JP2021074101A - Ophthalmologic measuring device - Google Patents

Abstract

To acquire shape information on an eye to be examined easily.SOLUTION: An ophthalmologic measuring device for measuring an eye to be examined includes: a projection optical system for projecting an index onto an anterior eye part of the eye to be examined; imaging means for acquiring an image of an anterior eye part of the eye to be examined by imaging the anterior eye part onto which the index is projected; position information acquisition means for acquiring designated position information when an examiner designates a position on a Purkinje image by the index in the image of the anterior eye part; and calculation means for acquiring shape information on the anterior eye part on the basis of the designated position information.SELECTED DRAWING: Figure 5

Description

The present disclosure relates to an ophthalmic measuring device for measuring an eye to be inspected.

As an ophthalmic measuring device, for example, a plurality of indexes are projected onto the anterior segment of the eye, and the anterior segment of the eye is photographed from the front direction. A device for measuring the shape of the anterior segment of the eye to be inspected by analyzing the reflected image of the index of is known. In such an apparatus, for example, the shape of the posterior surface of the cornea (for example, the curvature of the posterior surface of the cornea) can be measured by analyzing the reflected image (second Purkinje image) of the index by the posterior surface of the cornea. For example, the curvature of the posterior surface of the cornea is used to calculate the power of the intraocular lens.

Japanese Unexamined Patent Publication No. 2015-104554

However, in the conventional apparatus, when the amount of reflected light of the Purkinje image is small, it may not be detected from the anterior segment image, or it may be erroneously detected as another bright spot due to the influence of noise light. Therefore, it may be difficult to obtain the shape information of the eye to be inspected.

The present disclosure has been made in view of the conventional problems, and an object of the present disclosure is to easily obtain shape information of the eye to be inspected.

In order to solve the above problems, the present disclosure is characterized by having the following configurations.

(1) An ophthalmic measuring device for measuring an eye to be inspected, wherein the subject is photographed by photographing a projection optical system that projects an index onto the anterior segment of the eye to be inspected and the anterior segment on which the index is projected. An imaging means for acquiring an anterior ocular segment image for optometry, a position information acquisition means for acquiring designated position information when the examiner specifies a position related to a Purkinje image according to the index in the anterior segment image, and the designated position. It is characterized by comprising a calculation means for acquiring the shape information of the anterior segment based on the information.

According to the present disclosure, the shape information of the eye to be inspected can be easily obtained.

It is a schematic block diagram of the ophthalmic measuring apparatus in an Example. It is a figure which showed the projection optical system for corneal shape measurement seen from the side of the eye to be examined. It is a figure which showed the front eye part image which the 1st measurement index and the 2nd measurement index were projected and photographed. It is a flowchart which shows the operation of the apparatus in an Example. It is a figure which shows an example of the correction screen. It is a figure which shows an example of the correction screen.

<Embodiment>
Hereinafter, embodiments according to the present disclosure will be described. The ophthalmic measuring device of the present embodiment (for example, the ophthalmic measuring device 1) measures, for example, the shape of the anterior segment of the eye to be inspected. The ophthalmic measuring apparatus includes a projection optical system (for example, a projection optical system 30), an imaging unit (for example, an imaging optical system 20), a position information acquisition unit (for example, a control unit 100), and a calculation unit (for example, a control unit). 100) is provided. The projection optical system, for example, projects an index onto the anterior segment of the eye to be inspected. The photographing unit acquires an image of the anterior segment of the eye to be inspected, for example, by photographing the anterior segment on which the index is projected from the front direction (however, it does not have to be directly in front). The position information acquisition unit acquires the designated position information when the examiner specifies the position related to the Purkinje image based on the index in the anterior segment image. The designated position information may be, for example, the position information when the examiner specifies the position where the Purkinje image exists in the anterior segment image, or the examiner determines the position where the Purkinje image does not exist in the anterior segment image. It may be the position information at the time of designation. The Purkinje image appears as a bright spot on the anterior segment image. The calculation unit acquires, for example, the shape information of the anterior segment based on the designated position information.

By providing the above configuration, the ophthalmic measuring device provides shape information of the eye to be inspected based on the position regarding the Purkinje image specified by the examiner even when the Purkinje image cannot be automatically detected from the anterior segment image. (Corneal curvature, etc.) can be obtained. Therefore, it is possible to save the trouble of retaking the image of the anterior segment of the eye, and it is possible to easily acquire the shape information of the eye to be inspected.

The position information acquisition unit may receive, for example, an operation signal output from the operation unit (for example, the operation unit 80) in response to the operation of the examiner. For example, the examiner specifies the position related to the Purkinje image by operating the operation unit while checking the image of the anterior segment displayed on the display unit (for example, the monitor 70), and the position information acquisition unit at this time. The designated position information may be acquired based on the operation signal.

The calculation unit may detect the Purkinje image from the anterior segment image based on the designated position information and acquire the shape information based on the detection position of the Purkinje image. By providing the above configuration, the ophthalmologic measuring device can use some of the designated position information specified by the examiner even when it is difficult to detect the Purkinje image from the entire anterior segment image, for example. By performing image analysis in the region, the possibility that the Purkinje image can be detected increases. For example, the arithmetic unit may detect the Purkinje image by performing image analysis in the peripheral area of the position designated by the examiner, or may detect the Purkinje image by performing image analysis in the area designated by the examiner. Detection may be performed. When the examiner specifies a position where the Purkinje image does not exist, the arithmetic unit may detect the Purkinje image by performing image analysis at a position other than the position specified by the examiner.

The projection optical system may project a plurality of indexes onto the eye to be inspected. In this case, a plurality of Purkinje images are reflected at different positions on the anterior segment image. The position information acquisition unit may acquire the designated position information when the examiner specifies the position related to one of the Purkinje images corresponding to any of the plurality of indexes, or corresponds to each of the plurality of indexes. A plurality of designated position information when the examiner specifies the position regarding the Purkinje image to be used may be acquired. The calculation unit may acquire the shape information of the eye to be inspected based on a plurality of designated position information, or based on both the detection position of the Purkinje image automatically detected from the anterior segment image and the designated position information. The shape information of the eye to be inspected may be acquired.

The Purkinje image may be a second Purkinje image. For example, in the second Purkinje image, the index luminous flux projected by the projection optical system is reflected on the posterior surface of the cornea and reflected in the anterior segment image. In this case, the calculation unit may acquire shape information regarding the posterior surface of the cornea based on at least one of the designated position information and the second Purkinje image. Since the reflected light amount of the second Purkinje image is small, it is difficult to detect it from the anterior segment image. Further, the second Purkinje image may be erroneously detected as the fourth Purkinje image (reflective image on the posterior surface of the crystalline lens) by another index. Therefore, by using the designated position information designated by the examiner as in this device, the possibility that the second Purkinje image can be accurately detected increases.

The arithmetic unit may perform image processing on the front eye portion image to improve the visibility of the Purkinje image. For example, the control unit may perform image processing that locally emphasizes the contrast (for example, CLAHE), or performs image processing that emphasizes the structure based on the eigenvalues of the Hessian matrix (for example, blobness filter). You may. This facilitates the examiner's designation of the position of the Purkinje image.

When a plurality of indexes are projected onto the anterior segment of the eye by the projection optical system, the arithmetic unit is acquired by performing fitting processing on the detection positions of the plurality of Purkinje images detected from the images of the anterior segment of the eye. At least one of the fitting result and the fitting error may be displayed on the display unit (for example, the monitor 70). This makes it easier for the examiner to specify or correct the position of the Purkinje image because the examiner can confirm how likely the automatically detected point is. The fitting process is, for example, a process of fitting an ellipse or other figure to the detection position of the Purkinje image. The figure to be fitted may be set based on the arrangement of the index projected on the eye to be inspected. The fitting result is, for example, a fitted figure. In the case of ellipse fitting, for example, the calculation unit superimposes the position of the currently detected Purkinje image (bright spot) and the fitted ellipse on the anterior segment image and displays it. Further, the fitting error may be, for example, a numerical value based on the distance between the detected Purkinje image and the fitted figure (contour).

The calculation unit may display a plurality of fitting results on the display unit, or may display the fitting results having a small fitting error (high evaluation value) on the display unit.

The calculation unit may perform a fitting process when a predetermined number or more of Purkinje images are detected. For example, if 6 or more points of the second Purkinje image can be detected, a fitting process may be performed. Of course, even if the second Purkinje image can be detected at only 5 points or less, the fitting process may be performed as long as the second Purkinje image is detected evenly with respect to the predetermined arrangement. For example, if there is no large bias in the distance between the detected plurality of second Purkinje images, the fitting process may be performed.

The arithmetic unit may display a candidate point that may be a Purkinje image on the display unit in the anterior eye portion image. As a result, the examiner only has to specify a point that seems to be a Purkinje image from the candidate points, and saves the trouble of searching for a Purkinje image from scratch.

The calculation unit may acquire the shape information by excluding the detection position or the candidate point designated by the examiner. This makes it possible to prevent the corneal shape from being calculated based on the detection positions of other bright spots that are not Purkinje images.

The calculation unit may determine whether or not the automatic detection of the Purkinje image has been successful, and the notification unit may notify the examiner of the determination result at that time. This allows the examiner to easily grasp that it is necessary to specify the position of the Purkinje image or correct the detection position. The arithmetic unit may notify the examiner only when the automatic detection fails and prompt the examiner to specify the position of the Purkinje image or correct the detected position. The notification unit may be, for example, a display unit, a voice output unit, or the like. The display unit may be a display or an indicator light. The audio output unit may be, for example, a speaker or the like.

The calculation unit may determine, for example, the success or failure of automatic detection based on the fitting error when the detected Purkinje image is subjected to the fitting process. For example, the calculation unit may determine that the automatic detection of the Purkinje image has succeeded when the fitting error is small, and may determine that the automatic detection has failed when the fitting error is large. Since the shape of the fitted figure can be estimated to some extent from the arrangement of the index projected on the eye to be inspected, the calculation unit may determine the success or failure of the automatic detection based on the shape of the fitted figure. For example, when performing ellipse fitting, the calculation unit may determine that the automatic detection has failed when the ratio of the major axis to the minor axis is large.

Further, the calculation unit may perform a success / failure determination depending on, for example, whether or not the detected Purkinje image is included in the peripheral region of the fitted figure. For example, the arithmetic unit has the same ratio of major axis to minor axis with respect to the fitted ellipse, and whether or not there is a Purkinje image between two concentric ellipses, a small ellipse with a small size and a great ellipse with a large size. The success or failure may be determined by. That is, the success or failure may be determined based on whether or not the Purkinje image is detected in the region outside the small ellipse and inside the great ellipse.

Further, the calculation unit may determine, for example, the success or failure of the automatic detection based on the number of detected Purkinje images. For example, if a Purkinje image that is more than half of the number of projected indexes is detected, it may be determined that the automatic detection is successful, and if it is not detected, it may be determined that the automatic detection has failed. Further, if more than the minimum number of Purkinje images required for fitting is detected, it may be determined that the automatic detection is successful, and if it is desired to be detected, it may be determined that the automatic detection has failed.

When the automatic detection fails, the calculation unit may notify the examiner that the automatic detection may have failed by displaying the fitting result and the fitting error on the display unit.

<Example>
Hereinafter, exemplary embodiments of the present disclosure will be described with reference to the drawings.
<Outline configuration of the device>
The schematic configuration of the ophthalmic measuring device 1 according to the embodiment will be described with reference to FIGS. 1 and 2. In the following, "ophthalmology measuring device 1" will be abbreviated as "this device 1".

The apparatus 1 measures the cornea of the eye E to be inspected. At least, an anterior segment image (anterior segment anterior image) taken from the front direction is acquired, and information on the posterior surface of the cornea of the eye E to be inspected is obtained based on the second Purkinje image included (drawn) in the image. To be acquired.

As shown in FIG. 1, the apparatus 1 has at least a projection optical system 30, a photographing optical system (sometimes referred to as a “light receiving optical system”) 20, and a control unit 100. Further, the apparatus 1 may include a topo projection optical system 10 (an example of a "second projection optical system"), a measurement optical system 40, and an optometry optical system 50. The above-mentioned optical system is built in a housing (not shown). The housing is three-dimensionally moved with respect to the subject's eye by driving a well-known alignment movement mechanism 60. For example, the housing may be moved based on the operation of an operating member (eg, a joystick).

<Shooting optics>
The photographing optical system 20 includes an image pickup device 27 for capturing an image of the anterior segment of the eye to be inspected E. In the photographing optical system 20, the reflected light from the anterior segment of the eye is received by the image sensor 27. Then, an anterior segment image is generated based on the received signal from the image sensor 27. In this case, the light source of the illumination light to be applied to the anterior segment of the eye to generate the reflected light may be appropriately selected from the light source 11 and the observation light source (not shown).

In FIG. 1, the photographing optical axis of the photographing optical system 20 is illustrated as an optical axis L1. For convenience, the following description will be made assuming that the image center of the anterior segment image and the optical axis L1 coincide with each other. Further, for convenience, the optical axis L1 is shared with the measurement optical axis when measuring the cornea, which will be described later.

As an example, the photographing optical system 20 shown in FIG. 1 includes a dichroic mirror 23, an objective lens 24, a mirror 25, and an image pickup lens 26 in addition to the image pickup element 27. The image sensor 27 may be arranged at a position conjugate with the anterior segment of the eye to be inspected, for example. The dichroic mirror (beam splitter) 23 is an optical path branching member for branching the optical path of the photographing optical system 20 from the optical path of the measuring optical system 40 (details will be described later). Further, the optical axis L1 (shooting optical axis) is also used as the projected optical axis of the fixation lamp 51.

<Topo projection optical system>
The topo projection optical system 10 is used for measuring the anterior corneal shape. In the present embodiment, the topo projection optical system 10 uses a multiple ring image (platidd ring image or multiple Meyer ring image) as a measurement index (“third measurement index” in the present embodiment) in the topography examination of the anterior surface of the cornea. , Project on the cornea.

In the embodiment, the topo projection optical system 10 has a light source 11 and a plated plate 12 (see FIG. 2). The platinum plate 12 is arranged between the eye E to be inspected and the light source 11. Light from the light source 11 is projected onto the cornea in a ring shape from the concentric light emitting portions formed on the plated plate 12. The light emitted by the light source 11 may be visible light or infrared light.

The multiple ring image projected by the topo projection optical system 10 is photographed by the photographing optical system 20. Then, the captured multiple ring image is analyzed and the corneal topography is calculated. For a more detailed derivation method of corneal topography, refer to, for example, "Japanese Unexamined Patent Publication No. 10-108837" by the applicant.

The shape of the measurement index (third measurement index) projected by the topo projection optical system 10 is not necessarily limited to the multiple ring image. The measurement index may be a line or another two-dimensional pattern formed by a plurality of points. Specific examples include, in addition to the ring-shaped pattern illustrated above, a pattern consisting of a dot matrix in which point indexes are arranged in a grid pattern. Of course, patterns other than these may be used.

The ring-shaped pattern may form a continuous ring without interruption, or may form an intermittent ring pattern. The intermittent ring pattern may project a broken line ring onto the cornea, or may project a plurality of point indexes arranged on the circumference onto the cornea, and may be a combination of these. May be good.

Further, the cone method may be applied instead of the measurement method using the plated plate. In the cone method, instead of the plated plate 12, the cone forms the pattern in the third measurement index.

<Projection optics>
The projection optical system 30 projects an index for measuring information on the posterior surface of the cornea (hereinafter, referred to as a “measurement index” for convenience) onto the cornea. The measurement index is projected from an oblique direction with respect to the optical axis L1 (photographing optical axis). In the present embodiment, the measurement index is mainly projected to the region near the central part of the cornea in the proper alignment state. The proper alignment state may be, for example, a state in which the optical axis (visual axis) of the eye to be inspected substantially coincides with the optical axis L1.

The information regarding the posterior surface of the cornea may be, for example, information indicating the shape of the posterior surface of the cornea itself. Information indicating the shape of the posterior surface of the cornea itself includes, for example, the shape of the posterior surface of the cornea (topography, evasion, etc.), curvature (keratometry), position, and the like. Further, the information regarding the posterior surface of the cornea may be, for example, information specified by both the anterior and posterior surfaces of the cornea. Information specified by both the anterior and posterior surfaces includes, for example, corneal thickness, refractive power, and astigmatic axis angle in the cornea.

In the present embodiment, the measurement index projected by the projection optical system 30 toward the cornea of the eye to be inspected is divided into a first measurement index and a second measurement index. The first measurement index is projected with respect to the optical axis L1 symmetrically with the second measurement index. In other words, the projected optical axis of the first measurement index and the projected optical axis of the second measurement index are provided symmetrically with respect to the optical axis L1.

The anterior segment image obtained with the first measurement index and the second measurement index projected on the cornea includes the first Pulkinje image (reflection image by the anterior surface of the cornea) and the second Pulkinje image (reflection by the posterior surface of the cornea) of the measurement index. Image), a third Pulkinje image (reflection image by the front surface of the crystalline lens), and a fourth Pulkinje image (reflection image by the rear surface of the crystalline lens) can occur. Among them, the first Purkinje image is the brightest and is formed at the position farthest from the optical axis L1. The second Purkinje image is formed between the first Purkinje image and the optical axis L1. The third Purkinje image is formed closest to the optical axis L1 in each Purkinje image, and is easily distinguishable from other Purkinje images in this respect. The fourth Purkinje image is formed with the same brightness as the second Purkinje image. The fourth Purkinje image is an inverted image and is formed at a position substantially symmetrical with the second Purkinje image with the optical axis L1 in between.

Here, since the first measurement index and the second measurement index are projected symmetrically with respect to the optical axis L1, the fourth Pulkinje image (reflection image by the posterior surface of the crystalline lens) of the first measurement index is the anterior segment of the eye. In the image, the second Pulkinje image of the second measurement index (reflection image by the posterior surface of the cornea) is formed, and the fourth Pulkinje image of the second measurement index is the second Pulkinje image of the first measurement index in the anterior segment image. It is formed near the image. It should be noted that the vicinity referred to here includes the case where two bright spot images overlap.

The projection optical system 30 has a light source 31. The light emitted by the light source 31 may be infrared light or visible light. The projection optical system 30 may have a configuration in which the light emitted from the light source 31 is projected onto the cornea as a measurement index. The measurement index is preferably a line or a two-dimensional pattern formed by a plurality of points. More specific examples of the pattern include a ring-shaped pattern, a pattern consisting of a dot matrix in which point indexes are arranged in a grid pattern, and the like. By using the measurement index as a point, it becomes easy to detect a second Purkinje image having low brightness. Of course, the measurement index may be projected in a pattern other than these. The ring-shaped pattern is not limited to the pattern forming one ring, and may be a pattern forming multiple rings (a plurality of concentric rings). Further, the ring-shaped pattern may be one that forms a continuous ring without interruption, or may be one that forms an intermittent ring pattern. The intermittent ring pattern may project a broken line ring onto the cornea, or may project a plurality of point indexes arranged on the circumference onto the cornea, and may be a combination of these. May be good.

In the embodiment, the projection optical system 30 projects an intermittent ring pattern based on eight measurement indexes onto the cornea. The projection optical system 30 has a ring-shaped light source formed by eight point light sources 31a to 31h and openings 13a to 13h formed in the plated plate 12 (see FIG. 2).

In FIG. 2, the point light sources 31a to 31h are arranged on the back surface of the plated plate 12 when viewed from the eye E to be inspected. For example, the plated plate 12 has eight openings (13a to 13h) formed on the circumference centered on the optical axis L1, and the light from the respective point light sources 31a to 31h is the openings 13a to 13a. It is projected via 13h. Each of the openings 13a to 13h is formed on a meridian that equally divides the circumference. In FIG. 2, openings 13a to 13h are formed one by one on four meridian lines that divide the circumference into eight equal parts. In the embodiment of FIG. 2, the case where the point light sources 31a to 31h are provided on the back surface of the plated plate 12 will be described, but the present invention is not limited to this, and for example, the point light sources 31a to 31h are provided on the front surface of the plated plate 12. It may be arranged. That is, the ring-shaped light source may be a light source formed in a ring shape, a plurality of point light sources arranged in a ring shape, a plurality of point light sources arranged in a ring shape, and the like. It may be configured in combination with a ring-shaped pattern opening arranged in front of a point light source.

In the embodiment, as an example, the indexes projected from the point light sources 31a to 31d are used as the first measurement index, and the indexes projected from the point light sources 31e to 31h are used as the second measurement index. This will be described below.

FIG. 3 shows a first Purkinje image, a second Purkinje image, and a fourth Purkinje image formed based on the lighting of each point light source 31a to 31h in the anterior segment image (in FIG. 3, the third Purkinje image is shown. 3 Purkinje image is omitted).

In FIG. 3, the first Purkinje image, the second Purkinje image, and the fourth Purkinje image formed based on the lighting of the point light source 31a are indicated by reference numerals Ia1, Ia2, and Ia4, respectively. Further, the first Purkinje image, the second Purkinje image, and the fourth Purkinje image formed based on the lighting of the point light source 31b are designated by the reference numerals Ib1, Ib2, and Ib4, and similarly ... The first Purkinje image, the second Purkinje image, and the fourth Purkinje image formed based on the lighting are designated by Ih1, Ih2, and Ih4, respectively.

<Alignment optical system>
The index projected from the projection optical system 30 onto the cornea may be used as an alignment index. In this case, the index from the projection optical system 30 is used for alignment in the vertical direction (Y direction) and the horizontal direction (X direction). Further, in this case, a part of the indexes that can be projected from the projection optical system 30 onto the cornea may be used for alignment. For example, indexes emitted from the four point light sources of 31b, 31c, 31f, and 31g may be used as alignment indexes. In this case, the projection optical system 30 and the photographing optical system 20 also serve as an alignment optical system in the X and Y directions. The apparatus 1 may further have an optical system (not shown) that projects parallel light (infinity index) onto the cornea in order to perform alignment in the anteroposterior direction (Z direction). Alignment in the anteroposterior direction (Z direction) may be performed by a combination of parallel light and finite light by the projection optical system 30 (for details, refer to JP-A-6-46999 or the like). .. In this case, the projection optical system 30 and the photographing optical system 20 are included in the alignment optical system in the Z direction.

Of course, the alignment optical system used for alignment in each direction is not necessarily limited to the above-exemplified one. For example, a projection optical system for an alignment index may be provided separately from the projection optical system 30.

<Optometry optical system>
The fixation optical system 50 is used to guide the line-of-sight direction of the eye E to be inspected and to fix the eye E to be inspected at the time of measurement. In the present embodiment, the optometry optical system 50 has an internal optometry marker provided in the main body of the apparatus. That is, the optometry optical system 50 projects the optometry target from the inside of the device main body (in other words, the inside of the housing). In the present embodiment, the fixation optical system 50 guides at least the line-of-sight direction (visual axis) of the eye E to be inspected in the direction along the optical axis L1.

The optometry optical system 50 includes a visible light source (optometry lamp) 51, a projection lens 53, and a visible reflection / infrared transmission dichroic mirror 43. In this embodiment, the fixation lamp 51 is used as an internal fixation target. The visible light emitted from the fixation lamp 51 is converted into a parallel light flux by the projection lens 53, then reflected by the dichroic mirror 43, and projected as a fixation target on the fundus of the eye E to be inspected.

<Measurement optical system>
The measurement optical system 40 is used to measure the eye characteristics of the eye to be inspected, which are different from the information about the cornea of the eye to be inspected. The measurement optical system 40 includes, for example, an axial length measuring optical system that receives interference light from the measurement light and the reference light to measure the axial length, and an eye that receives the reflected light projected on the fundus of the eye of the subject. It may be an ocular refractive force measuring optical system or the like for measuring the refractive force.

In FIG. 1, the measurement optical system 40 is provided in the transmission direction of the dichroic mirror 23. The measuring optical system 40 includes at least a measuring optical unit 41. In FIG. 1, the measurement optical system 40 further includes a dichroic mirror 43. Further, the measurement optical system 40 shown in FIG. 1 shares the dichroic mirror 23 with the photographing optical system 20. The measurement optical unit 41 has a configuration in which a second measurement light is projected onto the eye of the subject and the reflected light is received. The measurement optical unit 41 may have a light source 42 that emits measurement light.

<Control system>
Next, the control system of the present device 1 will be described.

The present device 1 includes a control unit (processor) 100. The control unit 100 executes control processing for the entire device and various arithmetic processing.

The control unit 100 may include a CPU, ROM, RAM, and the like. Temporary data used for shooting and measurement is stored in the RAM, for example.

The control unit 100 is connected to, for example, a light source 11, 31, 51, an image sensor 27, a measurement optical unit 41, an alignment movement mechanism 60, a monitor 70, an operation unit 80, a storage device 105, and the like via a bus or the like.

The storage device 105 is a rewritable non-volatile storage device. In FIG. 1, the hard disk is illustrated as the storage device 105, but the present invention is not limited to this, and other storage devices such as a flash memory and a USB memory may be applied. In the storage device 105, for example, at least a program for causing the control unit 100 to execute various shooting processes, measurement processes, and the like may be stored. Further, the storage device 105 may store an anterior ocular segment image captured by the ophthalmologic measuring device 1.

On the monitor 70, various images taken by the present device 1, various measurement results measured by the present device 1, and the like are displayed.

The operation unit 80 is an input interface in the present device 1. When the operation unit 80 is operated by the examiner, an instruction corresponding to the operation is input to the control unit 100. The operation unit 80 may be, for example, a pointing device such as a mouse and a touch panel, a keyboard, or various buttons installed in the housing of the present device 1. Further, the joystick operated for alignment may be used as one of the operation units 80.

<Operation>
Next, with reference to the flowchart shown in FIG. 4, the measurement operation when the apparatus 1 acquires information on the posterior surface of the cornea will be described.

First, the optical system is aligned with the eye to be inspected (S1). Here, a case where alignment is automatically performed by controlling each part of the device by the control unit 100 is shown. However, the alignment may be performed manually. Further, it may be performed by a combination of manual alignment (coarse adjustment) and automatic alignment (fine adjustment).

At the time of alignment, the control unit 100 lights the fixation lamp 51a and the light sources 31b, 31c, 31f, 31g of the projection optical system 30. Further, the control unit 100 monitors a live image (observation image) of the anterior segment image of the eye E to be inspected based on the imaging signal output from the image pickup device 27 when the light sources 31b, 31c, 31f, and 31g are turned on. Display on 70. Further, the control unit 100 may electronically display the reticle indicating the alignment reference position (here, the position of the optical axis L1) on the monitor 70. At this time, the examiner urges the examinee to fix the fixation target.

After that, the control unit 100 detects the index by the light sources 31b, 31c, 31f, 31g based on the image pickup signal from the image pickup element 27. The control unit 100 drives the alignment movement mechanism 60 based on the detection result so that the centers of the four index images Ib1, Ic1, If1 and Ig1 are aligned with the alignment reference position (here, the position of the optical axis L1). The optical system of the ophthalmic measuring device 1 is moved so as to be arranged. Further, the control unit 100 projects an index (not shown) for detecting the working distance and controls the alignment movement mechanism 60 based on the image pickup signal from the image pickup element 27 to control the distance from the device to the corneal apex. Align in the front-rear direction so that (that is, the working distance) becomes a predetermined distance. In this embodiment, the control unit 100 turns off the light source 31 after the alignment is completed.

Next, the control unit 100 measures the shape of the anterior surface of the cornea (S2). The measurement of the corneal anterior shape in the present embodiment is performed by projecting a measurement index for measuring the corneal anterior shape onto the cornea from the topo projection optical system 10 provided separately from the projection optical system 30. Here, the measurement index by the multiple ring is projected from the topo projection optical system 10 onto the cornea. Then, an anterior segment image including a multiple ring image, which is a front reflection image of the cornea as a measurement index, is photographed via the photographing optical system 20. Based on the multiple ring image included in the anterior segment image, the control unit 100 acquires information indicating the anterior corneal shape. After the shooting or measurement is completed, the light source 11 of the topo projection optical system 10 is turned off.

Next, the processes S3 to S7 are executed by the control unit 100, whereby the apparatus 1 performs the measurement on the posterior surface of the cornea.

First, the control unit 100 projects the first measurement index and the second measurement index from the projection optical system 30 onto the cornea of the eye E to be inspected, and in that state, takes an image of the anterior eye portion (S3). For example, the light sources 31a to 31h of the projection optical system 30 are turned on all at once. Then, in this state, the anterior segment image is photographed via the photographing optical system 20. In the anterior segment image taken in this way, as shown in FIG. 3, the first Pulkiner image Ia1 to Ih1 and the second Pulkiner image Ia2 to Ih2 for each of the first measurement index and the second measurement index, And each of the fourth Purkinje images Ia4 to Ih4 are included.

Next, the control unit 100 identifies the positions of the first Purkinje images Ia1 to Ih1 and the second Purkinje images Ia2 to Ih2 in the anterior segment image (S4).

The first Purkinje images Ia1 to Ih1 are formed at a position farther from the optical axis L1 and are formed brighter than the other Purkinje images (however, in an image expressed darker in a brighter part, the image is expressed darker. The first Purkinje images Ia1 to Ih1 may be detected from the anterior segment image and their positions may be specified by utilizing the difference in characteristics such as (formed as a darker image). In this embodiment, the detected center position or center of gravity of the Purkinje image may be specified as the position of the Purkinje image. Further, the peak position of the brightness value in the detected Purkinje image may be specified as the position of the Purkinje image.

The second Purkinje images Ia2 to Ih2 in the anterior segment image are formed between the optical axis L1 and the first Purkinje images Ia1 to Ih1. Therefore, in the anterior segment image, for example, the control unit 100 has a brightness value larger than the threshold value between the optical axis L1 and the first Purkinje images Ia1 to Ih1. A region (smaller than) can be detected as a second Purkinje image.

Subsequently, the control unit 100 causes the monitor 70 to display the correction screen 200 as shown in FIG. 5 (S5). The correction screen 200 is a screen for designating the position of the Purkinje image that could not be detected by the control unit 100 and correcting the position of the Purkinje image detected by the control unit 100. For example, on the correction screen 200, the anterior segment image and the pointer P superimposed on the anterior segment image are displayed (FIG. 5A). The shape of the pointer P may be, for example, a closed curve (circle or quadrangle, etc.) for indicating that the Purkinje image is within the range, or an arrow for designating one point. Of course, the shape or size of the pointer P may be changed. The examiner moves the position of the pointer P by operating the operation unit 80 (mouse click, screen touch, keyboard input, etc.) and specifies the position of the Purkinje image on the anterior segment image (FIG. 5 (b)). .. The examiner may specify the positions of a plurality of Purkinje images. The control unit 100 acquires the position information (referred to as designated position information) of the point or area designated by the pointer P and stores it in a memory or the like.

In S4, as shown in FIG. 6, the control unit 100 may display the automatically detected bright spot detection position 201 and the fitting result 202 for that position on the correction screen 200. Since the Purkinje image is only a bright spot, it is difficult to distinguish the reflection by tears or other Purkinje images (for example, the second Purkinje image and the fourth Purkinje image) by the bright spot alone. Since the first and second Purkinje images can be elliptical-fitted as long as there is no irregular astigmatism, the control unit 100 may display in real time how well the currently detected bright spot fits the ellipse. As a result, the examiner can preferably correct the detection position 201 by confirming the fitted ellipse. When modifying the detection position 201 of the Purkinje image, for example, the examiner selects one of the detection positions of the Purkinje image displayed on the monitor 70 and points to another position on the anterior segment image such as pointer P. Specified by.

The control unit 100 may display elliptical parameters (major axis, minor axis, center coordinates, rotation angle, etc.), fitting error, and the like on the correction screen 200. The fitting error may be, for example, a parameter based on the distance between the bright spot and the ellipse. The figure to be fitted does not have to be an ellipse as long as it matches the shape of the cornea.

Next, the control unit 100 detects the Purkinje image based on the obtained designated position information (S6). For example, the control unit 100 detects the Purkinje image in the vicinity of the point designated by the pointer P or in the designated region. By obtaining the position of the Purkinje image to some extent by the pointer P in this way, the probability of detecting the Purkinje image by the control unit 100 increases. Further, since the accuracy of position designation is limited by the operation unit (input device or the like) used by the examiner, a more accurate position of the Purkinje image can be obtained by further performing the detection process based on the designated position information.

When the Purkinje image is detected, the control unit 100 acquires information on the posterior surface of the cornea, for example, based on at least the detection position of the specified second Purkinje image (S7).

When seeking information about the posterior surface of the cornea, a ray tracing method (ray tracing simulation) based on at least a second Purkinje image may be used. In this case, the curvature of the posterior surface of the cornea is obtained for each predetermined meridian (the meridian is a line on the surface including the measurement index and the optical axis L1).

The ray tracing method first assumes an anterior corneal model. The anterior corneal model may be a model in which the region near the center on the anterior surface of the cornea is spherically approximated. The shape of this corneal anterior model may be formed, for example, with a curvature or shape based on the information indicating the corneal anterior shape acquired by the processing of S2. Instead of this, from the position of the first Pulkinje image on the imaging surface, the light path of the photographing optical system 20 is traced in the reverse direction and projected onto the anterior surface of the cornea, and is reflected by the anterior surface of the cornea to reach the light sources 31a to 31h. The condition of the shape of the anterior surface of the cornea that satisfies the light beam (here, the curvature of the anterior surface of the cornea) may be obtained.

Next, the shape of the posterior surface of the cornea is derived based on the shape of the anterior surface model of the cornea and the position information of the second Purkinje image. For example, the shape of the posterior surface of the cornea may be obtained by a ray tracing simulation based on the second Purkinje image. In this case, it is assumed that the corneal anterior model whose shape is obtained in advance and the corneal posterior surface model in which the region near the center of the corneal posterior surface is spherically approximated. The posterior corneal model is arranged on the fundus side by the amount of the corneal thickness at the reference position of the cornea (the position where the optical axis L1 passes, for example, the apex of the cornea) with respect to the anterior corneal model. For the corneal thickness, for example, a value obtained in advance by a paki measurement such as an ultrasonic measurement method may be applied. When the corneal thickness is measured by the measurement optical system 40, the measurement result may be applied as the corneal thickness of the corneal anterior model and the corneal posterior model.

Then, using the curvature of the posterior surface model of the cornea as a variable, the position of the second Pulkinje image on the imaging surface is traced in the reverse direction of the optical path of the photographing optical system 20 to generate the anterior surface of the cornea (more specifically, the position where the first Pulkinje image is generated). ), And the condition of the shape of the posterior surface of the cornea (here, the curvature of the posterior surface of the cornea) is obtained so as to satisfy the light rays that reach the light source 11. For the refractive index of the cornea, for example, a default value (n≈1.33 or the like) such as the average value of the human eye may be used. By obtaining the curvature of the corneal posterior surface model in this way, the curvature of the corneal posterior surface in the eye to be inspected can be obtained. At this time, the shape and position of the posterior surface of the cornea can also be obtained.

The method of acquiring information on the shape of the cornea based on at least the second Purkinje image is not limited to the above-mentioned ray tracing method, and for example, other calculations based on the position information of the second Purkinje image and the like. It may be obtained by a method.

Based on the shape of the anterior surface of the cornea and the shape of the posterior surface of the cornea obtained in this way, the control unit 100 controls various posterior surfaces of the cornea such as the distribution of the corneal thickness, the refractive power of the cornea and its distribution, the astigmatic axis in the cornea, and the like. You can ask for information about. For these derivation methods, refer to, for example, "Japanese Unexamined Patent Publication No. 2015-104554" by the applicant.

As described above, by providing the above configuration, even if the Purkinje image cannot be automatically detected from the anterior segment image, the present device 1 can detect the eye to be inspected based on the position specified by the examiner. Since the shape information can be acquired, it is possible to omit retaking the anterior segment image. For example, even when the second Purkinje image and the fourth Purkinje image are formed in the vicinity, or when bright spots are generated due to reflection of eyelashes, the second Purkinje image can be detected more preferably.

The control unit 100 may perform image processing on the front eye portion image on the correction screen 200 so that the visibility of the bright spot is improved so that the examiner can easily specify the position of the Purkinje image. For example, the control unit 100 may perform image processing that locally emphasizes the contrast (for example, CLAHE), or image processing that emphasizes the structure based on the eigenvalues of the Hessian matrix (for example, application of a blobness filter). ) May be performed.

The control unit 100 may determine in S4 whether or not the Purkinje image has been successfully detected. For example, the control unit 100 may perform elliptical fitting with respect to the bright spot currently being detected, and determine the success or failure of the detection based on the fitting error at that time. For example, each of the automatically detected bright spots may be scored for the second Purkinje image-likeness (position, brightness, shape, size, etc.), and the success or failure of the detection may be determined based on the score value. .. For example, if the score value is equal to or greater than a predetermined value, it may be determined that the detection of the second Purkinje image has been successful, and if the score value is less than the predetermined value, it may be determined that the detection of the second Purkinje image has failed. .. For example, the control unit 100 may display the detection success / failure determination result on the monitor 70. As a result, the control unit 100 can prompt the examiner to specify or correct the position of the Purkinje image. The control unit 100 may display on the monitor 70 that the detection has failed only when it is determined that the detection of the Purkinje image has failed.

As shown in FIG. 6, the control unit 100 displays, in addition to the automatically detected positions of the bright spots, a candidate point 203 that may be a Purkinje image on the front eye portion image of the correction screen 200. You may. As a result, the examiner only needs to confirm the candidate point 203 of the Purkinje image mainly, and the trouble of searching for the Purkinje image can be reduced. For example, the examiner may specify the position of the Purkinje image by designating the candidate point 203 most likely to be the Purkinje image from among several candidate points 203.

The control unit 100 may exclude the automatically detected bright spot detection position 201 or the Purkinje image candidate point 203 designated by the examiner from the shape information analysis process. This makes it possible to prevent the corneal shape from being calculated based on the detection position 201 of another bright spot or the like that is not a Purkinje image. For example, the examiner determines whether the detection position 201 or the candidate point 203 of the Purkinje image displayed on the anterior segment image is a bright spot that is clearly not a Purkinje image or a first to fourth Purkinje image. It is specified that the bright spots that cannot be used are not used for the analysis of the corneal shape by the operation of the operation unit 80. In this case, the control unit 100 may acquire the shape information of the eye to be inspected based on the position other than the designated detection position 201 or the candidate point 203.

When the pointer P or the like is superimposed and displayed on the anterior segment image, the Purkinje image may be hidden by the pointer P and the position may not be known. In such a case, the control unit 100 may blink the pointer P on the front eye portion image. As a result, the position of the Purkinje image can be specified by the pointer P without losing sight of the position of the Purkinje image on the anterior segment image. In addition, both the front eye image for confirmation and the front eye image for operation are displayed on the monitor 70, and the front eye image for operation is displayed while confirming the position of the Purkinje image on the front eye image for confirmation. The displayed pointer P may be moved to specify the position of the Pulkinje image.

In S6, the Purkinje image is detected based on the designated position information specified by the examiner, but the present invention is not limited to this. For example, the processing of S6 may not be performed, and the information regarding the corneal shape may be acquired using the designated position information itself in S7.

In the above embodiment, it has been mainly described that the second Purkinje image is detected to acquire the corneal shape information regarding the posterior surface of the cornea, but the control unit 100 acquires the corneal shape information based on the other images. You may. For example, the positions of the first Purkinye image, which is the bright spot due to the reflected light on the front surface of the cornea, the third Purkinye image, which is the bright spot due to the reflected light on the front surface of the crystalline lens, and the fourth Purkinye image, which is the bright spot due to the reflected light on the rear surface of the crystalline lens. It may be detected and shape information such as the anterior surface of the cornea, the anterior surface of the crystalline lens, and the posterior surface of the crystalline lens may be acquired.

In the above embodiment, the topo projection optical system 10 is provided separately from the projection optical system 30 in order to measure the front surface shape of the cornea, but the present invention is not necessarily limited to this. For example, a measurement index projected from the projection optical system 30 to obtain information on the posterior surface of the cornea may also be used as a measurement index for measuring the anterior surface shape of the cornea. In this case, the control unit 100 calculates the front surface shape of the cornea based on the first Purkinje image based on the measurement index from the projection optical system 30. For more details, refer to "Japanese Patent Laid-Open No. 2003-111727" by the applicant. In the above embodiment, the projection optical system 30 projects a single ring index, whereas the topo projection optical system 10 projects a multiple ring (as a “third measurement index”). That is, since there are more measurement points related to the meridian direction than the measurement index from the projection optical system 30 on the index projected from the topo projection optical system 10, the corneal front shape can be measured in detail. Further, the topo projection optical system 10 may also serve as the projection optical system 30.

Although the present disclosure has been described above based on the examples, the present disclosure is not limited to the above examples, and various modifications are possible. The present disclosure is also realized by executing the following processing. That is, software (program) that realizes the functions of the above-described embodiment is supplied to the system or device via a network or various storage media, and the computer (or CPU, MPU, etc.) of the system or device reads the program. This is the process to be executed.

1 Ophthalmic measuring apparatus 31a to 31d 1st measuring index 31e to 31h 2nd measuring index 10 Topo projection optical system 20 Imaging optical system 27 Imaging element 30 Projection optical system 50 Fixed vision optical system

Claims (8)

An ophthalmic measuring device that measures the eye to be inspected.
A projection optical system that projects an index onto the anterior segment of the eye to be inspected,
An imaging means for acquiring an image of the anterior segment of the eye to be inspected by photographing the anterior segment on which the index is projected.
In the anterior segment image, a position information acquisition means for acquiring the designated position information when the examiner specifies the position related to the Purkinje image according to the index, and
An arithmetic means for acquiring the shape information of the anterior segment based on the designated position information, and
An ophthalmic measuring device comprising. The ophthalmology according to claim 1, wherein the calculation means detects the Purkinje image from the front eye portion image based on the designated position information, and acquires the shape information based on the detection position of the Purkinje image. measuring device. The Purkinje image includes at least a second Purkinje image due to the posterior corneal reflection of the index.
The ophthalmologic measuring apparatus according to claim 1 or 2, wherein the calculation means acquires the shape information regarding the posterior surface of the cornea. The ophthalmic measuring apparatus according to any one of claims 1 to 3, wherein the calculation means applies image processing for improving the visibility of the Purkinje image to the anterior segment image. The projection optical system projects a plurality of indexes onto the anterior segment of the eye.
The calculation means causes the display means to display at least one of the fitting result and the fitting error obtained by performing the fitting process on the detection positions of the plurality of Purkinje images detected from the anterior segment image. The ophthalmic measuring device according to any one of claims 1 to 4. The ophthalmic measuring apparatus according to any one of claims 2 to 5, wherein the calculation means causes a display means to display a candidate point that may be a Purkinje image in the anterior segment image. The ophthalmologic measuring apparatus according to claim 6, wherein the calculation means excludes the detection position or the candidate point designated by the examiner to acquire the shape information. The ophthalmology measuring device according to any one of claims 1 to 7, wherein the calculation means determines whether or not the automatic detection of the Purkinje image has been successful, and notifies the examiner of the determination result by the notification means.

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