Retinal function measurement apparatus

Abstract

A retinal function measurement apparatus capable of measuring a retinal function accurately and precisely. The apparatus has a first image obtaining optical system for obtaining a tomographic image of a fundus by optical coherence tomography using low coherent light, the optical system including a light source emitting the low coherent light, a scanning unit scanning measurement light being a part of the emitted low coherent light on the fundus, an interference optical system for synthesizing the measurement light reflected from the fundus and reference light being a part of the emitted low coherent light to interfere, and a first photodetector photo-receiving the interfered light, a stimulating light irradiation optical system for performing irradiation of stimulating light onto the fundus, and an image processing unit obtaining information on a retinal function by performing processing on a first tomographic image and a second tomographic image before/after the irradiation of the stimulating light.

What is claimed is: 
     
       1. A retinal function measurement apparatus comprising:
 a first image obtaining optical system that obtains a tomographic image of a fundus of an examiner's eye by optical coherence tomography using low coherent light, the first image obtaining optical system including a light source which emits the low coherent light, a scanning unit which scans measurement light being a part of the emitted low coherent light on the fundus, an interference optical system for synthesizing the measurement light reflected from the fundus and reference light being a part of the emitted low coherent light to interfere, and a first photodetector which photo-receives the interfered light;   a stimulating light irradiation optical system that performs irradiation of stimulating light, having a visible wavelength capable of stimulating a retina, onto the fundus;   a fixation target presenting optical system that performs fixation of the eye;   a memory that stores an obtained tomographic image;   a control unit that controls the first image obtaining optical system to obtain a first tomographic image of the fundus before the irradiation of the stimulating light onto the fundus and stores the first tomographic image in the memory, controls the stimulating light irradiation optical system to perform the irradiation of the stimulating light onto the fundus, controls the first image obtaining optical system to obtain a second tomographic image of the fundus after the irradiation of the stimulating light onto the fundus and stores the second tomographic image in the memory; and   an image processing unit that obtains information on a retinal function by performing processing on the first tomographic image before the irradiation of the simulating light and the second tomographic image after the irradiation of the stimulating light, which are stored in the memory.   
     
     
       2. The retinal function measurement apparatus according to  claim 1  further comprising a second image obtaining optical system for obtaining a front image of the fundus, and
 wherein the image processing unit calculates a relative positional deviation between a first front image obtained in obtaining the first tomographic image and a second front image obtained in obtaining the second tomographic image, and corrects a relative positional deviation between the first tomographic image and the second tomographic image based on the obtained positional deviation to perform the processing on both the tomographic images. 
 
     
     
       3. The retinal function measurement apparatus according to  claim 2 , wherein the second image obtaining optical system includes the light source and the scanning unit of the first image obtaining optical system, a confocal optical system with respect to the fundus, a beam splitter which divides the measurement light reflected from the fundus to guide the measurement light to the interference optical system and the confocal optical system, and a second photodetector which photo-receives the measurement light passed through the confocal optical system. 
     
     
       4. The retinal function measurement apparatus according to  claim 2 , wherein the second image obtaining optical system includes an illumination optical system, which shares a part of an optical path with the stimulating light irradiation optical system for performing irradiation of illumination light onto the fundus, and an image-pickup optical system for picking up the front image of the fundus by photo-receiving the illumination light reflected from the fundus. 
     
     
       5. The retinal function measurement apparatus according to  claim 2  further comprising a setting unit which sets positional information for obtaining the tomographic image on the obtained front image, and
 wherein the first image obtaining optical system obtains the tomographic image based on the set positional information. 
 
     
     
       6. The retinal function measurement apparatus according to  claim 1 , wherein the first image obtaining optical system includes an optical path length changing unit which changes an optical path length of the reference light in synchronization with the scanning of the measurement light by the scanning unit. 
     
     
       7. The retinal function measurement apparatus according to  claim 1 , wherein
 the first image obtaining optical system includes a dispersing unit which disperses the interfered light into frequency components, and   wherein the first photodetector photo-receives the dispersed light.   
     
     
       8. A retinal function measurement apparatus comprising:
 a first image obtaining optical system that obtains a tomographic image of a fundus by optical coherence tomography using low coherent light, the first image obtaining optical system including a light source which emits the low coherent light, a scanning unit which scans measurement light being a part of the emitted low coherent light on the fundus, an interference optical system for synthesizing the measurement light reflected from the fundus and reference light being a part of the emitted low coherent light to interfere, and a first photodetector which photo-receives the interfered light;   a stimulating light irradiation optical system that performs irradiation of stimulating light onto the fundus;   an image processing unit that obtains information on a retinal function by performing processing on a first tomographic image before the irradiation of the stimulating light and a second tomographic image after the irradiation of the stimulating light; and   a second image obtaining optical system that obtains a front image of the fundus,   wherein the image processing unit calculates a relative positional deviation between a first front image obtained in obtaining the first tomographic image and a second front image obtained in obtaining the second tomographic image, and corrects a relative positional deviation between the first tomographic image and the second tomographic image based on the obtained positional deviation to perform the processing on both the tomographic images.   
     
     
       9. The retinal function measurement apparatus according to  claim 8 , wherein the second image obtaining optical system includes the light source and the scanning unit of the first image obtaining optical system, a confocal optical system with respect to the fundus, a beam splitter which divides the measurement light reflected from the fundus to guide the measurement light to the interference optical system and the confocal optical system, and a second photodetector which photo-receives the measurement light passed through the confocal optical system. 
     
     
       10. The retinal function measurement apparatus according to  claim 8 , wherein the second image obtaining optical system includes an illumination optical system, which shares a part of an optical path with the stimulating light irradiation optical system for performing irradiation of illumination light onto the fundus, and an image-pickup optical system for picking up the front image of the fundus by photo-receiving the illumination light reflected from the fundus. 
     
     
       11. The retinal function measurement apparatus according to  claim 8 , further comprising a setting unit which sets positional information for obtaining the tomographic image on the obtained front image, and
 wherein the first image obtaining optical system obtains the tomographic image based on the set positional information.   
     
     
       12. A method for comparing tomographic images of a same portion of a fundus that are obtained by an optical coherence tomography device, the method comprising:
 obtaining a first three-dimensional tomographic image of the fundus by the optical coherence tomography device and a first front image of the fundus that is associated with the first three-dimensional tomographic image;   obtaining a second three-dimensional tomographic image of the fundus by the optical coherence tomography device at an interval from the obtainment of the first three-dimensional tomographic image and a second front image of the fundus that is associated with the second three-dimensional tomographic image;   performing alignment of the first front image and the second front image and associating the first three-dimensional tomographic image and the second three-dimensional tomographic image based on an alignment result; and   comparing the associated first and second three-dimensional tomographic images.    
     
     
       13. A method for comparing tomographic images of a same portion of a fundus that are obtained by an optical coherence tomography device, the method comprising:
 obtaining a first tomographic image of the fundus by the optical coherence tomography device and a first front image of the fundus that is associated with the first tomographic image;   obtaining a second tomographic image of the fundus by the optical coherence tomography device at an interval from the obtainment of the first tomographic image and a second front image of the fundus that is associated with the second tomographic image,   wherein the obtainment of at least one of the first tomographic image and the second tomographic image by the optical coherence tomography device is performed by controlling driving of an optical scanner that is provided to the optical coherence tomography device based on information on an obtainment position of a fundus tomographic image with respect to a previously obtained fundus front image and a fundus front image that is obtained by a fundus observation optical system so that measurement light is scanned within a predetermined scanning range of the measurement light on the fundus; and   comparing the obtained first and second tomographic images.