JP2019166277A - Ophthalmologic apparatus and cornea shape measurement method used therein - Google Patents

Abstract

To provide an ophthalmologic apparatus and a cornea shape measurement method used therein capable of highly accurately measuring a cornea shape of a subject eye.SOLUTION: The ophthalmologic apparatus comprises: a pattern light projection optical system; a cornea-captured image acquisition unit for acquiring a cornea-captured image which includes a pattern light reflection image; a projection control unit for changing the light amount of pattern light projected onto the cornea at least one or more times; an acquisition control unit for causing the cornea-captured image acquisition unit to reexecute the acquisition of the cornea-captured image each time the light quantity of pattern light is changed; a luminance value detection unit for detecting a luminance value of the reflection image from the cornea-captured image acquired for each light amount of pattern light; a selection unit for selecting, from among cornea-captured images by light amount, a cornea-captured image best suited for detecting a site for each site within the reflection image on the basis of a detection result of the luminance value detection unit; a site detection unit for detecting a site from the cornea-captured image selected by the selection unit, for each site; and a cornea shape calculation unit for calculating the cornea shape of the subject eye.SELECTED DRAWING: Figure 10

Description

  The present invention relates to an ophthalmologic apparatus for measuring a corneal shape of a subject eye and a method for measuring the corneal shape.

  For example, an ophthalmologic apparatus that measures the corneal shape of a subject's eye, such as a corneal topographer, is well known. This ophthalmologic apparatus projects concentric and multiple platidling light onto the cornea and obtains a photographed image (anterior segment image) obtained by photographing the cornea. Then, the ophthalmologic apparatus performs image analysis on the photographed image, detects a platide ring image that is a reflection image of the platid ring light, that is, a platid ring image composed of a plurality of concentric ring images, and generates the platid ring image. Based on the corneal shape of the cornea [corneal curvature, etc. of almost the entire cornea].

  In such an ophthalmologic apparatus, various efforts have been made to accurately measure the corneal shape of the eye to be examined.

  For example, the ophthalmologic apparatus described in Patent Literature 1 performs imaging of the cornea on which the same pattern of plactide light is projected a plurality of times, and analyzes the corneal shape from a plurality of imaging images obtained by the imaging a plurality of times. A platid ring image in which the necessary brightness is secured is selected, and the corneal shape is calculated based on the platid ring image.

  Further, the ophthalmologic apparatus described in Patent Document 2 performs pre-measurement (projection of an index and photographing of the cornea) on a narrow region on the cornea, and acquires in advance the corneal curvature of this region and the light amount level of the reflected image. Then, the ophthalmologic apparatus described in Patent Literature 2 determines the light amount of the projection light of the placido ring light at the time of the main measurement based on the acquisition result of the corneal curvature and the light amount level, and performs the main measurement (the placido ring light). The corneal shape of the eye to be examined is calculated by performing projection and imaging of the cornea).

JP 2007-215950 A JP 2012-135536 A

  In a platid ring image acquired by an ophthalmologic apparatus that measures a wide range of the cornea, such as a corneal topographer device, the state of the ring image obtained varies depending on the region on the cornea. For example, since the ring image located near the center of the cornea has the pupil as the background, the contrast with the background is high.

  On the other hand, since the ring image located in the intermediate portion of the cornea in the radial direction has an iris as a background, the contrast is reduced by the reflection of the iris. Therefore, in order to optimally detect a ring image located on the iris, a state in which the reflection of the ring light by the iris is suppressed by suppressing the amount of ring light compared to the case of detecting the ring image located on the pupil. It is desirable to photograph the cornea with.

  In addition, the ring image located on the outer peripheral portion of the cornea may be partly interrupted or darkened due to vignetting caused by eyelashes or the like. For this reason, in order to optimally detect a ring image of a portion that is vignetted by eyelashes, it is desirable to photograph the cornea in a state in which the amount of ring light is increased as compared with the case of detecting a ring image located on the pupil. .

  As described above, each ring image of the placido ring image has a different amount of ring light optimal for detection depending on a portion on the cornea. Therefore, as in the ophthalmologic apparatus described in Patent Document 1 and Patent Document 2, all ring images of the placido ring image are optimally detected even when the cornea is imaged a plurality of times or the cornea is pre-measured. It is difficult. Therefore, the ophthalmic apparatus described in Patent Document 1 and Patent Document 2 cannot measure the corneal shape with high accuracy.

  Therefore, a method is conceivable in which the light amount of the ring light projected for each part on the cornea is set in advance, that is, the light amount of each ring light of the placido ring light is individually set according to the part on the cornea. . However, the pupil diameter, the reflectance of the iris, the degree of eyelash coverage, etc. vary among individuals, and the difference depending on the measurement conditions increases. Therefore, the above method is not optimal.

  Further, when the ring image reflectance on the iris is low when detecting the ring image on the iris, it is easier to obtain a ring image with good contrast if the light amount of the ring light is increased. Furthermore, if the eyelashes are short when detecting a ring image located on the outer periphery of the cornea, or if the eyelashes are sufficiently wide and there are no eyelashes, the brightness value of the ring image may be increased if the amount of ring light is too high. The peak is saturated, and the detection accuracy of the ring image is deteriorated. Furthermore, even when detecting a ring image on the pupil, the amount of light is lower than usual in the case of the subject's eye that easily reflects ring light, such as the subject's eye into which an intraocular lens is inserted. The projection of the ring light is less susceptible to unnecessary reflection of the ring light.

  The present invention has been made in view of such circumstances, and an object thereof is to provide an ophthalmologic apparatus capable of measuring the corneal shape of an eye to be examined with high accuracy and a method for measuring the corneal shape.

  An ophthalmologic apparatus for achieving an object of the present invention includes a pattern light projection optical system that projects pattern light for measuring a corneal shape onto a cornea of a subject eye, and a cornea on which pattern light is projected from the pattern light projection optical system. A corneal imaging image acquisition unit that captures and acquires a corneal imaging image including a reflection image of the pattern light; and a projection control unit that changes the amount of pattern light projected onto the cornea from the pattern light projection optical system at least once. Each time the light amount of the pattern light is changed by the projection control unit, the acquisition control unit that re-executes the acquisition of the cornea image acquired by the cornea image acquisition unit, and the pattern light amount acquired by the cornea image acquisition unit Based on the luminance value detection unit that detects the luminance value of the reflected image from the cornea image and the detection result of the luminance value detection unit, for each part in the reflected image, a cornea image that is optimal for detecting the part is classified by light quantity. Corner of Based on the selection unit selected from the radiographed images, the selection result of the selection unit, the site detection unit that detects the site from the cornea radiograph image selected by the selection unit, and the site detection unit for each site A corneal shape calculating unit that calculates the corneal shape of the eye to be examined based on the detection result.

  According to this ophthalmologic apparatus, the detection error of the reflected image of the pattern light can be reduced, and the corneal shape can be accurately measured (highly accurate).

  In the ophthalmologic apparatus according to another aspect of the present invention, the selection unit has a cornea in which the SN value of the luminance value is highest in a cornea image in which the luminance value of the region is smaller than a predetermined saturation threshold for each region. A photographed image is selected from cornea photographed images by light quantity. As a result, it is possible to select a cornea image that is optimal for detecting a region in the reflected image.

  In the ophthalmologic apparatus according to another aspect of the present invention, the pattern light projection optical system projects platid ring light composed of a plurality of concentric ring lights as pattern light onto the eye to be examined, and the cornea photographing image acquisition unit The corneal radiograph including a platid ring image composed of a plurality of concentric ring images is acquired as a reflection image, and the luminance value detection unit obtains a plurality of ring images in the platid ring image for each corneal radiograph. The brightness value is detected, and the selection unit selects the cornea image that is optimal for ring image detection for each ring image from the cornea images for each light quantity, and the region detection unit selects each ring image. The ring image is detected from the cornea image selected by the unit, and the corneal shape calculation unit calculates the corneal shape based on the detection result for each ring image. Thereby, the detection error of each ring image of the placido ring image can be reduced, and the corneal shape can be accurately measured.

  In the ophthalmologic apparatus according to another aspect of the present invention, the pattern light projection optical system projects ring light as the pattern light onto the eye to be examined, and the cornea image acquisition unit acquires a cornea image including the ring image as a reflection image. The brightness value detection unit detects the brightness value of a plurality of parts in the ring image along the circumferential direction of the ring image for each cornea image, and the selection unit detects the part of each part in the ring image. The optimal cornea image for detection is selected from cornea images for each light quantity, and the region detection unit detects the region from the cornea image selected by the selection unit for each region. Thereby, even when the ring image straddles the pupil and iris of the eye to be examined, the ring image can be detected with high accuracy.

  In the ophthalmologic apparatus according to another aspect of the present invention, the pattern light projection optical system projects pattern light that is invisible light onto the eye to be examined.

  A method for measuring a corneal shape of an ophthalmologic apparatus for achieving an object of the present invention includes a pattern light projection step of projecting pattern light for measuring a corneal shape onto a cornea of an eye to be examined, and pattern light being projected in the pattern light projection step. A cornea image acquisition step for acquiring a cornea image including a reflection image of the pattern light, and a projection control for changing the amount of pattern light projected onto the cornea at least once in the pattern light projection step. Each time the light amount of the pattern light is changed by the step and the projection control step, the acquisition control step for re-execution of the cornea image acquisition step, and the cornea image acquired by the pattern light amount in the cornea image acquisition step From the brightness value detection step for detecting the brightness value of the reflected image and the detection result of the brightness value detection step, for each part in the reflected image Based on the selection step that selects the optimal reflected image for detecting the part from the reflected images for each light quantity and the selection result of the selection step, the part is detected from the reflected image selected in the selection step for each part. And a corneal shape calculation step for calculating a corneal shape of the eye to be examined based on a detection result for each region in the region detection step.

  The present invention can measure the corneal shape of the eye to be examined with high accuracy.

It is an optical arrangement | positioning figure which showed arrangement | positioning of the optical system of the ophthalmic apparatus of this invention. It is a front view of the placido ring seen from the eye to be examined. It is a front view of the light-receiving surface of the area sensor of a 2nd light reception optical system. It is a functional block diagram of the integrated control part of an ophthalmologic apparatus. It is explanatory drawing for demonstrating the placido ring light according to light quantity. It is explanatory drawing which showed an example of the picked-up image data according to the light quantity used as the detection target of the luminance value by a luminance value detection part. It is the graph which showed the detection result of the brightness | luminance value along the meridian direction of the picked-up image data of light quantity "small". It is the graph which showed the detection result of the brightness | luminance value along the meridian direction of the picked-up image data of light quantity "medium". It is the graph which showed the detection result of the luminance value along the meridian direction of the picked-up image data of light quantity "Large". It is explanatory drawing for demonstrating the detection of each ring image by a site | part detection part. It is a flowchart which shows the flow of a measurement process of the cornea shape of the eye to be examined by an ophthalmologic apparatus. It is explanatory drawing of the picked-up image data of 2nd Embodiment. It is explanatory drawing for demonstrating the detection of the luminance value for every picked-up image data by the luminance value detection part of 2nd Embodiment. It is the graph which showed the detection result of the luminance value along the kth detection line in FIG. 13 of each picked-up image data. It is the graph which showed the detection result of the luminance value along the nth detection line in FIG. 13 of each picked-up image data. It is explanatory drawing for demonstrating the detection for every site | part of the ring image by the site | part detection part of 2nd Embodiment. It is explanatory drawing for demonstrating the correspondence of the site | part of a ring image, and the picked-up image data which the site | part detection part of 2nd Embodiment detects.

[Configuration of Ophthalmic Apparatus of First Embodiment]
FIG. 1 is an optical layout diagram showing the layout of the optical system of the ophthalmologic apparatus 10 of the present invention. Here, the X-axis direction in the figure is the left-right direction with respect to the subject (the eye width direction of the eye E), the Y-axis direction is the vertical direction, and the Z-axis direction is before approaching the subject. The front-rear direction (also referred to as a working distance direction) is parallel to the direction and the rear direction away from the subject.

  As shown in FIG. 1, the ophthalmologic apparatus 10 is a complex machine that measures both the eye characteristics of the eye E and the cornea shape of the cornea Ec of the anterior eye portion of the eye E. In the present embodiment, the measurement of the eye refractive power and the eyeball wavefront aberration of the eye E will be described as an example for measuring the eye characteristics of the eye E. In addition, the measurement of the corneal shape of the present embodiment includes the measurement of corneal wavefront aberration obtained from the corneal shape in addition to the measurement of the corneal curvature and the radius of curvature of almost the entire region of the cornea Ec.

  The ophthalmologic apparatus 10 includes an eye characteristic measurement optical system 12, a cornea shape measurement optical system 14, an alignment optical system 16, and a fixation optical system 18.

[Optical characteristics measurement optical system]
The eye characteristic measurement optical system 12 includes a measurement light projection optical system 20 and a first light receiving optical system 22. The measurement light projection optical system 20 projects measurement light L1 for measuring eye characteristics onto the fundus oculi Ef of the eye E. The first light receiving optical system 22 receives the reflected light of the measurement light L1 reflected by the fundus oculi Ef, and outputs eye characteristic measurement data D1.

<Measurement light projection optical system>
The measurement light projection optical system 20 includes a measurement light source 26, a collimator lens 28, a polarization beam splitter 30, a dichroic mirror 32, a dichroic mirror 34, an objective lens 36, and a light source moving unit 38.

  For example, the measurement light source 26 emits measurement light L1 in the near-infrared wavelength region toward the collimator lens 28. For example, an SLD (Super luminescent diode), a laser light source, and an LED (Light emitting diode) are used as the measurement light source 26. The measurement light source 26 is held by a light source moving unit 38 so as to be movable along a direction parallel to the emission direction of the measurement light L1.

  The collimator lens 28 converts the measurement light L1 incident from the measurement light source 26 into parallel light, and then outputs the parallel light to the polarization beam splitter 30.

  The polarization beam splitter 30 reflects the P-polarized component of the measurement light L 1 incident from the collimator lens 28 toward the dichroic mirror 32. Further, the polarization beam splitter 30 transmits the S-polarized component of the reflected light of the measurement light L1 from the fundus oculi Ef that is incident from the dichroic mirror 32 and causes the S-polarized light component to enter the reflecting mirror 40 described later.

  The dichroic mirror 32 reflects the measurement light L1 incident from the polarization beam splitter 30 toward the dichroic mirror 34, reflects the reflected light of the measurement light L1 incident from the dichroic mirror 34 toward the polarization beam splitter 30, Further, the fixation target light L5 incident from a reflecting mirror 96 described later is transmitted and incident on the dichroic mirror 34.

  The dichroic mirror 34 reflects the measurement light L1 and the fixation target light L5 incident from the dichroic mirror 32 toward the objective lens 36, and directs the reflected light of the measurement light L1 incident from the objective lens 36 toward the dichroic mirror 32. Reflect. Further, the dichroic mirror 34 transmits reflected light of a later-described placido ring light L2 incident from the objective lens 36, emits the light toward a later-described half mirror 70, and later-described XY alignment light incident from the half mirror 70. The light passes through L4 and exits toward the objective lens.

  The objective lens 36 is used in common in each optical system except the ring light projection optical system 52 described later, and makes the measurement light L1, the XY alignment light L4, and the fixation target light L5 enter the eye E.

<First light receiving optical system>
The first light receiving optical system 22 shares the polarizing beam splitter 30, the dichroic mirrors 32 and 34, and the objective lens 36 with the measurement light projection optical system 20, and also includes a reflecting mirror 40, a lens 42, a collimator lens 43, and a Hartmann. A plate 44, an area sensor 46, and a sensor driving unit 48 are provided.

  The reflecting mirror 40 reflects the reflected light of the measuring light L1 incident from the polarizing beam splitter 30 toward the lens 42. Thereby, the reflected light of the measurement light L1 is converted into parallel light by the collimator lens 43 through the lens 42 and then enters the Hartmann plate 44.

  The Hartmann plate 44 has a plurality of two-dimensionally arranged microlenses, and divides the reflected light of the measurement light L1 incident from the lens 42 into a plurality of divided lights and enters the light receiving surface of the area sensor 46.

  The area sensor 46 is, for example, an image sensor of a complementary metal oxide semiconductor (CMOS) type or a charge coupled device (CCD) type. The area sensor 46 receives (images) a plurality of divided lights incident from the Hartmann plate 44 and converts the image data of a Hartmann image consisting of a plurality of point images corresponding to each divided light to the fundus of the eye E. The data is output to the overall control unit 100 (see FIG. 4) described later as Ef eye characteristic measurement data D1.

  The sensor driving unit 48 holds the collimator lens 43, the Hartmann plate 44, and the area sensor 46 movably along a direction parallel to the incident direction of the reflected light of the measurement light L1. The sensor driving unit 48 and the above-described light source moving unit 38 are driven so that the measurement light source 26, the fundus oculi Ef, and the area sensor 46 have a substantially conjugate positional relationship according to the refractive power of the eye E to be examined.

[Cornea shape measurement optical system]
The cornea shape measurement optical system 14 includes a ring light projection optical system 52 and a second light receiving optical system 54. The ring light projection optical system 52 corresponds to the pattern light projection optical system of the present invention, and projects the placido ring light L2 onto the cornea Ec of the anterior segment of the eye E to be examined. The second light receiving optical system 54 corresponds to the corneal radiographic image acquisition unit of the present invention, and takes an image of the cornea Ec (anterior eye portion) on which the placido ring light L2 is projected, that is, the placido ring light L2. The reflected light is imaged and the captured image data D2 of the anterior segment including the cornea Ec is output.

<Ring projection optical system>
The ring light projection optical system 52 includes a placido ring 58, a pair of light sources 60, and a pair of collimator lenses 62.

  FIG. 2 is a front view of the placido ring 58 viewed from the eye E side. As shown in FIG. 2 and FIG. 1 described above, the platide ring 58 is formed in a substantially annular shape, and has a central opening 66, a plurality of ring patterns 68, and a pair of openings 69.

  The center opening 66 is a circular opening hole formed at the center of the placido ring 58, and the center thereof substantially coincides with the optical axis of the objective lens 36. Through this central opening 66, the measurement light L1, the XY alignment light L4, and the fixation target light L5 enter the eye E, and the reflected light reflected by the eye E enters the objective lens 36.

  The plurality of ring patterns 68 are formed concentrically around the optical axis of the objective lens 36, and each transmits light. In addition, a plurality of LEDs 58 a (which may be various known light sources other than LEDs) are arranged along the ring pattern 68 on the back surface side (objective lens 36 side) of the platide ring 58.

  Each ring pattern 68 is illuminated by invisible light (for example, near infrared light) emitted from each LED 58a. As a result, as the pattern light for measuring the corneal shape of the present invention, the placido ring light L2 made of invisible light transmitted through each ring pattern 68 is projected onto the cornea Ec of the eye E and reflected by the cornea Ec. The reflected light of the platid ring light L 2 is incident on the objective lens 36. In addition, the wavelength range of the placido ring light L2 that is invisible light is not particularly limited.

  The LED 58a of this embodiment changes the illumination light amount of each ring pattern 68, that is, the light amount of the placido ring light L2 incident on the eye E under the control of the overall control unit 100 (see FIG. 4) described later.

  The pair of openings 69 are formed on the circumference of, for example, the third (or other than the third) ring pattern 68 from the inner side to the outer side of the platide ring 58.

  The pair of light sources 60 are provided on the back side of the platide ring 58 corresponding to the pair of openings 69, respectively. The pair of light sources 60 emits the Z alignment light L3 toward the pair of collimator lenses 62, respectively.

  The pair of collimator lenses 62 converts the Z alignment light L3 incident from the pair of light sources 60 into parallel light, and then emits the light toward the pair of openings 69. Thereby, a pair of Z alignment light L3 which each passed through a pair of opening 69 is projected on the cornea Ec of the eye E to be examined. Then, the reflected light of the pair of Z alignment lights L3 reflected by the cornea Ec of the eye E is incident on the objective lens 36 together with the reflected light of the aforementioned placido ring light L2.

[Second light receiving optical system]
Returning to FIG. 1, the second light receiving optical system 54 shares the dichroic mirror 34 and the objective lens 36 with the measurement light projection optical system 20, and also includes a half mirror 70, a relay lens 72, an imaging lens 74, and an area. Sensor 76.

  The half mirror 70 reflects XY alignment light L <b> 4 incident from a later-described reflecting mirror 84 toward the dichroic mirror 34. Further, the half mirror 70 transmits the reflected light of the placido ring light L 2, the pair of Z alignment light L 3, and the XY alignment light L 4 incident from the dichroic mirror 34 and enters the relay lens 72. Accordingly, each reflected light is incident on the light receiving surface of the area sensor 76 via the relay lens 72 and the imaging lens 74.

[Alignment optical system]
The alignment optical system 16 shares the dichroic mirror 34, the objective lens 36, and the half mirror 70 with the second light receiving optical system 54, and includes an alignment light source 80, a lens 82, and a reflecting mirror 84.

  The alignment light source 80 emits XY alignment light L4 toward the lens 82. After passing through the lens 82, the XY alignment light L4 is projected onto the cornea Ec of the eye E as parallel light through the reflecting mirror 84, the half mirror 70, the dichroic mirror 34, and the objective lens 36. Then, the reflected light of the XY alignment light L4 reflected by the cornea Ec enters the light receiving surface of the area sensor 76 via the objective lens 36, the dichroic mirror 34, the half mirror 70, the relay lens 72, and the imaging lens 74. Is done.

  The area sensor 76 is a CCD type or CMOS type imaging device. The area sensor 76 is arranged so as to be conjugate with a reflection image on the corneal surface of the eye E when the working distance of the ophthalmologic apparatus 10 is set to a predetermined distance.

  FIG. 3 is a front view of the light receiving surface of the area sensor 76 of the second light receiving optical system 54. As shown in FIG. 3, on the light receiving surface of the area sensor 76, a pair of a placido ring image 86, which is a reflection image based on the reflected light of the placido ring light L2, is superimposed on the anterior segment image by the imaging lens 74. A pair of bright spot images B1 which are reflected images based on the reflected light of the Z alignment light L3 and a bright spot image B2 which is a reflected image based on the reflected light of the XY alignment light L4 are formed.

  The area sensor 76 captures an image of the anterior segment of the eye E including the placido ring image 86, the pair of luminescent spot images B1, and the luminescent spot image B2, and captures the captured image data D2 as will be described later. 4). The photographed image data D2 corresponds to the cornea photographed image of the present invention.

  The placido ring image 86 corresponds to a reflection image (by the cornea Ec) of the pattern light of the present invention, and is a multiple ring image composed of a plurality of concentric (eight in the present embodiment) ring images 87. is there. In the present embodiment, the placido ring image 86 is composed of an eight-fold ring image 87, but may be composed of two or more ring images 87. Hereinafter, each ring image 87 is referred to as a first ring image 87, a second ring image 87,..., An eighth ring image 87 from the inside to the outside of the placido ring image 86. Further, when the ring images 87 are not particularly distinguished, they are simply referred to as “ring images 87”.

  Both the third ring image 87 (or another ring image 87 is acceptable) and the pair of bright spot images B1 indicate the alignment state of the ophthalmologic apparatus 10 with respect to the eye E in the Z-axis direction. Specifically, when the distance between the pair of bright spot images B1 and the diameter of the third ring image 87 coincide with each other, the alignment in the Z-axis direction is adjusted. Are misaligned (see JP 2011-115387 A).

  The detection method for detecting the alignment in the Z-axis direction is not limited to the above method. For example, a method of projecting a target on the cornea Ec from two or more different distances to detect alignment from the height ratio of each index image (magnification method), and irradiating the cornea Ec with a light beam from an angle different from the optical axis Then, a method for detecting alignment based on the displacement of the reflected light beam from the corneal apex (optical lever method), and a method for detecting alignment from parallax of captured images obtained by photographing the cornea Ec from two or more directions having different angles (stereo camera). Method) and a method of detecting alignment from the focus (contrast of the captured image) of the second light receiving optical system 54.

  The bright spot image B2 shows an alignment state of the ophthalmologic apparatus 10 with respect to the eye E to be examined in the X axis direction and the Y axis direction. Specifically, when the bright spot image B2 is located at the center of the area sensor 76, the alignment in the X-axis direction and the Y-axis direction is adjusted. And at least one of the alignment in the Y-axis direction is misaligned (see Japanese Patent Application Laid-Open No. 2011-115387).

[Fixed optical system]
Returning to FIG. 1, the fixation optical system 18 projects the fixation target light L <b> 5 for fixation or clouding of the eye E onto the eye E. The fixation optical system 18 shares the dichroic mirror 32, the dichroic mirror 34, and the objective lens 36 with the measurement light projection optical system 20 described above, and also includes a light source 88, a lens 90, a fixation target 92, and a lens 94. And a reflecting mirror 96 and a target moving unit 98.

  The light source 88 emits illumination light in the wavelength range of visible light toward the lens 90. The illumination light is collimated by the lens 90 and then enters the fixation target 92.

  The fixation target 92 is, for example, a landscape or a radiation pattern, and is illuminated from behind by illumination light incident from the lens 90. Thereby, fixation target light L5 is emitted from the fixation target 92 toward the lens 94. The fixation target light L5 is incident on the eye E through the lens 94, the reflecting mirror 96, the dichroic mirror 32, the dichroic mirror 34, and the objective lens 36, and is projected onto the fundus oculi Ef.

  The target moving unit 98 moves the light source 88, the lens 90, and the fixation target 92 as a unit according to the refractive power of the eye E. Thereby, the eye E can be fixed. Furthermore, the target moving unit 98 performs clouding to eliminate the influence of the adjustment of the eye E when measuring the eye refractive power of the eye E.

[Configuration of general control section]
FIG. 4 is a functional block diagram of the overall control unit 100 of the ophthalmologic apparatus 10. As shown in FIG. 4, the overall control unit 100 is an arithmetic circuit including various arithmetic units including a CPU (Central Processing Unit) or an FPGA (field-programmable gate array), a memory, and the like. In addition to the above-described optical systems, the overall control unit 100 is connected to an operation unit 102, a storage unit 104, a display unit 106, and an alignment driving unit 108. The overall control unit 100 performs overall control of the operation of each unit of the ophthalmologic apparatus 10 in accordance with an input operation to the operation unit 102 by the examiner.

  The storage unit 104 stores the measurement results of the eye characteristics and the corneal shape of the eye E, and also stores a measurement program (not shown) for executing measurement by the ophthalmologic apparatus 10. The display unit 106 displays the eye characteristics of the eye E, the measurement result of the corneal shape, and the like. The alignment drive unit 108 moves the respective optical systems of the ophthalmologic apparatus 10 relative to the eye E under the control of the overall control unit 100 in the directions of the XYZ axes, thereby causing the ophthalmologic apparatus to move relative to the eye E. 10 is auto-aligned.

  The overall control unit 100 executes an unillustrated measurement program read from the storage unit 104, thereby causing an eye characteristic measurement control unit 110, a first image acquisition unit 112, an eye characteristic calculation unit 114, a corneal shape measurement control unit 116, It functions as the second image acquisition unit 118, the alignment detection unit 120, the ring image analysis unit 122, and the corneal shape calculation unit 126.

  The eye characteristic measurement control unit 110 controls the measurement of the eye characteristics of the eye E by the ophthalmologic apparatus 10. The eye characteristic measurement control unit 110 controls the fixation optical system 18 to cause the eye E to be fogged (when measuring the eye refractive power) and at the same time, the eye characteristic measurement optical system 12 (the measurement light projection optical system 20 and the first optical system). The light receiving optical system 22) is controlled to execute the projection of the measurement light L1 on the fundus oculi Ef of the eye E, the imaging of the reflected light of the measurement light L1, and the output of the eye characteristic measurement data D1.

  Note that the measurement of the eye characteristic of the eye E is performed at an arbitrary timing different from the timing of measurement of the corneal shape described later. Further, measurement of the eye characteristics of the eye E is not essential, and may be omitted if unnecessary. In this case, the measurement of the eye characteristic of the eye E to be examined by the ophthalmologic apparatus 10 is omitted by inputting an operation for stopping the measurement of the eye characteristic to the operation unit 102.

  The first image acquisition unit 112 acquires the eye characteristic measurement data D1 of the fundus oculi Ef output from the first light receiving optical system 22, and outputs the eye characteristic measurement data D1 to the eye characteristic calculation unit 114.

  The eye characteristic calculation unit 114 analyzes the eye characteristic measurement data D1 input from the first image acquisition unit 112 and calculates eye characteristics such as eye refractive power and eyeball wavefront aberration of the eye E. Since the eye characteristic calculation method is a known technique (Japanese Patent Laid-Open No. 2011-115387), a detailed description thereof is omitted here. The eye characteristic calculation unit 114 stores the calculation result of the eye characteristics of the eye E to be examined in the storage unit 104 and the display unit 106.

  The corneal shape measurement control unit 116 corresponds to the projection control unit and the acquisition control unit of the present invention, and controls the measurement of the corneal shape by the ophthalmologic apparatus 10. The corneal shape measurement control unit 116 first controls the fixation optical system 18 to fix the eye E, and controls the ring light projection optical system 52 and the alignment optical system 16 to control the eye E. The placido ring light L2, the pair of Z alignment light L3, and the XY alignment light L4 are projected onto the cornea Ec. Further, the cornea shape measurement control unit 116 controls the second light receiving optical system 54 to reflect the reflected light of each light, that is, the placido ring image 86, the pair of bright spot images B1 shown in FIG. The imaging of the point image B2 and the output of the captured image data D2 for alignment detection are executed.

  Further, the corneal shape measurement control unit 116 controls the corneal shape measurement optical system 14 after the alignment is completed, the projection of the placido ring light L2 onto the cornea Ec by the ring light projection optical system 52, and the second light receiving optical system 54. The imaging (acquisition) of the placido ring image 86 and the output of the captured image data D2 are repeatedly executed three times.

  At this time, the corneal shape measurement control unit 116 controls the LED 58a of the ring light projection optical system 52 so that the light amount of the placido ring light L2 projected on the cornea Ec for the first time and the placido ring light projected for the second time. The light amount of L2 is different from the light amount of the placido ring light L2 projected for the third time. Specifically, in the present embodiment, the light amount of the placido ring light L2 projected onto the cornea Ec is increased stepwise in three stages. It should be noted that the light amount of the placido ring light L2 projected onto the cornea Ec at the first time is “small”, the light amount of the placido ring light L2 projected onto the cornea Ec at the second time is “medium”, and the light beam onto the cornea Ec at the third time. The amount of the projected ring light L2 is “large”.

  FIG. 5 is an explanatory diagram for explaining the placido ring light L2 for each light quantity. In the following description, it is assumed that “pupil Ep” includes a pupil image in captured image data D2, and “iris Ei” includes an iris image in captured image data D2.

  As shown in FIG. 5, the light amount “small” of the placido ring light L2 is a ring image 87 that is a reflection image of the ring light L2a of the placido ring light L2 projected on the iris Ei (indicated by a solid line in the figure). Is adjusted to a light amount suitable for detection from the captured image data D2. The light amount “medium” of the placido ring light L2 is detected from the captured image data D2 as a ring image 87 that is a reflection image of the ring light L2a projected on the pupil Ep (indicated by a one-dot chain line in the figure). The light intensity is adjusted to be suitable for

  The light amount “large” of the placido ring light L2 is obtained by taking a ring image 87, which is a reflection image of the ring light L2a of the placido ring light L2 projected on the outer peripheral portion of the cornea Ec (indicated by a dotted line in the figure), as captured image data. The amount of light is adjusted to be suitable for detection from D2. As described above, the ring light L2a projected on the outer peripheral portion of the cornea Ec is vignetted by the eyelash EL or the like. As a result, part of the ring image 87 is interrupted or the image becomes dark. For this reason, the light amount “large” is adjusted to a light amount that can prevent the ring image 87 from being interrupted or the ring image 87 from becoming dark.

  As described above, appropriate values are set in advance for each of the light amounts “small”, “medium”, and “large” of the placido light L2 through experiments or simulations.

  Returning to FIG. 4, the second image acquisition unit 118 constitutes the cornea photographed image acquisition unit of the present invention together with the above-described second light receiving optical system 54, and the photographed image data D <b> 2 from the second light receiving optical system 54. To get. When the second image acquisition unit 118 acquires the captured image data D2 for alignment detection from the second light receiving optical system 54 before alignment by the alignment driving unit 108, the second image acquisition unit 118 sends the captured image data D2 to the alignment detection unit 120. Output.

  Further, the second image acquisition unit 118 captures image data for each light quantity (“small”, “medium”, “large”) of the platid ring light L2 from the second light receiving optical system 54 after alignment by the alignment driving unit 108 described later. D2 is sequentially acquired, and the acquired captured image data D2 is sequentially output to the ring image analysis unit 122. Hereinafter, the light quantity of the placido light L2 is simply referred to as “by light quantity”.

  The alignment detection unit 120 analyzes the captured image data D2 for alignment detection input from the second image acquisition unit 118, and based on the positional relationship between the third ring image 87 and the pair of bright spot images B1 described above. Then, the alignment state in the Z-axis direction of the ophthalmologic apparatus 10 with respect to the eye E is detected. Moreover, the alignment detection part 120 detects the alignment state of the X-axis direction of the ophthalmologic apparatus 10 with respect to the eye E to be examined, and the Y-axis direction based on the position of the bright spot image B2.

  Then, the alignment detection unit 120 outputs the alignment detection result in each axial direction of the XYZ axes to the alignment driving unit 108. As a result, the alignment drive unit 108 performs auto-alignment of the ophthalmologic apparatus 10 with respect to the eye E. Instead of executing auto-alignment, the alignment detection result by the alignment detection unit 120 may be displayed on the display unit 106, and manual alignment for driving the alignment drive unit 108 in response to an input operation to the operation unit 102 may be performed. Good.

  The ring image analysis unit 122 analyzes the captured image data D2 for each light amount input from the second image acquisition unit 118, and performs optimal imaging for detection of the ring image 87 for each ring image 87 of the platid ring image 86. Selection of the image data D2 and detection of the ring image 87 from the selected photographed image data D2 are performed. The ring image analysis unit 122 functions as a luminance value detection unit 123, a selection unit 124, and a ring image detection unit 125.

  FIG. 6 is an explanatory diagram showing an example of the photographic image data D2 for each light quantity that is a target of luminance value detection by the luminance value detection unit 123. In FIG. 6, in order to clarify the pupil Ep and the iris Ei of the eye E, the platid ring image 86 is omitted from the captured image data D2 indicated by reference numeral 6B as the captured image data D2 indicated by reference numeral 6A of FIG. This is illustrated.

  As illustrated in FIG. 6, the luminance value detection unit 123 detects the luminance value (for example, 0 to 255 in the case of 8-bit data) of each pixel in the captured image data D2 acquired for each light amount. Then, the luminance value detection unit 123 outputs the detection result of the luminance value for each captured image data D2 to the selection unit 124. In addition, the code | symbol d in a figure shows the arbitrary radial directions which pass through the center position (possible center position is also possible) of the placido ring image 86 or the pupil Ep in the picked-up image data D2.

  FIG. 7 is a graph showing the detection result (luminance value profile) of the luminance value along the meridian direction d of the captured image data D2 with the light amount “small”. FIG. 8 is a graph showing the detection result of the luminance value along the meridian direction d of the captured image data D2 with the light amount “medium”. FIG. 9 is a graph showing the detection result of the luminance value along the meridian direction d of the captured image data D2 with the light amount “large”. In addition, code | symbol ST in each figure shows the saturation threshold value (for example, 255 if it is 8-bit data) of a luminance value.

  As shown in FIG. 7 to FIG. 9, the luminance value detection result for each captured image data D2 by the luminance value detection unit 123 includes changes in luminance values corresponding to the first ring image 87 to the eighth ring image 87, respectively. Waveforms V1 to V8 shown are included. Therefore, the luminance value of each ring image 87 can be detected for each captured image data D2 based on the detection result of the luminance value by the luminance value detection unit 123. Then, the luminance value of each ring image 87 increases in a stepwise manner as the light amount of the placido ring light L2 increases.

  Further, the reflectivity of the placido ring light L2 is low in the pupil Ep, whereas the reflectivity of the placido ring light L2 is high in the iris Ei. For this reason, in each captured image data D2, the background luminance value (the luminance value of the pupil Ep) added to the luminance value of the first ring image 87 to the third ring image 87 located on the pupil Ep is higher on the iris Ei. The background brightness value (the brightness value of the iris Ei) added to the brightness values of the fourth ring image 87 to the eighth ring image 87 located at the position is higher.

  Furthermore, as shown in FIG. 5 described above, the ring light L2a of the placido ring light L2 projected onto the outer peripheral portion of the cornea Ec is vignetted by the eyelash EL. For this reason, in each captured image data D2, the luminance value of the eighth ring image 87 is lower than the luminance values of the fourth ring image 87 to the seventh ring image 87.

  As shown in FIGS. 4 and 7 to 9, the selection unit 124 is based on the detection result of the luminance value for each captured image data D <b> 2 input from the luminance value detection unit 123, and the ring image of the placido ring image 86. For each 87 (corresponding to a portion in the reflection image of the present invention), the optimum photographed image data D2 for detecting the ring image 87 is selected from the photographed image data D2 for each light quantity.

  Specifically, the selection unit 124 selects, for each ring image 87 of the placido ring image 86, the captured image data D2 in which the luminance value (peak value) of the ring image 87 is smaller than the predetermined saturation threshold ST. Thus, the captured image data D2 having the highest SN ratio (signal-noise ratio) of the luminance value is selected from the captured image data D2 for each light quantity. The SN ratio here is [(the luminance value of the ring image 87) / (background luminance value)], in other words, the contrast ratio between the ring image 87 and the background image (pupil Ep or iris Ei).

  The luminance values of the first ring image 87 to the third ring image 87 located on the pupil Ep are respectively the photographic image data D2 (see FIG. 7) with the light amount “small” and the photographic image data D2 with the light amount “medium” (see FIG. 8). In the case of the captured image data D2 (see FIG. 9) with the light amount “large”, the saturation threshold ST is exceeded. The S / N ratio of the luminance values of the first ring image 87 to the third ring image 87 is higher in the captured image data D2 with the light amount “medium” than with the captured image data D2 with the light amount “small”. For this reason, the selection unit 124 selects the photographic image data D2 with the light amount “medium” as the optimum photographic image data D2 for detecting the third ring image 87 from the first ring image 87, and the selection result is the ring image detection. To the unit 125.

  The luminance values of the fourth ring image 87 to the seventh ring image 87 located on the iris Ei are less than the saturation threshold ST in the photographic image data D2 with the light amount “small”, whereas the luminance value is “medium”. The saturation threshold value ST is exceeded in the image data D2 and the captured image data D2 with the light amount “large”. For this reason, the selection unit 124 selects the photographic image data D2 having the light amount “small” as the optimum photographic image data D2 for detecting the fourth ring image 87 to the seventh ring image 87, and uses the selection result as the ring image detection. To the unit 125.

  Each brightness value of the eighth ring image 87 vignetted by the eyelash EL is less than the saturation threshold ST in any of the captured image data D2 with the light amount “small”, the light amount “medium”, and the light amount “large”. And among each picked-up image data D2, the SN ratio of the luminance value of the eighth ring image 87 of the picked-up image data D2 with the light amount “large” becomes the highest. For this reason, the selection unit 124 selects the photographic image data D2 with the light amount “large” as the photographic image data D2 optimal for the detection of the eighth ring image 87, and outputs the selection result to the ring image detection unit 125.

  FIG. 10 is an explanatory diagram for explaining detection of each ring image 87 by the ring image detection unit 125. As shown in FIG. 10, the ring image detection unit 125 corresponds to the part detection unit of the present invention, and based on the selection result of the captured image data D2 for each ring image 87 input from the selection unit 124, For each image 87, the ring image 87 is detected from the captured image data D2 selected by the selection unit 124. The detection of the ring image 87 here is the position detection of each position of the ring image 87, more specifically, the radius detection for each of a plurality of meridian directions d of the ring image 87.

  Specifically, the ring image detection unit 125 detects the seventh ring image 87 from the fourth ring image 87 from the captured image data D2 with the light amount “small”, and the first ring image from the captured image data D2 with the light amount “medium”. The third ring image 87 is detected from 87, and the eighth ring image 87 is detected from the photographed image data D2 with the light amount “large”.

  A known method is used for detection of each ring image 87 by the ring image detection unit 125. For example, the detection of one ring image 87 will be described as an example. The ring image detection unit 125 detects the edge intensity for each of a plurality of meridian directions d (for example, 360 at 1 ° pitch) of the ring image 87, and the meridian. The inflection point position is determined by differentiating the edge intensity of the ring image 87 for each direction d. Then, the ring image detection unit 125 determines the position of the inflection point for each meridian direction d of the ring image 87 as the position (radius) of the ring image 87. Similarly, the ring image detection unit 125 detects another ring image 87. The ring image detection unit 125 outputs the detection result of each ring image 87 to the cornea shape calculation unit 126. The method for detecting each ring image 87 is not limited to the above-described method, and various known methods may be used.

  The corneal shape calculation unit 126 calculates the corneal shape and corneal wavefront aberration of the eye E based on the detection result of each ring image 87 input from the ring image detection unit 125. Here, since the specific calculation method of a corneal shape and a corneal wavefront aberration is a well-known technique, specific description is abbreviate | omitted. The corneal shape calculation unit 126 stores the calculation result such as the corneal shape of the eye E in the storage unit 104 and displays the calculation result on the display unit 106. In addition, based on the alignment detection result in the Z-axis direction by the alignment detection unit 120 described above, an operating distance error of the ophthalmologic apparatus 10 at the time of corneal shape measurement is detected, and this error detection result is fed back to the corneal shape measurement result. Also good.

[Operation of ophthalmic apparatus]
FIG. 11 is a flowchart showing the flow of the corneal shape measurement process (corresponding to the corneal shape measurement method of the ophthalmologic apparatus of the present invention) of the eye E to be examined by the ophthalmic apparatus 10 configured as described above. In order to prevent the explanation from becoming complicated, measurement of the eye characteristics of the eye E will be omitted below.

  As shown in FIG. 11, first, the cornea shape measurement control unit 116 of the overall control unit 100 controls the fixation optical system 18 to project the fixation target light L5 onto the fundus oculi Ef of the eye E with a normal light amount. By doing so, the eye E is fixed (step S1).

  Further, the corneal shape measurement control unit 116 controls the alignment optical system 16 and the ring light projection optical system 52 so that the placido ring light L2, the pair of Z alignment light L3, and the XY alignment light are applied to the anterior eye part of the eye E to be examined. L4 is projected. Further, the cornea shape measurement control unit 116 controls the second light receiving optical system 54 to execute imaging of each reflected light (reflected image) from the eye E and output of captured image data D2 for alignment detection. . The captured image data D2 for alignment detection is input from the second light receiving optical system 54 to the alignment detection unit 120 via the second image acquisition unit 118.

  The alignment detection unit 120 analyzes the captured image data D2 for alignment detection input from the second image acquisition unit 118, the positional relationship between the third ring image 87 and the pair of bright spot images B1, and the bright spot image. Based on the position of B2, the alignment state of the ophthalmologic apparatus 10 with respect to the eye E to be examined in the XYZ axis directions is detected. Then, the alignment detection unit 120 outputs the alignment state detection result to the alignment driving unit 108. As a result, the alignment drive unit 108 performs auto-alignment of the ophthalmologic apparatus 10 with respect to the eye E (step S2). As described above, manual alignment may be performed instead of auto alignment.

  When the alignment is completed, the corneal shape measurement control unit 116 projects the placido ring light L2 with the light amount “small” onto the cornea Ec by the ring light projection optical system 52 (LED 58a) (step S3) and the second light receiving optical. The imaging of the cornea Ec by the system 54 and the output of the captured image data D2 (step S4) are executed. As a result, the first captured image data D2 corresponding to the light amount “small” of the placido light L2 is input from the second light receiving optical system 54 to the luminance value detection unit 123 via the second image acquisition unit 118. Step S3 corresponds to the pattern light projection step of the present invention, and step S4 corresponds to the cornea photographed image acquisition step of the present invention.

  After acquiring the first captured image data D2, the cornea shape measurement control unit 116 controls the ring light projection optical system 52 (LED 58a) to change the light amount of the placido ring light L2 from “small” to “medium”. (YES in step S5, step S6). Next, the corneal shape measurement control unit 116 projects the projection light L <b> 2 with the medium light amount onto the cornea Ec by the ring light projection optical system 52 (step S <b> 3), captures the cornea Ec by the second light receiving optical system 54, and Output of the captured image data D2 (step S4) is executed. As a result, the second captured image data D2 corresponding to the light amount “medium” of the placido light L2 is input from the second light receiving optical system 54 to the luminance value detection unit 123 via the second image acquisition unit 118.

  In the same manner, the corneal shape measurement control unit 116 projects the projection light L2 with the light amount “large” onto the cornea Ec by the ring light projection optical system 52 (step S3), and the cornea Ec by the second light receiving optical system 54. And the output of the captured image data D2 (step S4) are executed (YES in step S5). As a result, the third captured image data D2 corresponding to the light amount “large” of the placido light L2 is input from the second light receiving optical system 54 to the luminance value detection unit 123 via the second image acquisition unit 118. Step S5 corresponds to the projection control step and the acquisition control step of the present invention.

  The luminance value detection unit 123 that has received the input of the photographic image data D2 for each light quantity from the second image acquisition unit 118 detects the luminance value for each photographic image data D2, as shown in FIGS. (NO in step S5, step S7). Thereby, the luminance value of each ring image 87 is detected for each photographed image data D2. For this reason, step S7 corresponds to the luminance value detection step of the present invention. Then, the luminance value detection unit 123 outputs the detection result of the luminance value to the selection unit 124.

  Upon receipt of the luminance value detection result from the luminance value detection unit 123, the selection unit 124, as shown in FIGS. 7 to 9 described above, for each ring image 87, is optimal for detecting the ring image 87. The image data D2 is selected from the photographed image data D2 for each light quantity (step S8, corresponding to the selection step of the present invention). As a result, the optimum captured image data for the detection of the ring image 87 positioned on the pupil Ep, the detection of the ring image 87 positioned on the iris Ei, and the detection of the eighth ring image 87 vignetted by the eyelash EL. D2 is selected. Then, the selection unit 124 outputs the selection result of the captured image data D2 for each ring image 87 to the ring image detection unit 125.

  The ring image detection unit 125 that has received the selection result input from the selection unit 124, for each ring image 87, from the captured image data D2 selected by the selection unit 124 for each ring image 87, as shown in FIG. 87 is detected (step S9, corresponding to the site detection step of the present invention). Thereby, detection of each ring image 87 can be performed using the picked-up image data D2 optimal for each detection. As a result, each ring image 87 can be detected with high accuracy. Then, the ring image detection unit 125 outputs the detection result for each ring image 87 to the corneal shape calculation unit 126.

  The corneal shape calculation unit 126 that has received the detection result of each ring image 87 calculates the corneal shape and the corneal wavefront aberration using a known calculation method (step S10, corresponding to the corneal shape calculation step of the present invention). . Calculation results of the corneal shape and the like by the corneal shape calculation unit 126 are stored in the storage unit 104 and displayed on the display unit 106 (step S11).

[Effect of this embodiment]
As described above, in the ophthalmologic apparatus 10 according to the present embodiment, the light amount of the placido ring light L2 projected onto the cornea Ec is changed in stages, and the captured image data D2 for each light amount is acquired, and each ring image 87 is obtained. In addition, since the picked-up image data D2 most suitable for detection is selected and the detection is executed, each ring image 87 can be detected with high accuracy. As a result, the corneal shape of the eye E can be measured with high accuracy. In addition, since the captured image data D2 necessary for measuring the corneal shape can be obtained by this series of measurements, it is not necessary to repeat the measurement several times, and the burden on both the examiner and the subject can be reduced.

[Ophthalmic Device of Second Embodiment]
In the first embodiment, the measurement of the corneal shape when the center of the placido ring image 86 substantially coincides with the center of the eye E (pupil Ep and iris Ei) has been described as an example. In the embodiment, the measurement of the corneal shape in the case where the placido ring image 86 is eccentric with respect to the eye E (pupil Ep and iris Ei) will be described.

  FIG. 12 is an explanatory diagram of the captured image data D2 of the second embodiment. In FIG. 12 and subsequent figures, in order to prevent complication of the drawing, any one ring image 87 of the plurality of ring images 87 constituting the placido ring image 86 is illustrated, and the other ring images 87 are illustrated. Is omitted.

  As shown in FIG. 12, when the placido ring image 86 is eccentric with respect to the eye E or when the shape of the pupil Ep is distorted although not shown, the ring image 87 has the same diameter. The ring image 87 includes a part located on the pupil Ep and a part located on the iris Ei. For this reason, in the second embodiment, for each part in the ring image 87 along the circumferential direction of the ring image 87, the optimum photographed image data D2 for detecting the part is selected from the photographed image data D2 for each light quantity. To do.

  Since the second embodiment has basically the same configuration as that of the first embodiment, the same functions or configurations as those of the first embodiment are denoted by the same reference numerals and description thereof is omitted.

  The second image acquisition unit 118 of the second embodiment sequentially acquires the captured image data D2 for each light quantity from the second light receiving optical system 54 and the acquired captured image data D2 as in the first embodiment described above. Are sequentially output to the luminance value detection unit 123.

  FIG. 13 is an explanatory diagram for explaining the detection of the luminance value for each captured image data D2 by the luminance value detection unit 123 of the second embodiment. In addition, since the detection method of the luminance value from each picked-up image data D2 is common, the detection of the luminance value from one picked-up image data D2 is demonstrated here.

  The luminance value detection unit 123 according to the second embodiment analyzes the captured image data D2 and detects the placido ring image 86 from the captured image data D2 by a known method, whereby any ring in the placido ring image 86 is detected. The center position C of the image 87 (for example, the first ring image 87) is detected. Then, the luminance value detection unit 123 detects the luminance value of the pixel of the photographed image data D2 along the detection line α for each of a plurality of detection lines α extending radially (in the radial direction) with the center position C as a reference. The detection line α is substantially the same as the meridian direction d described above. Further, “1, 2, 3,... K,... N,. Then, the luminance value detection unit 123 detects the luminance value for the remaining two photographed image data D2 in the same manner.

  FIG. 14 is a graph showing a luminance value detection result (luminance value profile) along the k-th detection line α in FIG. 13 for each captured image data D2. FIG. 15 is a graph showing the detection result of the luminance value along the nth detection line α in FIG. 13 for each captured image data D2. As shown in FIGS. 14 and 15, the luminance value detection result along each detection line α includes a waveform V corresponding to the ring image 87. For this reason, the luminance value of the part in the ring image 87 corresponding to each detection line α can be detected for each photographed image data D2.

  As in the first embodiment, the luminance value of the portion in the ring image 87 corresponding to each detection line α increases stepwise in accordance with the increase in the amount of the placido ring light L2. Further, for example, when intersecting with the ring image 87 on the iris Ei as in the k-th detection line α, the reflectance of the placido ring light L2 by the iris Ei is increased, and thus the luminance value of the ring image 87 is increased. On the other hand, when the ring image 87 intersects the pupil Ep as in the nth detection line α, for example, the reflectance of the platid ring light L2 by the pupil Ep becomes low, and the luminance value of the ring image 87 becomes low. .

  The selection unit 124 of the second embodiment, based on the detection result of the luminance value of each detection line α for each captured image data D2 input from the luminance value detection unit 123, of the ring image 87 corresponding to each detection line α. For each part, the photographed image data D2 that is optimal for the part detection is selected from the photographed image data D2 for each light quantity.

  For example, in the k-th detection line α, the luminance value of the ring image 87 in the captured image data D2 with the light amount “small” is less than the saturation threshold ST, whereas the captured image data D2 with the light amount “medium” and the light amount “high”. The luminance value of the ring image 87 in both of the photographed image data D2 of “” exceeds the saturation threshold ST. Therefore, the selection unit 124 selects the photographic image data D2 having the light amount “small” as the photographic image data D2 that is optimal for detecting the part of the ring image 87 corresponding to the k-th detection line α, and the selection result is the ring. The image is output to the image detection unit 125.

  In the nth detection line α, the brightness value of the ring image 87 in both the captured image data D2 with the light amount “small” and the captured image data D2 with the light amount “medium” is less than the saturation threshold ST, The luminance value of the ring image 87 in the “large” captured image data D2 exceeds the saturation threshold ST. Then, the S / N ratio of the luminance value of the ring image 87 is higher in the captured image data D2 having the light amount “medium” than in the captured image data D2 having the light amount “small”. Therefore, the selection unit 124 selects the captured image data D2 with the light amount “medium” as the optimal captured image data D2 for detecting the part of the ring image 87 corresponding to the n-th detection line α, and the selection result is a ring. The image is output to the image detection unit 125.

  Similarly, the selection unit 124 outputs to the ring image detection unit 125 the selection result of selecting the photographed image data D2 that is optimal for detecting the part of the ring image 87 corresponding to the other detection line α.

  FIG. 16 is an explanatory diagram for explaining detection of each part of the ring image 87 by the ring image detection unit 125 of the second embodiment. FIG. 17 is an explanatory diagram for explaining a correspondence relationship between the part of the ring image 87 and the captured image data D2 detected by the ring image detection unit 125 of the second embodiment. Here, the mth detection line α to the uth detection line α (including the nth detection line α) intersect the ring image 87 on the pupil Ep, and the other detection lines α (including the kth detection line α). ) Crosses the ring image 87 on the iris Ei.

  As shown in FIGS. 16 and 17, the ring image detection unit 125 of the second embodiment is applied to each detection line α based on the selection result of the captured image data D2 for each detection line α input from the selection unit 124. For each corresponding part of the ring image 87, the part is detected from the captured image data D2 selected by the selection unit 124. The part detection here is part position detection, more specifically, part radius detection.

  For example, in the range R1 (see FIG. 17) from the m-th detection line α to the u-th detection line α, the light quantity “medium” is selected by the selection unit 124 as in the case of the n-th detection line α shown in FIG. The photographed image data D2 is selected. For this reason, the ring image detection unit 125 detects the part of the ring image 87 corresponding to each of the mth detection line α to the uth detection line α from the captured image data D2 with the light amount “medium”.

  In addition, in each detection line α in the range R2 (see FIG. 17) different from the range R1, the picked-up image with the light amount “small” is selected by the selection unit 124 as in the kth detection line α shown in FIG. Data D2 is selected. For this reason, the ring image detection unit 125 detects the portion of the ring image 87 corresponding to each of the remaining detection lines α from the captured image data D2 with the light amount “small”.

  Then, the ring image detection unit 125 outputs a detection result for each part of the ring image 87 corresponding to each detection line α to the corneal shape calculation unit 126.

  Similarly, the ring image analysis unit 122 (the luminance value detection unit 123, the selection unit 124, and the ring image detection unit 125) of the second embodiment is used for each portion of the other ring image 87 (not shown) of the placido ring image 86. Detection is executed, and the detection results of each part of the other ring image 87 are input to the corneal shape calculation unit 126.

  The corneal shape calculation unit 126 of the second embodiment calculates the corneal shape and corneal wavefront aberration of the eye E based on the detection result of each part for each ring image 87, as in the first embodiment.

  The flow of the eye characteristic and corneal shape measurement processing of the eye E by the ophthalmologic apparatus 10 of the second embodiment is the same as that of the first embodiment except for steps S7 to S9 shown in FIG. Are the same. That is, in the second embodiment, in step S7, the luminance value of the part in the ring image 87 corresponding to each detection line α is detected for each captured image data D2. Further, in the second embodiment, the picked-up image data D2 optimum for detection is selected for each part of the ring image 87 corresponding to each detection line α in step S8, and detected for each part of the ring image 87 in step S9. I do.

  As described above, also in the second embodiment, the light amount of the placido ring light L2 projected onto the cornea Ec is changed in stages, and the captured image data D2 for each light amount is acquired, and each part of the ring image 87 is obtained. By selecting the photographed image data D2 that is optimal for the detection of this and executing the detection, each part of the ring image 87 can be detected with high accuracy. As a result, the corneal shape of the eye E can be measured with high accuracy even when the placido ring image 86 is decentered with respect to the eye E or the shape of the pupil Ep is distorted.

[Others]
In the above-described embodiment, the eight-fold plactide light L2 has been described as an example of the pattern light for corneal shape measurement according to the present invention. However, the single or double plactide light L2 (including kerattling light) is described. The pattern light is not particularly limited as long as it is a pattern light that can be used for measuring a corneal shape such as dot light of a predetermined pattern.

  In the above embodiment, the corneal shape measurement control unit 116 controls the ring light projection optical system 52 to change the light amount of the placido ring light L2 projected onto the eye E in three stages. The amount of light may be changed at least once, and the number of times is not particularly limited. Further, in this case, the corneal shape measurement control unit 116 controls the second light receiving optical system 54 to capture the placido ring image 86 and output the captured image data D2 each time the light amount of the placido ring light L2 is changed. And re-execute. Thereby, at least two or more photographic image data D2 for each light quantity are obtained.

  In the above-described embodiment, the luminance value detection unit 123 starts the detection of the luminance value after the acquisition of the captured image data D2 for each light amount is completed. For the detection of the luminance value, the second light receiving optical system is used. It may be executed sequentially each time new photographed image data D2 is acquired by 54.

  In the above embodiment, the case where the ocular refractive power or the like is measured as the eye characteristic of the eye E by the ophthalmologic apparatus 10 has been described as an example. However, various eye characteristics other than the eye refractive power [intraocular pressure, fundus optics, Measurement of tomographic image, corneal endothelial cell, axial length, etc.] may be performed.

  In the above-described embodiment, the ophthalmologic apparatus 10 has been described by taking as an example a multi-function machine that measures both the eye characteristics of the eye E to be examined and the cornea shape of the cornea Ec. A corneal shape measuring device such as a corneal topographer for measuring the shape, and a keratometer for measuring a corneal curvature in a partial region of the cornea Ec are also included.

10 ... ophthalmic device,
14 ... Corneal shape measurement optical system,
52. Ring light projection optical system,
54. Second light receiving optical system,
58 ... Platide ring,
86 ... Platide ring image,
87 ... Ring statue,
100: General control unit,
116 ... corneal shape measurement control unit,
123 ... luminance value detection unit,
124 ... selection part,
125 ... Ring image detection unit,
126 ... corneal shape calculation unit

Claims (6)

A pattern light projection optical system that projects pattern light for corneal shape measurement onto the cornea of the eye to be examined; and
A cornea photographing image acquisition unit that images the cornea on which the pattern light is projected from the pattern light projection optical system and acquires a cornea photographing image including a reflection image of the pattern light;
A projection control unit that changes the amount of the pattern light projected onto the cornea from the pattern light projection optical system at least once;
An acquisition control unit that re-executes acquisition of the corneal imaging image by the corneal imaging image acquisition unit every time the light amount of the pattern light is changed by the projection control unit;
A luminance value detection unit that detects a luminance value of the reflected image from the cornea image acquired by the cornea image acquisition unit for each light amount of the pattern light;
Based on the detection result of the luminance value detection unit, for each part in the reflection image, a selection unit that selects the corneal photographing image optimal for detection of the part from the corneal photographing images for each light amount;
Based on the selection result of the selection unit, for each site, a site detection unit that detects the site from the cornea image selected by the selection unit;
Based on the detection result for each part by the part detection unit, a corneal shape calculation unit that calculates the corneal shape of the eye to be examined;
An ophthalmic device comprising:   The light quantity of the cornea image in which the SN ratio of the luminance value is the highest among the cornea images in which the luminance value of the region is smaller than a predetermined saturation threshold is selected by the selection unit. The ophthalmologic apparatus according to claim 1, wherein the ophthalmologic apparatus is selected from other cornea images. The pattern light projection optical system projects, as the pattern light, a placido ring light composed of a plurality of concentric ring lights onto the eye to be examined,
The cornea photographed image acquisition unit obtains the cornea photographed image including a placido ring image composed of a plurality of concentric ring images as the reflected image,
The brightness value detection unit detects the brightness values of the plurality of ring images in the placido ring image for each cornea image.
For each ring image, the selection unit selects the cornea image that is optimal for detection of the ring image from the cornea image for each light amount,
The part detection unit detects the ring image from the cornea image selected by the selection unit for each ring image,
The ophthalmic apparatus according to claim 1, wherein the corneal shape calculation unit calculates the corneal shape based on a detection result for each ring image. The pattern light projection optical system projects ring light onto the eye as the pattern light,
The cornea photographed image acquisition unit obtains the cornea photographed image including a ring image as the reflected image,
The luminance value detection unit detects the luminance values of the plurality of parts in the ring image along the circumferential direction of the ring image for each cornea image.
The selection unit selects, for each part in the ring image, the corneal photographing image that is optimal for detection of the part from the corneal photographing images for each light amount,
The ophthalmologic apparatus according to claim 1, wherein the part detection unit detects the part from the cornea image selected by the selection unit for each part.   The ophthalmologic apparatus according to claim 1, wherein the pattern light projection optical system projects the pattern light, which is invisible light, onto the eye to be examined. A pattern light projection step of projecting pattern light for measuring the shape of the cornea onto the cornea of the eye to be examined;
Photographing the cornea on which the pattern light is projected in the pattern light projecting step, and obtaining a cornea photographed image including a reflection image of the pattern light; and
A projection control step of changing the light amount of the pattern light projected onto the cornea in the pattern light projection step at least once;
Each time the amount of the pattern light is changed by the projection control step, an acquisition control step that re-executes the cornea image acquisition step,
A luminance value detecting step of detecting a luminance value of the reflected image from the cornea captured image acquired for each light quantity of the pattern light in the cornea captured image acquiring step;
Based on the detection result of the luminance value detection step, for each part in the reflection image, a selection step for selecting the reflection image optimal for detection of the part from the reflection image for each light amount;
Based on the selection result of the selection step, for each part, a part detection step for detecting the part from the reflection image selected in the selection step;
Based on the detection result for each region by the region detection step, a corneal shape calculation step for calculating the corneal shape of the eye to be examined;
A method for measuring a corneal shape of an ophthalmologic apparatus.

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