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N. Rawlings, A. F. Cruess, P. H. Artes; Assessment of Age-Related Macular Degeneration With a Radial Deformation Acuity Chart. Invest. Ophthalmol. Vis. Sci. 2009;50(13):232.
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Radial deformation acuity (RDA) is a visual hyperacuity which may be reduced in macular pathologies with subtle foveal distortion. In this study, we examined the correlation with disease severity, the test-retest reliability, and learning effects with a set of 6 handheld RDA charts, in patients with age-related macular degeneration (AMD) and in healthy controls.
Fifteen patients with AMD (mean age: 73 yrs, range: 47 - 86 yrs; mean logMAR: +0.28, range: -0.08 to 1.52) and 5 controls (mean age: 71 yrs; mean logMAR: +0.12) were examined with visual acuity (VA), contrast sensitivity (CS), Spectralis Fourier domain optical coherence tomography, and fundus photography. Twenty-one of 39 eyes had non-exudative AMD with drusen and pigment abnormalities. Nine eyes had foveal geographic atrophy (n=6) or exudative AMD (n=3). Shape discrimination was assessed with 6 RDA charts. All psychophysical tests were completed on 2 sessions separated by 2 weeks.
There was a strong correlation between log RDA and level of AMD (AREDS category, Spearman r= 0.80, p<0.001), which was similar or higher than that obtained with VA(r= 0.72) or CS (r= -0.59). The width of the 95% limits of agreement (Bland-Altman analysis) was 0.50 log for RDA, 0.36 logMAR for VA, and 0.49 log for CS. A learning effect was evident with RDA (0.13 log, p<0.001, Wilcoxon) but not with VA (p=0.43) or CS (p=0.58).
AMD patients showed deficits in RDA which correlated with the stage of disease (AREDS category). In some eyes, RDA appeared to be reduced out of proportion to VA or CS. This suggests that RDA may be useful for assessing and monitoring AMD.
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