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Karl Csaky, David Birch, Rosie Gelman, Joost Felius; The Relationship of Choroidal Thickness to Scotopic Sensitivity in Age-related Macular Degeneration (AMD). Invest. Ophthalmol. Vis. Sci. 2013;54(15):4097.
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Purpose. Scotopic (rod mediated) sensitivity is known to be decreased in AMD and is presumed to be due to rod photoreceptor structural loss but the relationship to other anatomic changes within the retina remains unclear. The goals of the present study were to 1) further understand the effects of different stages of AMD on retinal sensitivity and 2) to understand the relationship to altered choroidal thickness.
One eye from patients with early AMD (n=8; age = 71.4±10.2y), intermediate AMD (n=17; age = 75.4±8.6y) or central geographic atrophy (GA) (n=15; age 73.8±7.6y; GA area 3.2±3.3 mm2) or age-matched controls (n=11; age = 62.5±5.8y) was examined. Following dark adaptation, rod-mediated sensitivities were measured at numerous locations within the retinal arcades using a modified fundus microperimeter (MP-1S, Nidek Technologies). Test locations were unique to each patient and avoided areas of GA. Choroidal thickness was measured using an Enhanced Depth Imaging Protocol (EDI) by spectral domain optical coherence tomography (Heidelberg Engineering). Results were reported as percent change from normal for both retinal sensitivities and choroidal thicknesses.
The overall percent change from normal for scotopic retinal sensitivities = -2% ±32% (early AMD), -14%±43% (intermediate AMD), and -63%±40% (GA). The percent change from normal for choroidal thicknesses from each group were: -9%±27% (early AMD), -21%±29% (intermediate AMD), and -36%±37% (GA). Loss of rod-mediated sensitivity was strongly associated with the stage of AMD (P=0.001, ANOVA for ordered groups) but only weakly with changes in choroidal thickness (P=0.053, lin regression).
In this preliminary study, there was a strong statistically significant association between progressive loss of rod sensitivities and advancing AMD. However there was a weaker association between decreasing choroidal thickness, found at advancing stages of AMD, and reduced retinal sensitivities. These results suggest that rod sensitivities may be independent marker of AMD progression.
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