Purchase this article with an account.
S.A. Kabanarou, M.D. Crossland, C. Bellmann, A. Rees, L.E. Culham, G.S. Rubin; Binocular Viewing In AMD . Invest. Ophthalmol. Vis. Sci. 2004;45(13):3064.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Purpose: Non foveal viewing develops in age–related macular degeneration (AMD) when central scotomas occur in both eyes. AMD often affects the two eyes differently regarding the size and the location of the scotomas. Therefore, the preferred retinal locus (PRL) in one eye may not correspond with the PRL in the other eye, nor with the PRLs used if the subject views with both eyes. This binocular incongruity may interfere with the development of eccentric fixation and binocular vision. The purpose of this study is to investigate the PRLs used for binocular viewing and binocular function in patients with bilateral AMD. Methods: Seventeen patients with bilateral AMD were included in the study. Visual acuities were recorded monocularly and binocularly with best corrected refraction. A scanning laser ophthalmoscope (SLO) was used to identify PRLs and to map retinal scotomas monocularly for both eyes. An infrared eye tracker was used to evaluate gaze position changes (and indirectly retinal locus changes) between monocular and binocular fixation. Superimposition of the eyetacker data on the SLO maps demonstrated the retinal locus used for fixation for each eye under binocularly viewing conditions. Global binocular function was tested with Bagolini striated glasses and local binocular function was tested with a computer–driven display and CrystalEyes shutter glasses. Results: Three patients used the same PRL to fixate under monocular and binocular conditions for both eyes. Three patients demonstrated a shift in their PRLs in both eyes when viewing binocularly while the remaining eleven patients demonstrated a shift only in their worse seeing eye. We calculated the "shift distance" as the vector sum of the horizontal and vertical shift for each PRL. The range of the shift distance from monocular to binocular viewing varied from 2.88º to 17.48º of visual angle (mean 6.46 ± 3.70SD) in the latter two groups. According to SLO data, patients who used non corresponding monocular PRLs demonstrated a shift in their PRL in one or both eyes when viewing binocularly. In addition, the location of the binocular PRL in the worse seeing eye fell within the retinal scotomas in 5 patients. All patients exhibited global binocular function, but only four showed evidence of local binocular function near the PRL. Conclusions: There is evidence that AMD patients maybe use a different PRL when viewing binocularly. Interestingly, local binocular function near the PRL seems impaired in the majority of the cases even for the subjects whose binocular PRLs fall outside macular scotomas as elicited by SLO recordings.
This PDF is available to Subscribers Only