For example, the gaze of the subject's eye is guided by moving the fixation light position, and the center of the fundus observation image is positioned between the macula and the optic optic disc, so that the macula and optic optic disc are included in the fundus observation image. However, if the gaze of the subject's eye is not guided properly, or if simply moving the fixation light position is insufficient due to the positional relationship between the macula and the optic optic disc, appropriate OCT data cannot be obtained.

The control means then executes the guidance process described above to guide the macula and optic disc included in the fundus observation image into the imaging range of the OCT data captured by the OCT optical system, thereby aligning the analysis target with the appropriate position. For example, in this state, appropriate OCT data can be obtained by scanning the measurement light in the OCT optical system with a predetermined scanning pattern (e.g., raster scan, etc.). As a result, imaging of the test eye is performed efficiently, reducing the possibility of re-imaging.

<Example>
An example of a fundus imaging device in this embodiment will be described. The fundus imaging device may be an OCT device having a so-called optical coherence tomography configuration. The OCT device may have a time domain OCT as a basic configuration. The OCT device may also have a Fourier domain OCT as a basic configuration. The Fourier domain OCT may be a spectral domain OCT, a wavelength swept OCT, or the like.

Figure 1 is an external view of the OCT device 1. The OCT device 1 includes a base 101, a moving table 102, an operation unit 103, a monitor 104, a driving unit 105, a detection unit 106, a face support unit 110, an imaging unit 200, a control unit 300, etc.

The operation unit 103 inputs a signal for operating the imaging unit 200. For example, when the operation unit 103 is tilted, a movement signal is input for moving the movable stage 102 in at least one of the left-right direction (X direction) and the front-back direction (Z direction) relative to the base 101. Also, for example, when a knob (not shown) of the operation unit 103 is rotated, a movement signal is input for moving the imaging unit 200 in the up-down direction (Y direction) relative to the base 101.

The monitor 104 displays the OCT data of the subject's eye E, the analysis results of the OCT data, etc. on the screen. For example, the OCT data may be an OCT tomographic image, an OCT front image, etc. For example, the analysis results of the OCT data may be retinal thickness information, a retinal thickness map image generated based on the retinal thickness information, an analysis chart calculated based on the retinal thickness information, etc. The monitor 104 also functions as a touch panel that doubles as the operation unit 103. In other words, a movement signal for moving the imaging unit 200 is also input by operating the monitor 104.

The driving unit 105 moves the imaging unit 200 in the left-right, up-down, and front-back directions. For example, the driving unit 105 is a slide mechanism. As an example, the slide mechanism may have a motor, gears, guide rails, etc.

The detection unit 106 detects the position of the imaging unit 200. For example, the detection unit 106 is a variable resistor. Of course, the detection unit 106 is not limited to a variable resistor, and may be at least one of an optical sensor, a position sensor, a distance sensor, etc. The detection result of the detection unit 106 is output to the control unit 300.

The face support unit 110 supports the subject's face. The face support unit 110 has a forehead rest 111 and a chin rest 112. The subject's forehead is placed against the forehead rest 111. The subject's chin is placed on the chin rest 112. A detector 113 is provided on the chin rest 112.

The detector 113 detects whether or not the subject's chin is placed on the chin rest 112. For example, the detector 113 is a load sensor. Of course, the detector 113 is not limited to a load sensor, and may be at least one of an optical sensor, a pressure sensor, an ultrasonic sensor, etc. The detection result of the detector 113 is output to the control unit 300.

<Photography Department>
2 is a schematic diagram of the inside of the photographing unit 200. The photographing unit 200 houses an alignment target projection optical system 210, an anterior eye photographing optical system 220, an OCT optical system 230, an observation optical system 240, a fixation guiding optical system 250, a face photographing optical system 260, and the like.

<Alignment target projection optical system>
The alignment index projection optical system 210 projects an alignment index toward the cornea of the test eye E. The alignment index projection optical system 210 includes a first projection optical system 210a and a second projection optical system 210b. The first projection optical system 210a projects an alignment index at infinity toward the cornea of the test eye E. The first projection optical system 210a includes a light source 211, a collimator lens 212, and the like. For example, the light source 211 emits near-infrared light. For example, the light source 211 is arranged in a ring shape centered on the imaging optical axis. For example, the collimator lens 212 converts the light from the light source 211 into a parallel light beam. The second projection optical system 210b projects an alignment index at a finite distance toward the cornea of the test eye E. The second projection optical system 210b includes a light source 213, and the like. For example, the light source 213 emits near-infrared light. For example, the light source 213 is arranged in a ring shape around the imaging optical axis at a position different from that of the light source 211. The light from the second projection optical system 210b is used as alignment light for aligning the imaging unit with respect to the subject's eye E, and is also used as anterior segment illumination light for illuminating the anterior segment of the subject's eye E.

<Anterior Eye Segment Imaging Optical System>
The anterior eye imaging optical system 220 images the anterior eye of the subject's eye E. The anterior eye imaging optical system 220 includes an image sensor 221 and the like. For example, the image sensor 221 images the anterior eye illuminated by the light source 213. The image sensor 221 also serves as an image sensor for detecting an alignment index projected onto the cornea, and images the alignment index together with the anterior eye.

<OCT optical system>
The OCT optical system 230 detects an interference signal due to the measurement light and reference light irradiated to the subject's eye E. The OCT optical system 230 includes a coupler 231, a light source 232, a measurement optical system 233, an optical scanner 234, an objective optical system 235, a detector 236, a reference optical system 237, etc. The light source 232, the measurement optical system 233, the detector 236, and the reference optical system 237 are connected to the coupler 231 via optical fibers.

The OCT optical system 230 splits the light emitted from the light source 232 into measurement light and reference light by the coupler 231. For example, the measurement light is emitted into the air after passing through an optical fiber, and is guided to the fundus via the measurement optical system 233, the optical scanner 234, and the objective optical system 235. For example, when the measurement light is reflected at the fundus, it is returned to the optical fiber via a similar path. For example, the reference light passes through the optical fiber and is guided to the reference optical system 237. For example, when the reference light is reflected by a reference mirror (not shown) of the reference optical system 237, it is returned to the optical fiber via a similar path. The OCT optical system 230 causes the detector 236 to receive an interference signal (interference light) resulting from the combination of the measurement light and the reference light. The interference signal detected by the detector 236 is transmitted to the control unit 300.

<Observation optical system>
The observation optical system 240 is used as a fundus camera optical system, and captures a fundus image by photographing the fundus. For example, the observation optical system 240 captures an infrared fundus image by infrared light, and a color fundus image by visible light. In addition, for example, the observation optical system 240 captures a fluorescent fundus image by a predetermined excitation light. Note that the observation optical system 240 may have the configuration of a scanning laser ophthalmoscope (SLO) and capture an SLO front image of the fundus.

<Fixation Guidance Optical System>
The fixation guidance optical system 250 guides the gaze direction of the subject's eye E. The fixation guidance optical system 250 has a fixation light presented to the subject's eye E. For example, the fixation light is arranged on the measurement optical axis L and on the same circumference centered on the measurement optical axis L. By changing the presentation position of the fixation light two-dimensionally, the gaze of the subject's eye E is guided in multiple directions, and as a result, the imaging region of the subject's eye E is changed.

<Control Unit>
The control unit 300 is a processing device (processor) having electronic circuits that perform control processing of each unit and calculation processing. The control unit 300 includes a general CPU (Central Processing Unit), RAM, ROM, etc. For example, the CPU controls each component in the OCT device 1. For example, the RAM temporarily stores various information. For example, the ROM stores various programs for controlling the operation of the fundus imaging device 1. For convenience, the control unit 300 performs image processing of various images obtained by the fundus imaging device 1. In other words, the control unit 300 also functions as an image processing unit.

The control unit 300 is electrically connected to the operation unit 103, monitor 104, drive unit 105, detection unit 106, the light source and image sensor of each optical system, memory unit 301, etc. The memory unit 301 may be a non-transient storage medium that can retain the stored contents even if the power supply is cut off. For example, the memory unit 301 may be a hard disk drive, a flash ROM, a USB memory, etc. For example, the memory unit 301 may store information related to settings for obtaining OCT data, OCT data obtained by processing an interference signal detected by the detector 236, etc.

<Control operation>
The control operation of the fundus photographing apparatus 1 will now be described.

<Alignment between the subject's eye and the imaging unit>
The examiner instructs the subject to place his/her face on the face support unit 110. The control unit 300 may detect that the subject's face is placed on the chin rest 112, and automatically start alignment adjustment between the subject's eye E and the imaging unit 200.

The control unit 300 controls the fixation guidance optical system 250 to turn on a fixation light to focus the line of sight of the subject's eye E. The control unit 300 also controls the alignment index projection optical system 210 to turn on the light sources 211 and 213 to project an alignment index onto the cornea of the subject's eye E. The control unit 300 also controls the anterior eye imaging optical system 220 to image the subject's eye E with the image sensor 221. This results in an anterior eye observation image including an alignment index image of the subject's eye E, which is displayed on the monitor 104.

The control unit 300 uses the alignment target image to detect the direction and amount of misalignment between the corneal apex of the test eye E and the measurement optical axis L of the OCT optical system 230. The control unit 300 also moves the imaging unit 200 relative to the test eye E to eliminate the misalignment and align the corneal apex with the measurement optical axis L.

<Setting the imaging mode and scanning conditions>
The examiner sets the photographing mode of the subject's eye E and the scanning conditions of the measurement light. The examiner operates the monitor 104 and operates a selection switch for selecting the photographing mode. For example, one of the following is selected: a macular photographing mode for photographing the macular part of the fundus, a papilla photographing mode for photographing the optic papilla of the fundus, and a retina photographing mode for photographing both the macular part and the optic papilla. The control unit 300 sets the scanning conditions of the measurement light according to the selected photographing mode. For example, at least one of the scanning position (photographing position), the scanning part (photographing part), the scanning pattern, and the like is set as the scanning conditions. In this embodiment, by selecting the retina photographing mode, a raster scan of a 9 mm long x 12 mm wide area is set with the macular part and the optic papilla as the photographing targets.

<Acquisition of observed images>
The examiner photographs the subject's eye E to obtain an observation image of the fundus. For example, the examiner may be able to select either a three-dimensional OCT tomographic image or an OCT front image based on the three-dimensional OCT tomographic image as the observation image of the subject's eye E. In this embodiment, the OCT front image is selected as the observation image.

The examiner operates the monitor 104 and operates a start switch to start observing the subject's eye E. The control unit 300 turns on a fixation light on the measurement optical axis L to direct the line of sight of the subject's eye E forward. The control unit 300 also controls the OCT optical system 230 to position each optical member (for example, a reference mirror not shown) of the OCT optical system 230 at a preset position so that the fundus of the subject's eye E is photographed. For example, the control unit 300 also integrates the spectral intensity of the interference signal detected by scanning the measurement light. As a result, an OCT front image (hereinafter, front observation image 400) is obtained as an observation image and displayed on the monitor 104.

<Display of nipple target index>
FIG. 3 is an example of a front observation image 400. In this embodiment, since the line of sight of the subject's eye E is in the front direction, the macula m is located at the center of the front observation image 400. The control unit 300 electrically superimposes and displays an imaging range 401, a fixation light position 402, a nipponic target index 403, and the like on the front observation image 400. The imaging range 401 represents a scanning range of the measurement light by the OCT optical system 230. The imaging range 401 is changed in size and shape based on a set scanning pattern. The fixation light position 402 represents the position of the fixation light presented to the subject's eye E. For example, if the fixation light is arranged on the measurement optical axis L, it is displayed at the center position C of the front observation image 400 (FIG. 3). For example, if the fixation light is arranged on the same circumference centered on the measurement optical axis L, it is displayed around the center position C. The nipponic target index 403 represents a target position to which the nipponic area t included in the front observation image 400 is moved.

The fundus imaging device 1 obtains an OCT front image (hereinafter, a front image) as an image based on a 3D OCT tomographic image captured of the subject's eye E. In addition, based on the 3D OCT tomographic image, an analysis result of the retinal thickness of the fundus is obtained, and a retinal thickness map image in which the retinal thickness is color-coded two-dimensionally is generated. In this embodiment, by placing the macular region m and the optic disc t within the imaging range 401 of the front image, an analysis result for the macular region m and the optic disc t is obtained, and a retinal map image including the macular region m and the optic disc t is generated.

Figure 4 is an example of an appropriate position (appropriate range) of a characteristic part in a front observation image 400. The control unit 300 sets an appropriate position within the shooting range 401, taking into consideration the size of the analysis area required for analyzing the characteristic part. The analysis area set by the control unit 300 is stored in advance in the storage unit 301. For example, in the front observation image 400, an area where the macular part m is predicted to be located is stored as the analysis area of the macular part m. As an example, one area obtained by dividing the front observation image 400 in two in the left-right direction is stored as the analysis area of the macular part m. The control unit 300 sets such an analysis area of the macular part m as an appropriate position R1 where the macular part is to be located. The appropriate position R1 is analyzed by a predetermined method suitable for analyzing the macular part m. Also, for example, in the front observation image 400, an area where the optic nerve part t is predicted to be located is stored as the analysis area of the optic nerve part t. As an example, the other area obtained by dividing the front observation image 400 into two in the left-right direction is set as the analysis area for the nipple t. The control unit 300 sets this analysis area for the nipple t as the appropriate position R2 where the nipple should be placed. The appropriate position R2 is analyzed using a predetermined method suitable for analyzing the nipple t.

The number of divisions into such analysis regions may be different, and the number of regions to be analyzed may be different. Furthermore, such analysis regions may have different region sizes. Furthermore, such analysis regions may partially overlap. In other words, the analysis region of the macula m (appropriate position R1) and the analysis region of the optic disc t (appropriate position R2) may partially overlap.

However, if at least a portion of the macula m and the optic nerve t is outside the imaging range 401 in the frontal observation image 400, the macula m and the optic nerve t will not be located in their proper positions, and appropriate analysis results will not be obtained. For example, when the OCT optical system scans an area of 9 mm vertical x 12 mm horizontal with measurement light and the macula m is located in the center of the frontal observation image 400, the optic nerve t on the periphery of the frontal observation image 400 may be partially outside the imaging range 401.

For this reason, the control unit 300 superimposes on the front observation image 400 an index indicating a target position for moving the characteristic part to the appropriate position. In this embodiment, a nipple target index 403 for moving the nipple part t is superimposed on a position corresponding to the appropriate position R2. By matching (approximately matching) the nipple part t with the nipple target index 403, the macular part m and the nipple part t can be contained within the shooting range 401, and the macular part m and the nipple part t can be positioned in their respective appropriate positions.

<Aligning the nipple and nipple target index>
FIG. 5 is an example of the front observation image 400. The examiner matches the optic nips t in the front observation image 400 with the optic nips target index 403. For example, the examiner may instruct the examinee to change the angle of the examinee's face or the line of sight of the examinee's eye E. For example, the fixation lamp arranged on the measurement optical axis L may be switched to the fixation lamp arranged on the same circumference centered on the measurement optical axis L to change the line of sight of the examinee's eye E. For example, the operation unit 103 may be operated to move the photographing unit 200. As a result, the optic nips t is guided within the photographing range 401 of the front observation image 400, and the optic nips t is placed within the appropriate position R2. At the same time, the macula m is also guided within the photographing range 401, and the macula m is placed within the appropriate position R1.

At this time, the control unit 300 may detect the nipple t in the front observation image 400 by image processing (for example, a feature point extraction method) and notify the result of the determination as to whether the nipple t and the nipple target index 403 match. For example, the control unit 300 may calculate the luminance in the front observation image 400 and detect the part that approximately matches the luminance of the nipple stored in advance in the storage unit 301 as the nipple t. Also, for example, the control unit 300 may determine whether the detected nipple t and the nipple target position 403 match based on the amount of deviation between them. For example, when the nipple t and the nipple target index 403 match, the control unit 300 may change the display color of the nipple target index 403. Of course, a message indicating that the nipple t and the nipple target index 403 match may be generated as a voice or displayed on the monitor 104.

<Acquisition of photographed images>
The examiner operates the monitor 104 and a start switch to start photographing the subject's eye E. The control unit 300 controls the OCT optical system 230 to optimize the photographing conditions of the fundus of the subject's eye E. For example, the control unit 300 adjusts the optical path length, focus, polarizer, etc. to enable photographing of desired characteristic areas (here, the macular region m and the optic disc t) with high sensitivity and high resolution. The control unit 300 also controls the OCT optical system 230 to scan the measurement light based on a scanning pattern, thereby acquiring a three-dimensional OCT tomographic image of the fundus.

<Analysis of captured images>
In addition, the three-dimensional OCT tomographic image is obtained as an image including both the macular portion m and the optic disc portion t by aligning the optic disc portion t with the optic disc target index 403 as described above. The control unit 300 may detect the macular portion m from the appropriate position R1 in the three-dimensional OCT tomographic image and calculate the analysis value of the retinal thickness for the macular portion m. Similarly, in the three-dimensional OCT tomographic image, the optic disc portion t may be detected from the appropriate position R2 and calculate the analysis value of the retinal thickness for the optic disc portion t. For example, the analysis value may be a value obtained by calculating a basic statistical amount for each section. For example, the basic statistical amount may be a representative value (average value, median value, mode value, maximum value, minimum value, etc.), a degree of dispersion (variance, standard deviation, coefficient of variation, etc.), etc. The control unit 300 may also generate a retinal map image representing the distribution of the retinal thickness of the macular portion m and the optic disc portion t based on the three-dimensional OCT tomographic image. The control unit 300 may generate a front image by integrating the spectral intensity of the interference signal for each point in the X and Y directions based on the three-dimensional OCT tomographic image. The control unit 300 may store the three-dimensional OCT tomographic image, the analysis value, the retina map image, the front image, and the like in the storage unit 301.

Of course, the control unit 300 may perform an analysis to obtain information other than the retinal thickness of the macular region m and the optic nerve t. For example, an analysis may be performed to obtain information regarding the shape of the macular region m and the optic nerve t. In this case, an analytical value of the shape of at least one of the macular region m and the optic nerve t may be calculated based on the 3D OCT tomographic image. As an example, at least one of the area, volume, size, analytical parameters (C/D ratio of the optic nerve t, etc.), etc. may be calculated.

As described above, for example, the fundus imaging device in this embodiment acquires an observation image of the fundus, and performs a guidance process to guide an analysis target including at least one of the macular region and the optic disc contained in the observation image into the imaging range of the OCT data captured by the OCT optical system, thereby aligning the analysis target with an appropriate position. This makes it possible to efficiently image the subject's eye and reduce the possibility of re-imaging.

In addition, for example, the fundus imaging device in this embodiment outputs guide information for guiding an analysis target including at least one of the macular region and the optic disc to an appropriate position as a guidance process. By using the guide information, the examiner can easily align the macular region and the optic disc to the appropriate position.

In addition, for example, the fundus imaging device in this embodiment performs guidance processing by superimposing on the observation image an index indicating a target position for matching an analysis target including at least one of the macula and the optic disc to the appropriate position. The examiner can grasp the deviation between the macula or optic disc and the appropriate position from such an index, and can easily align the macula or optic disc to the appropriate position.

In addition, for example, the fundus imaging device in this embodiment can be set to a first imaging mode in which either the macular region or the optic disc is imaged, and a second imaging mode in which both the macular region and the optic disc are imaged. For example, in particular, in the second imaging mode, both the macular region and the optic disc must be within a specified imaging range, and it is easy for these areas to not be included (or to be missing in part). For this reason, when the second imaging mode is set, the analysis target including at least either the macular region or the optic disc is aligned with the appropriate position, allowing imaging of the subject's eye to proceed efficiently.

<Example of transformation>
In this embodiment, the configuration in which the nipple target index 403 for moving the nipple t is superimposed on the front observation image 400 has been described as an example, but the present invention is not limited to this. In this embodiment, a guide mark for guiding the nipple t to the nipple target index 403 may be superimposed on the front observation image 400 together with the nipple target index 403. In this case, the control unit 300 may display a guide mark for moving the imaging unit 200 based on the deviation between the nipple t and the nipple target index 403. In this case, the control unit 300 may also superimpose a guide mark M for moving the fixation light position 402 (in other words, changing the lighting position of the fixation light) based on the deviation between the nipple t and the nipple target index 403. This will be described below by taking the movement of the fixation light position 402 as an example.

Figure 6 is an example of a front observation image 400. Figure 6 (a) shows a state before the fixation light position 402 is moved. Figure 6 (a) shows a state after the fixation light position 402 is moved. For example, the line of sight of the subject's eye E is gazing at a fixation light arranged on the measurement optical axis L, and the fixation light position 402 is displayed at the center position C of the front observation image 400. The control unit 300 detects the nipple t from the front observation image 400 and calculates the amount and direction of deviation between the nipple t and the nipple target index 403. The control unit 300 also calculates the amount and direction to move the fixation light position 402 based on the deviation between the nipple t and the nipple target index 403. Furthermore, the control unit 300 displays a guide mark M at the closest position among the fixation light positions arranged on the same circumference centered on the measurement optical axis L based on the amount and direction to move the fixation light position 402.

The examiner operates the monitor 104 to select the guide mark M superimposed on the front observation image 400 (for example, by clicking the guide mark M). The control unit 300 moves the fixation light position 402 to the position of the guide mark M. The control unit 300 also turns off the fixation light on the measurement optical axis L and turns on the corresponding fixation light around the measurement optical axis L. For example, when this changes the line of sight of the subject's eye E, the optic nerve head t is guided to coincide with the optic nerve head target index 403, and the macula m and optic nerve head t are contained within the shooting range 401.

The fundus imaging device in this embodiment may thus detect an analysis target including at least one of the macular region and the optic disc from the observation image, and based on the detection result, output guide information for guiding the analysis target including at least one of the macular region and the optic disc to an appropriate position as a guidance process. By using the guide information, the examiner can easily eliminate the deviation between the macular region or the optic disc and the appropriate position, and easily align the macular region or the optic disc to the appropriate position.

In this embodiment, the examiner manually guides the nipple t to the nipple target index 403, but this is not limiting. In this embodiment, the control unit 300 may automatically guide the nipple t to the nipple target index 403. In this case, the control unit 300 automatically adjusts the scanning range (imaging range) of the measurement light by the OCT optical system 230 based on the deviation between the nipple t and the nipple target index 403.

For example, the control unit 300 may control the scanning of the optical scanner 234 to change the scanning position and scanning direction of the measurement light in the OCT optical system 230. Also, for example, the control unit 300 may control the turning on and off of the light source to change the presentation position of the fixation light in the fixation guidance optical system 250. Also, for example, the control unit 300 may control the driving of the drive unit 105 to move the imaging unit 200 in at least one of the vertical and horizontal directions relative to the test eye E. Also, for example, the control unit 300 may control the driving of a drive unit (not shown) to tilt (pivot) the imaging unit 200 in at least one of the vertical and horizontal directions relative to the test eye E. The control unit 300 may adjust the imaging range of the measurement light by the OCT optical system 230 by any one of these or a combination thereof to guide the optic disc t to the optic disc target index 403.

In this way, the fundus imaging device in this embodiment may guide the macular area and optic disc in the observation image into the imaging range of the OCT data captured by the OCT optical system by adjusting the imaging range of the OCT data. As a result, any deviation between the macular area and the optic disc and the appropriate position is automatically eliminated, and the macular area and optic disc are appropriately positioned within the imaging range.

In this embodiment, the configuration in which the appropriate positions (appropriate positions R1 and R2) are set in advance for the front observation image 400 has been described as an example, but the present invention is not limited to this. In this embodiment, the macular region m may be detected from the front observation image 400, and a region separated from the macular region m by a predetermined number of pixels may be set as the appropriate position R2 of the optic nerve t. In this embodiment, the appropriate position R2 of the optic nerve t may be set by detecting the optic nerve t from the front observation image 400. In this case, the optic nerve t may be detected based on the luminance of the front observation image 400. In this case, the optic nerve t may be detected based on the analysis result of the analysis of the retinal layer. More specifically, the region in which the retinal layer is not detected may be detected as the optic nerve t. In this embodiment, the axial length of the subject's eye E may be obtained, and the position of the optic nerve t predicted based on the axial length may be set as the appropriate position of the optic nerve t. In this case, the axial length of the subject's eye E may be measured using an axial length measuring device or the like, and input.

In this embodiment, the front observation image 400 may be a fundus image captured by the observation optical system 240. That is, the front observation image 400 may be an infrared fundus image captured by a fundus camera optical system, an SLO front image captured by an SLO optical system, or the like.

In addition, in this embodiment, an index indicating a target position to which the macular region m is to be moved may be superimposed on the front observation image 400. Of course, both the index of the target position for the macular region m and the nipple target index 403 for the nipple region t may be superimposed.

In addition, in this embodiment, in a macular imaging mode in which the macular portion m of the fundus is imaged, an index representing the target position of the macular portion m may be superimposed to guide the macular portion m within the scanning range of the measurement light by the OCT optical system 230 (i.e., within the imaging range). Similarly, in a papilla imaging mode in which the papilla t of the fundus is imaged, a papilla target index 403 for the papilla t may be superimposed to guide the papilla t within the scanning range of the measurement light. For example, even in these imaging modes, efficient imaging and analysis can be performed by guiding the macular portion m or the papilla t to the target position and matching it with the appropriate position set in advance.

In this embodiment, an example is shown in which an OCT front image (front observation image 400) is selected as the observation image, but the configuration may also be such that the nipple target index is superimposed when an OCT tomographic image is selected.

Figure 7 is an example of an OCT tomographic image 500. An imaging range 501, a nipponic target index 503, etc. are electrically superimposed on the OCT tomographic image 500. The position of the fixation light presented to the subject's eye E (fixation light position) may be displayed separately from the OCT tomographic image 500. Note that Figure 7(a) shows the OCT tomographic image 500 in a state where it is not tilted, and Figure 7(b) shows the OCT tomographic image 500 in a state where it is tilted.

The examiner may move or tilt the imaging unit 200 or change the position of the fixation light so that the optic nerve head t in the OCT tomographic image 500 is aligned with the optic nerve head target index 503. Alternatively, the control unit 300 may move or tilt the imaging unit 200 or change the position of the fixation light so that the optic nerve head t is aligned with the optic nerve head target index 503. Of course, both the movement or tilt of the imaging unit 200 and the change of the position of the fixation light may be performed. This allows the macula m and optic nerve head t to be contained within the imaging range 501, and the macula m and optic nerve head t to be positioned in their respective appropriate positions.

For example, if the retinal layer is photographed at an angle in the OCT tomographic image 500, appropriate analysis results for the macula m and the optic disc may not be obtained. For this reason, an index 504 indicating the degree to which the retinal layer is tilted may be displayed on the OCT tomographic image 500. For example, the control unit 300 may detect the retinal layer from the OCT tomographic image 500, and further calculate the slope of a linear approximation equation (straight-line approximation equation) of the retinal layer, and display the index 504 based on the detected slope. Of course, the calculation of the slope of the retinal layer is not limited to the method using the linear approximation equation. For example, the slope of the retinal layer may be calculated based on the luminance distribution of the retinal layer.
The examiner or the control unit 300 may align the optic disc t with the optic disc target index 503, and may also move or tilt the imaging unit 200 or change the presentation position of the fixation light so as to eliminate the inclination of the retinal layer.

The fundus imaging device in this embodiment may thus acquire an OCT tomographic image as an observation image, and align at least one of the analysis targets, the macular region and the optic disc, contained in the OCT tomographic image with the appropriate position. For example, by using the OCT tomographic image, it is possible to grasp the inclination of the retinal layer caused by the subject's face being tilted relative to the imaging unit, and to appropriately place the macular region and the optic disc within the imaging range.

1 Fundus imaging device 104 Monitor 200 Imaging unit 230 OCT optical system 300 Control unit 400 Front observation image 403 Optic disk target index 500 OCT tomographic image 503 Optic disk target index

Claims (6)

A fundus imaging apparatus having an OCT optical system that detects an interference signal caused by a measurement light and a reference light irradiated onto a fundus of a test eye, and acquires OCT data of the fundus based on the interference signal,
an observation image acquisition means for acquiring an observation image of the fundus;
A control means for executing a guidance process for guiding a macular region and an optic nerve head included in the observation image into an imaging range of the OCT data captured by the OCT optical system, the guidance process being for aligning an analysis target including both the macular region and the optic nerve head with an appropriate position set within the imaging range in consideration of a region size required for analysis of the analysis target;
and an analysis processing means for analyzing the OCT data including both the macular region and the optic nerve disc as analysis targets to obtain an analysis result for the macular region and the optic nerve disc,
The control means of this fundus photography device is characterized in that it performs the guidance process so that the measurement optical axis of the OCT optical system is positioned on the macula side of the center of the macula and the optic disc of the test eye, but away from the macula . In the fundus photographing apparatus according to claim 1,
The fundus imaging apparatus according to claim 1, wherein the control means outputs guide information for guiding the analysis target to the appropriate position as the guidance process. In the fundus photographing apparatus according to claim 1 or 2,
an adjustment unit that adjusts the imaging range of the OCT data captured by the OCT optical system;
The control means controls the adjustment means to adjust the photographing range as the guidance process in order to guide the analysis target into the photographing range. In the fundus photography apparatus according to any one of claims 1 to 3,
The fundus photographing apparatus is characterized in that the observation image is an OCT tomographic image of the fundus that can be photographed by the OCT optical system. In the fundus photography apparatus according to any one of claims 1 to 4,
a setting means for setting a first imaging mode for acquiring first OCT data obtained by imaging either the macular region or the optic disc, and a second imaging mode for acquiring second OCT data obtained by imaging both the macular region and the optic disc,
A fundus imaging device characterized in that, when the second imaging mode is set by the setting means, the control means executes the guidance process for aligning the analysis target with the appropriate position. In the fundus photography apparatus according to any one of claims 1 to 5,
The fundus photographing apparatus according to claim 1, wherein the control means executes the guidance process for aligning the optic disc with the appropriate position.

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