JP2007151623A - Retinal function measuring apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a retinal function measuring apparatus capable of stably measuring the retinal function of an eye to be examined. <P>SOLUTION: The retinal function measuring apparatus comprises an objective optical system arranged in front of the eye to be examined E, an observation light optical system 10 for illuminating the retinal region of the eye to be examined via the objective optical system, a light receiving optical system 20 for acquiring, a retinal image by receiving reflected light from the retinal region illuminated by the observation light optical system 10 via the objective optical system, and a retina stimulating optical system 30 for stimulating the retina by irradiating the retinal region of the eye to be examined with visible stimulating light. The retinal function measuring apparatus acquires information about change of the retinal function through operation processing of the retinal images before and after irradiation with the visible stimulating light by the retinal stimulating optical system 30. The objective optical system has an objective concave mirror 1 which illuminates the predetermined region of the retina of the eye to be examined with reflecting illumination light from the observation light optical system 10 and by converging the light in the vicinity of the pupil of the eye to be examined. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a retinal function measuring device that optically measures a retinal function of an eye to be examined.

As an apparatus for optically measuring the retinal function of the subject's eye, an illumination optical system that illuminates the retina of the subject's eye, a light-receiving optical system that receives light from the illuminated retinal region, and a stimulus to the retina of the subject's eye The optical system for retinal stimulation that irradiates light, and imaging changes in the retinal function of the subject's eye by determining changes in the brightness of the retinal region before and after the retinal region of the subject's eye is illuminated with the stimulating light Is disclosed (see Patent Document 1). Patent Document 1 describes that an optical system of a fundus camera (see, for example, Patent Document 2) is configured as a base.
Special Table 2002-521115 JP 2005-160550 A

By the way, in the case of a fundus camera, a black spot plate having a black spot at the center is arranged in the optical path of the illumination optical system that illuminates the fundus of the eye to be examined through an objective lens arranged in front of the eye of the test eye. Thus, the internally reflected light generated in the objective lens can be removed.
However, although the black spot plate can remove internally reflected light generated in the objective lens, it causes a decrease in the amount of illumination light in the vicinity of the center of the obtained retinal image (fundus image). In retinal image acquisition with a fundus camera, the partial reduction in the amount of light due to the black spot plate is negligible and is not particularly problematic, but it is required to detect a slight change in the amount of reflected light from the retina. In the case of the above-described retinal function measuring device, even such a small light amount decrease (light amount unevenness) greatly affects the measurement of the retinal function.

  In view of the above problems, an object of the present invention is to provide a retinal function measuring device that can stably measure the retinal function of an eye to be examined.

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

(1) an objective optical system disposed in front of the eye of the subject eye, an observation illumination optical system that illuminates the retina region of the subject eye via the objective optical system, and a retinal region illuminated by the observation illumination optical system A light-receiving optical system for receiving reflected light through the objective optical system to obtain a retinal image; and a retinal stimulation optical system for stimulating the retina by irradiating the retina region of the eye to be examined with visible stimulation light. In the retinal function measuring apparatus that acquires retinal function change information by performing arithmetic processing on the retinal image before and after irradiation of the visible stimulus light by the retinal stimulation optical system, the objective optical system is emitted from the observation illumination optical system And an objective concave mirror that illuminates a predetermined region of the retina of the eye to be examined by reflecting the reflected illumination light to converge once in the vicinity of the pupil of the eye to be examined.
(2) In the retinal function measuring device according to (1), the optical system for retinal stimulation stimulates the retinal region of the eye to be examined in a single shot or flicker with visible flash light.
(3) In the retinal function measuring device according to (1), the retinal function measuring device includes a determination unit that determines the degree of stability of the brightness of the illumination light emitted from the light source of the observation illumination optical system.

  According to the present invention, the retinal function of the eye to be examined can be stably measured.

  Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing an optical system of a retinal function measuring apparatus according to this embodiment.

  In FIG. 1, the optical system of the present apparatus includes an observation illumination optical system 10 that illuminates the retinal region of the eye E, and a light receiving optical system 20 that receives reflected light from the illuminated retinal region and obtains a retinal image. And a retinal stimulation optical system 30 that stimulates the retina by irradiating the retinal region of the subject's eye with visible stimulation light, and a fixation optical system 40 that causes the subject's eye to fixate.

  The observation illumination optical system 10 is an observation light source 11 such as a halogen lamp that emits infrared light, for example, an infrared filter 12 that transmits infrared light having a wavelength of 800 nm to 1000 nm, a condenser lens 13, and reflects infrared light to visible light. A dichroic mirror 14 having a characteristic of transmitting light, a ring slit 15 having a ring-shaped opening, a light projecting lens 16, a perforated mirror 17, a first total reflection mirror 18, a second total reflection mirror 19, and the objective concave mirror 1. The ring slit 15 and the perforated mirror 17 are disposed at a position substantially conjugate with the pupil of the eye to be examined. Here, the observation illumination light emitted from the observation light source 11 is converted into an infrared light beam by the infrared filter 12, collected by the condenser lens 13, and then reflected by the dichroic mirror 14 to pass through the ring slit 15. Illuminate. The light transmitted through the ring slit 15 reaches the perforated mirror 17 through the light projecting lens 16. The light reflected by the mirror part of the perforated mirror 17 is once converged in the vicinity of the pupil of the eye E by being reflected by the objective concave mirror 1 via the first total reflection mirror 18 and the second total reflection mirror 19. After that, it is diffused to continuously illuminate a predetermined region of the retina of the eye to be examined. In the present embodiment, the objective concave mirror 1, the second total reflection mirror 19, and the first total reflection mirror 18 form an objective optical system disposed in front of the eye to be examined.

  The retinal stimulation optical system 30 includes a stimulation light source 31 that emits visible flash light for stimulating the retinal region, a condenser lens 33, and a ring slit 15 that shares an optical path with the observation illumination optical system 10 to the objective concave mirror 1. Includes optics. The stimulus light source 31 emits visible flash light in a single shot or in a flicker shape. Here, the visible flash light emitted from the stimulation light source 31 is irradiated to the retinal region of the eye to be examined through the condenser lens 33 and the dichroic mirror 14 through the same optical path as the observation illumination light. Note that the stimulation light stimulates cells constituting the retina. Reference numeral 32 denotes a wavelength selection filter for selecting a wavelength to be used as stimulation light (for example, red), and is inserted into an optical path between the stimulation light source 31 and the condensing lens 33 according to circumstances. It is used to stimulate a specific part of the retina by irradiating it with stimulation light having a specific wavelength (eg, stimulating the long wavelength cone of the retina by using the red wavelength) .

  The light receiving optical system 20 includes an objective concave mirror 1, a second total reflection mirror 19, a first total reflection mirror 18, a focusing lens 21 movable in the optical axis direction, an imaging lens 22, and a two-dimensional light receiving element 23. In this case, the light receiving optical system 20 shares the optical path from the objective concave mirror 1 to the perforated mirror 17 with the observation illumination optical system 10. The focusing lens 21 moves in the optical axis direction by driving the drive mechanism 50. The reflected light from the retinal region illuminated by the observation light source 11 is reflected by the objective concave mirror 1, and once condensed in front of the perforated mirror 17 via the second total reflection mirror 19 and the first total reflection mirror 18. After that, it passes through the opening of the perforated mirror 17. Then, the reflected light that has passed through the aperture (hole portion) of the perforated mirror 17 is condensed by the imaging lens 22 via the focusing lens 21 and then imaged on the two-dimensional light receiving element 23.

  The fixation optical system 40 includes a fixation light source 41 that emits visible light, a pinhole 42, and a dichroic mirror 29 that has a characteristic of reflecting visible light and transmitting infrared light, and includes from the dichroic mirror 29 to the objective concave mirror 1. The optical path is shared with the light receiving optical system 20. The pinhole 42 is disposed at a position substantially conjugate with the observation point (imaging point) of the eye retina to be examined. The light source 41 and the pinhole 42 are configured to be movable on a plane perpendicular to the optical axis direction. The light emitted from the fixation light source 41 passes through the pinhole 42, is reflected by the dichroic mirror 29, and then passes through the optical path in the direction opposite to the reflected light from the retina (imaging lens 22 to objective concave mirror 1). An image is formed on the retina of the optometer.

  FIG. 2 is a block diagram showing a control system of the retinal function measuring apparatus in the present embodiment. A control unit 70 controls the entire apparatus. Connected to the control unit 70 are an observation light source 11, a light receiving element 23, a stimulus light source 31, a fixation light source 41, a drive mechanism 50, an image processing unit 71 for imaging the fundus image of the eye to be examined and retinal functions. The Reference numeral 75 denotes a monitor on which a retinal image formed by the image processing unit 71 is displayed. Reference numeral 72 denotes a storage unit for storing various information. Reference numeral 74 denotes a control unit for performing various input operations.

The operation of the retinal function measuring apparatus having the above configuration will be described.
The examiner drives the apparatus using a joystick (not shown) and performs alignment so that illumination light is irradiated onto the fundus of the eye to be examined and a desired image is displayed on the monitor 75. Then, the focus adjustment of the image is performed by driving the drive mechanism 50 using a focus adjustment switch provided in the control unit 74.

  When measuring the retinal function, a photographing button (not shown) of the control unit 74 is pressed in a state where a fundus image at a desired position is displayed on the monitor 75. When the photographing button is pressed, the control unit 70 stores the fundus image before the stimulation light emission in the storage unit 72 as a reference retinal image, and emits visible flash light toward the fundus of the eye E using the stimulation light source 31. Irradiate. The infrared illumination light continuously illuminates a predetermined region of the fundus of the eye E regardless of before and after the flash light irradiation. The control unit 70 further stores the retinal image after irradiation with flash light (stimulation light) in the storage unit 72. Not only one retinal image is taken after the flash light irradiation, but the retinal image may be stored continuously or temporally after the flash light irradiation so that a change in retinal function can be seen. In this case, data used for analysis may be extracted from a plurality of stored images.

  Then, the control unit 70 performs analysis based on a predetermined retinal image stored in the storage unit 72. In this case, the control unit 70 performs arithmetic processing on the retinal image before and after flash light irradiation stored in the storage unit 72 to obtain retinal function change information, and displays the result on the monitor 75 via the image processing unit 71. To do.

  Here, the principle for measuring the retinal function will be briefly described. That is, when stimulation light such as flash light is irradiated on the fundus of the eye E and the cells constituting the retina are stimulated, the activity of the nerve cells changes with the stimulation, and the site where the nerve activity occurs The intensity (reflectance) of the reflected light changes. For this reason, by reading the change in the brightness of the retinal image before and after the flash light irradiation, an intrinsic signal change resulting from the change in the activity of the nerve cell can be obtained. Therefore, the retinal function of the eye to be examined can be measured.

  When measuring the retinal function, the controller 70 first aligns the retinal image before flash light irradiation (reference retinal image) stored in the storage unit 72 with the retinal image after irradiation. For alignment, feature points (eg, blood vessel shape, nipple, macula, etc.) are extracted from the pre-irradiation retinal image (reference retinal image) and post-irradiation retinal image by image processing, and both images are moved relative to each other. The position where the feature points of both images most closely match is obtained by arithmetic processing by performing enlargement, reduction, or the like. Note that the alignment method is not limited to this, and a known image processing technique may be used.

  After such alignment of the retinal image before and after irradiation, the control unit 70 obtains, for each pixel, a change in the brightness of the retinal image after irradiation with respect to the brightness of the retinal image before irradiation. The change in brightness can be obtained by obtaining a difference, a ratio, or the like. The image processing unit 71 displays the brightness change information obtained by the control unit 70 on the monitor 75 in association with each pixel. As brightness change information, a method of displaying brightness change information as an image according to shading and height, numerical information of differences and ratios, and processing of this numerical information by a predetermined analysis program for evaluating retinal function It can be expressed by the information etc.

  In this embodiment, it is assumed that the retinal image acquisition before the flash light irradiation, the retinal image acquisition after the flash light irradiation, and the analysis of the retinal image are automatically performed. However, the present invention is not limited to this. It is also possible to perform the operation manually.

  Below, the effect | action of using the objective concave mirror 1 for the optical system of this embodiment is demonstrated. That is, since the objective concave mirror 1 is used, no internal reflection light is generated when the objective lens is used, and it is not necessary to arrange a black spot plate in the optical path of the illumination observation optical system. It is possible to prevent the occurrence of unevenness in the amount of light on the retina image. Therefore, when obtaining the change in brightness of the retinal image before and after irradiation of the stimulation light, if the eyeball of the subject's eye moves, alignment processing of the retinal image before and after irradiation of the subject's eye is performed in advance. However, the change in brightness is not caused by a factor unrelated to the change in retinal function. This makes it possible to obtain a highly reliable measurement result regarding the measurement of the retinal function in the vicinity of the center of the detected retinal image.

  FIG. 3 is a diagram showing the light amount level near the center of the retinal image when the objective concave mirror is used. In this case, specific light amount unevenness does not occur, and the light amount level is almost constant, so that it can be said that it is in a preferable state for measuring the retinal function.

  When measuring the retinal function as described above, after the brightness of the illumination light emitted from the observation light source 11 that illuminates the retinal region of the eye to be examined is stabilized over time, the retinal image before the stimulation light irradiation is obtained. get. In this case, the control unit 70 may have a determination function for determining the degree of stability of the brightness of the illumination light emitted from the light source 11. For example, the control unit 70 measures the brightness of the illumination light after the observation light source 11 is turned on, and the measurement result satisfies a predetermined allowable range for determining a preset stability level of the brightness of the illumination light. In such a case, it may be possible to display on the screen of the monitor 75 that the measurement can be started. In this way, the examiner can start measuring the retinal function with peace of mind.

It is the figure which showed the optical system of the retinal function measuring device of this embodiment. It is the block diagram which showed the control system of the retinal function measuring device in this embodiment. It is a figure showing the light quantity level of the center part vicinity of a retinal image in the case of using an objective concave mirror.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Objective concave mirror 18 1st total reflection mirror 19 2nd total reflection mirror 20 Light reception optical system 30 Retina stimulation optical system 70 Control part 75 Monitor

Claims (3)

An objective optical system disposed in front of the eye of the subject eye, an observation illumination optical system that illuminates the retinal region of the subject eye via the objective optical system, and reflected light from the retinal region illuminated by the observation illumination optical system A light receiving optical system for receiving a light through the objective optical system to obtain a retinal image, and a retina stimulation optical system for stimulating the retina by irradiating a visible stimulation light to a retina region of the eye to be examined. In a retinal function measuring device that acquires retinal function change information by calculating and processing retinal images before and after irradiation with visible stimulus light by a stimulation optical system,
The objective optical system includes an objective concave mirror that illuminates a predetermined region of the retina of the eye to be examined by reflecting the illumination light emitted from the observation illumination optical system so as to converge once in the vicinity of the pupil of the eye to be examined. Retinal function measuring device. 2. The retinal function measuring device according to claim 1, wherein the retinal stimulation optical system stimulates the retinal region of the eye to be inspected in a single shot or flicker with visible flash light. 2. The retinal function measuring apparatus according to claim 1, further comprising a determination unit that determines a degree of stability of brightness of illumination light emitted from a light source of the observation illumination optical system.

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