JP7183617B2 - Fundus camera - Google Patents

Description

The present disclosure relates to a fundus imaging device.

Various devices such as a fundus camera, a scanning laser ophthalmoscope (SLO), and an optical coherence tomography (OCT) are known as fundus imaging devices.

In obtaining fundus images, it is desirable to avoid vignetting or noise contamination due to the iris, eyelids, and eyelashes. For example, Patent Literature 1 discloses a technique for detecting the states of pupils, eyelids, and eyelashes by analyzing an anterior ocular observation image obtained in an alignment completed state. In Japanese Patent Laid-Open No. 2002-200000, further, whether or not the above vignetting and noise light occurs is displayed on the monitor based on the detection result.

Also, in recent years, attention has been focused on a non-mydriatic imaging device that captures images of the fundus with a wider angle of view (viewing angle). For example, Patent Document 1 proposes a scanning laser ophthalmoscope that photographs the fundus with an angle of view of about 90° or more (see Patent Document 2).

JP 2009-112665 A JP 2016-123467 A

There are individual differences in the diameter of the pupil at the time of natural mydriasis and the ease with which the eyelids and eyelashes cover the imaging optical path. Therefore, for example, even if the examiner changes the positional relationship (that is, the alignment state) between the device and the subject's eye with reference to the display of Patent Document 1, vignetting or vignetting due to the iris, eyelids, and eyelashes may occur. It may be difficult to avoid mixing of noise light. Further, if the required pupil diameter is constant, the larger the angle of view, the narrower the permissible alignment range. is likely to prolong.

The technical problem of the present disclosure is to solve at least one of the problems of the prior art, and to provide a fundus imaging device capable of capturing a good fundus image while quickly completing alignment adjustment between the device and the subject's eye. and

A fundus photographing apparatus according to a first aspect of the present disclosure includes a photographing optical system that irradiates illumination light onto the fundus of an eye to be inspected and photographs a fundus image based on light returned from the fundus of the illumination light ; The effective range in which the return light from the fundus can be effectively obtained in the imaging range of the optical system, and is at least one of the state of the pupil of the eye to be inspected, the state of the eyelids open, and the facial shape of the subject. and a control means for detecting the effective range, wherein the control means presets a reference value of the effective range for each eye to be examined, and the reference value for each eye to be examined and the detected value of the effective range. Compare with, compare with.

According to the present disclosure, it is possible to quickly complete the alignment adjustment between the device and the subject's eye while taking a good fundus image.

1 is a diagram showing the appearance of a fundus imaging device according to an example. FIG. 1 is a diagram showing an imaging optical system according to an example; FIG. FIG. 10 is a diagram showing a photographing optical system with a wide-angle attachment attached; It is a figure which shows the control system of SLO which concerns on an Example. FIG. 4 is a diagram showing an example of a fundus image; FIG. 10 is a diagram showing a fundus image with vignetting; FIG. 10 is a diagram for explaining changes in the effective area according to the working distance; It is a flow chart showing the operation of the device according to the embodiment. FIG. 10 is a diagram showing a positional relationship between an anterior segment observation optical system according to a modification and an eye to be examined;

"Overview"
Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.

A fundus imaging apparatus according to an embodiment is used for fundus imaging of an eye to be examined (see FIG. 1). The fundus imaging device has at least an imaging optical system (see FIGS. 2 and 3, for example) and a controller (see FIG. 4, for example). The ophthalmologic imaging apparatus may additionally include at least one of a drive section (also called an "alignment adjustment section", see FIG. 1), an observation optical system, an angle-of-view switching section, a monitor, and a speaker. good.

<Control part>
The control unit is a processing device (processor) that performs control processing of each unit in the fundus imaging apparatus and arithmetic processing. For example, the control unit is implemented by a CPU (Central Processing Unit), a memory, and the like. In this embodiment, the control section may also serve as the image processing section. The image processing unit generates a fundus image (see, for example, FIG. 5) and performs at least one of various image processing on the fundus image.

<Photographing optical system>
The imaging optical system irradiates the fundus of the subject's eye with illumination light. Also, a fundus image is taken based on the return light of the illumination light from the fundus.

The imaging optical system may capture a front image of the fundus as the fundus image. The imaging optical system is not necessarily limited to this, and may include a front imaging optical system (see FIGS. 2 and 3) that captures a front image of the fundus. The imaging optical system may also include an OCT optical system (not shown) that acquires OCT data of the fundus based on the spectral interference signal between the return light and the reference light. Alternatively, the imaging optical system may include both the front imaging optical system and the OCT optical system.

The imaging optical system may have an irradiation optical system and a light receiving optical system (see FIGS. 2 and 3). The irradiation optical system irradiates the fundus of the eye to be examined with illumination light. Additionally, the illumination optics may have a light source that emits illumination light (illumination light source). The light-receiving optical system may have a light-receiving element that receives the fundus-reflected light of the illumination light. In this case, the signal from the light receiving element is input to the image processing section, and as a result, the fundus image of the subject's eye is acquired (generated).

When the imaging optical system is a front imaging optical system, the imaging optical system may be a scanning optical system that performs imaging by scanning illumination light on the fundus. Also, in this case, the imaging optical system may be a non-scanning optical system. Examples of scanning optical systems include a spot scanning optical system and a line scanning optical system. In the spot scan type optical system, a spot-shaped illumination light is two-dimensionally scanned on the fundus. In a line scan type optical system, linear illumination light is scanned in one direction. For example, the line-shaped illumination light may be linearly scanned on the fundus or may be rotationally scanned on the fundus. In the case of rotational scanning, the center of rotation may be the optical axis of the imaging optical system. In the scanning optical system, any one of a point light receiving element, a line sensor, a two-dimensional light receiving element (imaging element) and the like can be appropriately adopted as the light receiving element. An example of a non-scanning optical system includes an optical system of a general fundus camera.

When the imaging optical system is an OCT optical system, OCT data is acquired based on optical interference between the light irradiated to the fundus and the reference light. The OCT optics may be FD-OCT. SD-OCT, SS-OCT, etc. are known as FD-OCT. In the following description, SD-OCT will be used unless otherwise specified. However, it is not necessarily limited to this, and each type of OCT optical system can be employed as part or all of the imaging optical system.

<Observation optical system>
The fundus imaging device may have an observation optical system. The observation optical system may observe the anterior segment of the eye or the fundus. The observation image may be a front image of the anterior segment or fundus observed from a predetermined direction. Various imaging conditions may be adjusted using an observation image acquired via the observation optical system. One of the various imaging conditions may include an alignment state. In this embodiment, part or all of the observation optical system may be shared with the imaging optical system. Also, the observation optical system may be an optical system completely independent of the imaging optical system. The fundus photographing apparatus may have not only one of the anterior segment observation optical system and the fundus observation optical system, but also both of them as the observation optical system.

<Drive unit (alignment adjustment unit)>
The drive unit is a mechanism that changes (adjusts) the positional relationship (alignment state) between the subject's eye and the imaging optical system. In this embodiment, the positional relationship between the passage range of the illumination light and return light and the pupil, eyelid, and eyelashes of the subject's eye is changed according to the alignment state. When the observation optical system is provided, the positional relationship between the observation optical system and the subject's eye is changed integrally with the photographing optical system.

The driving section may have an actuator that changes the positional relationship between the subject's eye and the imaging optical system based on a signal from the control section. Further, the drive unit may be a mechanical mechanism that changes the positional relationship between the subject's eye and the imaging optical system according to the force given by the examiner.

The drive unit may, for example, displace an imaging unit including an imaging optical system (and an observation optical system), or may move a face support unit (e.g., chin rest) that supports the subject's face. It may be displaced or may be a combination of both.

For example, in a typical alignment adjustment method, first, the positional relationship in the vertical and horizontal directions (also referred to as the XY directions) is adjusted, and then the positional relationship in the front-rear direction (working distance direction, also referred to as the Z direction) is adjusted. be. In the adjustment in the vertical and horizontal directions, for example, adjustment is made so that the optical axis of the photographing optical system is aligned with the visual axis of the subject's eye. Further, in the adjustment in the front-rear direction, the distance of the photographing optical system to the subject's eye is adjusted to a predetermined working distance. Various alignment indexes may be used in the alignment adjustment. In this case, the fundus imaging apparatus of this embodiment may have an index projection optical system that projects the alignment index onto the subject's eye.

The ophthalmologic imaging apparatus may adjust the positional relationship between the subject's eye and the imaging optical system by automatic alignment. In this case, the control unit may adjust the alignment state by driving the driving unit based on the observed image.

Further, the ophthalmologic imaging apparatus of the present embodiment does not necessarily have a driving section for alignment adjustment. For example, the alignment may be adjusted by adjusting the position of the subject's face without using an instrument with respect to the position-fixed imaging optical system.

<Shooting Assist>
In the present embodiment, the imaging assist illustrated below is executed in order to quickly complete the alignment adjustment between the device and the subject's eye and capture a good fundus image. More specifically, even if there is an area where the fundus cannot be imaged satisfactorily in part of the imaging range of the device, if the area is acceptable, alignment adjustment is completed and imaging proceeds. . At this time, for example, at least one of the state of the pupil and the state of the eyelids open may be taken into consideration as to whether or not the region that cannot be satisfactorily photographed should be allowed. Alternatively or additionally, the facial shape of the subject may be taken into consideration (details will be described in <Modifications> below). When photographing assist is executed, vignetting and other effects may occur mainly on the peripheral portion of the fundus image. In that case, the area (effective range) that can be used for observation and diagnosis is preferably, for example, 80% or more of the imaging range of the apparatus. Further, it is preferable that the photographing assist of the present embodiment is applied to an apparatus having an angle of view of 90° or more. Even if an effect such as vignetting occurs in a part of the periphery, a sufficiently wide range can be observed and diagnosed. In particular, an ultra-wide-angle imaging device with an angle of view of 100° or more can secure the effective range of a panoramic image (equivalent to an angle of view of 90°) using a conventional fundus image, even if a part of the fundus image is affected by vignetting or the like. obtain. Therefore, an ultra-wide-angle imaging device with an angle of view of 100° or more is more preferable because observation and diagnosis can be performed satisfactorily not only at the central portion of the fundus, but also at the peripheral portion, even when the imaging assist is used. be. For example, as shown in FIG. 6A, in the case of vignetting caused by eyelashes, shadows of the eyelashes appear in the fundus image from the upper end or from the lower end of the image. Further, as shown in FIG. 6B, in the case of vignetting caused by the iris, shadows are generated in the peripheral portion.

(1) Detection of Effective Range For example, the alignment state is changed by driving the driving section. At this time, in the present embodiment, the effective range is detected by the control unit at any time. Here, the effective range is a range within which the return light from the fundus can be effectively obtained, out of the imaging range (that is, the entire angle of view) of the imaging optical system. For example, if vignetting due to the iris or the like occurs in part of the shooting range, the range excluding that part becomes the effective range. Also, an area where noise occurs due to reflection from eyelashes or the like may be excluded from the effective range. The effective range changes according to at least one of the state of the pupil of the subject's eye and the state of the eyelids being open. The effective range also changes according to the alignment state. As an example, FIG. 7 shows changes in the effective range when the alignment state in the Z direction changes. As shown in FIG. 7, vignetting (due to the iris in FIG. 7) occurs in the periphery when the working distance is too short or too long as compared to the case where the working distance is proper.

The effective range may be detected based on an observed image of the anterior segment or fundus. As an example, when the effective range is detected based on the observed image of the fundus, noise occurs due to the areas in the observed image where light is blocked by the iris, eyelids, and eyelashes, and reflections from the eyelashes and the like. At least one of the areas may be detected by image processing, and the remaining areas may be detected as the effective range.

The control unit may inform the examiner of information indicating the size of the effective range in real time based on the detection result of the effective range. For example, an indicator may be displayed that indicates the size of the effective range numerically (eg, angle of view, ratio to shooting range, etc.). Also, the indicator is not limited to a numerical value, and may be, for example, one whose color changes according to the size of the effective range.

(2) The effective range reference value setting control unit may set the effective range reference value for each eye to be examined. The reference value is set based on the effective range detection result during the period in which the alignment state is changed. The reference value indicates the size of the effective range that should be secured during shooting. The reference value is set to a value that takes into consideration at least one of the state of the pupil and the state of the eyelids open, with the upper limit being the value that indicates the imaging range of the device.

For example, any of the values listed below may be adopted as the reference value for each eye to be examined. Of course, values other than those listed may be set as the reference value.
a. the maximum value of the effective range during the detection period; b. above a. A value that is a predetermined amount smaller than the maximum value of c. When multiple maximum values are seen in a graph plotting the effective range against the time axis, the average value of all or part of the multiple maximum values, or the center value etc.
d. Of the candidate values set in advance based on the photographing range of the apparatus (for example, values corresponding to 100%, 90%, 80% of the photographing range, etc.), the above a. ~ c. An approximation of the value of .

When the reference value is set, the control unit may notify the examiner or the subject of information indicating the reference value. For example, in the fundus observation image, an electronic mask may be superimposed outside the range corresponding to the reference value in the imaging range.

The length of the effective range detection period until the reference value is set may be predetermined. For example, the end of the detection period is determined based on any of the timing of starting observation, the timing of completion of alignment adjustment in the XY directions, and the timing of completion of focus adjustment after once performing alignment adjustment in XYZ. may be set at least. For example, the end of the detection period may be set to a point in time after a certain period of time has passed from any timing. When the alignment adjustment in the XY directions is completed, the substantially maximum effective range of the subject's eye can be detected during the change by changing the alignment state in the Z direction. Therefore, the end of the detection period is set based on either the timing at which the alignment adjustment in the XY direction is completed or the timing at which the XYZ alignment adjustment is once performed and then the focus adjustment is completed. is desirable.

Further, the control unit may determine at any time during detection of the effective area whether vignetting that occurs in the imaging range is due to at least one of the eyelids and the eyelashes. It may be determined based on the observed image. For example, when using a fundus observation image, it may be determined whether or not the vignetting is caused by at least one of the eyelids and/or the eyelashes based on the position, shape, or both of vignetting occurring in the observation image. For example, if vignetting occurs only at the vertical ends of the observed image and not at the horizontal ends, it may be determined that vignetting is caused by at least one of the eyelids and the eyelashes. . Also, as shown in FIG. 6B, when striped vignetting occurs, it may be determined that vignetting is caused by eyelashes.

If the vignetting is determined to be at least one of the eyelids and the eyelashes, guide information may be output to encourage opening of the eyelids. As for the guide information, for example, a voice such as "Please open your eyelids" may be output as the guide information. Also, the guide information may be text or graphical information displayed on the monitor 80 .

If vignetting occurs due to at least one of the eyelids and eyelashes during the detection period, the control unit may output guide information for prompting the eyelids to open, and then set the reference value.

(3) Comparison processing between the reference value and the detection value of the effective range After the reference value is set, the control unit detects the effective range. The detected valid range may be compared with a reference value (comparison process). The detection and comparison may each be performed repeatedly until the valid range is greater than or equal to the reference value. The detection of an effective range equal to or greater than the reference value may be used as a trigger for the operations exemplified in "(4) automatic photographing" and "(5) guide of photographing operation" below, for example. At this time, the trigger condition may be that an effective range equal to or greater than the reference value is continuously detected for a certain period of time. Further, when automatic alignment is performed, alignment control may be stopped (completed) at the stage when an effective range equal to or greater than the reference value is detected.

If an effective range equal to or greater than the reference value is not detected even after a predetermined time has passed since the reference value was set, the examiner or the subject may be notified of this as an error. In this case, the alignment adjustment may be redone by returning to the above "(1) Detection of effective range".

Further, when the guide information for prompting the eyelid opening is output in advance during the detection period, the guide information may be output again to prompt the eyelid opening after setting the reference value. It is believed that this makes it easier to quickly ensure an effective range equal to or greater than the reference value. As a result, alignment can be completed more quickly and imaging can proceed.

(4) Automatic photography For example, when the effective range is equal to or greater than the reference value as a result of comparison processing (in other words, when an effective range equal to or greater than the reference value is detected), the control unit automatically captures the fundus image. You can take pictures. A fundus image is captured without requiring an imaging operation (for example, pressing an imaging button) by the examiner.

The control unit may capture the fundus image immediately after the effective range equal to or greater than the reference value is detected. Such imaging, for example, when imaging is completed in a relatively short time, or when imaging with invisible light (for example, infrared light) as illumination light, is relatively burdensome for the subject due to imaging. Useful when there are few. Specifically, you can shoot smoothly over a larger effective range.

However, it is not necessarily limited to this. For example, the fundus image may be captured not immediately after the effective range equal to or greater than the reference value is detected, but after some time has passed.

In this case, for example, the control unit may give an advance notice of photographing to at least one of the examiner and the subject, and may photograph the fundus image after the advance notice. For example, when imaging takes a relatively long time, or when a relatively large burden on the examinee is assumed, such as when imaging with visible light as illumination light, it is recommended to give advance notice before imaging. is useful. The advance notice can prompt the subject to keep the eyelids open, for example.

Further, the control unit may further perform blink detection after the effective range equal to or greater than the reference value is detected, and photograph the fundus after the blink is detected. A blink may be detected based on an observed image of the anterior segment or fundus. When the fundus is photographed after a blink is detected, an effective range equal to or larger than the reference value is easily ensured during photographing, and photographing errors caused by blinking are reduced. However, it is preferable that the photographing be performed after an interval of about 0.5 seconds, not immediately after the detection of the blink. Since fixation is difficult to stabilize immediately after blinking, the subject's eye moves during photographing, and noise (such as flare) is likely to occur in the photographed image. On the other hand, as described above, the occurrence of noise is suppressed by taking a short time after the detection of the blink and performing the shooting. The time from the timing of blink detection to the timing of photographing may be a fixed value. However, it is not necessarily limited to this, and the control unit may further detect a fixation, and capture a fundus image at the timing when the stabilization of the fixation is further detected after the blink is detected. The fixation state can be detected based on, for example, an anterior segment observed image.

When photographing is performed based on the blink detection result, guide information for prompting the subject to blink may be output as an advance notice of photographing. For example, as audio guide information, a message such as "Blink and open your eyelids widely" may be output from a speaker.

By performing such photographing assistance, a fundus image in which a wider effective range is ensured for each eye to be examined can be photographed more quickly. As a result, the burden on the examiner and the subject accompanying imaging is reduced.

(5) Guidance of photographing operation For example, when the effective range is equal to or greater than the reference value as a result of the comparison processing, the control unit may guide the photographing of the fundus image. In this case, for example, the timing at which the shooting operation should be performed may be notified. More specifically, information may be displayed on the monitor indicating that the timing for photographing has come. A photographing operation (for example, pressing a photographing button) by the examiner is performed based on the above notification, so that a fundus image having an effective range equal to or larger than the reference value can be easily photographed.
Each timing at which photographing is automatically performed in the above "(4) Automatic photographing" can be appropriately replaced with the timing of notification start and applied.

(6) Adjustment of detection period When an effective field of view corresponding to 100% of the imaging range is detected, the detection period may be terminated immediately regardless of the length of the remaining detection period. In this case, a value corresponding to 100% of the shooting range may be set as the reference value.

Also, when an effective field of view corresponding to 100% of the photographing range is detected, the setting of the reference value and the subsequent processing of detecting the effective range are not necessarily required. For example, in this case, either "(4) automatic photographing" or "(5) guide of photographing operation" may be executed immediately, regardless of whether it is before or after setting the reference value.

Also, the length of the detection period may be adjusted according to changes in the effective field of view during the detection period.

<First Modification of Shooting Assist>
Further, during alignment adjustment, the drive section (alignment adjustment section) may be driven and controlled based on the observed image. In this case, regarding the Z direction, the effective range in each positional relationship may be detected while changing the positional relationship between the subject's eye and the imaging optical system at least within a predetermined range. Such alignment adjustment in the Z direction is preferably started after alignment adjustment in the XY directions, as described above. Thereafter, the control unit further adjusts the positional relationship between the subject's eye and the imaging optical system so that the positional relationship maximizes the effective range during the alignment adjustment in the Z direction, and then automatically or , the shooting may be performed manually.

In this case, the operations "(2) setting the reference value of the effective range" and "(3) comparing the effective range detected after setting the reference value and the reference value" may be executed. However, it is not necessary. Also, in the case of automatic or manual photography, part of the descriptions in "(4) Automatic photography" and "(5) Guide to photography operation" can be applied as appropriate.

<Second Transformation of Shooting Assist>
In the above description, the reference value of the effective range is set for each eye to be examined based on the detection result of the effective range during the period in which the alignment state changes. However, it is not necessarily limited to this. For example, the reference value may be a fixed value that does not depend on the detection result of the effective range of each subject's eye.

In this case, the reference value may be, for example, a value corresponding to 90% of the photographing range, a value corresponding to 80%, . . . Alternatively, it may be a value selected in advance by the examiner from among these values. Compared to the case where the reference value is set for each subject based on the alignment adjustment, it is considered that the fixed value can shorten the time required for alignment.

<Switching shooting modes>
The controller may switch the imaging mode of the device. For example, the shooting mode may be switched between a "first shooting mode" in which <shooting assistance> is not performed and a "second shooting mode" in which <shooting assistance> is performed. In the "first imaging mode", at least the effective range is not detected by the control unit. Further, the photographing ranges (angles of view) of the apparatus may differ between different photographing modes. At least the first angle of view and the second angle of view may be selectable as the imaging range. Here, the narrower imaging range is referred to as the "first angle of view", and the wider imaging range is referred to as the "second angle of view". For example, the first angle of view may be less than 90° and the second angle of view may be 90° or more. For example, the first angle of view may be approximately 45° to 60°, and the second angle of view may be approximately 90° to 150°. Here, if the required pupil diameter is constant, the alignment tolerance becomes narrower as the angle of view increases, and vignetting caused by the iris, eyelids, and eyelashes, and noise caused by reflection on the eyelashes, etc. can be avoided by alignment adjustment. become more difficult. Therefore, the second shooting mode in which <shooting assistance> is performed may be selected in the case of the “second angle of view”. That is, in this case, the control unit may select the shooting mode in conjunction with the switching of the angle of view.

<View angle switching part>
The fundus imaging device may additionally have an angle-of-view switching unit. The angle-of-view switching unit switches the angle of view in the imaging optical system. In other words, the angle-of-view switching unit changes the power of the imaging optical system.

The angle-of-view switching unit may switch the angle of view by, for example, switching the configuration of the objective optical system (for example, lens configuration or mirror configuration) in the imaging optical system. As an example, the angle of view of the device may be selectively switched between two predetermined angles by attaching and detaching (inserting and removing) an attachment optical system (see FIG. 3) such as a lens attachment.

However, the method for switching the angle of view of the photographing optical system is not limited to attaching and detaching (inserting and removing) the attachment optical system. For example, the angle of view may be switched by replacing part or all of the objective optical system. Also, the angle of view may be switched by a zoom mechanism that switches the arrangement of optical elements in the objective optical system.

"Example"
A typical embodiment of the present invention will be described below with reference to the drawings. First, the overall configuration of the fundus imaging apparatus 1 will be described with reference to FIGS. 1 to 3. FIG.

<External configuration>
As shown in FIG. 1, in this embodiment, the device main body has an imaging section 4, an alignment mechanism 5, a base 6, and a face support unit 7. As shown in FIG. The imaging unit 4 stores an optical system for imaging the eye E to be examined. This optical system will be described later with reference to FIGS.

The alignment mechanism 5 (“alignment adjustment unit” in this embodiment) is used to align the device with the eye E to be examined. In this embodiment, the positioning mechanism 5 three-dimensionally moves the imaging unit 4 with respect to the base 6 . The photographing unit 4 may be movable in each of the Y direction (vertical direction), the X direction (horizontal direction), and the Z direction (vertical direction). Unless otherwise specified, the following description assumes that the positioning mechanism 5 is manually driven based on the operation of the joystick 8 or the like.

The face support unit 7 supports the subject's face with the subject's eye E facing the photographing unit 4, as shown in FIG. It should be noted that the face support unit 7 is fixed to the base 6 in this embodiment.

<SLO optical system>
In this embodiment, the fundus photographing apparatus 1 has a front photographing optical system 200 (see FIGS. 2 and 3) for photographing a front image of the fundus. In this embodiment, the front imaging optical system is an SLO (Scanning Laser Opthalmoscope: SLO) optical system. Further, in this embodiment, the front imaging optical system 200 also serves as a fixation optical system. The SLO optical system 200 acquires a front image of the fundus Er by scanning the fundus Er with laser light and receiving the return light of the laser light from the fundus Er.

In the following description, the fundus imaging device 1 captures a fundus image by two-dimensionally scanning laser light condensed on a spot on an observation surface based on the operation of a scanning unit (optical scanner). obtain. However, it is not necessarily limited to this, and the SLO optical system 200 may be a so-called line scan type optical system. In this case, the viewing surface is scanned with a linear light beam. Also, a non-scanning optical system may be used as the front imaging optical system instead of the scanning optical system as in this embodiment.

The SLO optical system 200 includes an irradiation optical system 10 and a light receiving optical system 20 .

First, with reference to FIG. 2, the optical system when the imaging angle of view is the first angle of view will be described. In this embodiment, when the attachment optical system 3 (see FIG. 3) is not attached, the photographing angle of view is set to the first angle of view.

The irradiation optical system 10 includes a scanning section 16 and an objective optical system 17 . The objective optical system 17 of this embodiment includes at least one lens. Further, as shown in FIG. 2, the irradiation optical system 10 further includes a laser light source 11, a perforated mirror 13, a lens 14 (part of the diopter correction unit 40 in this embodiment), and a lens 15. .

A laser light source 11 is the light source of the irradiation optical system 10 . In this embodiment, the laser light from the laser light source 11 is used as imaging light. The laser light source 11 of this embodiment can emit light of multiple colors simultaneously or selectively. As an example, in this embodiment, the laser light source 11 emits light of a total of four colors, namely three colors in the visible range of blue, green, and red, and one color in the infrared range. Light of each color may be capable of being emitted simultaneously in any combination. In this embodiment, the light of each color emitted from the laser light source 11 is used for photographing the fundus. A fundus image captured based on the reflected light of the fundus may be referred to as a reflected image, and a fundus image captured based on fluorescence from a fluorescent substance present in the fundus Er may be referred to as a fluorescence image.

Any or all of an infrared image, a color image, a red-free image, a monochrome visible image, and the like may be captured as the reflected image. Also, as the fluorescence image, either or all of the contrast-enhanced fluorescence image and the autofluorescence image may be captured. The contrast-enhanced fluorescence image may be an image obtained by fluorescence emission of a contrast agent intravenously injected into the fundus Er, and may be, for example, an FA image (fluorescein contrast-enhanced image) or an ICGA image (indocyanine green contrast-enhanced image). image). Further, the autofluorescence image may be an image obtained by fluorescence emission of a fluorescent substance accumulated in the fundus Er, for example, an image obtained by fluorescence emission of lipofuscin.

In this embodiment, laser light from the laser light source 11 passes through an opening formed in the perforated mirror 13 , passes through the lenses 14 and 15 , and then travels toward the scanning section 16 . The laser light reflected by the scanning unit 16 passes through the dichroic mirror 51, passes through the objective optical system 17, and is irradiated onto the fundus Er of the eye E to be examined. As a result, the laser light is reflected and scattered by the fundus Er, or excites a fluorescent substance present in the fundus Er to generate fluorescence from the fundus. These lights (that is, reflected/scattered light, fluorescence, etc.) are emitted from the pupil as light (return light) from the subject's eye accompanying the irradiation of the laser light.

The scanning unit 16 (also referred to as “optical scanner”) is a unit for scanning the fundus Er with a laser beam emitted from the laser light source 11 . In the following description, unless otherwise specified, the scanning unit 16 includes two optical scanners that scan laser beams in different directions. That is, it includes an optical scanner 16a for main scanning (eg, for scanning in the X direction) and an optical scanner 16b for sub-scanning (eg, for scanning in the Y direction). In the following description, the optical scanner 16a for main scanning is a resonant scanner, and the optical scanner 216b for sub-scanning is a galvanomirror. However, other optical scanners may be applied to the optical scanners 16a and 16b. For example, for each of the optical scanners 16a and 16b, in addition to other reflection mirrors (galvanomirrors, polygon mirrors, resonant scanners, MEMS, etc.), an acoustooptic device (AOM) that changes the traveling (deflecting) direction of light, etc. may apply.

The objective optical system 17 is the objective optical system of the fundus imaging device 1 . The objective optical system 17 is used to irradiate the subject's eye E with laser light scanned by the scanning unit 16 and guide the laser light to the fundus Er. Therefore, the objective optical system 17 forms a turning point P around which the laser beam that has passed through the scanning unit 16 is turned. The turning point P is formed on the reference optical axis L<b>1 of the irradiation optical system 10 and at a position optically conjugate with the scanning unit 16 with respect to the objective optical system 17 . In the present disclosure, "conjugated" is not necessarily limited to a perfect conjugated relationship, but includes "substantially conjugated". That is, the "conjugate" in the present disclosure includes the case where the positions are shifted from the perfect conjugate position within a range permitted by the purpose of use of the fundus image (for example, observation, analysis, etc.). In this embodiment, the objective optical system 17 of the fundus photographing device 1 is realized only by lenses, but it is not necessarily limited to this, and may be realized by a combination of lenses and mirrors.

The laser light that has passed through the scanning unit 16 passes through the objective optical system 17, passes through the turning point P, and is irradiated to the fundus Er. Therefore, the laser light that has passed through the objective optical system 17 is rotated around the pivot point P as the scanning unit 16 operates. As a result, in this embodiment, the fundus Er is scanned two-dimensionally with laser light. The laser light applied to the fundus Er is condensed at a condensing position (for example, the surface of the retina).

Next, the light receiving optical system 20 will be described. The light receiving optical system 20 has one or more light receiving elements. For example, the light receiving optical system 20 may have a plurality of light receiving elements 25, 27, 29 as shown in FIG. In this case, at least one of the light receiving elements 25 , 27 , 29 receives the light from the fundus Er by the laser light irradiated by the irradiation optical system 10 .

As shown in FIG. 2, the light-receiving optical system 20 in this embodiment may share the members arranged from the objective optical system 17 to the perforated mirror 13 with the irradiation optical system 10 . In this case, light from the fundus Er traces the optical path of the irradiation optical system 10 and is guided to the perforated mirror 13 . The perforated mirror 13 removes at least part of the noise light reflected by the cornea of the subject's eye E and the optical system inside the apparatus (for example, the lens surface of the objective lens system, etc.), while removing the light from the fundus Er. It is guided to the independent optical path of the light receiving optical system 20 .

The optical path branching member for branching the irradiation optical system 10 and the light receiving optical system 20 is not limited to the perforated mirror 13, and other optical members (for example, a half mirror) may be used.

The light-receiving optical system 20 of this embodiment has a lens 21 , a pinhole plate 23 , and a light separating section (light separating unit) 23 on the reflected light path of the perforated mirror 13 .

The pinhole plate 23 is arranged on the fundus conjugate plane and functions as a confocal diaphragm in the fundus imaging device 1 . That is, when the diopter is properly corrected by the diopter corrector 40 , the light from the fundus Er that has passed through the lens 21 is focused on the aperture of the pinhole plate 23 . The pinhole plate 23 removes light from positions other than the focal point (or focal plane) of the fundus Er, and the remainder (light from the focal point) is sent to at least one of the light receiving elements 25, 27, and 29. be guided.

The light separator 23 separates the light from the fundus Er. In this embodiment, the light separation unit 23 wavelength-selectively separates the light from the fundus Er. Further, the light separating section 23 may also serve as a light branching section that branches the optical path of the light receiving optical system 20 . For example, as shown in FIG. 2, the light separation section 23 may include two dichroic mirrors (dichroic filters) 31 and 32 having different light separation characteristics (wavelength separation characteristics). The optical path of the light receiving optical system 20 is branched into three by two dichroic mirrors 31 and 32 . Also, one of the light receiving elements 25, 27 and 29 is arranged at the end of each branched optical path.

For example, the light separation unit 23 separates the wavelengths of light from the fundus Er, and causes the three light receiving elements 25, 27, and 29 to receive light in different wavelength ranges. For example, light of three colors of blue, green, and red may be received by the light receiving elements 25, 27, and 29 one by one. In this case, a color image may be obtained from the light receiving results of the light receiving elements 25, 27, and 29. FIG.

In addition, the light separation unit 23 may allow different light receiving elements to receive the fundus spontaneous fluorescence and the infrared light that is the fundus reflected light of the observation light. Thereby, it may be possible to capture an infrared image simultaneously with a fluorescence image. In this embodiment, blue light emitted from the laser light source 11 is used as excitation light for spontaneous fluorescence.

The control unit 70 forms a fundus image based on the received light signals output from the light receiving elements 25, 27, and 29, for example. More specifically, the control unit 70 forms a fundus image in synchronization with optical scanning by the scanning unit 16 . For example, every time the optical scanner 16b for sub-scanning reciprocates n times (n is an integer equal to or greater than 1), the control unit 70 outputs at least one frame (in other words, one sheet) of the fundus image to the light receiving element every time). In the following description, for the sake of convenience, it is assumed that one frame of fundus image is formed based on one reciprocation of the optical scanner 16b for sub-scanning, unless otherwise specified. In this embodiment, the three light receiving elements 25, 27, and 29 are provided, so the control unit 70 selects up to three types of images based on the signals from the respective light receiving elements 25, 27, and 29 for sub-scanning. is generated each time the optical scanner 16b makes one round trip.

The control unit 70 may cause the monitor 80 to display a plurality of frames of fundus images sequentially formed based on the operation of the apparatus as observation images in chronological order. The observation image is a moving image made up of fundus images acquired substantially in real time. In addition, the control unit 70 takes in (captures) a part of the plurality of fundus images that are sequentially formed as a photographed image (capture image). At that time, the captured image is stored in the storage medium. A storage medium in which captured images are stored may be a non-volatile storage medium (eg, hard disk, flash memory, etc.). In this embodiment, for example, a fundus image formed at a predetermined timing (or period) after a trigger signal (for example, a release operation signal, etc.) is output is captured.

Next, the alignment optical system 50 is described. The alignment optical system 50 of this embodiment has a dichroic mirror 51, an alignment light source 52, and a light receiving element 55, as an example. As an example, in this embodiment, the alignment optical system 50 may include a lens 53 as an optical element for correcting the magnification of the alignment index.

Alignment light emitted from the alignment light source 52 is reflected by the dichroic mirror 51 and irradiated toward the subject's eye E via the objective optical system. The alignment light reflected by the cornea of the subject's eye E passes through the objective optical system, is reflected by the dichroic mirror 51 , and is received by the light receiving element 55 via the lens 53 . The light receiving element 55 detects the alignment state of the subject's eye E with respect to the objective optical system based on the light receiving result. A signal output from the light receiving element 55 is input to the control section 70 (see FIG. 4). The control unit 70 may generate an image indicating the alignment state of the subject's eye E (hereinafter also referred to as "alignment image") based on the input signal. The alignment image may be, for example, an image including an alignment index image representing alignment light reflected by the cornea of the eye E to be examined.

Here, the lens 53 is movable along the optical axis, thereby changing the focal length of the alignment optical system and switching the magnification of the alignment index image. The fundus imaging device 1 may be provided with a drive unit 53a that moves the lens 53 . The lens 53 is displaced according to attachment/detachment (insertion/removal) of the attachment optical system 3 (that is, according to switching of the angle of view).

In this embodiment, the fundus photographing device 1 does not have an anterior segment observation optical system. However, of course, the anterior segment observation optical system may be provided in the ophthalmologic imaging apparatus 1 . In this case, part of the alignment optical system 50 may be an anterior segment observation system.

Next, with reference to FIG. 3, an optical configuration when the shooting angle of view is the second angle of view, which is a wider angle of view, is shown. In this embodiment, the attachment optical system 3 is arranged between the objective optical system 17 and the subject's eye E, thereby configuring the objective optical system 18 for photographing at the second angle of view. The attachment optical system 3 of this embodiment has at least one lens. As shown in FIG. 3, the attachment optical system 3 may have multiple lenses.

<Attachment optical system>
A lens attachment including the attachment optical system 3 is attached to and detached from (inserted into and removed from) the housing surface of the photographing unit 4, so that the attachment optical system 3 is positioned between the objective lens 17 on the device main body side and the subject's eye E. Insertion and removal are performed.

At least the lens 332 bends the measurement light that has passed through the first turning point P1 toward the optical axis L1, thereby forming the second turning point P2 at a position conjugate with the optical scanner 16 with respect to the attachment optical system 3 and the objective optical system 17. be done. That is, the attachment optical system 3 is an optical system that relays the turning point P1 to the turning point P2.

In this embodiment, the turning amount of the measurement light at the second turning point P2 is larger than the turning amount at the first turning point P1. In this embodiment, the angle of view of the device is defined by the amount of turning. In this embodiment, the angle of view (turning amount) is about 60° in the retracted state (first mode), and the angle of view (turning amount) is about 100° in the inserted state (second mode).

<Control system>
As shown in FIG. 4 , the fundus imaging device 1 also includes an arithmetic controller (arithmetic control section) 70 . In addition, the fundus imaging device 1 may be provided with a memory 71, a monitor 80, an operation unit 75, and the like. An arithmetic controller (hereinafter referred to as a controller) 70 is connected to the laser light source 11, the front imaging optical system 200, and the like. The operation unit 75 may be a touch panel, mouse, keyboard, or the like. The operation unit 75 may be a separate device from the fundus imaging apparatus 1 . The control section 70 may control each section based on the operation signal output from the operation section 75 . For example, an operation for selecting a shooting mode, an operation for releasing, or the like may be input to the operation unit 75 .

<Action>
Next, the operation of the fundus imaging device 1 will be described with reference to the flowchart of FIG.

First, the control unit 70 selects a shooting mode from at least two shooting modes, manual mode and assist mode (S1). The manual mode is the "first shooting mode" in this embodiment, and the assist mode is the "second shooting mode" in this embodiment.

After setting the imaging mode, the control unit 70 starts obtaining an observation image (S2). In this embodiment, the acquired observation images are sequentially displayed on the monitor 80 . In this embodiment, the alignment between the device and the subject's eye is manually adjusted in both the manual mode and the assist mode. Observed images are used in manual alignment.

Next, the controller 70 turns on the internal fixation lamp (S3). The control unit 70, for example, controls the imaging optical system to temporarily turn on the visible light at the timing when the laser scans a predetermined presentation position. Thereby, an internal fixation lamp is formed and presented to the subject's eye.

After that, different operations are executed according to preset shooting modes.

<Assist mode>
First, the case where the assist mode is set will be described (S4: assist mode). In the assist mode of the present embodiment, a fundus image is automatically captured at the stage where an effective range with an appropriate width is secured for each eye to be examined. In the assist mode, the alignment is adjusted using the observation image, and the reference value (Vt) of the effective range is set based on the observation image at the time of adjustment (S5, S6). Further, the control unit 70 controls the visibility correction unit 40 to adjust the focus (S7).

In this embodiment, in the alignment, the examiner first positions the photographing unit 4 away from the subject so that the anterior segment of the eye is displayed on the monitor 80 . The examiner adjusts the positional relationship between the subject's eye E and the imaging optical system in the XY directions so that the center of the pupil of the anterior segment image and the center of the screen of the monitor 80 overlap.

After that, the examiner brings the photographing unit 4 closer to the subject's eye E while observing the observation image. A pupil image is displayed on the monitor 80, and eventually a fundus image is projected. In this case, when the apparatus is brought close to the subject's eye E to the vicinity of the appropriate working distance, the alignment index image is displayed on the monitor 80 together with the fundus image. The examiner can align the subject's eye E with reference to this alignment index image. For example, the alignment state in the vertical and horizontal directions is adjusted so that the alignment index image is displayed at the center of the alignment image. Also, the distance between the photographing unit 4 and the subject's eye E (that is, the alignment state in the front-rear direction) is adjusted with reference to the imaging state of the alignment index image. At this time, the imaging unit 4 may be moved back and forth so that the alignment index image is in focus.

Also, in this embodiment, the control unit 70 starts detecting the effective range after a fundus image is acquired as an observation image and is displayed. For example, the presence or absence of the alignment index image may be detected in the alignment image based on the signal from the light receiving element 55, and detection of the effective range may be started when the alignment index image is detected. Instead of this, a detection unit that detects the distance from the subject's eye E to the photographing unit 4 may be provided. As the detection unit, for example, a sensor (not shown) that detects the position of the imaging unit 4 (or the positioning mechanism 5) on the base 6 may be used.

The control unit 70 sequentially detects the effective range that changes with the alignment adjustment during a predetermined period. For example, the reference value (Vt) is set based on the effective range detected within several seconds from the start of detection. In this embodiment, as an example, the maximum value of the effective range detected within several seconds from the start of detection is set as the reference value (Vt). The unit of the effective range and the reference value may be, for example, the number of pixels, the area, the ratio (dimensionless amount) to the imaging range of the device, or other It may be a unit.

Subsequently, detection of the effective range is continued and compared with the reference value (S8). If the effective range is below the reference value (S8: No), the alignment state is readjusted by the examiner (S9). Also, the comparison between the current effective range and the reference value is repeated until the effective range is greater than or equal to the reference value.

In this embodiment, when the current effective range becomes equal to or greater than the reference value as a result of the adjustment of the alignment state, an advance notice of photographing is given (S10), and a fundus image is photographed (S11). In this embodiment, as an example, visible light is emitted as illumination light (imaging light) for a plurality of seconds, and a plurality of fundus images are continuously captured.

In the various processes ( S<b>12 ), for example, the captured fundus image is stored in the memory 71 and displayed on the monitor 80 . At this time, an averaged image may be generated from a plurality of fundus images, and the averaged image may be stored or displayed.

In the assist mode of this embodiment, although the examiner is in charge of alignment adjustment, the apparatus side is in charge of the timing of photographing, thus reducing the operational burden on the examiner. In addition, in the case of an eye to be examined that is difficult to photograph the entire photographing range, it is easy to quickly photograph an image with a wider effective range.

<Manual mode>
Returning to S4, the case where the manual mode is set will be described (S4: manual mode).

In the manual mode of this embodiment, alignment and focus are first adjusted using an observed image (S13, S14). Further, the control unit 70 controls the visibility correction unit 40 to adjust the focus (S7). In the manual mode of this embodiment, a fundus image is captured based on the imaging operation (pressing of the imaging switch) by the examiner (S15→S11). After that, various processes (S12) are executed in the same manner as in the assist mode. In manual mode, a fundus image is captured in an alignment state desired by the examiner.

Although the above has been described based on the embodiments, the present disclosure is not limited to the above embodiments.

<Modification>
As described above, the present disclosure has been described based on the embodiments and examples, but the present disclosure is not limited to the above embodiments and examples, and various modifications are permitted based on the so-called ordinary knowledge of those skilled in the art. be done.

For example, in the above embodiments, the effective area was detected based on the observation image of the fundus. However, as described above, the effective region can be detected, for example, based on the observed image of the anterior segment. In this case, the optical axis of the observation optical system intersects the front direction of the face, which is effective in detecting the open eyelid state when the angle of view is larger. That is, since the eyelashes and eyelids protrude toward the device side from the surface of the eyeball, it is difficult to properly evaluate the degree of vignetting in the observation image when the anterior segment of the eye is viewed from the front direction of the face. On the other hand, when the optical axis of the observation optical system intersects the front direction of the face, it becomes easier to properly grasp the degree of vignetting caused by eyelashes and eyelids. As an example, as shown in FIG. 9, when the optical axis of the observation optical system 400 is arranged along the upper edge of the irradiation range of the illumination light, based on the positional relationship with the optical axis of the observation optical system 400, Vignetting caused by the upper eyelid and upper eyelashes can be properly grasped. In addition, even with the observation optical system 400 that observes the anterior segment of the subject's face from the lateral direction, the open eyelid state can be properly detected. The horizontal direction here includes an oblique direction.

Further, for example, in the above embodiments and examples, the effective range corresponding to at least one of the eyelid open state and the pupil state of the eye to be inspected is detected. Baseline values were set according to at least one. However, it is not necessarily limited to this. Alternatively or additionally to the eyelid-open state and the pupil state, an effective range according to the subject's facial shape may be detected. Also, the reference value of the effective range may be set according to the facial shape of the subject.

That is, it is considered that the effective range may be limited by the subject's facial shape. For example, if the face is deeply sculpted, the tip of the device (e.g., the tip of the lens barrel) may come into contact with the subject's nose, cheeks, etc., resulting in improper alignment (especially in the working distance direction). Adjustment may not be possible. In this case, vignetting may occur even if the eyelids and pupils of the eye to be examined are properly opened.

Therefore, an observation optical system that observes the subject's face from the lateral direction is effective, for example, in order to detect the effective range according to the facial shape of the subject. This observation optical system may also serve as an anterior segment observation optical system. Of course, other methods may be used to acquire information about the facial shape of the subject.

In this case, the allowable range of alignment adjustment for each subject according to the facial shape of the subject is determined by the facial shape of the subject in the observed image from the lateral direction and the shape information of the distal end portion of the apparatus. may be analyzed based on The shape information of the tip of the device may be known information. For example, if the proper working distance of the device is 10 mm, and the limit value of the working distance based on the above analysis result (value corresponding to the facial shape of the subject) is 12 mm, the effective range corresponding to the working distance of 12 mm can be inferred. The estimated effective range may be used as the detected value or as a reference value to be compared with the detected value. Further, when setting the reference value based on the effective range detected from the observation image of the fundus, the effective range estimated from the face shape of the subject may be used as information for narrowing down the reference value. .

Further, for example, in the above embodiment, the period during which the effective area is detected by the control unit (detection period) and the setting condition of the reference value are determined in advance. This detection period may be changed according to the proficiency of the imaging operation of the examiner. For example, when shooting in manual mode, the control unit learns the maximum effective range during observation, the effective range at the time of shooting, the time from the start of observation to shooting, etc. Based on the learning data, the assist The setting conditions of the detection period and the reference value in the mode may be changed.

1 fundus photographing device 70 control unit 200 front photographing optical system E eye to be examined

Claims (2)

a photographing optical system for irradiating the fundus of an eye to be inspected with illumination light and photographing a fundus image based on the return light of the illumination light from the fundus ;
An effective range in which return light from the fundus can be effectively obtained in the imaging range of the imaging optical system, and at least any one of the state of the pupil of the eye to be examined, the state of the eyelids open, and the facial shape of the subject and a control means for detecting the effective range according to
The control means sets a reference value of the effective range in advance for each eye to be examined, and compares the reference value for each eye to be detected with the detected value of the effective range. The control means sets the reference value for each subject eye based on a detection result of the effective range in a predetermined detection period,
2. The fundus imaging apparatus according to claim 1, wherein said effective range detected after said reference value is set is compared with said reference value.

Images