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L. Tarita–Nistor, E.G. Gonzalez, S.N. Markowitz, M.J. Steinbach; Binocular Function in Patients With Age–Related Macular Degeneration . Invest. Ophthalmol. Vis. Sci. 2005;46(13):5234.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: We examined two aspects of binocular function in patients with age–related macular degeneration (AMD): summation/inhibition of visual acuity, and rivalry. Methods: The performance of 16 AMD patients (mean age = 82.5) with visual acuities between 20/70 and 20/200 in the better eye was compared with that of 14 age–matched controls (mean age = 74.5) with no macular pathology and 21 young people (mean age = 33.4 yrs). Monocular and binocular acuities were measured using a multiple E optotype test at high, medium and low contrast levels. Binocular ratios (BR), defined as the better eye acuity divided by the binocular acuity were calculated, values greater than one indicating binocular summation and smaller or equal to one inhibition. We also measured eye dominance (proportion of time the participants reported perceiving the input to each eye) and rivalry rates (number of dominance alternations per minute) using sinusoidal gratings at orthogonal orientations presented dichoptically at three levels of contrast. Results: Acuity decreased with contrast level for all groups. For participants who experienced summation (BR > 1), BR was the same for all three groups. For observers who experienced inhibition (BR < 1), the BR of the AMD group was similar to that of the age–matched controls and significantly lower than that of the young controls. The proportion better–eye dominance did not change as a function of either group or contrast. Worse–eye dominance however, was lower in the AMD group than in the age–matched and young control groups. The rivalry rate of the young control group was significantly higher than that of the other two groups and it decreased as a function of contrast. The rivalry rate of the age–matched group was higher than that of the AMD group, but it did not change as a function of contrast for either of these two groups. Conclusions: Some aspects of binocular function in people with AMD (acuity, proportion of worse–eye dominance and rivalry rate) are different, while others (the amount of inhibition and the relationship between rivalry rate and contrast) seem to be affected by age rather than pathology, and still others (BR and the proportion of better–eye rivalry dominance), are comparable to those of young people.
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