PURPOSE: Various methods have been used to obtain a topographic map of bleached photopigments in human retinas in the past. The purpose of this study was to determine whether the bleaching topography of the photoreceptors could be obtained by snapshot imaging reflectometry. METHODS: Four to five fundus photographs of one rhesus monkey and three healthy human subjects were taken by white flashes at intervals of 4 s, with a commercial fundus camera with minimal modifications. The flash-induced reflectance increases (bleaching) were calculated by dividing the reflectance of the first image into the subsequent images, pixel by pixel. RESULTS: The topography of the bleached macula corresponded well with the anatomical distribution of the cones. The ratio of reflectance changes in the center to that in the surrounding tissue was high for red and low for green and blue images. These results indicate that the reflectivity changes were not artifacts but were derived from changes in the photopigment density in the cones and rods. CONCLUSIONS: The topography of bleached photoreceptors obtained with a commercial fundus camera from one monkey and three healthy human subjects showed that this technique has potential as a new clinical method for examining photoreceptor function in both normal and diseased retinas.
PURPOSE: Various methods have been used to obtain a topographic map of bleached photopigments in human retinas in the past. The purpose of this study was to determine whether the bleaching topography of the photoreceptors could be obtained by snapshot imaging reflectometry. METHODS: Four to five fundus photographs of one rhesus monkey and three healthy human subjects were taken by white flashes at intervals of 4 s, with a commercial fundus camera with minimal modifications. The flash-induced reflectance increases (bleaching) were calculated by dividing the reflectance of the first image into the subsequent images, pixel by pixel. RESULTS: The topography of the bleached macula corresponded well with the anatomical distribution of the cones. The ratio of reflectance changes in the center to that in the surrounding tissue was high for red and low for green and blue images. These results indicate that the reflectivity changes were not artifacts but were derived from changes in the photopigment density in the cones and rods. CONCLUSIONS: The topography of bleached photoreceptors obtained with a commercial fundus camera from one monkey and three healthy human subjects showed that this technique has potential as a new clinical method for examining photoreceptor function in both normal and diseased retinas.
Authors: Paul S Bernstein; Binxing Li; Preejith P Vachali; Aruna Gorusupudi; Rajalekshmy Shyam; Bradley S Henriksen; John M Nolan Journal: Prog Retin Eye Res Date: 2015-11-02 Impact factor: 21.198