JP6635638B1 - Detection device, program, and detection method - Google Patents

Abstract

An apparatus, a program, and a method capable of more accurately detecting the position of a lens equator are provided. A tomographic image of an eye to be inspected is acquired (S1), and a front surface, a rear surface, and the like of a crystalline lens represented on the tomographic image are specified (S2 to S4). A first provisional lens having the shape of the front surface of the lens also on the rear surface is set (S5). A second provisional lens having the shape of the rear surface of the lens also on the front surface is set (S6). A third provisional lens is determined which is determined from a curve along the front surface of the lens and a curve along the rear surface of the lens (S7). The equator of the first to third temporary lens is specified (S8 to S10). The center of gravity of a triangle having each equator as a vertex is detected (S11). A straight line connecting the left and right centroid points is set as a straight line between the centroid points (S12). The intersection of the perpendicular drawn from the equator of the third temporary lens into a straight line between the centers of gravity is detected (S13). A fourth temporary lens is set with the center of gravity or the intersection detected in steps S11 and S13 as the equator (S14). The fourth temporary lens is displayed on the display unit (S15). [Selection diagram] FIG.

Description

  The present invention relates to an apparatus, a program, and a method for detecting a position of an equatorial part of a lens.

  2. Description of the Related Art As an examination apparatus used for an ophthalmologic examination, there is known an optical coherence tomography apparatus that takes a tomographic image of an anterior eye part by optical coherence tomography (OCT). In an OCT tomographic image, the equatorial portion of the crystalline lens located on the back side of the iris may not be captured in the tomographic image because measurement light is blocked by the iris. In this specification, the equator of the crystalline lens means the maximum diameter of the crystalline lens. The position of the lens equator, for example, when determining the fixed position of the intraocular lens when inserting the intraocular lens into the eye for cataract treatment, or when estimating the fixed position of the inserted intraocular lens It is useful information.

  Regarding the detection of the position of the lens equator, Patent Literatures 1 and 2 disclose methods of estimating the position of the equator based on the shape of the central portion where the lens is imaged. In this method, a point where a curve along the front surface of the lens and a curve along the rear surface of the lens intersect is estimated as the position of the equator. In Patent Document 2, it is estimated that the intraocular lens is fixed at the estimated equatorial position.

JP 2018-15440 A Japanese Patent No. 5875090

  By the way, if an ultrasonic biomicroscope is used, a shape including the lens equator can be obtained. The inventors have verified that the position of the equator obtained by the same method as that of Patent Documents 1 and 2 is different from the position of the equator of the lens obtained by measurement with an ultrasonic biological microscope. An ultrasonic biological microscope may be used to more accurately detect the position of the lens equator, but measurement using an ultrasonic biological microscope requires more time and effort than the OCT measurement, and the burden on the subject is large.

  The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide an apparatus, a program, or a method that can more accurately detect the position of the lens equator based on a tomographic image in which the lens equator is not captured. .

In order to solve the above-described problems, the detection device of the present invention includes:
An image acquisition unit that acquires a tomographic image of the subject's eye,
A first setting unit that sets a first provisional lens that also has the shape of the front surface of the lens expressed on the tomographic image on the rear surface;
A second setting unit that sets a second provisional lens that also has the shape of the posterior surface of the lens represented on the tomographic image on the front surface;
A third setting unit that sets a third provisional lens determined from a curve along the front surface of the lens and a curve along the back surface of the lens represented on the tomographic image;
A first acquisition unit that acquires a first temporary equatorial portion that is an equatorial portion of the first temporary lens;
A second acquisition unit that acquires a second temporary equator that is an equator of the second temporary lens;
A third acquisition unit that acquires a third temporary equator that is an equator of the third temporary lens;
A center-of-gravity point acquisition unit that acquires a center of gravity of a triangle having the first temporary equator, the second temporary equator, and the third temporary equator as vertices;
Is provided.

The detection device of the present invention
An image acquisition unit that acquires a tomographic image of the subject's eye,
A first front surface curve setting unit that sets a first front surface curve along the lens front surface represented on the tomographic image;
A first posterior curve setting unit that sets a first posterior curve determined by the shape of the posterior lens on the tomographic image at the position of the posterior lens on the tomographic image;
A second front curve setting unit that sets a second front curve determined by the shape of the rear lens surface represented on the tomographic image at a position of the front surface of the lens on the tomographic image;
A second posterior curve setting unit that sets a second posterior curve along the posterior lens surface represented on the tomographic image;
A first intersection acquisition unit that acquires a first intersection, which is an intersection of the first front curve and the first rear curve,
A second intersection acquisition unit that acquires a second intersection, which is an intersection of the second front curve and the second rear curve,
A third intersection acquisition unit that acquires a third intersection, which is an intersection of the first front curve and the second rear curve,
A center-of-gravity point acquisition unit that acquires a center of gravity of a triangle having the first intersection, the second intersection, and the third intersection as vertices;
Is provided.

Also, the program of the present invention
An image acquisition unit that acquires a tomographic image of the subject's eye,
A first setting unit that sets a first provisional lens that also has the shape of the front surface of the lens expressed on the tomographic image on the rear surface;
A second setting unit that sets a second provisional lens that also has the shape of the posterior surface of the lens represented on the tomographic image on the front surface;
A third setting unit that sets a third provisional lens determined from a curve along the front surface of the lens and a curve along the back surface of the lens represented on the tomographic image;
A first acquisition unit that acquires a first temporary equatorial portion that is an equatorial portion of the first temporary lens;
A second acquisition unit that acquires a second temporary equator that is an equator of the second temporary lens;
A third acquisition unit that acquires a third temporary equator that is an equator of the third temporary lens;
A center-of-gravity point acquisition unit that acquires a center of gravity of a triangle having the first temporary equator, the second temporary equator, and the third temporary equator as vertices;
And let the computer function.

Further, the detection method of the present invention,
An image acquisition step of acquiring a tomographic image of the eye to be examined,
A first setting step of setting a first provisional lens having the shape of the front surface of the lens on the tomographic image also on the rear surface;
A second setting step of setting a second provisional lens having the shape of the posterior lens on the tomographic image also on the front,
A third setting step of setting a third provisional lens defined by a curve along the front surface of the lens and a curve along the back surface of the lens represented on the tomographic image;
A first obtaining step of obtaining a first temporary equatorial portion that is an equatorial portion of the first temporary lens;
A second acquisition step of acquiring a second temporary equator, which is an equator of the second temporary lens,
A third obtaining step of obtaining a third temporary equator, which is an equator of the third temporary lens,
A center-of-gravity point obtaining step of obtaining a center of gravity of a triangle having the first temporary equator, the second temporary equator, and the third temporary equator as vertices;
Is provided.

  According to verification by the inventor, the center of gravity obtained by the present invention is more to the position of the equator obtained from the measurement of the ultrasonic biological microscope than the position of the equator obtained by the same method as in Patent Documents 1 and 2. It was found that the error in the thickness direction of the crystalline lens was small. That is, the center of gravity obtained in the present invention is detected at a position closer to the actual equator in the thickness direction of the lens. Therefore, the position of the lens equator can be detected more accurately based on the center of gravity obtained in the present invention.

It is a block diagram of an OCT apparatus. FIG. 3 is a diagram of the eye as viewed from the front, illustrating a scanning direction of measurement light for obtaining a tomographic image. It is a flowchart of the process which detects the position of the equator of a crystalline lens. 4 is a flowchart of a setting process of a first provisional crystalline lens as a detailed process of step S5 in FIG. 3. 4 is a flowchart of a setting process of a second provisional lens as detailed processing of step S6 in FIG. 3. 4 is a flowchart of a setting process of a third provisional lens as detailed processing of step S7 in FIG. FIG. 4 is a schematic diagram of a tomographic image acquired in step S1 of FIG. FIG. 4 is a diagram illustrating a first provisional crystalline lens set in step S5 of FIG. 3 in a tomographic image. FIG. 4 is a diagram illustrating a second temporary crystalline lens set in step S6 of FIG. 3 in a tomographic image. FIG. 4 is a diagram illustrating a third provisional crystalline lens set in step S7 of FIG. 3 in a tomographic image. FIG. 4 is a diagram exemplifying a barycentric point, a straight line between the barycentric points, and an intersection of a perpendicular line obtained in steps S11, S12, and S13 in FIG. FIG. 4 is a diagram illustrating a fourth provisional crystalline lens set in step S14 of FIG. 3 in a tomographic image. FIG. 4 is a diagram showing a tomographic image of a normal example, in which the provisional crystalline lens, the center of gravity, a straight line between the centers of gravity, and the like obtained in each step of FIG. 3 are shown in the tomographic image. FIG. 4 is a diagram illustrating a tomographic image of a cataract example, in which the provisional crystalline lens, the center of gravity, and a straight line between the centers of gravity obtained in each step of FIG. 3 are shown in the tomographic image.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a configuration diagram of an OCT apparatus 1 (OCT: Optical Coherence Tomography). The OCT apparatus 1 is an apparatus that captures a tomographic image of the anterior segment of the subject's eye by optical coherence tomography (OCT). The OCT apparatus 1 divides the low coherent light source light into measurement light and reference light that irradiate the eye to be examined, and based on the interference light between the measurement light reflected from the eye and the reference light, the anterior ocular segment. Obtain a tomographic image of. Further, the OCT apparatus 1 acquires a tomographic image from a wide range of the eye by scanning the eye with the measurement light.

  Specifically, the OCT apparatus 1 includes a measurement unit 3 that measures a tomographic image of an anterior eye, a nonvolatile storage unit 11 that stores various information such as a measured tomographic image, and an operator performs various input operations. An operation unit 12, a display unit 13 for displaying a tomographic image and the like, and a control unit 2 connected thereto are provided. In addition, the OCT apparatus 1 scans an examination window (not shown) through which light for tomographic imaging (such as measurement light) enters and exits, and faces the subject so that the subject's eye is positioned in front of the examination window. A supporting portion (a chin receiving portion or a forehead contact portion) (not shown) for supporting is also provided.

  The measuring unit 3 is configured similarly to the measuring unit of a known OCT device. That is, the light source 4 that emits the low coherent light source light, the light of the light source 4 is split into the measurement light and the reference light, and the measurement light is irradiated to the eye to be examined, and the interference light between the reflected light and the reference light is obtained. An optical system 5, a scanning unit 6 for scanning the measurement light on the eye to be inspected, a light detection unit 7 for detecting the interference light obtained by the interference optical system 5 as a tomographic image signal, and an alignment light for detecting the position of the eye to be inspected Optical system 9 for irradiating the eye to be examined with a fixation lamp for guiding the line of sight (the visual axis) of the eye to be examined in a direction corresponding to the optical axis of the measuring unit 3 And a drive for moving the optical system of the measuring unit 3 in the X, Y, and Z directions so that the positional relationship between the subject's eye and the measuring unit 3 has a predetermined relationship based on the position of the alignment light applied to the subject's eye. A part 10 and the like are provided. Note that the Z direction is a direction corresponding to the front-back direction (depth direction) of the subject's eye, the X direction is a direction perpendicular to the Z direction, and the Y direction is a direction perpendicular to both the X direction and the Z direction. . The interference light signal (tomographic image signal) measured by the measurement unit 3 (light detection unit 7) is sent to the control unit 2.

  The operation unit 12 is, for example, an operation unit for setting various measurement conditions of the tomographic image by the measurement unit 3, an operation unit for instructing the measurement unit 3 to start measurement of the tomographic image, and an operation unit of the tomographic image stored in the storage unit 11. It comprises an operation unit for selecting a tomographic image to be analyzed. The operation unit 12 may be a mechanical switch, or may be a touch panel provided on a screen of the display unit 13. The operation unit 12 also includes an operation unit for setting which position (direction) to measure a tomographic image and setting for measuring an omnidirectional tomographic image.

  The control unit 2 includes a CPU 14, a RAM (not shown), and a nonvolatile memory 15 such as a ROM. The control unit 2 controls measurement of a tomographic image by the measurement unit 3, writing and reading of information to and from the storage unit 11, display of the display unit 13, and the like. In addition, the control unit 2 receives various input operations from the operation unit 12 and executes processing according to the received input operations. When measuring the tomographic image, the control unit 2 looks at the eye to be examined from the front as shown in FIG. 2 and extends in a radial direction in a circle centered on a point 100 (hereinafter, referred to as a measurement center point) in the pupil. By controlling the scanning unit 6 of the measuring unit 3 so that the measuring light is scanned (referred to as B-scan) along the scanning line, one tomographic image in which the anterior segment is cut by a straight line extending in the radial direction is obtained. . At this time, it is also possible to set the position (direction) of the tomographic image to be measured based on the input operation from the operation unit 12.

  In addition, when the measurement mode of the omnidirectional tomographic image is set by the operation unit 12, the control unit 2 controls the scanning unit 6 to perform the B-scan on the circumference around the measurement center point 100. By scanning in the direction (referred to as C-scan), a tomographic image can be obtained at a plurality of positions along the circumferential direction. The scan interval of the C-scan can be, for example, 5 degrees or more (36 or more tomographic images), but may be another angle interval. The measurement center point 100 is set at a position such as a visual axis, an optical axis, or a cornea vertex of the subject's eye by alignment based on the alignment optical system 8 and the fixation lamp optical system 9 of the measurement unit 3. The visual axis of the eye is a line connecting the point of gaze of the eye and the fovea. The optical axis of the eye is a line connecting the center of the cornea and the center of the lens.

  The control unit 2 obtains a tomographic image by calculating a tomographic image signal (interference light signal) sent from the measuring unit 3, causes the display unit 13 to display the obtained tomographic image, and stores the obtained tomographic image in the storage unit 11. Or let it. When storing the tomographic image in the storage unit 11, the control unit 2 includes information that can specify the subject and the subject's eye (name of the subject and whether the subject is the left eye or the right eye) The tomographic image is stored in the storage unit 11 in association with information on which position the tomographic image is cut and the measurement date and time. Further, a program 16 for various processes executed by the control unit 2 is mounted on the memory 15 of the control unit 2. The program 16 includes a program for detecting the position of the equator of the lens.

  Hereinafter, the details of the process of detecting the position of the equator of the lens, which is performed by the control unit 2, will be described. FIG. 3 shows an example of a flowchart of this processing. The process of FIG. 3 is executed by reading the program 16 (see FIG. 2). When the process of FIG. 3 starts, the CPU 14 of the control unit 2 acquires a tomographic image of the anterior ocular segment to be analyzed (S1). At this time, if the measurement of the tomographic image has not been performed yet, the measuring section 3 is caused to measure the tomographic image, and the measured tomographic image is acquired. If the tomographic image has already been measured, the target tomographic image is read from the storage unit 11.

  Here, FIG. 7 is a schematic diagram of a tomographic image acquired in step S1. In the tomographic image in FIG. 3, each part of the anterior segment such as the cornea 21, the iris 22, and the crystalline lens 23 (the crystalline capsule) is shown. However, only the central portion of the crystalline lens 23 is shown, and the shape around the equator (the outer peripheral portion) of the crystalline lens 23 whose light is blocked by the iris 22 is not shown.

  Next, the front lens surface 23a (see FIG. 7) and the rear lens surface 23b (see FIG. 7) represented in the tomographic image acquired in step S1 are specified (S2). This specification may be performed as follows, for example. That is, sample images of the front and rear surfaces of the crystalline lens are stored in the storage unit 11. Then, a boundary line of each part in the tomographic image is detected, template matching for matching each shape defined by the boundary line with the sample image is performed, and a shape portion having a high degree of similarity to the sample image is determined as a lens front surface 23a or It is specified as the rear surface 23b. Instead of the template matching, a tomographic image is displayed on the display unit 13 and a pointer is displayed in the displayed tomographic image. The lens front surface 23a or the rear surface 23b in the tomographic image may be indicated by a pointer based on an input operation of the operation unit 12 by the operator, thereby specifying the lens front surface 23a or the rear surface 23b. Note that the real image portion 23a on the front surface of the crystalline lens shown in the tomographic image indicates the central portion of the anterior lens capsule. The real image portion 23b on the posterior surface of the lens shown in the tomographic image indicates the center of the posterior lens capsule.

  Next, the vertex 23c (see FIG. 7) of the lens front surface 23a and the vertex 23d (see FIG. 7) of the lens rear surface 23b specified in step S2 are specified (S3). Specifically, for example, a curve approximating the shape of the lens front surface 23a is obtained by the least square method or the like, and a point where the curvature becomes maximum or minimum on this approximate curve is obtained as the vertex 23c of the lens front surface 23a. Similarly, an approximate curve of the shape of the posterior surface 23b of the lens is obtained by a least square method or the like, and a point on the approximate curve at which the curvature becomes maximum or minimum is obtained as the vertex 23d of the posterior surface 23b of the lens. Note that the approximation curve may be a circle, an ellipse, a second-order or higher polynomial, a curve approximated by a trigonometric function, an exponential function, or a logarithmic function. Good.

  Next, a straight line passing through the vertices 23c and 23d specified in step S3 is set as the lens center line 24 (see FIG. 7) (S4). The crystalline lens center line 24 is a straight line that passes through the center of the crystalline lens and extends in the depth direction of the subject's eye (in other words, the front-back direction) (in other words, the vertical direction of the paper surface of FIG. 7).

  Next, on the tomographic image acquired in step S1, in other words, on the two-dimensional plane on which the tomographic image is shown, the first provisional crystalline lens 25 (see FIG. 8) having the shape of the crystalline lens front surface 23a also on the rear surface is set (see FIG. 8). S5). Specifically, for example, the process of FIG. 4 is executed as step S5. That is, a curve 25a (see FIG. 8) along the crystalline lens front surface 23a specified in step S2 is set on the tomographic image acquired in step S1, in other words, on a two-dimensional plane on which the tomographic image is shown (S21). The curve 25a is defined as a first front curve, and the first front curve 25a is obtained by approximating the shape of the lens front surface 23a with a circle having a constant radius of curvature, and is represented as a part (ie, an arc) of the approximate circle. You. The first front curve 25a may be obtained by a known approximation method such as the least square method. Step S21 is equivalent to obtaining a circle approximating the shape of the crystalline lens front surface 23a. The circle of the first front surface curve 25a is represented, for example, as a circle that passes through the vertex 23c of the front surface 23a of the lens and whose center is located behind (the vitreous body) the vertex 23c on the extension of the lens center line 24. . The first anterior curve 25a is represented as a circular arc convex toward the cornea.

  Next, a curve 25b (see FIG. 8) determined by the shape of the crystalline lens front surface 23a is set at the position of the crystalline lens rear surface 23b on the two-dimensional plane on which the tomographic image is shown in the tomographic image acquired in step S1 (S22). ). The curve 25b is defined as a first posterior surface curve. Specifically, the first posterior surface curve 25b passes through the vertex 23d of the posterior surface 23b of the lens, and has a center in front of the vertex 23d on the extension of the lens center line 24 (the cornea). Side) and is represented as a part of a circle (ie, an arc) having the same radius of curvature as the first front curve 25a. The first rear surface curve 25b is represented as a circular arc convex on the opposite side (vitreous body side) from the first front surface curve 25a.

  The outer peripheral shape of the first provisional crystalline lens 25 is determined by the first front surface curve 25a and the first rear surface curve 25b set in steps S21 and S22. The first provisional crystalline lens 25 has the same maximum thickness as the maximum thickness (specifically, for example, the distance between the front vertex 23c and the rear vertex 23d) of the real lens portion 23 (the central portion of the lens) shown on the tomographic image. The lens has a shape symmetrical with respect to the lens center line 24, and both the front and rear surfaces have a shape represented by an arc having a radius of curvature determined by the lens front surface 23a.

  Returning to the processing of FIG. 3, next, on the tomographic image acquired in step S1, in other words, on the two-dimensional plane on which the tomographic image is shown, the second temporary lens 26 having the front surface 23b of the lens at the front surface (see FIG. 9) (S6). Specifically, for example, the process of FIG. 5 is executed as step S6. That is, a curve 26b (see FIG. 9) along the lens posterior surface 23b specified in step S2 is set on the tomographic image acquired in step S1, in other words, on a two-dimensional plane on which the tomographic image is shown (S31). The curve 26b is defined as a second rear surface curve, and the second rear surface curve 26b is obtained by approximating the shape of the lens rear surface 23b with a circle having a constant radius of curvature, and is represented as a part (ie, an arc) of the approximate circle. You. The second rear surface curve 26b may be obtained by a known approximation method such as the least square method. Step S31 is synonymous with obtaining a circle approximating the shape of the rear surface 23b of the crystalline lens. The circle of the second posterior surface curve 26b is represented, for example, as a circle that passes through the vertex 23d of the posterior surface 23b of the lens and whose center is located on the front side (corneal side) of the vertex 23d on the extension of the lens center line 24. The second rear surface curve 26b is represented as a circular arc convex toward the vitreous body.

  Next, a curve 26a (see FIG. 9) determined by the shape of the lens posterior surface 23b is set on the tomographic image acquired in step S1, in other words, at the position of the crystalline lens front surface 23a on the two-dimensional plane where the tomographic image is shown (S32). ). The curve 26a is defined as a second front surface curve. Specifically, the second front surface curve 26a passes through the vertex 23c of the lens front surface 23a and has a center behind the vertex 23c on the extension of the lens center line 24 ( It is located on the vitreous body side) and is represented as a part of a circle (ie, an arc) having the same radius of curvature as the second rear surface curve 26b. The second anterior curve 26a is represented as a circular arc convex on the opposite side (corneal side) of the second posterior curve 26b.

  The outer peripheral shape of the second temporary lens 26 is determined by the second rear surface curve 26b and the second front surface curve 26a set in steps S31 and S32. The second temporary lens 26 has the same maximum thickness as the maximum thickness of the lens real image portion 23 (center of the lens) shown on the tomographic image, and has a shape symmetrical with respect to the lens center line 24. In addition, both the front surface and the rear surface have a shape represented by an arc having a radius of curvature determined by the lens rear surface 23b.

  Returning to the processing of FIG. 3, next, on the tomographic image acquired in step S1, in other words, on the two-dimensional plane on which the tomographic image is shown, a third temporary lens determined from the lens front surface 23a and the lens rear surface 23b specified in step S2. The lens 27 (see FIG. 10) is set (S7). Specifically, for example, the process of FIG. 6 is executed as step S7. That is, a curve 27a (see FIG. 10) along the crystalline lens front surface 23a is set on the tomographic image acquired in step S1, that is, on a two-dimensional plane on which the tomographic image is shown (S41). The curve 27a is defined as a third front curve, and the third front curve 27a is obtained by approximating the shape of the crystalline lens front surface 23a with a circle having a constant radius of curvature, and is represented as a part (ie, an arc) of the approximate circle. You. The third front curve 27a may be obtained by a known approximation method such as the least square method. Step S41 is equivalent to obtaining a circle approximating the shape of the crystalline lens front surface 23a. The circle of the third front curve 27a passes through the vertex 23c of the lens front surface 23a, for example, and is represented as a circle whose center is located behind (the vitreous body) the vertex 23c on the extension of the lens center line 24. . The third anterior curve 27a is represented as an arc that is convex toward the cornea. The circle of the third front curve 27a is the same as the circle of the first front curve 25a set in step S21 in FIG. That is, step S41 is substantially the same as step S21 in FIG.

  Next, a curve 27b (see FIG. 10) along the posterior surface 23b of the lens is set on the tomographic image acquired in step S1, in other words, on a two-dimensional plane on which the tomographic image is shown (S42). This curve 27b is used as a third back surface curve, and the third back surface curve 27b is obtained by approximating the shape of the lens back surface 23b with a circle having a constant radius of curvature, and is expressed as a part (ie, an arc) of the approximate circle. You. The third rear surface curve 27b may be obtained by a known approximation method such as the least square method. Step S42 is equivalent to obtaining a circle approximating the shape of the posterior surface 23b of the crystalline lens. The circle of the third posterior surface curve 27b is, for example, a circle that passes through the vertex 23d of the posterior surface 23b of the lens and whose center is located on the front side (corneal side) of the vertex 23d on the extension of the lens center line 24. The third rear surface curve 27b is represented as a circular arc convex on the vitreous body side. The circle of the third rear surface curve 27b is the same as the circle of the second rear surface curve 26b set in step S31 in FIG. That is, step S42 is substantially the same as step S31 in FIG.

  The outer peripheral shape of the third provisional crystalline lens 27 is determined by the third front curve 27a and the third rear curve 27b set in steps S41 and S42. The third provisional lens 27 has the same maximum thickness as the maximum thickness of the lens real image portion 23 (center of the lens) shown on the tomographic image, and has a shape symmetric with respect to the lens center line 24. The method of setting the third provisional lens 27 by the processing of FIG. 6 is the same as the method of estimating the lens shape shown in Patent Documents 1 and 2. Steps S5 to S7 in FIG. 3 may be executed in any order.

  Returning to the processing of FIG. 3, the equator portions 25 c and 25 d (see FIG. 8) set at step S <b> 5 and located at both ends in the major axis direction of the first temporary lens 25 shown as the tomographic image are combined with the first temporary equator. A part is specified (S8). Specifically, the first intersections 25c and 25d, which are the intersections between the front surface 25a (first front surface curve) and the rear surface 25b (first rear surface curve) of the first temporary lens 25, are determined as the first temporary equator.

  Next, the equator portions 26c and 26d (see FIG. 9) located at both ends in the major axis direction of the second temporary lens 26 set as the tomographic image and set in step S6 are specified as the second temporary equator portions (S9). . Specifically, the second intersections 26c and 26d, which are the intersections between the front surface 26a (second front surface curve) and the rear surface 26b (second rear surface curve) of the second temporary lens 26, are determined as the second temporary equator.

  Next, the equator portions 27c and 27d (see FIG. 10) located at both ends in the major axis direction of the third temporary lens 27 set as the tomographic image and set as the tomographic image are specified as the third temporary equator portions (S10). . Specifically, the third intersections 27c and 27d, which are the intersections between the front surface 27a (third front curve) and the rear surface 27b (third rear curve) of the third temporary lens 27, are determined as the third temporary equator. Steps S8 to S10 may be performed in any order.

  Next, among the equator portions 25c, 25d, 26c, 26d, 27c, and 27d specified in steps S8 to S10, the major axis direction of each of the temporary lenses 25 to 27 (in other words, the direction perpendicular to the lens center line 24) ( Furthermore, in other words, a triangle 28 (see FIG. 11) having the first to third temporary equator portions 25c, 26c, and 27c located at one end of the tomographic image (in the horizontal direction of the paper surface) and the other end thereof. The respective centroid points 30, 31 (see FIG. 11) of the triangle 29 (see FIG. 11) having the vertices of the first to third temporary equator portions 25d, 26d, 27d are detected (S11). The center of gravity of the triangle may be obtained as follows. That is, a line connecting each vertex of the triangle and the midpoint of each base is drawn, and the intersection of these lines is determined as the center of gravity.

  Next, on the tomographic image acquired in step S1, in other words, on the two-dimensional plane on which the tomographic image is shown, a straight line 32 (see FIG. 11) connecting between the two centroid points 30, 31 detected in step S11 is set as the centroid. A straight line between points is set (S12).

  Here, FIGS. 13 and 14 show the process of FIG. 3 on the tomographic image of the anterior ocular segment obtained by the OCT device similar to the OCT device 1 of FIG. 1, and the lens center line set in each step. 24 is a diagram showing, in the tomographic image, 24, provisional crystalline lenses 25 to 27, centroid points 30, 31, a line 32 between centroid points, and the like. FIG. 13 illustrates a tomographic image of the eye A having a normal crystalline lens, and FIG. 14 illustrates a tomographic image of the eye B having a cataract. 13 and 14 show a tomographic image 40 (hereinafter, referred to as a UBM image) of a lens outer peripheral shape obtained by measurement with an ultrasonic biological microscope, superimposed on an OCT tomographic image. The UBM image 40 in FIG. 13 is a tomographic image of the eye A to be inspected by an ultrasonic biological microscope. The UBM image 40 in FIG. 14 is a tomographic image of the eye to be inspected B by an ultrasonic biological microscope. 13 and 14, the left and right lens equator portions 41 and 42 obtained from the UBM image 40 are indicated by crosses.

  As shown in FIGS. 13 and 14, the actual lens equatorial portions 41 and 42 are located on the straight line 32 between the center of gravity points in both the normal case and the cataract case. In addition, the present inventor considered that 15 eyes of normal cases and 15 eyes of cataracts per eye in four directions of 2-8 o'clock, 3-9 o'clock, 4-10 o'clock, and 6-12 o'clock in FIG. A tomographic image was obtained. Then, the processing of FIG. 3 is performed on each of the 60 images of the normal case (15 eyes × 4 directions) and the 60 images of the cataract case (15 eyes × 4 directions) to obtain the center of gravity and the straight line between the centers of gravity. Was. Then, the positional relationship between the straight line between the centers of gravity and the equator obtained from the UBM image was evaluated. As a result, in any of the examples, the equatorial portion of the UBM image was located on the straight line between the centers of gravity.

  From the above, it can be estimated that the actual equator is located on the straight line 32 between the centers of gravity set in step S12 (see FIG. 11). This means that the actual equator is located at the position in the depth direction (the position in the direction in which the lens centerline extends) of the centroid points 30 and 31 detected in step S11.

  On the other hand, as shown in FIGS. 13 and 14, the equator portions 27c and 27d (the third temporary equator portion specified in step S10) estimated by the same method as in Patent Documents 1 and 2 are the equator in the UBM image 40. The error in the thickness direction of the crystalline lens (direction of the crystalline lens center line) with respect to the portions 41 and 42 is large.

  As shown in FIGS. 13 and 14, perpendiculars 33 and 34 are dropped from the third temporary equator portions 27c and 27d specified in step S10 to the straight line 32 between the centers of gravity, and the perpendiculars 33 and 34 and the straight line 32 between the centers of gravity are removed. It has been found that the intersections 35 and 36 with are detected at positions closer to the actual equatorial parts 41 and 42. The error between the intersections 35 and 36 and the actual equator 41 and 42 was calculated for the 60 images of the normal case and the 60 images of the cataract case (total of 120 images), and the maximum error was 660 μm (0.66 mm). That is, in each case, the error was 1 mm or less.

  Therefore, as a step S13 of the process of FIG. 3, as shown in FIG. 11, as shown in FIG. , 36 are detected.

  Next, on the tomographic image obtained in step S1, in other words, on the two-dimensional plane on which the tomographic image is shown, the left and right centroid points 30, 31 detected in step S11 or the left and right intersection points 35, 36 detected in step S13 are set. A fourth provisional crystalline lens 37 (see FIG. 12) which is the equator and passes through the front vertex 23c and the rear vertex 23d specified in step S3 is set (S14). At this time, the front surface and the rear surface of the fourth temporary lens 37 are represented by, for example, arcs having a constant radius of curvature. The radius of curvature of the front surface of the fourth temporary crystalline lens 37 may be different from the radius of curvature of the rear surface thereof, or may be the same. In the examples of FIGS. 12, 13 and 14, the fourth provisional crystalline lens 37 having the center of gravity points 30, 31 as the equator is shown.

  Next, the left and right centroid points 30, 31 detected in step S11, the straight line 32 between the centroid points set in step S12, the intersection points 35, 36 detected in step S13, the fourth temporary lens 37 set in step S14. Is superimposed on the tomographic image acquired in step S11 and displayed on the display unit 13 (S15). In step S15, the coordinates of the centroid points 30, 31 and the intersection points 35, 36 may be displayed on the display unit 13. Thereafter, the processing in FIG. 3 ends.

  As described above, according to the present embodiment, even when the entire shape of the crystalline lens is not shown in the tomographic image, the fourth provisional crystalline lens 37 simulating the overall shape of the crystalline lens is displayed. (Eg, a doctor) or the subject can easily grasp the overall shape of the crystalline lens. In addition, the display of the fourth temporary lens 37 indicates whether or not the shape of the lens is normal, how much the lens is inclined with respect to a reference line such as a corneal center line or a visual axis, and how much the lens is eccentric. Can be intuitively grasped.

  Since the equator (center of gravity 30, 31 or intersection 35, 36) of the fourth temporary lens 37 is detected at a position near the actual equator, for example, when an intraocular lens is inserted, the equator of the lens is The intraocular lens can be accurately fixed at the position. As a result, the intraocular lens can be inserted in a state where the inclination with respect to the crystalline lens is suppressed.

  Note that the present invention is not limited to the above embodiment, and various modifications are possible. For example, steps S5 to S7 and S14 in FIG. 3 show examples in which the front and rear surfaces of the first to fourth temporary lens elements 25 to 27 and 37 are approximated by circular arcs having a constant curvature. However, the present invention is not limited thereto, and may be approximated by an ellipse, a second-order or higher polynomial, a trigonometric function, an exponential function, a logarithmic function, or the like.

  In the above embodiment, the control unit 2 corresponds to the detection device of the present invention. The processing in FIG. 3 corresponds to the detection method of the present invention. The control unit 2 executing step S1 in FIG. 3 corresponds to the image acquisition unit of the present invention, and step S1 corresponds to the image acquisition step. The control unit 2 executing step S5 corresponds to a first setting unit, and step S5 corresponds to a first setting step. The control unit 2 executing step S6 corresponds to a second setting unit, and step S6 corresponds to a second setting step. The control unit 2 executing step S7 corresponds to a third setting unit, and step S7 corresponds to a third setting step. The control unit 2 executing step S8 corresponds to a first obtaining unit and a first intersection obtaining unit, and step S8 corresponds to a first obtaining step. The control unit 2 executing step S9 corresponds to a second obtaining unit and a second intersection obtaining unit, and step S9 corresponds to a second obtaining step. The control unit 2 executing step S10 corresponds to a third obtaining unit and a third intersection obtaining unit, and step S10 corresponds to a third obtaining step. The control unit 2 that executes step S11 corresponds to a center-of-gravity point acquiring unit, and step S11 corresponds to a center-of-gravity point acquiring step.

  The control unit 2 that executes step S21 in FIG. 4 and step S41 in FIG. 6 corresponds to a first front curve setting unit. The control unit 2 executing step S22 in FIG. 4 corresponds to a first rear surface curve setting unit. The control unit 2 executing step S31 in FIG. 5 and step S42 in FIG. 6 corresponds to a second rear surface curve setting unit. The control unit 2 executing step S32 in FIG. 5 corresponds to a second front surface curve setting unit.

  The control unit 2 executing step S12 in FIG. 3 corresponds to a straight line acquisition unit. The control unit 2 executing step S13 corresponds to an intersection obtaining unit. The control unit 2 that executes steps S14 and S15 corresponds to a display control unit.

DESCRIPTION OF SYMBOLS 1 OCT apparatus 2 Control part 3 Measuring part 13 Display part 16 Program 23 Real lens image part 25 First temporary lens 25a First front curve 25b First rear curve 25c, 25d Equatorial part (first temporary equatorial part) of first temporary lens
26 second temporary lens 26a second front curve 26b second rear curve 26c, 26d equatorial portion of second temporary lens (second temporary equator)
27 third temporary lens 27a third front curve 27b third rear curve 27c, 27d equatorial portion of third temporary lens (third temporary equator)
30, 31 Triangular barycentric point 32 Straight line between barycentric points 35, 36 Intersection point between perpendicular and straight line between barycentric points 37 Fourth temporary lens

Claims (13)

An image acquisition unit that acquires a tomographic image of the subject's eye,
A first setting unit that sets a first provisional lens that also has the shape of the front surface of the lens expressed on the tomographic image on the rear surface;
A second setting unit that sets a second provisional lens that also has the shape of the posterior surface of the lens represented on the tomographic image on the front surface;
A third setting unit that sets a third provisional lens determined from a curve along the front surface of the lens and a curve along the back surface of the lens represented on the tomographic image;
A first acquisition unit that acquires a first temporary equatorial portion that is an equatorial portion of the first temporary lens;
A second acquisition unit that acquires a second temporary equator that is an equator of the second temporary lens;
A third acquisition unit that acquires a third temporary equator that is an equator of the third temporary lens;
A center-of-gravity point acquisition unit that acquires a center of gravity of a triangle having the first temporary equator, the second temporary equator, and the third temporary equator as vertices;
A detection device comprising: An image acquisition unit that acquires a tomographic image of the subject's eye,
A first front surface curve setting unit that sets a first front surface curve along the lens front surface represented on the tomographic image;
A first posterior curve setting unit that sets a first posterior curve determined by the shape of the posterior lens on the tomographic image at the position of the posterior lens on the tomographic image;
A second front curve setting unit that sets a second front curve determined by the shape of the rear lens surface represented on the tomographic image at a position of the front surface of the lens on the tomographic image;
A second posterior curve setting unit that sets a second posterior curve along the posterior lens surface represented on the tomographic image;
A first intersection acquisition unit that acquires a first intersection, which is an intersection of the first front curve and the first rear curve,
A second intersection acquisition unit that acquires a second intersection, which is an intersection of the second front curve and the second rear curve,
A third intersection acquisition unit that acquires a third intersection, which is an intersection of the first front curve and the second rear curve,
A center-of-gravity point acquisition unit that acquires a center of gravity of a triangle having the first intersection, the second intersection, and the third intersection as vertices;
A detection device comprising: The detection device according to claim 1 , wherein the center-of-gravity point acquiring unit acquires the center-of-gravity points of the two triangles obtained on both sides in the major axis direction of the crystalline lens.   The detection device according to claim 2, wherein the center-of-gravity point obtaining unit obtains the center-of-gravity points of the two triangles obtained on both sides in the major axis direction of the crystalline lens.   The detection device according to claim 3, further comprising a straight line acquisition unit that acquires a straight line that connects a center of gravity of one of the triangles and a center of gravity of the other of the triangles.   The detection device according to claim 4, further comprising: a straight line acquisition unit that acquires a straight line connecting a center of gravity of one triangle and a center of gravity of the other triangle. Detection device according to claim 5 comprising a perpendicular dropped to the third temporary equator or al the line, the intersection point acquiring unit that acquires an intersection point between the straight line.   The detection device according to claim 6, further comprising: an intersection acquisition unit configured to acquire an intersection between the perpendicular drawn from the third intersection to the straight line and the straight line. The detection device according to any one of claims 1 to 6 , further comprising a display control unit configured to display a temporary crystalline lens having the center of gravity as an equator on the tomographic image. 9. The detection device according to claim 7 , further comprising a display control unit configured to display a provisional crystalline lens having the intersection as an equator acquired by the intersection acquisition unit on the tomographic image. 10. Detection device according to any one of claims 1 to 10, wherein the image acquisition section for acquiring the tomographic image by the optical coherence tomography. An image acquisition unit that acquires a tomographic image of the subject's eye,
A first setting unit that sets a first provisional lens that also has the shape of the front surface of the lens expressed on the tomographic image on the rear surface;
A second setting unit that sets a second provisional lens that also has the shape of the posterior surface of the lens represented on the tomographic image on the front surface;
A third setting unit that sets a third provisional lens determined from a curve along the front surface of the lens and a curve along the back surface of the lens represented on the tomographic image;
A first acquisition unit that acquires a first temporary equatorial portion that is an equatorial portion of the first temporary lens;
A second acquisition unit that acquires a second temporary equator that is an equator of the second temporary lens;
A third acquisition unit that acquires a third temporary equator that is an equator of the third temporary lens;
A center-of-gravity point acquisition unit that acquires a center of gravity of a triangle having the first temporary equator, the second temporary equator, and the third temporary equator as vertices;
A program that functions as a computer. An image acquisition step of acquiring a tomographic image of the eye to be examined,
A first setting step of setting a first provisional lens having the shape of the front surface of the lens on the tomographic image also on the rear surface;
A second setting step of setting a second provisional lens having the shape of the posterior lens on the tomographic image also on the front,
A third setting step of setting a third provisional lens defined by a curve along the front surface of the lens and a curve along the back surface of the lens represented on the tomographic image;
A first obtaining step of obtaining a first temporary equatorial portion that is an equatorial portion of the first temporary lens;
A second acquisition step of acquiring a second temporary equator, which is an equator of the second temporary lens,
A third obtaining step of obtaining a third temporary equator, which is an equator of the third temporary lens,
A center-of-gravity point obtaining step of obtaining a center of gravity of a triangle having the first temporary equator, the second temporary equator, and the third temporary equator as vertices;
A detection method comprising: