JP7218858B2 - Image analysis device, method of operating image analysis device, and ophthalmic device - Google Patents

Description

The present invention relates to an image analysis apparatus and an image analysis method for analyzing a captured image of reflected light of a measurement pattern projected onto the fundus of an eye to be examined, and an ophthalmologic apparatus including this image analysis apparatus.

In ophthalmology, a plurality of types of ophthalmic devices are used to measure the ocular characteristics of an eye to be examined (e.g., eye refractive power, corneal shape, etc.), or to diagnose diseases of the eye to be examined [e.g., cataract, keratoconus (irregular astigmatism), etc.]. inspection. For example, an autorefractometer (a refractometer and a keratometer) is used to measure the refractive power and corneal shape of an eye to be examined (see Patent Document 1).

In addition, for cataract testing in the subject's eye, for example, a special ophthalmologic instrument that measures the wavefront aberration and scattering of the reflected light reflected by a fairly small area of the subject's eye's retina (substantially regarded as a point light source) is used. (See Patent Document 2). Furthermore, a special keratometer capable of quantitatively evaluating the shape of keratoconus, for example, is used to examine keratoconus of an eye to be examined (see Patent Document 3).

JP 2017-63979 A JP 2006-280476 A JP 2007-215956 A

By the way, in ophthalmology, special ophthalmologic apparatuses such as those described in Patent Documents 2 and 3 need to be used when examining eyes to be examined for various diseases (cataracts, keratoconus, etc.). For this reason, the introduction cost of the ophthalmic apparatus is high, and the problem of securing the installation space for the ophthalmic apparatus arises. Therefore, as in the autoreflection keratometer described in Patent Document 1, an existing ophthalmology system that projects a measurement pattern onto an eye to be inspected and obtains a captured image of the reflected light of the measurement pattern to measure the ocular characteristics of the eye to be inspected. There is a strong need to test for disease in the subject's eye using existing ophthalmic equipment that is widely used in prescribing equipment such as eyeglasses and contact lenses.

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances. and intended to provide

An image analysis apparatus for achieving the object of the present invention comprises an image acquisition unit for acquiring a captured image of reflected light from a measurement pattern projected onto an eye to be inspected; and a high-order aberration detection unit that detects a specific high-order aberration of the eye to be inspected that causes distortion of the ring image, based on the ring image detected by the ring image detection unit. , provided.

According to this image analysis apparatus, it is possible to determine (estimate) the presence or absence of a disease in the eye to be examined and the type of the disease by detecting specific high-order aberrations of the eye to be examined that cause distortion of the ring image.

In the image analysis apparatus according to another aspect of the present invention, the high-order aberration detection unit includes an ellipse approximation unit that fits an ellipse to the ring image detected by the ring image detection unit, and an ellipse fitted by the ellipse approximation unit. and the ring image detected by the ring image detection unit, and an aberration that calculates a specific high-order aberration of the eye to be examined based on the residual calculated by the residual calculation unit. and an analysis unit. This makes it possible to detect specific high-order aberrations of the subject's eye.

In the image analysis apparatus according to another aspect of the present invention, the aberration analysis unit calculates the Zernike coefficient of the Zernike polynomial as the calculation result of the specific high-order aberration of the eye to be examined by fitting the residual to the differential of the Zernike polynomial. do. This makes it possible to detect specific high-order aberrations of the subject's eye. Also, since there is only one ring, the residual from the ellipse fit with the angle on the ring as a parameter may simply be Fourier transformed to evaluate the cubic and quartic coefficients.

An image analysis apparatus according to another aspect of the present invention includes a state determination section that determines the state of the subject's eye based on the detection result of the high-order aberration detection section. This makes it possible to determine the presence or absence of a disease in the subject's eye and the type of the disease.

In the image analysis apparatus according to another aspect of the present invention, the image acquisition unit includes, as the captured images, a first captured image of the fundus reflected light of the eye refractive power measurement pattern projected onto the fundus of the subject's eye, and the subject's eye. a second captured image of the corneal reflected light of the corneal shape measurement pattern projected on the cornea, the ring image detection unit detects the ring image for each type of captured image, and the higher-order aberration detection unit , a specific high-order aberration of the subject's eye is detected for each type of captured image, and the state determination unit determines the state of the subject's eye for each type of captured image. This makes it possible to determine the presence or absence of a disease in the subject's eye and the type of the disease.

In the image analysis apparatus according to another aspect of the present invention, the image acquisition unit includes, as the captured images, a first captured image of the fundus reflected light of the eye refractive power measurement pattern projected onto the fundus of the subject's eye, and the subject's eye. a second captured image of the corneal reflected light of the corneal shape measurement pattern projected on the cornea, the ring image detection unit detects the ring image for each type of captured image, and the higher-order aberration detection unit , a specific high-order aberration of the subject's eye is detected for each type of captured image, and the state determination unit determines the state of the subject's eye based on the detection result of the high-order aberration detection unit for each type of captured image. This makes it possible to determine the presence or absence of a disease in the subject's eye and the type of the disease.

An ophthalmologic apparatus for achieving the object of the present invention comprises a projection optical system for projecting a measurement pattern onto an eye to be inspected, and a measurement optical system for outputting a ring image based on the reflected light of the measurement pattern projected onto the eye to be inspected. , and the image analysis device described above.

An image analysis method for achieving the object of the present invention comprises an image acquisition step of acquiring a captured image of reflected light from a measurement pattern projected onto an eye to be inspected; and a high-order aberration detection step of detecting a specific high-order aberration of the subject's eye that causes distortion of the ring image, based on the ring image detected in the ring image detection step. An image analysis method comprising:

An image analysis method according to another aspect of the present invention has a state determination step of determining the state of the subject's eye based on the detection result of the high-order aberration detection step.

INDUSTRIAL APPLICABILITY According to the present invention, an examination of a disease of an eye to be examined can be performed using an existing ophthalmologic apparatus.

1 is a schematic diagram of an ophthalmic device; FIG. 3 is a block diagram showing a schematic configuration of an optical system and a control device; FIG. 3 is a functional block diagram of an image analysis circuit; FIG. FIG. 4 is an explanatory diagram for explaining the relationship between the aberration of an eye to be inspected and the shape of a referling image; FIG. 4 is a diagram showing the shape of a ring image in Zernike polynomials when an eye to be examined has higher-order aberrations; FIG. 10 is an explanatory diagram for explaining ellipse approximation by an ellipse approximation unit; FIG. 5 is an explanatory diagram for explaining residual calculation by a residual calculation unit; FIG. 4 is an explanatory diagram for explaining residuals; FIG. 10 is an explanatory diagram for explaining an example of a determination table; FIG. 4 is a flowchart showing a flow of evaluation processing of the state of an eye to be examined by an ophthalmologic apparatus; FIG. 10 is a schematic diagram showing a modification of the measurement pattern projection optical system and the measurement optical system;

[Ophthalmic equipment]
FIG. 1 is a schematic diagram of an ophthalmic device 10 of the present invention. As shown in FIG. 1, the ophthalmologic apparatus 10 is an autorefractometer that measures eye refractive power and corneal shape as eye characteristics of an eye E to be examined. This ophthalmologic apparatus 10 has a function of judging (estimating) the condition of the eye E to be inspected in addition to the eye refractive power and corneal shape of the eye E to be inspected, specifically examining diseases such as cataracts and keratoconus of the eye E to be inspected. have The ophthalmologic apparatus 10 includes a base 12 , a face receiving section 13 , a pedestal 14 and a measurement head 15 .

In the figure, the X-axis direction is the lateral direction (interpupillary direction of the subject's eye E) with respect to the subject, the Y-axis direction is the vertical direction, and the Z-axis direction is the subject (subject's eye E ) and the rearward direction away from the subject (also referred to as the working distance direction).

The face receiving portion 13 is provided integrally with the base 12 at a position on the front side of the measuring head 15 in the Z-axis direction. The face support section 13 has a chin support 13a and a forehead support 13b whose positions are adjustable in the Y-axis direction, and supports the subject's face during measurement (during examination) by the ophthalmologic apparatus 10. FIG.

The pedestal 14 is provided on the base 12 and is movable with respect to the base 12 in each direction of the XZ axis (forward, backward, leftward, and rightward directions). A measuring head 15 and an operating lever 16 are provided on the mount 14 .

The operation lever 16 is provided on the pedestal 14 and on the rearward side (operator side) of the measuring head 15 in the Z-axis direction, and is operated when moving the measuring head 15 in each of the XYZ-axis directions. It is an operating member. For example, when the operation lever 16 is tilted in the Z-axis direction (front-back direction) or the X-axis direction (left-right direction), the measuring head 15 is moved in the Z-axis direction or the X-axis direction by an electric drive mechanism (not shown). . Further, when the operating lever 16 is rotated around its longitudinal axis, the measuring head 15 is moved in the Y-axis direction (up and down direction) by an elevating mechanism (not shown) according to the rotating operation direction. A measurement button is provided on the top of the operation lever 16 for starting the measurement of the subject's eye E by the ophthalmologic apparatus 10 .

The measuring head 15 has a function of measuring the eye refractive power and corneal shape of the eye E to be examined. This eye refractive power and corneal shape measurement function is also used to inspect the subject's eye E for cataracts, keratoconus, and the like, although the details will be described later. A monitor 17 is provided on the rear surface of the measuring head 15 in the Z-axis direction. In the measurement head 15, an optical system 18 (including an imaging device, various light sources, and various driving units) corresponding to eye refractive power and corneal shape measurement, and a control device 20 are provided.

The monitor 17 is, for example, a touch panel type liquid crystal display device. The monitor 17 displays, for example, an observation image of the anterior ocular segment of the eye to be examined E used for alignment of the measuring head 15 and the measurement results of the ocular refractive power and corneal shape of the eye to be examined E obtained by the measuring head 15. , a determination result (presence or absence of a disease, etc.) of the condition of the eye to be examined E, which will be described later, and an input screen for performing operations (settings) related to measurement are displayed.

FIG. 2 is a block diagram showing a schematic configuration of the optical system 18 and the control device 20. As shown in FIG. As shown in FIG. 2, the optical system 18 includes a fixation target projection optical system 22, a kerat system 23, an observation optical system 24, an alignment optical system 26, a measurement pattern projection optical system 28, and a measurement optical system. 30 and. Note that the detailed configuration of each optical system of the auto refkeratometer is a known technique (see Patent Document 1 above), so a detailed description thereof will be omitted here.

The fixation target projection optical system 22 projects the target light of the fixation target onto the fundus of the eye E to fix or fog the eye E to be inspected.

The kerato system 23 corresponds to the projection optical system of the present invention, and projects a pattern for measuring the shape of the cornea onto the cornea of the eye E to be examined. As the corneal shape measurement pattern, for example, a single or multiple ring-shaped light flux is used, but in the present embodiment, a single ring-shaped light flux is used in order to prevent complication of the description. When the corneal shape measurement pattern is projected onto the cornea of the eye to be examined E from the kerato system 23, the corneal reflected light (also referred to as return light) of this measurement pattern becomes an observed image of the anterior segment (anterior segment image) is received by the observation optical system 24 .

The observation optical system 24 is for observing the anterior segment of the subject's eye E, and outputs image data of an observation image obtained by photographing the anterior segment with an imaging device or the like to the control device 20 . As a result, an observation image of the anterior segment is displayed on the monitor 17 by the control device 20 .

Further, when measuring the corneal shape of the eye E to be examined, the observation optical system 24 captures (receives) the corneal reflected light of the pattern for measuring the corneal shape reflected by the cornea of the eye E to be examined by the imaging device. Image data of the captured image 32B of the corneal reflected light (corresponding to the second captured image of the present invention) is obtained. This captured image 32B includes a keratling image 34B, which is a ring image based on the corneal reflected light. Image data of the captured image 32B is output from the observation optical system 24 to the control device 20 .

The measurement pattern projection optical system 28 corresponds to the projection optical system of the present invention, and projects a pattern for measuring the refractive power of the eye E to be examined onto the fundus of the eye E to be examined. A ring-shaped luminous flux is used as the pattern for measuring the eye refractive power. Note that a point-shaped light beam may be used instead of the ring-shaped light beam, and the shape of the pattern for eye refractive power measurement is not particularly limited. When the measurement pattern projection optical system 28 projects the measurement pattern onto the fundus of the eye to be examined E, the measurement optical system 30 receives the fundus reflected light (also referred to as return light) of the measurement pattern. The shape of the fundus reflected light is distorted by the refractive power of the eye E to be examined. When the subject's eye E has cataract, depending on the degree of cataract, an image affected by scattering in the lens is observed when the measurement pattern is projected and when the fundus reflected light is detected.

When measuring the refractive power of the eye to be examined E, the measurement optical system 30 captures (receives) the fundus reflected light of the eye refractive power measurement pattern reflected by the fundus of the eye to be examined E using the imaging element. Image data of the captured image 32A of the fundus reflected light (corresponding to the first captured image of the present invention) is obtained. This captured image 32A includes a referencing image 34A, which is a ring image based on the fundus reflected light. Image data of the captured image 32A is output from the measurement optical system 30 to the control device 20. FIG.

The imaging of the image 32A by the measurement optical system 30 and the imaging of the image 32B by the observation optical system 24 can be performed by the same imaging element by sharing the optical path from the middle of both optical systems. be. In that case, the refringing image 34A and the keratling image 34B can be obtained continuously by switching the optical paths, etc., whereas it was possible to obtain them simultaneously through separate optical paths.

The control device 20 is an arithmetic circuit including various processors, memories, and the like. Various processors include CPU (Central Processing Unit), GPU (Graphics Processing Unit), DSP (Digital Signal Processing Unit), ASIC (Application Specific Integrated Circuit), and programmable logic devices [for example, SPLD (Simple Programmable Logic Devices), CPLDs (Complex Programmable Logic Devices) and FPGAs (Field Programmable Gate Arrays)]. Various functions of the control device 20 may be realized by one processor, or may be realized by a plurality of processors of the same type or different types.

The control device 20 is connected to the operation lever 16, the monitor 17, each part of the optical system 18 described above, and the storage part 40. FIG. The control device 20 includes an overall control circuit 36 and an image analysis circuit 38 which are realized by the arithmetic circuit described above or by the arithmetic circuit executing software or the like.

In the storage unit 40, various programs including a program 42 for operation of the control device 20, measurement data of the ocular refractive power and corneal shape of the eye E to be examined, and determination results of the condition of the eye E to be examined (presence or absence of disease) are stored. Information is stored. Further, the storage unit 40 is provided with a determination table 43 used for determination by a state determination unit 52 (see FIG. 3), which will be described later. Note that the storage unit 40 may be provided outside the ophthalmologic apparatus 10 (for example, a server on the Internet).

The overall control circuit 36 executes a program 42 pre-stored in the storage unit 40 to control the operation of each unit of the ophthalmologic apparatus 10 including the optical system 18 (for example, acquisition and display of an observation image of the anterior segment, automatic alignment, and so on). , and acquisition of the captured images 32A and 32B).

The image analysis circuit 38 corresponds to the image analysis device of the present invention. The image analysis circuit 38 executes the program 42 in the storage unit 40 to analyze the captured image 32A (refringing image 34A), calculate the eye refractive power of the eye E to be examined, and generate the captured image 32B (keratling image 34B) is analyzed to calculate the corneal shape of the eye E to be examined.

Further, the image analysis circuit 38 analyzes the captured images 32A and 32B (the referencing image 34A and the keratling image 34B), and generates distortion of the referencing image 34A and the keratling image 34B among the wavefront aberrations of the eye E to be examined. Detect specific high-order aberrations. Then, the image analysis circuit 38 determines (estimates) the condition of the eye to be examined E including the presence or absence of a disease of the eye to be examined E and its type (cataract, keratoconus, etc.) based on the detection result of the specific high-order aberration. .

Here, the wavefront aberrations (low-order and high-order aberrations) of the subject's eye E are generally arbitrary deviations at arbitrary positions of the actual wavefront from its corresponding reference wavefront. The reference wavefront is a spherical wavefront that is closest to the actual wavefront that forms an aberration-free image. Classical expressions for these aberrations are defocus, astigmatism, coma, and spherical aberration. These wavefront aberrations can also be represented by mathematical descriptors. Examples of such descriptors include the use of Taylor expansion polynomials, Zernike polynomials, and some of the spherical harmonics. Local approximation functions such as spline functions can also be used. In this embodiment, Zernike polynomials are used. Fourier transforms are also used in practical examples. Higher-order aberrations are third-order or higher-order aberrations. Higher order aberrations include, for example, coma, spherical aberration, and trefoil, tetrafoil, and the like.

[Configuration of image analysis circuit]
FIG. 3 is a functional block diagram of the image analysis circuit 38. As shown in FIG. As shown in FIG. 3, the image analysis circuit 38 executes the above-described program 42 to obtain an image acquisition unit 46, a ring image detection unit 48, a high-order aberration detection unit 50, a state determination unit 52, and an eye characteristic detection unit 52. It functions as a calculation unit 54 . It should be noted that what is described as "-unit" in the present embodiment may be "-circuit", "-device", or "-device". That is, what is described as "--unit" may consist of firmware, software, hardware, or a combination thereof.

The image acquisition unit 46 is an image input interface that is wired or wirelessly connected to the measurement optical system 30 . The image acquisition unit 46 acquires the image data of the captured image 32A from the measurement optical system 30 and the image data of the captured image 32B from the observation optical system 24, and outputs these image data to the ring image detection unit 48.

The ring image detection unit 48 analyzes the image data of the captured images 32A and 32B, detects the referencing image 34A from the captured image 32A, and detects the kerating image 34B from the captured image 32B. For example, known edge detection processing is used to detect the referling image 34A and the keratling image 34B, but the method is not particularly limited.

The high-order aberration detection unit 50 analyzes the referencing image 34A and the keratling image 34B, respectively, and corrects the distortion based on the distortion of the referencing image 34A and the keratling image 34B caused by a specific high-order aberration of the eye E to be examined. A specific high-order aberration of the subject's eye E to be generated is detected. Hereinafter, the relationship between the disease of the eye E to be examined and the distortion of the Leffling image 34A due to high-order aberrations of the eye E to be examined will be described, taking the Leffling image 34A as an example.

FIG. 4 is an explanatory diagram for explaining the relationship between the aberrations (low-order aberrations and high-order aberrations) of the subject's eye E and the shape of the referling image 34A. In FIG. 4, the symbol "Ea" is the pupil of the subject's eye E, the symbol "Ef" is the fundus (retina) of the subject's eye E, the arrow "L" indicates the luminous flux of the fundus reflected light, and the symbol "OP". is the optical axis of the objective lens (not shown) of the measurement head 15, and the symbol "f" is the length from the pupil of the subject's eye E to the fundus.

As shown in FIG. 4, if it is assumed that the eye E to be examined is aplanatic, the fundus reflected light (refringing image 34A) incident on the pupil of the eye to be examined E at a certain angle is maintained at that angle. , is incident on the fundus of the subject's eye E to form a referling image 34A on the fundus. In this case, the referencing image 34A on the pupil is represented by the following [equation 1], and the referencing image 34A on the fundus is represented by the following [equation 2].

In the formula [Equation 1], "(X, Y)" is an arbitrary point of the referencing image 34A on the pupil, "R" is the radius of the referencing image 34A on the pupil, and "θ" is the pupil It is an angle formed by an arbitrary reference axis (X-axis or Y-axis) of the upper referling image 34A and an arbitrary line segment [a line segment connecting the point (X, Y) and the origin]. Further, in the formula [Equation 2], "(x, y)" is an arbitrary point of the referencing image 34A on the fundus, "r" is the radius of the referencing image 34A on the fundus, and "θ" is the fundus. It is an angle formed by an arbitrary reference axis of the upper referling image 34A and an arbitrary line segment [a line segment connecting the point (x, y) and the origin].

Here, since the subject's eye E has aberration, the position of each point on the referencing image 34A on the fundus is affected by the aberration of each point on the pupil corresponding to each of these points. Therefore, the positions of the points on the fundus referencing image 34A deviate from the positions of the points on the assumption that the subject's eye E has no aberrations. In this case, the positional deviation (Δx, Δy) of each point on the refringing image 34A on the fundus can be expressed by the following [Equation 3], where W (X, Y) is the wavefront aberration of the eye E to be examined. be done. Therefore, the referencing image 34A on the fundus when the aberration of the eye E to be examined is taken into account is given by the following [Equation 4], where the position of each point is [x(θ), y(θ)]. expressed.

In this way, the refringing image 34A on the fundus (the refringing image 34A detected from the captured image 32A) is distorted according to the type of aberration of the eye E to be examined.

FIG. 5 is a diagram showing the shape (distortion) of a ring image (refringing image 34A) when the subject's eye E has higher-order aberrations, expressed by Zernike polynomials. Z(n, m) [n: order, m: number of waves in the direction of rotation] in the figure indicates the type of known Zernike mode. Reference numeral 5A in FIG. 5 is a diagram when there is a horizontal trefoil aberration [Z(3,3)], and reference numeral 5B in FIG. 5 is a diagram when there is a vertical trefoil aberration [Z(3,-3)]. , and reference numeral 5C in FIG. 5 is a diagram with vertical/horizontal tetrafoil aberration [Z(4,4)].

As shown in FIG. 5, when the subject's eye E has large-order aberrations, that is, high-order aberrations, the ring image is distorted and does not have a perfect elliptical shape. The present inventors have found that, for example, when the subject's eye E has keratoconus, the distortion of the ring image increases due to the influence of the horizontal trefoil aberration [Z(3,3)], and when the subject's eye E has cataracts, distortion of the ring image (type of high-order aberration of the eye to be examined E) and the disease of the eye to be examined E It was found that there is a correlation between

The inventors of the present invention also found that the keratling image 34B also has a correlation with its distortion shape (type of high-order aberration of the eye E to be examined).

Therefore, in the present embodiment, the high-order aberration detection unit 50 analyzes the refringing image 34A and the keratling image 34B, and determines the distortion of the refringing image 34A and the keratling image 34B from the distortion of the refringing image 34A and the kerattling image 34B. Detect next-order aberrations.

Returning to FIG. 3, the high-order aberration detection unit 50 functions as an ellipse approximation unit 50a, a residual difference calculation unit 50b, and an aberration analysis unit 50c.

FIG. 6 is an explanatory diagram for explaining ellipse approximation by the ellipse approximation unit 50a. Note that the referling image 34A, the keratling image 34B, and the ellipses 60A and 60B (also referred to as approximate ellipses) in FIG. 6 are image diagrams, and may differ from actual images (the same applies to FIG. 7 described later).

As shown in FIG. 6, when the ring image detection unit 48 detects a referencing image 34A from the captured image 32A, the ellipse approximating unit 50a approximates the referencing image 34A to an ellipse 60A. Further, when the ring image detection unit 48 detects the keratling image 34B from the captured image 32B, the ellipse approximating unit 50a approximates the keratling image 34B to the ellipse 60B. Since the method of fitting the ellipses 60A and 60B to the ring images such as the referling image 34A and the keratling image 34B is a known technique, a detailed description thereof will be omitted here.

FIG. 7 is an explanatory diagram for explaining the residual calculation by the residual calculator 50b. As shown in FIG. 7, when the ellipse approximation unit 50a sets an ellipse 60A for the referling image 34A, the residual calculating unit 50b calculates a residual 62A between the ellipse 60A and the referling image 34A. Further, when the ellipse approximating unit 50a sets an ellipse 60B for the keratling image 34B, the residual calculating unit 50b calculates a residual 62B between the ellipse 60B and the kerattling image 34B.

FIG. 8 is an explanatory diagram for explaining the residuals 62A and 62B. As shown in FIG. 8, taking third- and fourth-order (n=3, 4) aberrations among the aberrations (higher-order aberrations) of the eye E to be examined as an example, a residual 62A with respect to the referling image 34A is calculated. As a result, the aberration components of Z(4,-2) and Z(4,2) [that is, Z(n,2)] corresponding to the ellipse are removed from the aberration of the eye E to be examined. Z(3,-1), Z(3,1), and Z(4,0) are aberration components that affect the position of the referencing image 34A. It does not appear. Residual 62A thus contains certain higher-order aberrations that cause distortion of the referencing image 34A. The specific high-order aberrations include higher-order aberrations such as Z(3, 3) and Z(4, 4), which become larger due to the disease of the eye E to be examined.

For similar reasons, the residual 62B for the keratling image 34B also contains certain higher order aberrations that cause distortion of the keratling image 34B.

Returning to FIG. 3, the aberration analysis unit 50c calculates the Zernike coefficients of each Zernike mode [Z(n,m)] of the residuals 62A and 62B based on the calculation results of the residuals 62A and 62B by the residual calculation unit 50b. A specific high-order aberration of the subject's eye E is calculated using a method of discrimination (calculation).

Specifically, the aberration analysis unit 50c calculates the Zernike coefficients of the Zernike polynomials by fitting the residuals 62A and 62B to the differentiation of the Zernike polynomials using the above [Equation 3]. Here, in the above [Math. . As a result, since the wavefront aberration W can be differentiated, the wavefront aberration W can be expressed as Zernike polynomials as shown in the following [Equation 5]. Note that C1, C2, C3, . . . are Zernike coefficients in the following [Formula 5].

The Zernike coefficients of the terms of the Zernike polynomials are obtained by solving the differentiation of the wavefront aberration W, as shown in the formula [Equation 5]. As a result, it is possible to determine the magnitude of the Zernike coefficient of each term of the Zernike polynomial, so it is possible to determine which Zernike coefficient is large in each term. As a result, it is possible to determine which of the Zernike modes of the residuals 62A and 62B has a larger Zernike coefficient. That is, it can be determined whether or not the Zernike coefficients of the characteristic Zernike modes corresponding to the disease of the eye to be examined E, such as Z(3,3) and Z(4,4), are increased.

The high-order aberration detection unit 50 uses, as the detection result of the specific high-order aberration of the eye E to be examined, the calculation result of the above-described aberration analysis unit 50c, that is, the calculation result of the Zernike coefficients of the Zernike modes of the residuals 62A and 62B. Output to state determination unit 52 . Further, the high-order aberration detection section 50 outputs to the state determination section 52 the calculation results of the residuals 62A and 62B by the residual calculation section 50b.

The state determination unit 52 determines (estimates) the state of the subject's eye E, for example, the presence or absence of a disease and the type of disease, based on the detection result of the high-order aberration detection unit 50 . Note that the state determination unit 52 of the present embodiment determines the state of the subject's eye E using the determination table 43 (see FIG. 2) in the storage unit 40 .

FIG. 9 is an explanatory diagram for explaining an example of the determination table 43. As shown in FIG. As shown in FIG. 9, the determination table 43 includes an individual determination table 43A and a comprehensive determination table 43B.

The individual determination table 43A is used by the state determination unit 52 for each type of ring image of the referencing image 34A and the keratling image 34B (for each type of the captured images 32A and 32B), that is, for each type of the residuals 62A and 62B. This is information for determining the state of each individually. In this individual determination table 43A, the magnitude of Zernike coefficients of characteristic Zernike modes corresponding to the disease of the eye E to be examined, such as Z(3, 3) and Z(4, 4), and the disease of the eye E to be examined associated with the type.

For example, when the Zernike coefficient of the Zernike mode [Z(3, 3)] is larger than a predetermined threshold value, the disease of the subject eye E is keratoconus, and the Zernike mode [Z When the Zernike coefficient of (4, 4)] is larger than a predetermined threshold, information is registered that the disease of the eye E to be examined is cataract. As a result, the state determination unit 52 determines that the eye E to be examined has keratoconus when the Zernike coefficient of the Zernike mode [Z(3,3)] corresponding to at least one of the residuals 62A and 62B is greater than the threshold. It is determined that In addition, the state determination unit 52 determines that the eye E to be examined has keratoconus when the Zernike coefficient of the Zernike mode [Z(4, 4)] corresponding to at least one of the residuals 62A and 62B is larger than the threshold. Determine that there is.

The comprehensive determination table 43B is used by the state determining unit 52 to comprehensively determine the state of the subject's eye E based on various detection results of the high-order aberration detecting unit 50 for each type of ring image (for each type of the captured images 32A and 32B). This is information for determination. The comprehensive determination table 43B includes general determination information 43B1 and symptom determination information 43B2.

In the general determination information 43B1, information indicating that some abnormality (disease) has occurred in the eye E to be examined when the residuals 62A and 62B calculated by the residual calculator 50b are greater than a predetermined threshold is registered. It is Accordingly, the state determination unit 52 can determine (estimate) whether or not there is an abnormality in the subject's eye E based on the calculation results of the residuals 62A and 62B.

The symptom determination information 43B2 associates the Zernike coefficient of each Zernike mode for each type of ring image (for each type of residuals 62A and 62B) and the type of disease of the eye E to be examined.

For example, in the symptom determination information 43B2, when the Zernike coefficients (especially odd-numbered orders) of each Zernike mode in both the residuals 62A and 62B (the referencing image 34A and the keratling image 34B) are larger than a predetermined threshold, , information indicating that the subject's eye E has keratoconus is registered. Further, in the symptom determination information 43B2, the Zernike coefficient of each Zernike mode of the residual 62A (Refling image 34A) is equal to or less than the threshold, and the Zernike coefficient of each Zernike mode of the residual 62B (Keratling image 34B) is lower than the threshold. If it becomes large, the internal aberration of the eye E to be inspected is large, and information is registered to the effect that the eye E to be inspected has a cataract. Thereby, the state determination unit 52 can comprehensively determine the disease (keratoconus, cataract, etc.) of the subject's eye E based on the Zernike coefficients of each Zernike mode of both the residuals 62A and 62B.

The state determination unit 52 monitors the results of the individual determination of the state of the eye E using the individual determination table 43A and the comprehensive determination results of the state of the eye E using the comprehensive determination table 43B. and output to the storage unit 40 or the like. As a result, various determination results of the state of the subject's eye E by the state determination unit 52 are displayed on the monitor 17 and stored in the storage unit 40 . Various determination results of the state of the eye E to be examined by the state determination unit 52 are also used for secondary examination of the eye E to be examined.

When measuring the eye refractive power of the eye to be examined E, the eye characteristic calculation unit 54 calculates the eye refractive power of the eye to be examined E by a known method based on the referencing image 34A detected by the ring image detection unit 48 from the captured image 32A. do. In addition, when measuring the corneal shape of the eye to be examined E, the eye characteristic calculation unit 54 calculates the corneal shape of the eye to be examined E by a known method based on the keratling image 34B detected by the ring image detection unit 48 from the captured image 32B. Calculate. The measurement results of the eye characteristics such as the eye refractive power and the corneal shape of the eye to be examined E are also output from the eye characteristics calculation unit 54 to the monitor 17, the storage unit 40, and the like.

[Operation of Ophthalmic Device]
FIG. 10 is a flow chart showing the flow of evaluation processing of the state of the subject's eye E using the image analysis method of the present invention by the ophthalmologic apparatus 10 configured as described above. Since the alignment of the measuring head 15 with respect to the eye E to be examined, the fixation or fogging of the eye to be examined E, and the measurement of the ocular characteristics of the eye to be examined E are well-known techniques, description thereof will be omitted here.

As shown in FIG. 10, the measurement pattern projection optical system 28 projects the eye refractive power measurement pattern onto the fundus of the eye to be examined E, and the measurement optical system 30 captures the fundus reflected light of the measurement pattern. Then, the image data of the captured image 32A is output from the measurement optical system 30 to the image acquisition section 46 of the image analysis circuit 38 (step S1). As a result, the image acquisition unit 46 acquires the image data of the captured image 32A and outputs this image data to the ring image detection unit 48 (step S2, corresponding to the image acquisition step of the present invention).

Further, when the projection of the corneal shape measurement pattern onto the cornea of the eye E to be examined by the kerato system 23 and the imaging of the corneal reflected light of the measurement pattern by the observation optical system 24 are executed, the image is acquired from the observation optical system 24 . Image data of the captured image 32B is output to the unit 46 (step S3). As a result, the image acquisition unit 46 acquires the image data of the captured image 32B and outputs this image data to the ring image detection unit 48 (step S4, corresponding to the image acquisition step of the present invention). Either acquisition of the captured image 32A or acquisition of the captured image 32B may be executed first.

After acquiring the captured images 32A and 32B, the ring image detection unit 48 detects the referencing image 34A from the captured image 32A, and detects the kerating image 34B from the captured image 32B (step S5, ring image detection of the present invention). step).

When the detection of the referencing image 34A and the keratling image 34B by the ring image detection section 48 is completed, the detection of specific high-order aberrations of the subject's eye E by the high-order aberration detection section 50 is started. As a result, as shown in FIGS. 6 and 7 already described, after the ellipse 60A approximation to the referencing image 34A and the ellipse 60B approximation to the keratling image 34B are executed by the ellipse approximating unit 50a (step S6), The residuals 62A and 62B are calculated by the residual calculator 50b (step S7).

Next, the aberration analysis unit 50c calculates the Zernike coefficients of the Zernike polynomials by fitting the residuals 62A and 62B to the differential of the Zernike polynomials using the above [Equation 3], thereby obtaining the Zernike coefficients of the residuals 62A and 62B. The Zernike coefficient of the mode is calculated (step S8). Thereby, a specific high-order aberration of the eye E to be examined is detected. Accordingly, steps S6 to S8 correspond to high-order aberration detection steps of the present invention. Then, the high-order aberration detection unit 50 outputs the determination result of the Zernike coefficient of each Zernike mode for each of the residuals 62A and 62B and the calculation result of the residuals 62A and 62B to the state determination unit 52, respectively.

The state determination unit 52 determines the residuals 62A and 62B by referring to the individual determination table 43A shown in FIG. The state of the subject's eye E is individually determined for each type (step S9). Further, the state determination unit 52 refers to the comprehensive determination table 43B shown in FIG. Comprehensive determination (rough determination and symptom determination) of the state of is performed (step S10). Note that steps S9 and S10 correspond to the state determination step of the present invention.

Then, the state determination unit 52 outputs various determination results of the state of the subject's eye E to the monitor 17, the storage unit 40, and the like. As a result, the determination result of the state of the subject's eye E is displayed on the monitor 17 and stored in the storage unit 40 . In addition, when it is determined that the eye E to be examined has a disease, a secondary examination of the eye E to be examined is performed using another examination device or the like.

[Effect of this embodiment]
As described above, the ophthalmologic apparatus 10 of the present embodiment analyzes the referencing image 34A and the keratling image 34B to detect specific high-order aberrations of the eye E to be examined, thereby determining the state of the eye E (presence or absence of disease and type) can be determined. Thereby, the disease of the subject's eye E can be examined using the existing ophthalmologic apparatus 10 such as an autoreflection keratometer.

[others]
In the above-described embodiment, both the individual determination and the comprehensive determination of the state of the subject's eye E are performed based on the results of analyzing both the referling image 34A and the keratling image 34B. 34B may be analyzed to perform individual determination of the condition of the eye E to be inspected. In this case, a known refractometer, keratometer, or the like can be used as the ophthalmologic apparatus 10 .

In the above embodiment, the measurement pattern projection optical system 28 projects a ring-shaped measurement pattern onto the fundus of the eye E to be examined, and the measurement optical system 30 captures the reflected light of the measurement pattern from the fundus. The configurations of the pattern projection optical system 28 and the measurement optical system 30 are not particularly limited.

FIG. 11 is a schematic diagram showing a modified example of the measurement pattern projection optical system 28 and the measurement optical system 30. As shown in FIG. Note that FIG. 11 shows only the essential parts of the measurement pattern projection optical system 28 and the measurement optical system 30 . As shown in FIG. 11 , the measurement pattern projection optical system 28 projects a light flux of a ring-shaped measurement pattern P emitted from an illumination light source (not shown) onto the fundus of the eye E through a half mirror 100 . The measurement optical system 30 forms an optical path branched from the measurement pattern projection optical system 28 (observation optical system 24 ) via the half mirror 100 . The measurement optical system 30 captures the fundus reflected light of the measurement pattern P projected onto the fundus of the subject's eye E using the imaging element 102 and outputs a captured image 32A including a referling image 34A.

At this time, if a blood vessel exists in the fundus of the eye E to be examined, the reflectance of the fundus reflected light tends to be low at that site. For this reason, for the purpose of noise removal, a known rotary prism 104 (see Japanese Patent Laid-Open No. 10-014876) is arranged in the measurement pattern projection optical system 28, and by rotating this rotary prism 104, the reflected light from the fundus is may be homogenized.

In the above embodiment, the residuals 62A and 62B are fitted to the differentiation of the Zernike polynomials to calculate the Zernike coefficients of the Zernike polynomials to calculate the specific high-order aberrations of the eye E to be examined. A polynomial or function of may be used to compute a particular high-order aberration of the subject's eye E from the residuals 62A, 62B. Further, the method of analyzing the Leffling image 34A and the keratling image 34B to calculate the specific high-order aberration of the eye to be examined E is not limited to the method described in the above embodiment, and any analysis method may be used. good too.

In the above embodiment, the state determination unit 52 refers to the determination table 43 to perform individual determination and comprehensive determination of the state of the eye E to be examined. or by using a deep learning method or the like, various determinations of the state of the subject's eye E may be made.

In the above-described embodiment, the specific high-order aberrations of the subject's eye E that cause the distortion of the referling image 34A and the keratling image 34B include trefoil [Z(3,3), etc.], tetrefoil [Z(4,4), etc. ] has been described as an example, the types of specific high-order aberrations of the present invention are not limited to these.

In the above embodiment, the image analysis circuit 38 is provided with the state determination section 52, but the state determination section 52 may be provided in another device. In other words, the image analysis circuit 38 may detect specific high-order aberrations of the eye E to be examined.

In the above-described embodiment, the image analysis circuit 38 corresponding to the image analysis apparatus of the present invention is incorporated in the ophthalmologic apparatus 10. terminal, etc.). That is, a processor of an arithmetic device or the like may function as the image analysis circuit 38 of the present invention.

10... Ophthalmic device,
18... optical system,
20 ... control device,
23... kerat system,
28 ... measurement pattern projection optical system,
30 ... measurement optical system,
32A, 32B ... captured images,
34A...Refering image,
34B ... keratling image,
38 ... image analysis circuit,
43 ... Judgment table,
46 ... image acquisition unit,
48 ... ring image detection unit,
50... Higher-order aberration detector,
50a... elliptical approximation part,
50b ... residual calculation unit,
50c... Aberration analysis unit,
52 ... state determination unit,
54 ... eye characteristic calculation unit,
60A, 60B...ellipse,
62A, 62B... residuals

Claims (7)

an image acquisition unit that acquires a captured image of the reflected light of the measurement pattern projected onto the eye to be inspected;
a ring image detection unit that detects a ring image based on the reflected light from within the captured image acquired by the image acquisition unit;
a high-order aberration detection unit that detects a specific high-order aberration of the subject eye that causes distortion of the ring image based on the ring image detected by the ring image detection unit;
a state determination unit that determines the state of the subject eye based on the detection result of the high-order aberration detection unit;
with
The image acquiring unit, as the captured images, a first captured image of fundus reflected light of a pattern for measuring eye refractive power projected onto the fundus of the eye to be inspected, and a corneal shape projected onto the cornea of the eye to be inspected. Acquiring a second captured image of the corneal reflected light of the measurement pattern,
The ring image detection unit detects the ring image for each type of the captured image,
The high-order aberration detection unit detects a specific high-order aberration of the subject eye for each type of the captured image,
The image analysis device , wherein the state determination unit determines the state of the subject's eye for each type of the captured image. an image acquisition unit that acquires a captured image of the reflected light of the measurement pattern projected onto the eye to be inspected;
a ring image detection unit that detects a ring image based on the reflected light from within the captured image acquired by the image acquisition unit;
a high-order aberration detection unit that detects a specific high-order aberration of the subject eye that causes distortion of the ring image based on the ring image detected by the ring image detection unit;
a state determination unit that determines the state of the subject eye based on the detection result of the high-order aberration detection unit;
with
The image acquisition unit uses, as the captured images, a first captured image of fundus reflected light of a pattern for measuring eye refractive power projected onto the fundus of the eye to be inspected, and a corneal shape projected onto the cornea of the eye to be inspected. Acquiring a second captured image of the corneal reflected light of the measurement pattern,
The ring image detection unit detects the ring image for each type of the captured image,
The high-order aberration detection unit detects a specific high-order aberration of the subject eye for each type of the captured image,
The image analysis device, wherein the state determination unit determines the state of the subject's eye based on the detection result of the high-order aberration detection unit for each type of the captured image. The high-order aberration detection unit is
an ellipse approximation unit that fits an ellipse to the ring image detected by the ring image detection unit;
a residual calculation unit for calculating a residual between the ellipse fitted by the ellipse approximation unit and the ring image detected by the ring image detection unit;
an aberration analysis unit that calculates a specific high-order aberration of the subject eye based on the residual calculated by the residual calculation unit;
The image analysis device according to claim 1 or 2 , comprising: 4. The image analysis according to claim 3 , wherein the aberration analysis unit calculates Zernike coefficients of the Zernike polynomials as calculation results of specific high-order aberrations of the eye to be examined by fitting the residuals to differentials of the Zernike polynomials. Device. a projection optical system that projects a measurement pattern onto an eye to be inspected;
a measurement optical system that outputs a ring image based on the reflected light of the measurement pattern projected onto the eye to be inspected;
The image analysis device according to any one of claims 1 to 4 ;
An ophthalmic device comprising: A method for operating an image analysis device comprising: an image acquisition unit that acquires a captured image of reflected light of a measurement pattern projected onto an eye to be inspected; and an analysis unit that analyzes the captured image acquired by the image acquisition unit,
an image acquisition step in which the image acquisition unit acquires the captured image;
A ring image detection step in which the analysis unit detects a ring image based on the reflected light from within the captured image acquired in the image acquisition step ;
a high-order aberration detection step in which the analysis unit detects a specific high-order aberration of the subject eye that causes distortion of the ring image based on the ring image detected in the ring image detection step ;
a state determination step in which the analysis unit determines the state of the eye to be examined based on the detection result of the high-order aberration detection step;
and run
In the image acquisition step, the image acquisition unit uses, as the captured images, a first captured image of fundus reflected light of a pattern for eye refractive power measurement projected onto the fundus of the eye to be inspected, and a cornea of the eye to be inspected. obtaining a second captured image of the corneal reflected light of the projected corneal shape measurement pattern;
wherein, in the ring image detection step, the analysis unit detects the ring image for each type of the captured image;
wherein, in the high-order aberration detection step, the analysis unit detects a specific high-order aberration of the eye to be inspected for each type of the captured image;
An operation method of an image analysis device, wherein the analysis unit determines the state of the subject's eye for each type of the captured image in the state determination step . A method for operating an image analysis device comprising: an image acquisition unit that acquires a captured image of reflected light of a measurement pattern projected onto an eye to be inspected; and an analysis unit that analyzes the captured image acquired by the image acquisition unit,
an image acquisition step in which the image acquisition unit acquires the captured image;
A ring image detection step in which the analysis unit detects a ring image based on the reflected light from within the captured image acquired in the image acquisition step;
a high-order aberration detection step in which the analysis unit detects a specific high-order aberration of the subject eye that causes distortion of the ring image based on the ring image detected in the ring image detection step;
a state determination step in which the analysis unit determines the state of the eye to be examined based on the detection result of the high-order aberration detection step;
and run
In the image acquisition step, the image acquisition unit uses, as the captured images, a first captured image of fundus reflected light of a pattern for eye refractive power measurement projected onto the fundus of the eye to be inspected, and a cornea of the eye to be inspected. obtaining a second captured image of the corneal reflected light of the projected corneal shape measurement pattern;
wherein, in the ring image detection step, the analysis unit detects the ring image for each type of the captured image;
wherein, in the high-order aberration detection step, the analysis unit detects a specific high-order aberration of the eye to be inspected for each type of the captured image;
An operation method of an image analysis device, wherein the analysis unit determines the state of the subject's eye based on the detection result of the high-order aberration detection step for each type of the captured image in the state determination step.

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