SCANNING LASER OPHTHALMOSCOPIC ANALYSIS OF THE PATTERN OF VISUAL-LOSSIN AGE-RELATED GEOGRAPHIC ATROPHY OF THE MACULA

PURPOSE: We explored the clinical impression that geographic atrophy o f the retinal pigment epithelium, a form of advanced age related macul ar degeneration, is perceived by the patient as progressing gradually, even when fixation switches from foveal to extrafoveal. METHODS: We a nalyzed the responses of 60 patients with geographic atrophy to a ques tion naire administered as part of a five year study of the natural co urse of geographic atrophy, funded by the National Eye Institute. We p erformed scanning laser ophthalmoscope perimetry on all patients. We e xamined two additional patients with geographic atrophy who reported a brupt visual loss. RESULTS: No eye with geographic atrophy was reporte d by any patient to have had sudden visual loss. Although most patient s with geographic atrophy show foveal fixation until the fovea is atro phic and then show extrafoveal fixation, scanning laser ophthalmoscope perimetry in three patients with geographic atrophy showed alternatio n between a foveal and an extrafoveal retinal locus for fixation. Two patients with geographic atrophy who complained of abrupt visual loss were found to have occult choroidal neovascularization, which evolved in one patient to classic choroidal neovascularization. The neovascula rization was difficult to detect because of the presence of geographic atrophy and its associated ophthalmoscopic and fluorescein angiograph ic features. CONCLUSIONS: Visual loss in geographic atrophy is nearly always perceived by the patient as being gradual, even when considerab le decreases in visual acuity occur and when foveal vision and fixatio n are lost. A possible explanation for this perception is that there i s a transitional period during which a patient uses both a foveal and extrafoveal site for fixation. The complaint of abrupt visual loss in a patient with geographic atrophy should raise the suspicion of choroi dal neovascularization, which may be occult and difficult to detect.