JP2015104467A - Ophthalmologic apparatus and control method for ophthalmologic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ophthalmologic apparatus capable of easily performing alignment and focusing with respect to a subject eye.SOLUTION: An ophthalmologic apparatus comprises: a body part having an image pickup device for capturing an image of a subject eye and a focusing member; index projection means for projecting on the subject eye an index which is used for at least one of focusing operation and alignment operation between the main part and the subject eye; index light quantity control means for controlling the light quantity of the index to be projected by the index projection means; and index evaluation means for calculating the sum of the gray level value of each pixel of the index image captured by the image pickup device, the gray level value being the one on the image pickup device. The light quantity is controlled such that the sum becomes a predetermined value.

Description

  The present invention relates to an ophthalmologic apparatus and a control method thereof.

  Conventionally, in an ophthalmologic apparatus typified by a fundus camera or an auto-reflector, a photographer performs precise positioning and focusing between the apparatus and the subject's eye in the up / down / left / right and working distance (front / rear) direction, and then captures the subject's eye. do. This alignment and focus adjustment are performed by simultaneously imaging an eye observation image to be examined and an index image for alignment or focus using the same image sensor and using both images.

  In general, the gradation value of the eye observation image or index image captured by the image sensor is determined by the amount of light that illuminates the eye and the reflectance of the eye. Since the reflectance of the eye to be examined varies between individuals, even if the amount of light that illuminates the eye to be examined is the same, the gradation values of the eye observation image and the index image are different.

  As a technique for filling such individual differences in the reflectance of the eye to be examined, techniques disclosed in Japanese Patent Application Laid-Open No. 2012-50570 and Japanese Patent No. 4937840 are exemplified.

  The technique disclosed in Japanese Patent Application Laid-Open No. 2012-50570 makes the gradation value of the eye observation image appropriate regardless of the individual difference in the reflectance of the eye. With this technology, the amount of eye observation light is controlled so that the average gradation value of the entire observation image including the eye observation image and the index image becomes a predetermined value so that the gradation value of the eye observation image is appropriate. doing. However, in the average gradation value of the entire observation image calculated by the technique, it is assumed that the contribution by the index image is sufficiently small.

  The technique disclosed in Japanese Patent No. 4937840 makes the gradation value of the eye observation image and the gradation value of the index image suitable at the same time regardless of individual differences in the reflectance of the eye. In this technique, the object is achieved by combining the eye observation light source and the index light source with the same light source.

JP 2012-50570 A Japanese Patent No. 4937840

  With the technology disclosed in Japanese Patent Application Laid-Open No. 2012-50570, the gradation value of the eye observation image can be made appropriate regardless of individual differences in the reflectance of the eye to be examined. However, the gradation value of the index image cannot be made appropriate regardless of individual differences in the reflectance of the eye to be examined. Therefore, accurate alignment and focusing cannot be performed unless the tone value of the index image is appropriate.

  On the other hand, with the technique disclosed in Japanese Patent No. 4937840, the tone value of the index image can be made appropriate regardless of individual differences in the reflectance of the eye to be examined. However, the condition is that the eye light source to be examined and the light source for the index are used as the same light source. In general, devices that satisfy this condition are limited to measuring devices in the anterior segment.

  Accordingly, an object of the present invention is to provide an ophthalmologic apparatus in which the appearance of an index image is the same regardless of individual differences and is easy to align and focus.

  An ophthalmologic apparatus according to an embodiment of the present invention for solving the above-described problems has the following configuration.

That is, a main body having an imaging element that captures an image of the eye to be examined and a focusing member that performs a focusing operation at the time of capturing the image;
Index projection means for projecting an index to be used for the operation of at least one of alignment and focusing between the main body and the eye to be examined;
Index light quantity control means for controlling the light quantity of the index in the index projection means;
Index evaluation means for calculating a sum of gradation values for each pixel in the image sensor of the image of the index obtained by the image sensor, and
The index light amount control means controls the light amount of the index so that the sum becomes a predetermined value.
In addition, a method for controlling an ophthalmologic apparatus according to another embodiment of the present invention includes a main body having an imaging element that captures an image of an eye to be examined and a focusing member that performs a focusing operation when capturing the image. A method for controlling an ophthalmic device comprising:
An index projecting step of projecting an index to be used for the operation of at least one of positioning and focusing between the main body and the eye to be examined;
An index evaluation step of calculating a sum of gradation values for each pixel in the image sensor of the index image obtained by the image sensor;
An index light amount control step of controlling the light amount of the index so that the sum becomes a predetermined value.

  According to the present invention, it is possible to provide a photographer with an ophthalmologic apparatus with the same appearance of the index image regardless of individual differences in the reflectance of the eye to be examined.

It is a block diagram of the non-mydriatic retinal camera in one Example of the present invention. FIG. 3 is a diagram illustrating a fundus observation image, a positioning index image, and a focus index image 21 captured by an image sensor in a fundus camera shown as an example. It is a flowchart which shows operation | movement of the index image extraction part at the time of observation of a to-be-tested eye, an index image evaluation part, and the light source control part for an index. It is a figure which shows the gradation value on the dotted line of the alignment index image of the eye to be examined A (the state of alignment and focusing between the eye to be examined and the apparatus is the same as that of the eye to be examined B). It is a figure which shows the gradation value on the dotted line of the alignment index image of the eye to be examined B (the state of alignment and focusing between the eye to be examined and the apparatus is the same as that of the eye to be examined A). FIG. 5 is a diagram showing gradation values on a dotted line of an alignment index image of the eye to be examined A in a state in which the alignment state of the eye A and the apparatus in the working distance direction is different from the state of FIG.

[Example]
Hereinafter, a preferred embodiment of the present invention will be described with reference to the accompanying drawings. FIG. 1 shows a configuration diagram of a non-mydriatic retinal camera 100 as an example of an ophthalmologic apparatus.

First, the configuration of the non-mydriatic fundus camera 100 will be described.
On the optical axis L1 facing the fundus Er of the eye E, an objective lens 1 and a perforated mirror 2, a focus lens 3, an imaging lens 4, and an image sensor 5 are sequentially arranged behind the objective lens 1. These constitute a fundus photographing optical system for the eye E to be examined. In the present embodiment, the image sensor 5 corresponds to an image sensor that captures an image of the eye E, and the focus lens 3 corresponds to a focusing member for performing a focusing operation when capturing the image. Further, the non-mydriatic retinal camera 100 having a fundus photographing optical system including the imaging element and the focusing member corresponds to the main body portion in the present embodiment.

  On the other hand, a lens 8, a focus index projection unit 20, a dichroic mirror 9, a condenser lens 10, and an observation light source 11 are arranged on the optical axis L 2 in the reflection direction of the perforated mirror 2. In addition, a condenser lens 12 and a photographing light source 13 are arranged on the optical axis L3 in the reflection direction of the dichroic mirror 9. The fundus illumination optical system is configured by the configuration on the optical axes L2 and L3.

  The dichroic mirror 9 has a characteristic of transmitting the wavelength band of the observation light source 11 and reflecting the wavelength band of the imaging light source 13. The observation light source 11 includes a plurality of LEDs and is a light source that irradiates the eye to be inspected with light having a wavelength in the infrared region. The imaging light source 13 is a light source that irradiates the fundus Er with light having a wavelength in the visible region.

  Further, in the vicinity of the perforated mirror 2, in order to project an index for positioning the non-mydriatic retinal camera 100 and the eye E toward the anterior eye portion of the eye to be examined, the light guide 6a and the alignment index are projected. A light source for light 7a is arranged. Further, a light guide 6b and an alignment index light source 7b (not shown) are arranged in the back side of the light guide 6a and the alignment index light source 7a with respect to the optical axis L1. The reflected light from the anterior ocular segment of the subject projected by the light guides 6a and 6b and the alignment indicator light sources 7a and 7b has the working distance between the subject eye E and the non-mydriatic retinal camera 100 at an appropriate position. In some cases, the contrast is maximized on the image sensor 5.

  In addition, an index image extraction unit 14, an index image evaluation unit 15, an index light source control unit 16, a fundus camera control unit 17, and a display unit 18 are configured inside the non-mydriatic fundus camera 100.

Specifically, the index image extraction unit 14 is connected to the image sensor 5 and the index image evaluation unit 15. The index image extraction unit 14 serving as an index extraction unit extracts only the index image from the output of the image sensor 5. Further, the index image evaluation unit 15 as index evaluation means is connected to the index light source control unit 16. The index image evaluation unit 15 numerically evaluates the index image extracted by the index image extraction unit 14 and notifies the index light source control unit 16 of the evaluation value. The index light source control unit 16 performs light emission control of the alignment index light sources 7a and 7b based on the output of the index image evaluation unit 15, that is, controls the light quantity of the index. Further, the fundus camera control unit 17 is connected to the image sensor 5, the observation light source 11, the imaging light source 13, the display unit 18, and the focus index projection unit 20. Then, the light emission control of the observation light source 11, the imaging light source 13, and the focus index projection unit 20 and the display of the image captured by the image sensor 5 on the display unit 18 are performed.
In the configuration of the non-mydriatic fundus camera 100 described above, the process from observation to photographing will be described.

First, observation will be described.
When the photographer positions the eye E to be examined in front of the objective lens 1, the fundus camera control unit 17 causes the observation light source 11 to emit light. Observation illumination light emitted from the observation light source 11 passes through the fundus illumination optical system from the observation light source 11 to the objective lens 1 and illuminates the fundus Er through the pupil Ep of the eye E to be examined. The reflected light from the fundus Er illuminated by the observation light source 11 passes through the fundus photographing optical system that reaches the objective lens 1, the perforated mirror 2, the focus lens 3, and the imaging lens 4, and reaches the image sensor 5.

  At the same time, the index light source control unit 16 causes the alignment index light sources 7a and 7b to emit light, and projects the index for alignment onto the anterior eye portion of the eye to be examined through the optical path from the light guides 6a and 6b to the objective lens 1. The reflected light of the projected index from the anterior segment of the eye to be examined passes through the fundus photographing optical system that reaches the objective lens 1, the perforated mirror 2, the focus lens 3, and the imaging lens 4, and reaches the image sensor 5.

  At the same time, the focus index projection unit 20 projects the focus index light toward the fundus Er of the subject's eye. Reflected light from the fundus Er of the projected index light for focus passes through the fundus photographing optical system that reaches the objective lens 1, the perforated mirror 2, the focus lens 3, and the imaging lens 4, and reaches the image sensor 5.

  The fundus observation image, the alignment index image, and the focus index image captured by the image sensor 5 are displayed on the display unit 18 by the fundus camera control unit 17. FIG. 2 shows an alignment index image, a fundus observation image, and a focus index image captured by the image sensor 5. In FIG. 2, the fundus observation image is indicated by Er ′, the alignment index images are indicated by 7 a ′ and 7 b ′, and the focus index image is indicated by 21.

  The photographer operates the operation rod (not shown) while viewing the fundus observation image Er ′ and the alignment index images 7a ′ and 7b ′ displayed on the display unit 18 to move the non-mydriatic fundus camera 100 up and down, left and right, and back and forth. Move to. Thereby, alignment with the to-be-examined eye E and the non-mydriatic retinal camera 100 of the up-down-left-right and working distance direction is performed. In the present embodiment, in the alignment in the working distance direction that coincides with the optical axis L1 direction, the non-mydriatic retinal camera 100 is moved back and forth so that the contrast of the alignment index images 7a 'and 7b' is maximized. In addition, the photographer adjusts the focus lens 3 while performing the focus adjustment while viewing the focus index image 21.

  Next, the photographing procedure will be described. When the precise alignment and focus adjustment between the eye E to be examined and the non-mydriatic retinal camera 100 described above are completed, the photographer performs photographing by operating a photographing start switch (not shown). be able to.

  When the photographing start switch is operated, the fundus camera control unit 15 causes the photographing light source 13 to emit light. The photographing illumination light emitted from the photographing light source 13 passes through the fundus illumination optical system from the photographing light source 13 to the objective lens 1 and illuminates the fundus Er. The reflected light from the fundus Er illuminated by the imaging light source 13 passes through the fundus imaging optical system that reaches the objective lens 1, the perforated mirror 2, the focus lens 3, and the imaging lens 4, and reaches the image sensor 5. The fundus photographed image captured by the image sensor 5 is subjected to color tone conversion processing by the fundus camera control unit 17, processed for gamma curve calculation, and displayed on the display unit 18.

  Next, features of the present invention will be described with reference to the flowchart of FIG. The flowchart of FIG. 3 shows the operations of the index image extraction unit 14, the index image evaluation unit 15, and the index light source control unit 16 at the time of observation, which are features of the present invention.

  An object of the present invention is to provide a photographer with an ophthalmologic apparatus in which the appearance of an index image is the same regardless of individual differences in the reflectance of the eye to be examined. In this embodiment, two subjects with different reflectances of the anterior segment are used. Description will be made by taking optometry A and B as examples. It should be noted that the reflectance of the anterior eye portion is higher for the eye A to be examined than the eye B for examination, and the reflectance of the fundus oculi Er is the same for both eyes A and B.

  First, when the observation light source 11 and the alignment index light sources 7a and 7b emit light and the fundus observation image Er ′ and the alignment index images 7a ′ and 7b ′ are captured by the image sensor 5, the index image extraction unit 14 An output image of the image sensor 5 is acquired (step 101). At that time, the image sensor 5 captures both the observation image Er ′ and the index image 7 a ′ of the eye E and displays them on the display unit 18.

  At this time, the observation illumination light from the observation light source 11 and the index light from the alignment index light sources 7a and 7b are illuminated with the same amount of light as the eyes A and B, respectively, but the image pickup device 5 acquired in step 101 is used. Output images differ between the eyes A and B to be examined. The difference appears in the gradation values of the alignment index images 7a 'and 7b' due to the difference in reflectance of the anterior segment described above. In order to illustrate this, the gradation values on the dotted line 19 in FIG. 2 are as shown in FIGS. 4 shows the case of eye A to be examined and FIG. 5 shows eye B to be examined. Points H1 and H2 in FIG. 2 correspond to H1 and H2 in FIGS. 4 and 5, the gradation value of the alignment index image 7a ′ of the subject eye A (the gradation value Pa at the point H2) is the alignment index image of the subject eye B due to the difference in the reflectance of the anterior eye portion. It can be seen that it is higher than the gradation value 7a ′ (the gradation value Pb at the point H2). On the other hand, since the reflectance of the fundus is equal to each other, the tone value of the fundus observation image Er ′ of the eye A to be examined (the tone value Po at the point H1) and the tone value of the fundus observation image Er ′ of the eye B to be examined (point) It can be seen that the gradation values Po) in H1 are equal.

  Next, the index image extraction unit 14 detects the position of the alignment index image 7 a ′ or 7 b ′ in the image from the output image of the image sensor 5 acquired in step 101. Thereby, it can be seen that the alignment index image 7a 'is in the range from the point H3 to the point H4. Here, the position of the alignment index image may be detected by either one of 7a 'and 7b' or both. In the present embodiment, a case where 7a 'is detected will be described as an example (step 102).

  Next, the index image extraction unit 14 subtracts the tone value Po of the fundus observation image Er 'around it from each tone value of the alignment index image 7a' whose position has been detected in Step 102 (Step 103). Here, the tone value Po of the surrounding fundus observation image Er 'is obtained by referring to some tone values of the fundus observation image Er' existing in the vicinity of the alignment index image 7a '. In other words, the index image extraction unit 14 subtracts the tone value of the depiction site of the image of the eye Er ′ from the tone value of the depiction site of the index image 7 a ′ imaged by the image sensor 5. Only the image 7a 'is extracted. Then, only the extracted index image 7 a ′ is output to the index image evaluation unit 15.

  Since the gradation values Po of the fundus observation image Er ′ illuminated by the observation light source 11 other than the index image 7a ′ are superimposed on the gradation values of the alignment index image 7a ′ at the points H3 to H4. Only the alignment index image 7a ′ (the shaded portion in FIGS. 4 and 5) is extracted by performing the subtraction process in step 103. In other words, the influence of the observation illumination light is removed.

  Next, the index image evaluation unit 15 calculates the sum of the gradation values of the index image 7a ′ output in the above-described step 103, that is, the sum of the gradation values for each pixel of the image sensor 5 (the shaded portion in FIGS. 4 and 5). (Area) is calculated to obtain an evaluation value (step 104).

  4 and 5, the contrast value of the alignment index image 7a ′ (indicated by Pa-Po in the case of the subject eye A and Pb-Po in the case of the subject eye B) is shown. At first glance, it appears as if it appears as a function of the reflectivity of the anterior segment of the optometer, and it seems to be good to use it as an evaluation value. However, in the present invention, the contrast value of the alignment index image 7a 'is not used as the evaluation value, but the sum of the gradation values of the alignment index image 7a' is used as the evaluation value. The reason will be described with reference to FIG.

  FIG. 6 shows the gradation values on the dotted line 19 in FIG. 2 when the alignment of the eye A and the apparatus in the working distance direction is different from that in FIG. In the case of FIG. 6, the contrast of the alignment index image 7 a ′ is smaller than that of FIG. 4 (Pc with respect to Pa). Even if it is the same eye A to be examined, the contrast value changes depending on the alignment state in the working distance direction with the apparatus, so the contrast value of the alignment index image 7a 'cannot be used as an evaluation value.

  On the other hand, the sum of the gradation values of the alignment index image 7a ′ output in step 103 is the evaluation value because the value does not change even if the alignment in the working distance direction between the eye A and the apparatus changes. Can be used.

  Next, the index light source controller 16 controls the light emission amounts of the alignment index light sources 7a and 7b so that the evaluation value output in step 104 becomes a predetermined value (step 105). This makes it possible to provide the photographer with an ophthalmologic apparatus with the same appearance of the index image regardless of individual differences in the reflectance of the eye to be examined.

  In steps 103 and 104, the vertical line of the dotted line 19 shown in FIG. 2 has been described as an example, but processing may be performed in the two-dimensional direction of the vertical and horizontal directions in the image.

  Since the present invention removes the influence of the fundus observation image Er ′ superimposed on the index image in Step 103, the flow from Step 101 to Step 105 may be executed in real time during the observation. It may be executed once at the start, and thereafter executed when the amount of light emitted from the observation light source 11 changes.

  In the embodiment described here, the case where the appearance of the alignment index images 7a 'and 7b' is made equal regardless of the individual difference in the reflectance of the anterior eye part has been described. In this case, the observation light source 11 and the alignment index light sources 7a and 7b are separate light sources.

  That is, according to the present invention, when the observation light source and the index light source are configured as separate light sources, the appearance of the index image can be made equal regardless of individual differences in the reflectance of the eye to be examined. For example, if the light source for observation 11 and the focus index projection unit 20 are configured with different light sources, it is possible to provide the photographer with a focus index image that is visible even when the subject's eye has different reflectance of the fundus Er. Therefore, instead of the index light sources 7a and 7b, the focus index projection unit 20 may be used as the index light source. That is, in the present embodiment, the configuration that functions as the index projection means is defined as projecting the index used for at least one of the alignment operation and the focusing operation between the main body and the eye to be examined. Is preferred.

  In the ophthalmologic apparatus in which the light source for observing the eye to be examined and the light source for projecting the index are individually configured by arranging the configuration described above, the appearance of the index image is the same regardless of individual differences in the reflectance of the eye to be examined. That is, it becomes easy to align and focus.

(Other examples)
The present invention can also be realized by executing the following processing. That is, software (program) that realizes the functions of the above-described embodiments is supplied to a system or apparatus via a network or various storage media, and a computer (or CPU, MPU, or the like) of the system or apparatus reads the program. The processing to be executed also constitutes one aspect of the present invention.

  The present invention is not limited to the above-described embodiments, and various modifications and changes can be made without departing from the spirit of the present invention. For example, in the above embodiment, the case where the object to be measured is the eye is described, but the present invention can also be applied to the object to be measured such as skin or organ other than the eye. In this case, the present invention has an aspect as a medical device such as an endoscope other than the ophthalmologic apparatus. Therefore, it is desirable that the present invention is grasped as an inspection apparatus exemplified by an ophthalmologic apparatus, and the eye to be examined is grasped as one aspect of the object to be examined.

5: Image sensor 6a: Light guide 6b: Light guide 7a: Light source for alignment index 7b: Light source for alignment index 11: Light source for observation 13: Light source for imaging 14: Index image extraction unit 15: Index image evaluation unit 16: Index light source control unit 17: fundus camera control unit 18: display unit 20: focus index projection unit 21: focus index image 100: non-mydriatic fundus camera Er ′: fundus observation image 7a ′: alignment index image 7b ′: position Alignment index image

Claims (9)

A main body having an image sensor for capturing an image of the eye to be examined and a focusing member for performing a focusing operation at the time of capturing the image;
Index projection means for projecting an index to be used for the operation of at least one of alignment and focusing between the main body and the eye to be examined;
Index light quantity control means for controlling the light quantity of the index in the index projection means;
Index evaluation means for calculating a sum of gradation values for each pixel in the image sensor of the index image obtained by the image sensor;
The ophthalmic apparatus characterized in that the indicator light quantity control means controls the light quantity of the indicator so that the sum becomes a predetermined value. The imaging device captures both the image of the eye to be examined and the image of the index,
The ophthalmologic apparatus according to claim 1, further comprising: an index extraction unit that extracts only the index image from the output of the image sensor and outputs the extracted image to the index evaluation unit.   The ophthalmologic apparatus according to claim 2, wherein the sum of the gradation values by the index evaluation unit is obtained in an image of the index extracted by the index extraction unit.   The index extraction means extracts only the index image by subtracting the tone value of the depiction site of the image of the eye to be examined from the tone value of the depiction site of the image of the index imaged by the imaging device. The ophthalmologic apparatus according to claim 2, wherein: A method for controlling an ophthalmologic apparatus comprising: an image sensor that captures an image of an eye to be inspected; and a main body unit that has a focusing member for performing a focusing operation when capturing the image,
An index projecting step of projecting an index to be used for the operation of at least one of positioning and focusing between the main body and the eye to be examined;
An index evaluation step of calculating a sum of gradation values for each pixel in the image sensor of the index image obtained by the image sensor;
An index light amount control step for controlling the light amount of the index so that the sum becomes a predetermined value. The imaging device captures both the image of the eye to be examined and the image of the index,
6. The method of controlling an ophthalmologic apparatus according to claim 5, further comprising an index extraction step of extracting only an image of the index from the output of the image sensor in the index evaluation step.   7. The method of controlling an ophthalmologic apparatus according to claim 6, wherein the sum of the gradation values in the index evaluation step is performed on the index image extracted in the index extraction step.   The index extraction step extracts only the index image by subtracting the gradation value of the depiction site of the image of the subject's eye from the gradation value of the depiction site of the image of the index imaged by the imaging device. The method for controlling an ophthalmologic apparatus according to claim 6 or 7, wherein:   A program for causing a computer to execute each step of the method for controlling an ophthalmologic apparatus according to any one of claims 5 to 8.

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