JP6410498B2 - Ophthalmic apparatus and control method thereof - Google Patents

Description

  The present invention relates to an ophthalmologic apparatus used for ophthalmic medical care and the like, and a control method thereof. More specifically, the present invention relates to an ophthalmic apparatus that is used in ophthalmic medical care and the like and sets an appropriate photographing position by processing an obtained image and a control method thereof.

  Examination of the fundus is widely performed for the purpose of early diagnosis of lifestyle diseases and diseases that occupy the top causes of blindness. For the examination of the fundus, for example, a scanning laser opthalmoscope (SLO) which is an ophthalmologic apparatus using the principle of a confocal laser microscope is used. The SLO is a device that performs a raster scan of the fundus of the laser as measurement light and obtains a planar image with high resolution and high speed from the intensity of the return light. In recent years, adaptive optics SLO (AO-SLO: adaptive Optics SLO) has been developed that enables acquisition of a planar image with high lateral resolution. In the AO-SLO, the aberration of the eye to be examined is measured in real time by the wavefront sensor, and the aberration of the measurement light generated in the eye to be examined and its return light is corrected by the wavefront correction device of the compensation optical system. In such AO-SLO, it is further attempted to extract a photoreceptor cell in the retina using the acquired planar image of the retina, and to diagnose a disease and evaluate a drug response from an analysis of the density and distribution thereof.

  When evaluating changes in photoreceptor cells due to disease progression or drug response, it is necessary to detect photoreceptor cells from AO-SLO images acquired at high resolution. In order to photograph a photoreceptor cell, it is necessary to focus on the layer in which the photoreceptor cell exists. However, if the photoreceptor cell layer is damaged, the focus position may not be set correctly. For such a case, for example, a method disclosed in Patent Document 1 has been proposed. In this method, a determination process related to a normal / abnormal part of visual function is performed from a tomographic image taken by optical coherence tomography (OCT: Optical Coherence Tomography). The result of this determination process is displayed superimposed on the front image of the fundus, and the laser irradiation position at the time of laser treatment is acquired based on this display.

JP 2012-135550 A JP 2012-213513 A

Human Photoceptor Topography CHRISTINE A. CURCIO, KENNETH R. SLOAN, ROBERT E. KALINA, AND ANITA E. HENDRICKSON THE JOURNAL OF COMPARATIVE NEUROLOGY 292: 497-523 (1990)

  When detecting photoreceptor cells with AO-SLO, it is necessary to distinguish between cases where the photoreceptor cells are not rendered because they are deficient and cases where photoreceptor cells are not rendered due to imaging reasons such as focus shift. . When the effect of the disease is on the photoreceptor cells, photographing with AO-SLO is often difficult. That is, it is difficult to determine whether the photoreceptor cell has not been correctly photographed or whether the photoreceptor cell defect state has been photographed.

  In the method disclosed in Patent Document 1, a tomographic image is obtained by using OCT, and information relating to photoreceptor cells is obtained from the image. Then, the normal / abnormal part of the visual function is determined using this information. Therefore, the combined use of OCT is essential.

  In the method disclosed in Patent Document 2, a shooting position of a low-angle image is set along a structure such as a blood vessel drawn with a wide-field image, and imaging is performed. However, this method does not take into consideration the case where it is difficult to set the shooting position in a wide-angle image such as the existence range of photoreceptor cells. Therefore, no correspondence is suggested for the determination of whether or not the photoreceptor cells have been accurately photographed.

  In view of the above problems, an object of the present invention is to provide an apparatus that can depict a more accurate state of a photoreceptor layer and a control method thereof.

In order to solve the above problems, an ophthalmologic apparatus according to one embodiment of the present invention includes:
Image acquisition means for acquiring a planar image of the fundus of the eye to be examined;
Determining means for determining whether or not the planar image is an image including a boundary between a region where a photoreceptor cell of the eye to be examined exists and a region where the photoreceptor cell does not exist;
Setting means for setting a position for acquiring the next plane image based on the determination by the determination means;
Control means for causing the image acquisition means to acquire a planar image of the position set by the setting means;
Said image acquiring means, said determining means, said setting means, and a display control unit that Ru is displayed on the display means the concatenation of the boundary included in the plurality of the planar images obtained by repeating the processing by the control means ,
It is provided with.

  According to the present invention, it is possible to depict a more accurate state of the photoreceptor layer in the fundus examination.

It is a block diagram which shows the function structure of the ophthalmologic apparatus 20 which concerns on Example 1 of this invention. It is a flowchart which shows the process sequence of the ophthalmologic apparatus 20 which concerns on Example 1 of this invention. It is a schematic diagram which shows the state which showed the some AO-SLO image on the WF-SLO image. It is a schematic diagram of a fixation lamp map for designating a fixation position. It is the flowchart which showed the detail of the boundary determination of step S250 shown in FIG. It is an example of the frequency conversion image obtained by performing frequency conversion to an AO-SLO image. It is a figure explaining the method of extracting the parameter | index which judges the presence or absence of a photoreceptor cell from a frequency conversion image. It is an example of the imaging position in the case of imaging | photography with respect to the whole area | region where a photoreceptor cell exists. It is a flowchart which shows the process sequence of the ophthalmologic apparatus 20 in connection with Example 2 of this invention. It is an example of the imaging | photography position in the case of imaging | photography the boundary of the area | region where a photoreceptor cell exists. This is an example showing the existence of photoreceptor cells for each divided region. It is a flowchart which shows the process sequence of the ophthalmologic apparatus 20 in connection with Example 3 of this invention. It is an example of the imaging | photography position in the case of image | photographing a boundary part in detail using an AO-SLO image from which resolution differs. It is an example of the image which superimposes and shows these regarding the area | region where the photoreceptor cell acquired with time is present.

(Example 1)
In this embodiment, when a retina image is acquired by AO-SLO, imaging is started from an area where a photoreceptor cell is highly likely to exist. After the first designated area is photographed, each AO-SLO is photographed at a position where the photographing areas are shifted in the vertical and horizontal directions while maintaining the overlapping of the photographing areas. The region where the photoreceptor cells are present is photographed through the above steps. Hereinafter, these processes will be described in detail.

  In the actual process, an area where a photoreceptor cell is highly likely to be present is first identified based on the type of disease and the progress of past imaging. Specifically, in the case of a disease in which photoreceptor cells are known to be lost from the fovea like Stargard's disease, the periphery of the fundus is a region where the photoreceptor cells are highly likely to exist. In the case of a disease in which photoreceptor cells are known to be lost from the peripheral part, such as retinitis pigmentosa, the fovea is a region where the photoreceptor cells are highly likely to exist. Further, in the past, when shooting with AO-SLO, the region where the photoreceptor cells existed at that time and the position far from the boundary of the region is the region where the photoreceptor cells are highly likely to exist.

  In this manner, imaging is started from an area where a photoreceptor cell is highly likely to exist, and after confirming that a photoreceptor cell is present in the area, the imaging area is shifted vertically and horizontally while maintaining the overlap of the imaging area. -Continue shooting SLO. In addition, when a region where a photoreceptor cell is defective is found at that time, the position is set as a boundary image position where the boundary of the defective region exists, and the boundary search is performed again in a different direction from the periphery of the first imaging position.

  In this way, by photographing the area where the photoreceptor cells are present, when the photoreceptor layer is present, a high-quality photoreceptor cell layer is drawn, and for the area where photoreceptor cells are missing, the boundary of the area is correctly defined. It becomes possible to draw. That is, in the present invention, an AO-SLO image is taken from an area where a photoreceptor cell is highly likely to exist due to the type of disease or a past course, and the AO-SLO is searched while searching for a boundary on the fundus where the photoreceptor cell exists. Take a picture. As a result, when a photoreceptor layer is present, it is possible to render a high-quality photoreceptor cell layer, and to correctly render the boundary of a region where photoreceptor cells are defective.

<Plane image>
FIG. 3 schematically shows the arrangement on the fundus of each of a plurality of AO-SLO images and WF-SLO images acquired by the AO-SLO used in this example. In AO-SLO, the position of the fixation lamp is changed, and images are taken at different positions on the retina by photographing with the eye to be examined staring at different positions. FIG. 4 shows a fixation lamp map for operating the fixation lamp presentation position.

  First, the fixation lamp is presented with the center selected in the fixation lamp map of FIG. Hereinafter, this position is referred to as a reference position. At this time, when the eye to be examined staring at the fixation lamp to be presented is photographed, an AO-SLO image and a WF-SLO image near the macula can be photographed.

The WF-SLO image has an image size of 8 mm × 6 mm and a pixel size of 533 × 400, and is an image obtained by photographing a wide range of the retina, and an entire image of the retina is acquired. By associating with the WF-SLO image, it is presented at which position on the entire retina each AO-SLO image having a narrow angle of view is captured. As the AO-SLO image, there are types in which the size of the imaging region is 1.7 mm × 1.7 mm, 0.82 mm × 0.82 mm, and 0.34 mm × 0.34 mm, and the pixel sizes are all 400 × 400 in common. That is, shooting is performed under the condition that three kinds of resolution AO-SLO images are obtained. Here, an AO-SLO image with an imaging area of 1.7 mm × 1.7 mm is an L image, an AO-SLO image with a 0.82 mm × 0.82 mm is an M image, and an AO-SLO image with a 0.34 mm × 0.34 mm is an S image. To do. The shooting time and frame rate of the AO-SLO image can be changed. Here, the frame rate is 32 frames per second, the shooting time is 2 seconds, and the image is composed of 64 images.
The AO-SLO image and the WF-SLO image are called planar images.

<Configuration of ophthalmic apparatus>
FIG. 1 is a block diagram illustrating a functional configuration of the ophthalmologic apparatus 20 according to the first embodiment.
In FIG. 1, the ophthalmologic apparatus 20 includes a processing device 10, a planar image photographing device 3, and a display unit 4. The processing device 10 performs image processing and calculation of aberration correction coefficients. The planar image capturing apparatus 3 captures a planar image of a WF-SLO (Wide-Field SLO) image and an AO-SLO image, which is a wide field angle SLO without aberration correction. The display unit 4 presents the calculation result of the processing device 10 to the user. In this embodiment, the ophthalmologic apparatus 20 is also connected to an external database (DB) 1. The DB 1 stores images and patient data acquired by other modalities, and past images and data acquired by the planar image capturing device 3. Further, the ophthalmologic apparatus 20 can acquire these data and the like as necessary.

  The processing apparatus 10 includes an image acquisition unit 100, an information acquisition unit 110, a control unit 120, a storage unit 130, an image processing unit 140, and an output unit 150. The image acquisition unit 100 acquires a planar image acquired by the planar image capturing device 3. The acquired planar image is stored in the storage unit 130 through the control unit 120. In the present embodiment, the image acquisition unit 100 can also acquire an OCT tomogram acquired by the OCT imaging apparatus 2 via the database 1. The image acquisition unit 100 in this embodiment corresponds to an image acquisition unit that acquires a planar image of the fundus of the eye to be examined. The information acquisition unit 110 acquires measurement data at the time of user input and aberration correction, and various data stored in the database 1.

  The image processing unit 140 includes an alignment unit 141, a boundary acquisition unit 142, a shooting position setting unit 143, and a connection unit 144. The alignment unit 141 associates the area on the WF-SLO image with the AO-SLO image, and performs alignment between these images. The boundary acquisition unit 142 further subdivides the single AO-SLO image and determines whether or not a photoreceptor cell is included in each of the subdivided regions. Further, based on this discrimination result, the presence or absence of the boundary of the region where the original AO-SLO image is present is obtained. The boundary acquisition unit 142 according to the present embodiment corresponds to a boundary acquisition unit that acquires a boundary between a region where a photoreceptor cell of the eye to be examined exists and a region where the photoreceptor cell does not exist from a planar image.

  The imaging position setting unit 143 sets an imaging area in which an AO-SLO image is acquired next based on the presence / absence of a boundary. In addition, the connecting unit 144 associates each imaging region on the WF-SLO image with respect to all the captured images including the boundary of the photoreceptor cells based on the alignment result of each AO-SLO image. As will be described later, the connecting unit 144 in this embodiment corresponds to a setting unit that connects boundaries acquired from a plurality of AO-SLO images and demarcates the existence area of the photoreceptor cell in the fundus.

  Note that the image processing unit 140 may extract a photoreceptor cell layer or an RPE layer from an OCT tomogram acquired from the OCT imaging apparatus 2 and specify a region where the photoreceptor cell layer is normal. In this case, when the photoreceptor cell is damaged such as a defect, it is preferable to obtain an assumed photoreceptor cell layer. Further, the position of the WF-SLO image corresponding to the OCT tomographic image is obtained, and the region where the photoreceptor cell is determined to be normal is associated with the region on the WF-SLO image. Then, based on the result of the layer analysis, the AO-SLO control method may be determined from the state of the photoreceptor layer at the imaging position designated by the user.

  The output unit 150 outputs a region where a normal photoreceptor layer associated with the WF-SLO image is present to a monitor or the like, and modifies the method for controlling the photographing of the AO-SLO image at the photographing position designated by the user. specify.

<Processing procedure of image processing apparatus>
Next, the processing procedure of the ophthalmologic apparatus 20 of this embodiment will be described with reference to the flowchart of FIG.

<Step S210>
In step S <b> 210, the image acquisition unit 100 acquires a planar image of the eye retina imaged by the planar image capturing device 3. Then, the acquired planar image is stored in the storage unit 130 through the control unit 120. In the present embodiment, the case where the planar image is a WF-SLO image will be described. However, the present invention is not limited to the WF-SLO image, and may be an AO-SLO image obtained by photographing a wide angle of view.

<Step S220>
In step S <b> 220, the information acquisition unit 110 first acquires information about a position where a photoreceptor cell is likely to exist as a shooting position when shooting an AO-SLO by shooting AO-SLO. The first photographing position may be set by the user based on past photographed images or information from other modalities, or the first photographing position is set in advance for each disease, and the position is acquired. In some cases. Specifically, in the case of retinitis pigmentosa, the fovea may be the first imaging position. Then, the acquired shooting position is stored in the storage unit 130 through the control unit 120.

<Step S230>
In step S230, the image acquisition unit 100 transmits information on the imaging position acquired in step S220 to the planar image imaging device 3, and acquires an AO-SLO image of the position on the fundus. Then, the acquired AO-SLO image is stored in the storage unit 130 through the control unit 120.

<Step S240>
In step S240, the alignment unit 141 performs alignment between the WF-SLO image acquired in step S210 and the AO-SLO image acquired in step S230. The result of associating the position of the AO-SLO image with the position on the WF-SLO is stored in the storage unit 130 through the control unit 120.

<Step S250>
In step S250, the image processing unit 140 determines whether the AO-SLO image stored in the storage unit 130 has a boundary between the region where the photoreceptor cell exists and the region where the photoreceptor cell is missing.

  Next, a procedure for determining the presence of a boundary in step S250 will be described with reference to the flowchart of FIG.

<Step S510>
In step S510, the boundary acquisition unit 142 divides the acquired AO-SLO image into small regions. Here, there can be a plurality of methods of area division. However, if the size of one area is reduced, the accuracy of frequency conversion in the subsequent steps may be lowered. However, if the number of regions increases, the boundary between the region where the photoreceptor cells exist and the region where the photoreceptor cells do not exist may be obtained more accurately.

Considering the above, in this embodiment, an AO-SLO image of 400 × 400 pixels is divided into 16 regions of 100 × 100. Here, when performing a two-dimensional DFT (discrete Fourier transform) of an image, the number of pixels in the small region needs to be 2 N pixels. For this reason, in this embodiment, preprocessing is performed by padding or the like so that an area of 100 × 100 pixels becomes 128 × 128 pixels, and then DFT is performed.
The divided areas are stored in the storage unit 130 through the control unit 120.

<Step S520>
In step S520, the boundary acquisition unit 142 performs frequency conversion on each of the 16 regions divided in step S510.

FIG. 6 shows an example when the frequency of the divided region is converted. In the region where the photoreceptor cells can be confirmed, as shown in FIG. 6A, a ring-like structure is seen at a spatial frequency corresponding to the density of the photoreceptor cells. On the other hand, in a region where photoreceptor cells cannot be confirmed, a ring-shaped structure cannot be confirmed as shown in FIG.
The frequency conversion image acquired in this way is stored in the storage unit 130 through the control unit 120.

<Step S530>
In step S530, the boundary acquisition unit 142 determines whether or not a photoreceptor cell exists for each region divided in step S510. Specifically, based on the frequency conversion result obtained in step S520, the presence / absence of the photoreceptor cell is determined based on the intensity of the signal of the spatial frequency corresponding to the density of the photoreceptor cell.

  Specifically, as shown in FIG. 7 (a), when the size of the frequency conversion image is NxN, polar coordinate display with the center of the frequency conversion image being (N / 2, N / 2) as the origin ( r, θ). Then, a function I (r) obtained by integrating the values of the pixels of the frequency conversion image in the θ direction is calculated. However, r = 0, 1, 2,... N / 2. FIG. 7B shows a function I (r) acquired for the image shown in FIG. That is, the boundary acquisition means acquires a boundary that determines the presence / absence of photoreceptor cells as a region based on the intensity of a signal corresponding to the density of photoreceptor cells obtained by frequency-converting a planar image.

  Here, the density of photoreceptor cells can be determined from the generally known relationship between the distance from the fovea and the photoreceptor cell density. Here, there is a report based on anatomical data shown in Non-Patent Document 1, for example, as the photoreceptor density generally known. Therefore, it is possible to obtain the distance from the fovea of the AO-SLO image based on the alignment result in step S240, and obtain the photoreceptor density at the photographing position from this distance.

As an index for determining whether or not a photoreceptor cell exists, there is a method of using a value of a function I (r ₀ ) corresponding to a spatial frequency r ₀ corresponding to the density of the photoreceptor cell. Alternatively, in consideration of the fact that the value of I (r ₀ ) greatly depends on the contrast of the AO-SLO image, a function corresponding to the spatial frequency r ₀ corresponding to the density of the photoreceptor cells and a spatial frequency 2r ₀ that is twice that density. There is a method using a ratio of I (r ₀ ) and I (2r ₀ ). The following description is based on a method using the value of I (r ₀ ), but the index is not limited to this.

Determines that the cells are present viewing larger than the threshold value I _E which is I (r _0), it is determined that if smaller photoreceptor cells is absent than a certain threshold I _L. The value of I (r ₀₎ is the case is between I _E and I _L is assumed to be indefinite. For example, I _E = 2000 and I _L = 1000 were used as threshold values.

  The determination result of whether or not photoreceptor cells are present in each region thus obtained is stored in the storage unit 130 through the control unit 120.

<Step S540>
In step S540, the boundary acquisition unit 142 determines the boundary based on the presence determination result of the photoreceptor cell in each region obtained in step S530. Specifically, when there are photoreceptors in all 16 regions, it is determined that there is no boundary. Further, it is determined that there is a boundary when the region where the photoreceptor cell exists and the region where the photoreceptor cell does not exist in 16 regions. In that case, when there is an indefinite region sandwiched between a region where a photoreceptor cell exists and a region where a photoreceptor cell does not exist, the indefinite region is set as a boundary region. When a region where a photoreceptor cell exists and a region where a photoreceptor cell does not exist are adjacent to each other, the region where the adjacent photoreceptor cell exists is defined as a boundary region. Furthermore, if it is determined that there are no photoreceptor cells in all 16 regions, it is determined that imaging has failed.

  The determination result as to whether or not a boundary exists in the acquired image is stored in the storage unit 130 through the control unit 120.

<Step S260>
In step S260, the shooting position setting unit 143 sets the next shooting position based on the boundary determination result in step S540.

  FIG. 8 shows a schematic diagram of the fundus in the case of retinitis pigmentosa. In retinitis pigmentosa, it is known that photoreceptor cells are missing from the periphery. The circular gray area shown in the vicinity of the fovea in FIG. 8 is an area where photoreceptor cells exist, Let the peripheral part be a missing region.

  In step S220, the foveal position is set as the first imaging position. When it is determined that there is no boundary as a result of processing the AO-SLO image (image at image position 1) taken at the foveal position according to steps 510 to 540, the next shooting position is the current shooting position. The position (image position 2) that is adjacent to the left side of the current image and has an overlapping area with the current shooting position. Here, the size of the overlapping area is about 15% of the shooting angle of view of AO-SLO, and here it is set to 60 pixels because it is 400 × 400 pixels. However, it is not limited to this size, and can be appropriately changed according to the fixation state of the eye to be examined, the presence or absence of a tracking system, and the like.

  The shooting position of the next AO-SLO image set in this way is stored in the storage unit 130 through the control unit 120. That is, the image acquisition unit 100 includes a module that functions as an imaging position setting unit that sets an imaging position on the fundus for capturing a planar image in accordance with the boundary position acquired by the boundary acquisition unit.

  Here, the method for setting the next imaging position will be described in more detail in the case of the retinitis pigmentosa example shown in FIG.

  The processing in steps S240 to S250 is performed on the image photographed at the image position 2. Here, when it is determined that there is no boundary in the image as in the image taken at the image position 1, the position adjacent to the left of the image position 2 and similarly overlapped by 60 pixels (image position 3) Is the next shooting position.

  Next, the same processing is performed on the image photographed at the image position 3. Here, when it is determined that there is a boundary at the image position 3, a position where 60 pixels overlap on the right side of the image 1 is set as a next photographing position (image position 4). A similar process is performed on the image taken at the image position 4. As a result, when it is determined that there is no boundary at the image position 4, the next right image position (image position 5) is set as the next photographing position.

  Next, the same processing is performed on the image photographed at the image 5 position. Here, when it is determined that there is a boundary at the image position 5, the image position 6 having an overlap of 60 pixels above the image position 1 is set as the next photographing position. If it is determined that there is no boundary at the image position 6 as a result of the same processing performed on the image captured at the image position 6, the image position 7 above the image position 7 is set to the next shooting position. And

  Next, similar processing is performed on the image captured at the image position 7. Here, when it is determined that a boundary exists at the image position 7, the image position 8 having an overlap of 60 pixels below the image position 1 is set as the next photographing position.

  In this way, the imaging position is shifted left and right and up and down from the first imaging position of the fovea position to the place where the boundary of the region where the photoreceptor cell exists. A rectangular area (image 9 to image 20 in FIG. 8) that covers the ten o'clock for the ten o'clock-type imaging area thus obtained is set as the next imaging position in order.

  If it is determined in step S540 that the imaging has failed, the imaging position moved from the set imaging position toward an area where the probability of existence of photoreceptor cells is higher is presented. Specifically, in the case of retinitis pigmentosa shown in FIG. 8, the position is a position moved 60 pixels in the direction of the fovea from the imaging position where imaging failed. This is to take into account the possibility that the focus adjustment becomes unstable and the imaging has failed because the photoreceptor cell has already been lost near the center of the imaging position initially set.

  Finally, after completion of the imaging at the image positions 1 to 20, it is further confirmed that there is no image in the outermost peripheral portion of the imaging range in which only photoreceptor cells exist and it is determined that there is no boundary. If such an image exists, the next shooting position is set as the next shooting position where the image is not shot. If no such image exists, the flow moves to step S270 without setting the next shooting position.

<Step S270>
In step S270, the control unit 143 obtains the next imaging position set by the imaging position setting unit in step S260, and determines whether or not an area where all photoreceptor cells including the boundary portion are captured has been captured. If shooting of all areas has not been completed and the next shooting position has been set, the process returns to step S230, and information on the shooting position acquired in step S260 is transmitted to the planar image shooting apparatus 3, An AO-SLO image of the position is acquired. And the acquired AO-SLO image is preserve | saved at the memory | storage part 130 through the control part 120, and it follows to step S240.

  If the next photographing position is not set, the completion of photographing is transmitted to the flat image photographing device 3 through the output unit 150, and the flow proceeds to step S280.

<Step S280>
In step S280, the connecting unit 144 stores, for all captured images including the boundary of photoreceptor cells, information on the region where the photoreceptor cell set on the planar image in step S540 is present, the region that does not exist, and the boundary region. Obtained from 130. Then, based on the alignment result of each planar image in step S240, these images or information are connected by associating the above regions with the WF-SLO image. The acquired connection result of the region where the photoreceptor cells are present and the boundary region is stored in the storage unit 130 through the control unit 120. At the same time, it is presented on the display unit 4 through the output unit 150. At this time, the boundary position is presented superimposed on the WF-SLO image acquired in step S210. That is, the connecting unit 144 described here also constitutes an alignment unit that associates the acquired boundary with the photographing position on the fundus where the planar image is acquired.

  With the above configuration, when a retina image is acquired by AO-SLO, it is possible to capture the entire region where the photoreceptor cells exist together with the boundary.

(Example 2)
In Example 1, imaging is started from an area where a photoreceptor cell is highly likely to be found, and the boundary between the photoreceptor cell is searched while confirming the existence of the photoreceptor cell. The method of taking a picture was explained. In the second embodiment, a case will be described in which only the boundary region that is the boundary between the existing region and the missing region is captured, not the entire region where the photoreceptor cells are present.

  Since the functional configuration of the ophthalmologic apparatus used in this embodiment is not different from the configuration of FIG. 1 used in Embodiment 1 in this embodiment, the description thereof is omitted. Next, a processing procedure of the ophthalmologic apparatus 20 according to the present embodiment will be described with reference to the flowchart of FIG. However, steps S210 to S250 and step S270 are the same as the respective processes described with reference to FIG.

<Step S1060>
In step S1060, the shooting position setting unit 143 sets the next shooting position based on the boundary determination result in step S540.

  FIG. 10 shows a schematic diagram of the fundus in the case of retinitis pigmentosa. In retinitis pigmentosa, it is known that photoreceptor cells are missing from the periphery, but the circular gray area shown in the vicinity of the fovea in FIG. 10 is an area where photoreceptor cells exist, Let the peripheral part be a missing region.

  In step S220, the fovea position is set as the first imaging position. Transition in the case where it is determined that there is no boundary at the image position 1 as a result of performing the processing according to steps S510 to S540 for the AO-SLO image (image at the image position 1) taken at the fovea position The process will be described. In this case, the next shooting position is a position (image position 2) that is adjacent to the left of the current shooting position and has an overlapping area with the current shooting position. Here, the size of the overlapping area is about 15% of the shooting angle of view of AO-SLO, and here it is set to 60 pixels because it is 400 × 400 pixels. However, it is not limited to this size, and can be appropriately changed according to the fixation state of the eye to be examined, the presence or absence of a tracking system, and the like.

  The shooting position of the next AO-SLO image set in this way is stored in the storage unit 130 through the control unit 120.

  Here, the method for setting the next imaging position will be described in more detail in the case of the retinitis pigmentosa shown in FIG.

  The process of steps S240 to S250 is performed on the AO-SLO image captured at the image position 2. Here, in the same way as the AO-SLO image at the image position 1, if it is determined that there is no boundary at the position, the position adjacent to the left of the image position 2 and similarly overlapped by 60 pixels (image position 3) Is the next shooting position.

  Next, similar processing is performed on the AO-SLO image captured at the image position 3. Here, when it is determined that a boundary exists in the image position 3, the boundary search is started from the fovea, and the image obtained at the image position 3 is defined as a search start image as an image including the boundary first. To do. Also, the direction in which the boundary is connected at the image position 3 is confirmed. For example, when the upper side of the angle of view and the boundary are in contact with each other, it is determined that the boundary extends above the angle of view. Then, the image position 4 adjacent to the upper part of the image position 3 along the extending direction of the boundary is set as the next photographing position. That is, the adjacent position selection method here is determined based on the photoreceptor cell presence determination result obtained for each region in step S250.

  FIG. 11A shows the result of the presence determination of the photoreceptor cells in each region obtained in step S250 for the image obtained at the image position 3 in FIG. Here, the dark-colored area represents the area where the photoreceptor cell is determined to be present, the transparent area represents the area where the photoreceptor cell is not present, and the light-colored area represents the area where the existence of the photoreceptor cell could not be determined. ing. Here, it is assumed that there is a boundary in a region where the existence of a photoreceptor cell sandwiched between a dark color region and a transparent region cannot be determined.

  According to FIG. 11A, in the image, the region indicating the boundary extends from the lower right corner to the approximate center of the upper side, and the boundary is expected to cross the upper side of the image. . In such a case, the next photographing position is set to a position overlapping 60 pixels above the image position 3. That is, when the boundary crosses any of the upper, lower, left, and right sides of the shooting angle of view, similarly, a position overlapping 60 pixels in the direction of the corresponding side is set as the next shooting position.

  Next, FIG. 11B also shows the result of the existence determination of photoreceptor cells in each region for the image obtained at the image position 4 in FIG. In the case of the image obtained at the image position 4, the assumed boundary position is at the upper right corner position. In this case, the next shooting position is set so that the upper right corner overlaps by 60 × 2 = 120 pixels. The photographing position set in this way is indicated by an image position 5 in FIG.

  In FIG. 10, the boundary search is performed clockwise, but the direction may be either clockwise or counterclockwise. If the position where the image being analyzed is obtained overlaps with the image position 3 where the search start image is obtained, the next shooting position is not set.

  Similarly to the first embodiment, when it is determined that the imaging has failed in step S540, a new imaging position moved from the set imaging position toward a region where the probability of existence of photoreceptor cells is higher is presented. It is preferable to do.

(Example 3)
In the first embodiment, the method of photographing the entire region where the photoreceptor cells exist while searching for the boundary where the photoreceptor cells are missing has been described. Furthermore, in the second embodiment, a method for performing imaging along the boundary between a region where a photoreceptor cell is missing and a region where the photoreceptor cell is present has been described. However, when the area where the photoreceptor cells are present is large, the area to be imaged becomes enormous in the method of Example 1, which places a burden on the eye to be examined, such as extending the examination time. In the second embodiment, the number of imaging regions is reduced as compared with the first embodiment. However, when the shape of the boundary is irregular, the boundary may not be searched correctly.

  Therefore, in this embodiment, the entire area where the photoreceptor cells are present is imaged by the same method as in the first embodiment using the AO-SLO image with a reduced resolution, and the boundary is limited to a portion where the boundary is desired to be clearly obtained. A method of photographing the target area with the resolution AO-SLO will be described.

  The functional configuration of the ophthalmologic apparatus used in the present embodiment is not different from that of the ophthalmologic apparatus according to the first embodiment shown in FIG. Next, a processing procedure performed by the ophthalmologic apparatus 20 in the present embodiment will be described with reference to the flowchart of FIG. However, steps S210 to S280 are the same as the contents of each process described with reference to FIG.

  In this embodiment, the AO-SLO image acquired in step S220 is a low-resolution image that has been subjected to aberration correction, and the AO-SLO image acquired in step S1220 is a high-resolution image that has been subjected to aberration correction. Yes. Specifically, the low-resolution AO-SLO image is a resolution that is difficult to detect the photoreceptor cells individually but can grasp the region where the photoreceptor cells are present and the region where the photoreceptor cells are missing. This is the M image. A high-resolution AO-SLO image is an image having a resolution at which a photoreceptor cell can be individually detected, and the above-described S image of a planar image corresponds to this. However, the resolution is not limited to the above, and the resolution used can be changed according to the size and range of the photographed disease and the density of photoreceptor cells to be resolved.

<Step S1220>
In step S1220, the information acquisition unit 110 acquires the shooting position of the high-resolution planar image selected by the user based on the information on the region where the photoreceptor cells exist presented to the user in step S280 and the boundary thereof.
Then, the acquired shooting position is stored in the storage unit 130 through the control unit 120.

<Step S1230>
In step S1230, the image acquisition unit 100 transmits the information on the imaging position acquired in step S1220 to the planar image imaging device 3, and acquires the high-resolution AO-SLO image at the position.

  If the shooting position acquired in step S1220 is an area including the boundary acquired in step S280, shooting is performed with the focus position set at a plurality of locations at the same shooting position. Specifically, the image is captured at the focus position acquired by the aberration correction (focus reference image), and an image having three steps of 10 μm before and after is acquired. That is, imaging is performed by moving the focus position to the 10 μm, 20 μm, and 30 μm vitreous side, and the 10 μm, 20 μm, and 30 μm choroid side, and a total of seven images are acquired.

  This is because, near the boundary, the beacon reflected light necessary for aberration correction becomes unstable depending on the state of the photoreceptor layer, and it may be difficult to photograph at the correct focus position. Since the visual state of the photoreceptor layer is greatly affected by the shift of the focus position, the boundary between the regions where the photoreceptor cells exist with higher accuracy is obtained by acquiring images at a plurality of focus positions as described above. It becomes possible.

For the same reason, when the imaging position acquired in step S1220 is outside the boundary of the region where the photoreceptor cells acquired in step S280 exist, that is, when the region is determined to have no photoreceptor cells. Presents an alert to that effect to the user. And whether to perform normal shooting even when the beacon reflected light is unstable, whether to manually set the focus position, or to use the focus position that was used when shooting in the area where nearby photoreceptor cells exist, etc. Present a choice of.
The acquired high-resolution AO-SLO image group is stored in the storage unit 130 through the control unit 120.

<Step S1240>
In step S1240, the alignment unit 141 aligns the WF-SLO image acquired in step S210 and the high-resolution AO-SLO image group acquired in step S1230. The result of associating each high-resolution AO-SLO image with the position on the WF-SLO image in this manner is stored in the storage unit 130 through the control unit 120.

<Step S1250>
In step S <b> 1250, the image processing unit 140 determines whether a boundary between a region where a photoreceptor cell exists and a region where a defect exists exists in the AO-SLO image group stored in the storage unit 130. Note that the details of the process performed in this step are the same as the processes performed in steps S510 to S540 in FIG. However, the process is performed on all the seven images acquired in step S1230, and the existence of photoreceptor cells is determined for each area of each image. Then, the regions where the photoreceptor cells are present are connected, and the boundary when the region where the photoreceptor cells are present is the largest.

  FIG. 13 shows a schematic diagram of the arrangement of each of the high-resolution AO-SLO image groups on the WF-SLO image photographed in this example. As described above, in this embodiment, the second planar image having a resolution different from that of the planar image obtained in the process before the step is acquired based on the photoreceptor existing region acquired up to step S280. . This second planar image is obtained by increasing the resolution in the planar image photographing device 3 and causing it to function as the second image acquisition means.

  Here, as described above, when the acquired second planar image includes a boundary of photoreceptor cells, the second image acquisition unit has a plurality of focus points for the imaging position where the second planar image is acquired. It is preferable to perform shooting at a position. In this case, the boundary acquisition unit 142 more preferably acquires again the boundary of the existence region of the photoreceptor cell from each of the second plane images photographed at the plurality of focus positions. Alternatively, as described above, when the acquired second planar image includes photoreceptors, the second image acquisition unit performs imaging at a plurality of focus positions with respect to the imaging position at which the second planar image is acquired. Preferably it is done. In this case, it is more preferable that the boundary acquisition unit 142 reselects the second planar image used for connection by the connection unit 144 from each of the second images captured at a plurality of focus positions.

Example 4
In the third embodiment, a method for photographing a higher-resolution AO-SLO based on the region where the photoreceptor cells exist and the boundary obtained by the method shown in the first embodiment using the low-resolution AO-SLO has been described. . Further, at that time, the processing in the case where the imaging position of the high-resolution AO-SLO includes the boundary of the region where the photoreceptor cells exist has been described. Therefore, in the present embodiment, a description will be given of processing in a case where the imaging position of the high-resolution AO-SLO is a region that does not include a boundary and in which a photoreceptor cell exists.

  Specifically, when the photographing position is an area where a photoreceptor cell exists, if a focus position is set correctly, there is a high possibility that a detailed photoreceptor cell image can be acquired. For this purpose, AO-SLO images are taken in advance at a plurality of focus positions. The plurality of sheets may be seven sheets as described in the third embodiment or a wider range. Further, a focus range for photographing may be set in advance according to the past photographing history of the eye to be examined and the photographing position.

  From the plurality of AO-SLO images obtained at different focus positions, an image in which photoreceptor cells are depicted is selected. Specifically, an image having the largest index size is selected using the frequency-converted image of the AO-SLO image shown in step S250 of the first embodiment.

  Furthermore, instead of selecting each image, region division as shown in step S510 of the first embodiment may be performed, and regions having a large index size may be connected to generate an image.

(Example 5)
In Embodiments 1 to 4, a method for photographing a region where a photoreceptor cell exists and its boundary while searching for a boundary between a region where a photoreceptor cell exists and a region where the photoreceptor cell is missing using only an AO-SLO image at the time of photographing About. However, there is a case where information is obtained in advance about an area where a photoreceptor cell is likely to exist.

  Specifically, information obtained from other modalities such as an OCT tomogram and a fluorescence fundus contrast image acquired at the same time may be referred to. Alternatively, the boundary of the photoreceptor cell obtained from the AO-SLO image taken in the past may be referred to for the same eye to be examined. That is, in the case of the present embodiment, the boundary is acquired based on the OCT tomographic image about the eye to be examined, acquired from a planar image of the eye to be examined acquired in the past, selected from a plurality of boundaries acquired in the past, etc. You may decide by.

  FIG. 14 shows an example in which the information on the boundary of photoreceptor cells obtained at the time of past imaging is displayed superimposed on the WF-SLO image. In FIG. 14, with respect to the region where the photoreceptor cells acquired during the past four observations are obtained, the newer region is shown in a darker color. By presenting such information to the user, it is possible for the user to predict the location of the photoreceptor cell at the current stage. Specifically, in FIG. 14, since the reduction speed of the region where the photoreceptor cells are present is faster on the right side than on the left side, there is a possibility that a boundary exists more inside than the boundary at the time of the previous photographing. It is.

  Further, the difference between photoreceptor cell boundaries obtained at the time of past imaging can be extracted as an area and can be set as an analysis target area. Specifically, when the difference area between the boundary at the previous shooting and the boundary at the previous shooting was obtained, the photoreceptor cells included in the difference area existed at the previous shooting but were missing at the previous shooting. It becomes. By analyzing and comparing the photoreceptor cells included in the difference area and the photoreceptor cells included in the boundary at the previous imaging, it is possible to analyze the photoreceptor cells that will be deficient soon. That is, in such a case, the boundary acquisition unit 142 extracts a difference between a plurality of boundaries acquired in the past as an analysis target region.

  If there are other modalities or past progress information, it is possible to predict a region where a photoreceptor cell is likely to exist. Therefore, it can be considered that shooting with higher accuracy becomes possible by combining with a method of searching for a boundary by analyzing a shot AO-SLO image as shown in the first to fourth embodiments.

  Specifically, when it is determined in step S250 whether or not a boundary is included in the captured image, if it is different from the prediction, an alert is presented to the user and at the same time the focus position is changed to the same position. It is possible to indicate an option such as re-shooting with.

  Also, because there are cases where there are other modalities and past progress information depending on the eye to be examined, it is possible to switch between modes that use other modalities and past progress information and modes that do not use at the time of imaging To do.

(Other embodiments)
An object of the present invention is to supply a storage medium storing software program codes for realizing the functions of the above-described embodiments to a system or apparatus. Needless to say, this can also be achieved by the computer (or CPU or MPU) of the system or apparatus reading and executing the program code stored in the storage medium.

DESCRIPTION OF SYMBOLS 1 Database 2 OCT imaging device 3 Planar image imaging device 4 Display part 10 Processing apparatus 20 Ophthalmological apparatus 100 Image acquisition part 110 Information acquisition part 120 Control part 130 Storage part 140 Image processing part 141 Positioning part 142 Boundary acquisition part 143 Shooting position setting Part 144 connecting part 150 output part

Claims (11)

Image acquisition means for acquiring a planar image of the fundus of the eye to be examined;
Determining means for determining whether or not the planar image is an image including a boundary between a region where a photoreceptor cell of the eye to be examined exists and a region where the photoreceptor cell does not exist;
Setting means for setting a position for acquiring the next plane image based on the determination by the determination means;
Control means for causing the image acquisition means to acquire a planar image of the position set by the setting means;
Said image acquiring means, said determining means, said setting means, and a display control unit that Ru is displayed on the display means the concatenation of the boundary included in the plurality of the planar images obtained by repeating the processing by the control means ,
An ophthalmologic apparatus comprising: The determination means determines whether or not the image includes the boundary based on a signal intensity corresponding to the density of the photoreceptor cells obtained by frequency-converting the planar image. The ophthalmic apparatus according to 1. It said determination means divides the previous SL plane image into a plurality of regions, characterized by determining based on the intensity of the signal of each area obtained an image of each divided area by frequency conversion according to claim 1 or The ophthalmic apparatus according to 2. Based on the concatenation of the boundary, any one of claims 1 to 3, further comprising a second image acquisition means for acquiring a second planar image of higher resolution of the planar image resolution An ophthalmic device according to claim 1. 5. The ophthalmic apparatus according to claim 4 , wherein the second image acquisition unit acquires a plurality of second planar images by performing imaging while setting a plurality of focus positions at the same imaging position. 6 . . The judgment unit may ophthalmic device according to claim 5, wherein each of the captured said second planar image in the plurality of focus positions is determined whether the image including the boundary. The apparatus further comprises selection means for selecting the second plane image used for connecting the boundaries based on the determination result of the second plane image captured at the plurality of focus positions by the determination unit. The ophthalmic apparatus according to claim 5 . Image acquisition means for acquiring a planar image of the fundus of the eye to be examined ;
Boundary acquisition means for acquiring a boundary between a region where photoreceptor cells are present and a region which does not exist in the planar image ;
Setting means for setting a position to acquire the next plane image based on the position of the acquired boundary in the plane image ;
Control means for causing the image acquisition means to acquire a planar image of the position set by the setting means;
Display results of boundaries of the existing regions of the photoreceptor cells included in the plurality of planar images acquired by repeating the processing by the image acquisition means, the boundary acquisition means, the setting means, and the control means. and display control means for Ru to be displayed,
An ophthalmologic apparatus comprising: The program for functioning a computer as each means of the ophthalmic apparatus as described in any one of Claims 1 thru | or 8 . A storage medium storing the program according to claim 9 . An image acquisition step of acquiring a planar image of the fundus of the eye to be examined by the image acquisition means ;
A determination step of determining whether or not the planar image is an image including a boundary between a region where a photoreceptor cell of the eye to be examined exists and a region where the photoreceptor cell does not exist;
Based on the determination in the determination step, a setting step for setting a position for acquiring the next plane image;
A control step of causing the image acquisition means to acquire a planar image of the position set in the setting step;
The image acquisition step, the determination step, the setting step, and a display control step of Ru is displayed on the display means the concatenation of the boundary included in the obtained plurality of the planar image by repeating the process in the control step ,
A method for controlling an ophthalmic apparatus, comprising: