JP2012010798A - Ophthalmologic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an image of a subject's eye from which a bright-point image has been removed, regarding an ophthalmologic device for inspecting and measuring the subject's eye.SOLUTION: The ophthalmologic device includes: a light projection optical system for projecting first and second light beams to different positions of the subject's eye; an imaging optical system for imaging using an imaging element an image of the subject's eye illuminated by the optical light projection system; a control means for projecting the first and second light beams at different timings and obtaining, based on imaging signals output from the imaging element, a first image produced by the first light beam and a second image produced by the second light beam; and an image processing means for obtaining an anterior eye image from which part of the reflected light beam by the light projection optical system has been removed through an imaging process for comparing the brightness information of the first and second images and imaging one of the first or second images whose brightness is lower than the other.

Description

  The present invention relates to an ophthalmologic apparatus for inspecting and measuring a subject's eye.

  In an ophthalmologic apparatus such as an autokeratometer or tonometer, an anterior ocular segment illumination light source and an anterior ocular segment imaging optical system for alignment / observation / measurement (for example, kerato measurement, pupil diameter measurement) are arranged. (See Patent Document 1).

JP 2007-125260 A

  By the way, since the anterior ocular segment illumination light is irradiated from the front or obliquely of the eye, a bright spot image by the anterior ocular segment illumination light is formed in the anterior ocular segment image, which may interfere with measurement and observation. For example, when the pupil diameter is to be measured from the anterior segment image, the pupil edge and the bright spot may overlap, resulting in a measurement error.

  In view of the above problems, an object of the present invention is to provide an ophthalmologic apparatus capable of acquiring an eye image to be examined from which a bright spot image has been removed.

  In order to solve the above problems, the present invention is characterized by having the following configuration.

(1) A light projecting optical system that projects the first light and the second light toward different positions of the eye to be examined, and an imaging optical that images the eye image illuminated by the light projecting optical system using an image sensor. The system, the first light and the second light are projected at different timings, and based on the imaging signal output from the imaging device, the first image by the first light and the second light A part of the reflected light by the light projecting optical system by control means for acquiring the second image and image processing for comparing the luminance information of the first image and the second image to image the lower one And an image processing means for acquiring an anterior ocular segment image from which is removed.
(2) In the ophthalmologic apparatus according to (1), the light projecting optical system projects the first light and the second light toward an anterior eye portion of an eye to be examined, and the imaging optical system And an image pickup optical system that picks up an anterior segment image illuminated by the light projecting optical system with an image pickup device.
(3) In the ophthalmologic apparatus according to (2), the light projecting optical system includes a first light source that emits the first light and a second light source that emits the second light. The anterior segment is illuminated with light emitted from two light sources.
(4) In the ophthalmologic apparatus according to (3), the image processing means further detects a positional deviation between the first image and the second image, and corrects the positional deviation between the images by image processing. It is characterized by.
(5) The ophthalmologic apparatus according to (4), further comprising pupil diameter measuring means for measuring a pupil diameter based on the anterior segment image from which a part of the reflected light has been removed.
(6) In the ophthalmologic apparatus according to (5), the illumination optical system also serves as a projection optical system that projects a corneal shape measurement index onto the cornea, and further detects a corneal index image captured by the imaging device. And corneal shape calculating means for obtaining the corneal shape.
(7) In the ophthalmologic apparatus according to (6), the illumination optical system is a projection optical system that projects a plurality of ring pattern indexes on the cornea.

  According to the present invention, an eye image to be examined from which a bright spot image has been removed can be acquired.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram showing an optical system of an ophthalmologic apparatus according to this embodiment.

  This apparatus has a first light source (41) and a second light source (51), and projects light emitted from the first light source and the second light source toward the eye E (for example, the anterior eye segment, the fundus). A light projecting optical system (40, 50), and an image capturing optical system (30) for capturing an image of the eye to be examined (for example, the anterior eye portion and the fundus) illuminated by the light projecting optical system, Projection optics by image processing for comparing the luminance information of the first image and the second image acquired when the first light source and the second light source are turned on at different timings and imaging the lower luminance An anterior ocular segment image from which part of the reflected light from the system is removed is acquired.

  For example, the first light source (41) and the second light source (51) are arranged at different positions and irradiate light toward different regions of the eye E. The first light source (41) projects first light toward the eye E, and the second light source (51) projects second light toward the eye E. The light projecting optical system (40, 50) is used as, for example, anterior segment illumination.

  More specifically, the present optical system includes an axial length measurement optical system (measurement unit) 10, a kerato projection optical system 50 that projects a corneal shape measurement index onto the eye cornea to be examined, an alignment projection optical system 40, an anterior eye It is roughly divided into an anterior ocular segment front imaging optical system 30 that captures a partial front image. The following optical system is built in a housing (not shown). Further, the casing is three-dimensionally moved with respect to the subject's eye via an operation member (for example, a joystick) by driving a known alignment moving mechanism.

  The projection optical system 50 has a ring-shaped second light source 51 disposed around the measurement optical axis L1, and measures a corneal shape (curvature, astigmatic axis angle, etc.) by projecting a ring index onto the eye cornea to be examined. Used to do. The second light source 51 is, for example, an LED that emits infrared light or visible light. In addition, about the projection optical system 50, at least 3 or more point light sources should just be arrange | positioned on the same periphery centering on the optical axis L1, and may be an intermittent ring light source. Further, it may be a placido index projection optical system that projects a plurality of ring indexes. Further, the second light source 51 of the projection optical system 50 also serves as anterior segment illumination that illuminates the anterior segment with infrared light from an oblique direction.

  The alignment projection optical system 40 is disposed inside the second light source 51, has a ring-shaped first light source 41 (for example, λ = 970 nm) disposed around the optical axis L1, and is disposed on the subject's eye cornea. Used to project alignment indicators. And the alignment parameter | index projected on the cornea is used for position alignment (for example, automatic alignment, alignment detection, manual alignment, etc.) with respect to a subject's eye. For the first light source 41, for example, an LED that emits infrared light or visible light is used. In the present embodiment, the projection optical system 40 is an optical system that projects a ring index onto the subject's eye cornea, and the ring index also serves as a Mayer ring (also can be used as a cornea shape index). Further, the first light source 41 of the projection optical system 40 also serves as anterior segment illumination that illuminates the anterior segment with infrared light from an oblique direction. The projection optical system 40 may further include an optical system that projects parallel light on the cornea, and the front-rear alignment may be performed by a combination with the finite light by the projection optical system 40.

  The anterior ocular segment imaging optical system 30 includes a dichroic mirror 33, an objective lens 47, a total reflection mirror 62, a filter 34, an imaging lens 37, and a two-dimensional imaging element 35, and captures an anterior ocular segment front image of the eye to be examined. Used for.

  The anterior ocular segment light reflected by the projection optical system 50 and the projection optical system 40 forms an image on the two-dimensional image sensor 35 via the dichroic mirror 33, the objective lens 47, the total reflection mirror 62, the filter 34, and the imaging lens 37. Is done.

  The axial length measurement optical system 10 emits low-coherent light, divides the emitted light into measurement light and reference light, irradiates at least the measurement light to the eye to be examined, and reflects light and reference light from the eye to be examined. Are combined and made incident on the light receiving element. Based on the light reception signal output from the light receiving element, the axial length is calculated based on the timing when the interference light is detected by the light receiving element. In the present embodiment, the measurement light source of the axial length measurement optical system 10 also serves as a fixation lamp.

  Next, the control system will be described. The control unit 80 controls the entire apparatus and calculates measurement results. The control unit 80 is connected to each member of the axial length measurement optical system 10, the first light source 41, the second light source 51, the image sensor 35, the monitor 70, the memory 85, and the like. The control unit 80 is connected to an operation unit 84 for performing various input operations.

  In addition to various control programs, the memory 85 stores a software program for the control unit 80 to calculate the axial length / corneal shape, pupil diameter, and the like, and is used as a calculation unit. For example, the control unit 80 detects a corneal index image captured by the image sensor 35 and measures the corneal shape.

  The operation of the apparatus having the above configuration will be described. The examiner moves the apparatus in the vertical and horizontal directions and the front-rear direction using an operation means such as a joystick (not shown) while observing the alignment state of the subject's eye displayed on the monitor 70, and the apparatus is moved with respect to the subject's eye E. Put it in the positional relationship. In this case, the examiner fixes the fixation target to the subject's eye.

  FIG. 2 is a diagram illustrating an anterior ocular segment observation screen on which an anterior ocular segment image captured by the image sensor 35 is displayed. During the alignment, the first light source 41 and the second light source 51 are turned on. Here, as shown in FIG. 2, the examiner performs vertical and horizontal alignment so that the electronically displayed reticle LT and the ring index R1 by the first light source 41 are concentric. In addition, the examiner performs front-rear alignment so that the ring index R1 is in focus. A ring index R2 from the second light source 51 is displayed outside the ring index R1. When a predetermined trigger signal is generated, the control unit 80 captures an anterior eye image.

  Here, a method for acquiring the anterior segment image from which the bright spot image has been removed will be described. When a predetermined trigger signal is generated, the control unit 80 turns on the first light source 41 and the second light source 51 at different timings, and based on the imaging signal output from the imaging element 35, the first light source 41 performs the first light source 41 and the second light source 51. The first anterior segment image A1 and the second anterior segment image A2 obtained by the second light source 51 are acquired (see FIGS. 4A and 4B). Then, the anterior ocular segment image from which the index image has been removed is obtained by image processing for comparing the luminance information of the first anterior ocular segment image A1 and the second anterior ocular segment image A2 and imaging the lower luminance ( (Refer FIG.4 (c)).

  This will be described more specifically with reference to the flowchart shown in FIG. When a predetermined trigger signal is generated, the control unit 80 turns off the second light source 51. Then, imaging of the anterior segment is performed with the first light source 41 turned on, and an anterior segment image A1 with the first light source 41 as illumination light is acquired (see FIG. 4A). The photographed anterior segment image A1 is stored in the memory 85.

  Next, the control unit 80 turns on the second light source 51 and turns off the first light source 41. Then, the anterior segment is imaged with the second light source 51 turned on, and an anterior segment image A2 is obtained with the second light source 51 as illumination light (see FIG. 4B). The photographed anterior segment image A2 is stored in the memory 85.

  As described above, when imaging of the anterior ocular segment image using the first light source 41 and the second light source 51 is completed, the control unit 80 detects the pixel in each of the anterior segment image A1 and the anterior segment image A2. Luminance information (luminance distribution) is detected every time.

  Next, the control unit 80 compares the luminance value for each of the same pixel positions between the anterior segment image A1 and the anterior segment image A2. Then, the lower luminance value (minimum value between images) between the pixels of the anterior segment image A1 and the anterior segment image A2 is stored together with its position information as luminance data used for the image from which the bright spot has been removed. 85.

  When the comparison of all the pixels is completed, the control unit 80 calls the pixel data stored in the memory 85. Then, luminance data corresponding to each pixel position is arranged, and an anterior ocular segment image A3 (see FIG. 4C) from which bright spots are removed is acquired. As described above, a calculation process for selecting the minimum value is performed from at least two or more anterior segment images, and one anterior segment image is acquired.

  Here, in the acquisition of the anterior segment image A3, the position of the ring index R1 displayed in FIG. 4A corresponds to the brightness value of the ring index R1 and this position of the image of FIG. 4B. Compared with the luminance value of the part, the luminance value of FIG. 4B having a lower luminance value is selected. As a result, the ring index R1 is not displayed. The same applies to the ring index R2, and the brightness value of FIG. 4A having a lower brightness value is selected at the position of the ring index R2. As a result, the anterior segment image A3 is an image from which bright spots with high luminance values are removed. Therefore, it is possible to acquire an anterior segment image in which no bright spot or the like is displayed. The acquired image can be used for anterior ocular segment image observation, pupil diameter measurement, and the like. Such an anterior segment image A3 is output to a monitor 70, a printer, or the like.

<Calculation of pupil diameter>
Hereinafter, as an example, a method for obtaining the edge position of the pupil from the anterior segment image A3 and measuring the pupil diameter will be described with reference to FIG.

  This apparatus measures the pupil diameter based on the anterior segment image from which the index image has been removed. 5A shows a pupil image stored in the memory 85, and FIG. 5B shows a video signal on the scanning line L. FIG. In order to know the boundary (edge) between the pupil (dark part) and the iris (bright part), first, the signal waveform in FIG. The signal waveform at this time is as shown in FIG. Since this signal is a positive / negative signal, when it is squared, it becomes a positive numerical signal shown in FIG. In FIG. 5D, if the edges of the first waveform signal having the height e1 and the last waveform signal having the height e2 are defined as, for example, half points of the height (amplitude), the pixel position n1 and n2 are the coordinate positions of the edges on the scanning line L.

Further, the pixel number n in the interval is obtained from the pixel positions n1 and n2. Here, when the length of one pixel is K and the optical magnification is P, the distance between the pixel positions n1 and n2 (pupil diameter PS) is:
PS = n * K / P
It can be obtained from the following formula. That is, since the values of K and P are known values unique to the apparatus, the pupil diameter can be obtained by obtaining the number n of pixels.

  Here, for example, when a ring index (bright spot) is displayed in the anterior ocular segment image and the ring index and the pupil edge overlap, it becomes impossible to discriminate between the ring index and the video signal of the pupil edge, resulting in a measurement error. Become.

  That is, for the anterior segment images A1 and A2, the pupil edge can be determined by the anterior segment image A3 even when at least one of the ring index R1 and the ring index R2 overlaps the pupil edge.

  FIG. 6 shows an anterior ocular segment image having an elliptical pupil or the like in which the pupil edge overlaps both the ring index R1 and the ring index R2. Even in such a case, the bright spot as shown in FIG. 6C is removed from the two anterior eye images shown in FIGS. 6A and 6B by the method shown in FIG. An eye image can be acquired. That is, since the brightness value of the image where the ring index and the pupil edge do not overlap is selected as the brightness data, the index image included in the image is removed, and an image capable of discriminating the pupil edge is acquired. .

  As described above, in the anterior segment image A3 in which no bright spot or the like is displayed, the pupil edge can be determined, so that the pupil diameter can be measured without any measurement error or the like.

  Note that when an image such as the anterior segment image A3 is obtained, image processing may be performed so that a low luminance value is selected as a result in two or more images. For example, the brightness value of the ring index is calculated by an experiment or the like, and a predetermined threshold that can remove the ring index is set based on the result. Then, in each of the anterior eye images A1 and A2, luminance information is acquired, and the luminance value is set to almost zero for a position where the luminance value is equal to or greater than the threshold value. Then, the anterior segment images A1 and A2 are compared for each pixel, the higher luminance value is selected as luminance data, and an image is acquired. In this case, since the brightness value is 0 for the position of the ring index in each image, the brightness value of the other image is selected, and as a result, an image from which bright spots and the like are removed is acquired. Is done. That is, in the above description, the higher luminance value is selected during the image processing for obtaining the anterior segment image A3, but as a result, the lower luminance value is selected.

  When comparing luminance information between the anterior eye image A1 and the anterior eye image A2, the control unit 80 determines the position between the first anterior eye image A1 and the second anterior eye image A2. The brightness value may be compared for each pixel position after detecting the shift and correcting the position shift between the images by image processing. In addition, for example, pattern matching using an iris pattern or the like is used for the position shift detection. A ring index may be used.

  For example, the control unit 80 detects the center coordinates and the R2 center coordinates of the ring index R1 from the anterior eye image A1 and the anterior eye image A2, respectively. Then, the shift amount of the R2 center coordinate (X, Y) with respect to the center coordinate (X, Y) of R1 is calculated, and the anterior segment image A2 is moved by the shift amount with respect to the anterior segment image A1. As a result, the positional deviation between the images is corrected, and the comparison process is performed with high accuracy.

  In the above description, the control unit 80 continuously acquires two images. However, the timing for acquiring the two images may have a time lag. Further, the image acquisition may be configured to acquire one image at a time when a predetermined trigger signal is issued. In this case, a configuration in which alignment is performed every time an image is acquired is better because a positional shift can be corrected.

  The control unit 80 determines the corneal shape of the eye to be examined (for example, the corneal curvature in the strong main meridian direction and the weak main meridian direction, the astigmatic axis angle of the cornea, etc.) based on the ring index image R2 in the anterior segment image A2. It is also possible to calculate. Note that the second corneal curvature may be calculated from the index image R1 of the anterior segment image A1. Thereby, the pupil diameter and the corneal shape can be measured smoothly.

  Note that the control unit 80 may acquire a graphic image by performing image processing for combining a predetermined graphic display with the anterior segment image A3. For example, a graphic corresponding to the corneal astigmatic axis direction of the eye E may be superimposed on the anterior eye image A3.

  The present invention can also be applied to other ophthalmologic apparatuses having an anterior ocular segment imaging optical system. For example, the present invention can also be applied to an objective eye refractive power measurement device and a fundus photographing device.

  In the application of the present invention, two ring indexes have been described as examples. However, the present invention is not limited to this. For example, it may be a projection optical system that projects a plurality of ring pattern indices onto the cornea. More specifically, three or more ring indexes may be used. In this case, in order to remove the bright spots, the respective ring indexes are turned on in order, the images are taken in order, and the brightness is compared with three or more images.

  The same light source may be used as the first light source and the second light source. In this case, a first light shielding member (for example, a liquid crystal shutter) and a second light shielding member are provided in front of the light source, and light to the eye E Is controlled. Thereby, the first light source and the second light source are formed.

  In addition, the bright spots formed on the anterior segment image are removed instead of the ring index target image. For example, the present invention can also be applied to dot-like luminescent spots used as alignment luminescent spots. Moreover, it is not restricted to anterior ocular segment illumination, What is necessary is just the structure which projects the light radiate | emitted from the 1st light source and the 2nd light source toward the anterior ocular segment. For example, it may be configured to project an infinity index.

  In the ophthalmologic apparatus for obtaining the eye image to be examined, the luminance information of the first image and the second image acquired at different timings is compared, not limited to the light emitted from the first light source and the second light source, and According to the image processing for imaging the lower one, it is possible to remove noise light (for example, external illumination) generated irregularly in the eye image to be examined.

It is a schematic block diagram shown about the optical system of the ophthalmologic apparatus which concerns on this embodiment. It is a figure which shows the anterior ocular segment observation screen on which the imaged anterior segment image was displayed. It is a flowchart which shows the method of acquiring the anterior ocular segment image from which the bright spot image was removed. An anterior segment image when the anterior segment is photographed with different illumination light is shown. It is a figure explaining the method of calculating | requiring a pupil edge position. The image at the time of image | photographing the anterior eye part which has an elliptical pupil with different illumination light is shown.

DESCRIPTION OF SYMBOLS 10 Optical axis length measurement optical system 30 Anterior ocular segment front imaging optical system 40 Alignment projection optical system 41 First light source 50 Kerato projection optical system 51 Second light source 70 Monitor 80 Control unit 85 Memory

Claims (7)

A light projecting optical system that projects the first light and the second light toward different positions of the eye to be examined;
An imaging optical system that captures an image of the eye to be examined illuminated by the light projecting optical system with an imaging element;
The first light and the second light are projected at different timings, and the first image by the first light and the second image by the second light are based on the imaging signal output from the imaging element. Control means for obtaining
An anterior ocular segment image from which a part of the reflected light by the light projecting optical system is removed is obtained by image processing for comparing the luminance information of the first image and the second image and imaging the lower one. Image processing means;
An ophthalmologic apparatus comprising: The ophthalmic device according to claim 1.
The light projecting optical system projects the first light and the second light toward the anterior segment of the eye to be examined,
The imaging optical system includes an imaging optical system that images an anterior segment image illuminated by the light projecting optical system with an imaging element;
An ophthalmologic apparatus comprising: The ophthalmic apparatus according to claim 2.
The light projecting optical system includes a first light source that emits the first light and a second light source that emits the second light, and the anterior eye unit is formed by the light emitted from the first and second light sources. An ophthalmic apparatus characterized by illuminating The ophthalmic device according to claim 3.
The ophthalmologic apparatus, wherein the image processing means further detects a positional deviation between the first image and the second image, and corrects the positional deviation between the images by image processing. The ophthalmic device according to claim 4.
The ophthalmologic apparatus further comprises pupil diameter measuring means for measuring a pupil diameter based on the anterior segment image from which a part of the reflected light is removed. The ophthalmic device according to claim 5.
The illumination optical system also serves as a projection optical system that projects an index for corneal shape measurement onto the cornea,
The ophthalmologic apparatus further comprises corneal shape calculating means for detecting a corneal index image picked up by the image pickup device to obtain a corneal shape. The ophthalmic device according to claim 6.
The ophthalmologic apparatus, wherein the illumination optical system is a projection optical system that projects a plurality of ring pattern indices onto the cornea.

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