Strabismus determination device, strabismus determination method, and program

Abstract

[Problem] To make it possible to easily determine strabismus. [Solution] A strabismus determination device, characterized by comprising: an image acquisition unit that acquires an image obtained by imaging an eye of a subject from the front of the subject; a cornea detection unit that analyzes the image and detects the cornea from the image; and a strabismus determination unit that determines the degree of strabismus on the basis of the width and / or the height of the cornea.

Description

Strabismus assessment device, strabismus assessment method, and program

[0001] The present invention relates to a strabismus determination device, a strabismus determination method, and a program.

[0002] Strabismus is assessed by reflecting light from a light source onto the subject's eyes (Patent Document 1).

[0003] Special table 2015-525597 publication

[0004] However, in Patent Document 1, it is necessary to set up a light source and measure the reflection of light, which is time-consuming.

[0005] The present invention has been made in view of the above background, and aims to provide a technique that can easily determine strabismus.

[0006] The main invention of the present invention for solving the above problem is a strabismus assessment device, characterized by comprising an image acquisition unit that acquires an image of the subject's eyes taken from the front of the subject, a cornea detection unit that analyzes the image and detects the cornea from the image, and a strabismus assessment unit that determines the degree of strabismus based on at least one of the width and height of the cornea.

[0007] Other problems and solutions disclosed in this application will be made clear in the section on preferred embodiments of the invention and the drawings.

[0008] According to the present invention, strabismus can be easily diagnosed.

[0009] Fig. 1 is a diagram illustrating an image of a subject's eyes. Fig. 2 is a diagram illustrating an example of the hardware configuration of the strabismus judgment device 2. Fig. 3 is a diagram illustrating an example of the software configuration of the strabismus judgment device 2. Fig. 4 is a diagram illustrating the flow of processing by the strabismus judgment device 2. Fig. 5 is a diagram illustrating how a subject is photographed according to a second embodiment. Fig. 6 is a diagram illustrating the flow of processing by the strabismus judgment device 2 according to the second embodiment.

[0010] A strabismus assessment device 2 according to one embodiment of the present invention will be described below. The strabismus assessment device 2 of this embodiment is designed to assess the degree of strabismus of a subject based on an image of the subject.

[0011] Fig. 1 is a diagram illustrating an image of a subject's eyes. In this embodiment, it is assumed that the subject is photographed from the front using a strabismus assessment device 2. The example in Fig. 1 shows a state of so-called strabismus, in which the right eye 11 is not facing forward.

[0012] The left eye 12 faces forward, and in this case, the cornea 121 of the left eye 12 is substantially circular. That is, the width W2 and height H2 of the cornea 121 are substantially the same.

[0013] On the other hand, the right eye 11 faces to the right of the subject (left in the drawing), and in this case, the cornea 111 of the right eye 11 is elliptical. Therefore, the width W1 of the cornea 111 is smaller than the height H1.

[0014] The strabismus assessment device 2 of this embodiment can assess the degree of strabismus based on the shape of the corneas 111 and 121. Specifically, the ratio of the widths W1 and W2 of the corneas 111 and 121 to the heights H1 and H2 of the corneas 111 and 121 (H1÷W1, H2÷W2) can be determined as the degree of strabismus. In this embodiment, the narrower the corneal width, the higher the degree of strabismus can be determined. Note that the difference between the width W1 of the cornea 111 of the right eye 11 and the width W2 of the cornea 121 of the left eye 12 may also be used as the degree of strabismus. Alternatively, the difference between the widths (W1max, W2max) of the right eye 11 and the left eye 12 when facing forward and the widths (W1, W2) of the right eye 11 and the left eye 12 when facing forward may also be used as the degree of strabismus.

[0015] <Strabismus Assessment Device 2> FIG. 2 is a diagram illustrating an example of the hardware configuration of the strabismus assessment device 2. Note that the illustrated configuration is merely an example, and other configurations may also be used. The strabismus assessment device 2 includes a CPU 201, a memory 202, a storage device 203, a communication interface 204, a camera 205, and an input / output device 206. The storage device 203 stores various data and programs, and is, for example, a hard disk drive, a solid-state drive, or a flash memory. The communication interface 204 is an interface for connecting to a communication network, and is, for example, an adapter for connecting to Ethernet (registered trademark), a modem for connecting to a public telephone network, a wireless communication device for wireless communication, a USB (Universal Serial Bus) connector or an RS232C connector for serial communication, etc. The input / output device 206 is a device for inputting and outputting data, and is, for example, a touch panel display. The input / output device 206 may include multiple devices, and may include, for example, a keyboard, a mouse, a touch panel, buttons, a microphone, a display, a printer, a speaker, etc. Each functional unit of the strabismus assessment device 2 described below is realized by the CPU 201 reading a program stored in the storage device 203 into the memory 202 and executing it, and each storage unit of the strabismus assessment device 2 is realized as part of the storage area provided by the memory 202 and the storage device 203.

[0016] 3 is a diagram showing an example of the software configuration of the strabismus assessment device 2. The strabismus assessment device 2 includes an image acquisition unit 211, a cornea detection unit 212, a strabismus assessment unit 213, and an image storage unit 231.

[0017] The image acquisition unit 211 acquires an image of the subject's eyes taken from a frontal view of the subject. The image acquisition unit 211 can, for example, output a message to the user instructing the user to take an image from the front of the face, and can also acquire an image taken by the user with the camera 205.

[0018] The image storage unit 231 stores the images acquired by the image acquisition unit 211. The image storage unit 231 can store image data in association with a user ID that identifies the user, the date and time of shooting, and the shooting direction (for example, the angle can be expressed as an angle centered on the surface of the subject's face (for example, between the eyebrows), with the front of the subject being set to 0 degrees).

[0019] The cornea detection unit 212 analyzes the image and detects (a graphic representing) the cornea from the image. The cornea detection unit 212 detects a shape surrounding the area corresponding to the cornea using a known image processing technique, and detailed description of the process will be omitted here. In this embodiment, the cornea detection unit 212 detects the cornea as (approximating) a circular or elliptical shape.

[0020] The strabismus determination unit 213 determines the degree of strabismus based on at least the width of the cornea. In this embodiment, the strabismus determination unit 213 can determine the degree of strabismus based on the ratio of the corneal width W to the corneal height H. When the corneas 111 and 121 are detected, the strabismus determination unit 213 estimates an ellipse that approximates the shape of the corneas 111 and 121. A known method can be used for the ellipse estimation process. The strabismus determination unit 213 can calculate the width W and height H from the estimated ellipse. This allows the height H to be accurately calculated even when part of the corneas 111 and 121 is hidden by the eyelids or the like. Note that only the height H may be calculated from the ellipse, and the width W may be calculated from the detected corneas 111 and 121.

[0021] The strabismus determination unit 213 can also determine the degree of strabismus from only the width W. For example, the cornea detection unit 212 detects the corneas 111, 121 of both the right eye and the left eye from the image, and the strabismus determination unit 213 compares the width W1 of the right eye with the width W2 of the left eye to determine, for example, the difference (absolute value) between the width W1 of the right eye and the width W2 of the left eye as the degree of strabismus. Alternatively, the user may be instructed to move both eyes left and right, and the cornea detection unit 212 may detect the corneas 111, 121 from a video capturing the movement of the eyes or from still images captured multiple times in time series of the movement of the eyes, and the strabismus determination unit 213 may identify the maximum values ​​W1max, W2max of the width W1 of the right eye and the width W2 of the left eye, respectively. Next, the user is instructed to look straight ahead, and an image is taken from the front of the face. The cornea detection unit 212 detects the corneas 111, 121 from the image taken from the front of the user, and the strabismus determination unit 213 calculates the widths W1, W2 of the detected corneas 111, 121 and can determine the degree of strabismus based on the average, larger, or smaller of the differences (W1max, W2max) between the maximum values ​​W1max, W2max and the widths W1, W2 of the corneas in the image taken from the front (W1max-W1, W2max-W2).

[0022] <Operation> FIG. 4 is a diagram illustrating the flow of processing by the strabismus determination device 2.

[0023] The strabismus assessment device 2 uses the camera 205 to capture an image of the subject's eyes from the front (S301). Note that it is up to the subject to decide whether or not the image is captured from the front, and the strabismus assessment device 2 itself can be configured not to determine whether or not the image is captured from the front of the subject. The strabismus assessment device 2 detects the subject's eyes from the captured image (S302). It may be configured to detect only the right eye, only the left eye, or both eyes.

[0024] The strabismus assessment device 2 obtains the detected corneal width W and height H (S303), and can assess the degree of strabismus based on the ratio of the width W to the height H (S304). As described above, the degree of strabismus can also be determined based on the difference (W1-W2) between the left and right corneal widths W1 and W2, or based on at least one of the differences (W1max-W1, W2max-W2) between the maximum corneal widths W1max and W2max (or at least one of them) when the eyes are moved left and right and the corneal widths W1 and W2 in an image captured from the front, or the average value of these differences.

[0025] As described above, the strabismus assessment device 2 of this embodiment can assess the degree of strabismus of a subject solely from an image taken by the subject himself.

[0026] 5 is a diagram illustrating how a subject is photographed according to the second embodiment. In the second embodiment, not only is photography performed in a direction D1 facing the front of the subject, but photography is also performed from directions D2 and / or D3 angled relative to the front of the subject.

[0027] The image acquisition unit 211 acquires a first image (image taken in the shooting direction of D1) of the subject taken from the front and a second image (image taken in the shooting direction of D2 and / or D3) of the subject taken at an angle to the front of the subject, the cornea detection unit 212 detects the first and second corneas from the first and second images, and the strabismus determination unit 213 can determine the degree of strabismus based on the width of the first and second corneas.

[0028] FIG. 6 is a diagram illustrating the processing flow of the strabismus assessment device 2 according to the second embodiment. The strabismus assessment device 2 captures images of the subject's eyes from the front (S301) and then captures images of the subject's eyes at an angle (S321). The strabismus assessment device 2 detects the subject's cornea from the captured images (S302) and detects the corneal width W in each image (S322). The strabismus assessment device 2 can determine the degree of strabismus based on the ratio of the corneal width W in the angled image to the corneal width W in the frontal image (S323). In this case, for example, if the corneal width W in the second image captured at the D2 direction is larger than the corneal width W in the first image captured at the D1 direction, it can be determined that the cornea is oriented in a direction closer to parallel to the D2 direction than to the D1 direction. The degree of strabismus can be determined based on the change in size in this case.

[0029] <Third Embodiment> In the first and second embodiments, strabismus in which the line of sight is shifted in the left-right direction (exotropia or esotropia) is assumed, but in the third embodiment, strabismus in which the line of sight is shifted in the up-down direction (vertical strabismus) is determined.

[0030] In the third embodiment, the degree of vertical strabismus can be determined as a value corresponding to the ratio (W1÷H1, W2÷H2) of the heights H1 and H2 of the corneas 111 and 121 to the widths W1 and W2 of the corneas 111 and 121. In the third embodiment, the smaller the corneal height, the higher the degree of vertical strabismus can be determined. Note that the difference between the height H1 of the cornea 111 of the right eye 11 and the height H2 of the cornea 121 of the left eye 12 may also be determined as the degree of vertical strabismus. Alternatively, the difference between the heights (H1max, H2max) of the right eye 11 and the left eye 12 when facing forward and the heights (H1, H2) of the right eye 11 and the left eye 12 when facing forward may also be determined as the degree of vertical strabismus.

[0031] In the third embodiment, the strabismus determination unit 213 determines the degree of vertical strabismus based on at least the height of the cornea. In the third embodiment, the strabismus determination unit 213 can determine the degree of strabismus according to the ratio of the corneal height H to the corneal width W. When the strabismus determination unit 213 detects the corneas 111, 121, it estimates an ellipse that approximates the shape of the corneas 111, 121. A known method can be used for the ellipse estimation process. The strabismus determination unit 213 can obtain the width W and height H from the estimated ellipse. This allows the width W and height H to be accurately calculated even when part of the corneas 111, 121 is hidden by the eyelids or the like.

[0032] The strabismus determination unit 213 can also determine the degree of vertical strabismus from only the height H. For example, the cornea detection unit 212 detects the corneas 111, 121 of both the right eye and the left eye from the image, and the strabismus determination unit 213 compares the right eye height H1 with the left eye height H2, and determines, for example, the difference (absolute value) between the right eye height H1 and the left eye height H2 as the degree of vertical strabismus. Alternatively, the user may be instructed to move both eyes up and down, and the cornea detection unit 212 may detect the corneas 111, 121 from a video capturing the eye movement or from still images captured multiple times in time series of the eye movement, and the strabismus determination unit 213 may identify the maximum values ​​H1max and H2max of the right eye height H1 and the left eye height H2, respectively. Next, the user is instructed to look straight ahead, and an image is taken from the front of the face. The cornea detection unit 212 detects the corneas 111, 121 from the image taken from the front of the user, and the strabismus determination unit 213 calculates the heights H1, H2 of the detected corneas 111, 121 and can determine the degree of vertical strabismus based on the average, larger, or smaller of the differences (H1max, H2max) between the maximum values ​​H1max, H2max and the corneal heights H1, H2 in the image taken from the front.

[0033] Fourth Embodiment In a fourth embodiment, the degree of strabismus is determined in both the left-right direction and the up-down direction.

[0034] In the fourth embodiment, the degree of strabismus can be determined based on both the ratio of the height H1, H2 of the cornea 111, 121 to the width W1, W2 of the cornea 111, 121 (W1 ÷ H1, W2 ÷ H2) and the ratio of the width W1, W2 of the cornea 111, 121 to the height H1, H2 of the cornea 111, 121 (H1 ÷ W1, H2 ÷ W2). In the fourth embodiment, the narrower the corneal width and the smaller the corneal height, the higher the degree of strabismus can be determined. Note that the difference between the width W1 and height H1 of the cornea 111 of the right eye 11 and the width W2 and height H2 of the cornea 121 of the left eye 12 may also be determined as the degree of strabismus. Furthermore, using the widths and heights (W1max, H1max, W2max, H2max) of the right eye 11 and the left eye 12 when they are facing forward and the widths and heights (W1, H1, W2, H2) that appear in the captured image, the sum or weighted sum of the width differences (W1max-W1, W2max-W2) and height differences (H1max-H1, H2max-H2) can be determined as the degree of strabismus.

[0035] In the fourth embodiment, as in the above-described embodiments, an ellipse that approximates the corneas 111 and 121 can be estimated, and the degree of strabismus can be calculated using the width W and height H of the ellipse.

[0036] In the fourth embodiment, the strabismus determination unit 213 can also determine the degree of vertical strabismus from only the width W and height H. For example, the cornea detection unit 212 detects the corneas 111, 121 of both the right and left eyes from the image, and the strabismus determination unit 213 compares the width W1 and height H1 of the right eye with the width W1 and height H2 of the left eye, and can determine the degree of strabismus by summing, for example, the difference (absolute value) between the width W1 and width W2 of the right eye and the difference (absolute value) between the height H1 and height H2 of the left eye.

[0037] Furthermore, the user is instructed to move both eyes up and down, and the cornea detection unit 212 detects the corneas 111 and 121 from a video of the eye movement or from still images of the eye movement captured multiple times in time series, and the strabismus determination unit 213 can identify the maximum values ​​H1max and H2max of the right eye height H1 and the left eye height H2, respectively. Next, the user is instructed to look straight ahead, and an image is taken from the front of the face, and the cornea detection unit 212 detects the corneas 111 and 121 from the image taken from the front of the user. The strabismus determination unit 213 calculates the heights H1 and H2 of the detected corneas 111 and 121, and can determine the degree of vertical strabismus based on the average, larger, or smaller of the differences (H1max - H1, H2max - H2) between the maximum values ​​H1max and H2max and the corneal heights H1 and H2 in the image taken from the front.

[0038] Although the present embodiment has been described above, the above embodiment is intended to facilitate understanding of the present invention and is not intended to limit the present invention. The present invention may be modified or improved without departing from the spirit thereof, and equivalents thereof are also included in the present invention.

[0039] For example, the degree of strabismus in the left-right direction and the degree of strabismus in the up-down direction may be calculated and output separately.

[0040] <Disclosure> The present disclosure also includes the following configurations. [Item 1] A strabismus assessment device comprising: an image acquisition unit that acquires an image of a subject's eye taken from a frontal view of the subject; a cornea detection unit that analyzes the image and detects the cornea from the image; and a strabismus assessment unit that determines the degree of strabismus based on at least one of the width and height of the cornea. [Item 2] The strabismus assessment device according to item 1, wherein the strabismus assessment unit estimates an ellipse that represents the shape of the cornea, and determines the degree of strabismus based on the width and height of the ellipse. [Item 3] The strabismus assessment device according to item 2, wherein the strabismus assessment unit determines the degree of strabismus according to at least one of the ratio of the width to the height and the ratio of the height to the width. [Item 4] The strabismus assessment device according to Item 1, wherein the images include images of a right eye and a left eye, the cornea detection unit detects a first cornea of ​​the right eye and a second cornea of ​​the left eye from the images, and the strabismus assessment unit determines the degree of strabismus based on at least one of a width and a height of the first cornea and at least one of a width and a height of the second cornea. [Item 5] The strabismus assessment device according to Item 1, wherein the image acquisition unit acquires a first image of the subject taken from the front and a second image of the subject taken at an angle relative to the front of the subject, the cornea detection unit detects the first and second corneas from the first and second images, and the strabismus assessment unit determines the degree of strabismus based on at least one of a width and a height of the first and second corneas. [Item 6] A method for determining strabismus, characterized in that an information processing device executes the steps of: acquiring an image of the subject's eye photographed from the front of the subject; analyzing the image to detect the cornea from the image; and determining the degree of strabismus based on at least one of the width and height of the cornea.[Item 7] A program for causing an information processing device to execute the steps of: acquiring an image of the subject's eye photographed from the front of the subject; analyzing the image to detect the cornea from the image; and determining the degree of strabismus based on at least one of the width and height of the cornea.

[0041] 2 Strabismus determination device

Claims

1. A strabismus assessment device comprising: an image acquisition unit that acquires images of the right and left eyes of a subject taken from in front of the subject; a cornea detection unit that analyzes the images and detects the cornea of ​​the right eye and the cornea of ​​the left eye from the images; and a strabismus assessment unit that determines the degree of strabismus based on the difference between at least one of the width and height of the cornea of ​​the right eye and at least one of the width and height of the cornea of ​​the left eye.

2. A strabismus assessment device as described in claim 1, characterized in that the strabismus assessment unit estimates ellipses indicating the shapes of the cornea of ​​the right eye and the cornea of ​​the left eye, and determines the degree of strabismus based on the difference between at least one of the width and height of the ellipse corresponding to the right eye and at least one of the width and height of the ellipse corresponding to the left eye.

3. A strabismus assessment device as described in claim 1, characterized in that the strabismus assessment unit assesses the degree of strabismus based on the difference between the ratio of the corneal width of the right eye to the corneal height of the right eye and the ratio of the corneal width of the left eye to the corneal height of the left eye.

4. A strabismus assessment device as described in claim 1, characterized in that the image acquisition unit acquires a first image taken from the front of the subject and a second image taken at an angle to the front of the subject, the cornea detection unit detects the first and second corneas of the right and left eyes from the first and second images, and the strabismus assessment unit determines the degree of strabismus based on the difference between at least one of the width and height of the first cornea of ​​the right eye and at least one of the width and height of the second cornea of ​​the left eye.

5. A method for determining strabismus, characterized in that an information processing device executes the following steps: acquiring images of the right and left eyes of a subject taken from in front of the subject; analyzing the images to detect the cornea of ​​the right eye and the cornea of ​​the left eye from the images; and determining the degree of strabismus based on the difference between at least one of the width and height of the cornea of ​​the right eye and at least one of the width and height of the cornea of ​​the left eye.

6. A program for causing an information processing device to execute the steps of: acquiring images of the right and left eyes of a subject taken from in front of the subject; analyzing the images to detect the cornea of ​​the right eye and the cornea of ​​the left eye from the images; and determining the degree of strabismus based on the difference between at least one of the width and height of the cornea of ​​the right eye and at least one of the width and height of the cornea of ​​the left eye.

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