Binocular function and stereopsis in neovascular age-related macular degeneration

PURPOSE: A macular lesion preventing the foveal fixation could lead to the fixation from eccentric points in age-related macular degeneration (AMD). There is a lack of knowledge about the binocular function of these patients and the role of preferred retinal locus loci in binocularity. This study aims to examine binocular fusion and stereopsis in a unique group of patients who have unilateral choroidal neovascular membrane (CNVM) involving the fovea.
METHODS: Twenty-five patients with the diagnosis of the CNVM in one eye and type I or type II drusen in the other eye were examined. The Bagolini test was performed to determine binocular fusion. The Stereo Butterfly test was used for stereo acu-ity determination. CNVM measurements were done with an optical coherence tomography.
RESULTS: In the Bagolini test, 12 patients saw two lines with break in one of the lines. Eleven patients saw two lines crossing at higher or lower than the center. Two patients saw only one line. One of 25 patients had gross stereopsis (2500 s of arc). The area of the CNVM was extending to the perifovea in 2 patients suppressing the other eye. In remaining 23 patients, CNVM was located in fovea or extended up to the parafovea.
CONCLUSION: Binocular fusion is possible if the CNVM lesion size and location allow usage of the fovea-parafovea visual angle. Our study results support that the binocular function of patients with neovascular AMD depends on the corresponding retinal areas and the fusional limit of non-corresponding points.