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Eleonora M Lad, Arthika Chandramohan, Alice Ventura, Scott W Cousins; Evaluation of visual function impairments in patients with dry age-related macular degeneration. Invest. Ophthalmol. Vis. Sci. 2014;55(13):5213.
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The two main objectives of this study are: 1) to evaluate the feasibility of performing visual function testing in patients with early and intermediate dry macular degeneration (AMD), and 2) to test the hypothesis that these patients have visual function impairments even in the presence of normal visual acuity.
In this prospective study, 22 patients were enrolled: 16 with dry AMD from Age-related eye disease study (AREDS) stages 2 and 3, and 6 age-matched controls. During the baseline examination, study subjects underwent microperimetry with eye tracking (CenterVue MAIA), low luminance visual acuity (LLVA), contrast sensitivity, and cone contrast test (CCT) (Innova Systems Inc). Low luminance deficit on LLVA testing was the difference in numbers of letters read at standard vs. low luminance (0.5 cd/m2). A dilated retinal examination and Spectralis SD-OCT imaging were performed. Follow-up visual function testing was administered at 1-2 months to assess test-retest reliability, which was determined by calculating the intraclass correlation coefficient (ICC). Group comparisons were performed to evaluate the differences between the control group and the dry AMD groups AREDS 2 and AREDS3.
There was a high test-retest repeatability at 1 month for all visual function metrics (ICCs 0.79 to 0.94) with the exception of log contrast sensitivity (ICC 0.07). Compared to normal, age-matched controls, patients with dry AMD AREDS stage 3 showed significant deficits on LLVA, MAIA microperimetry, and red and blue CCT (p<0.05). There was no significant difference in visual acuity (EVA), contrast sensitivity, and green CCT between the control and AREDS3 AMD group.
This pilot study supports the feasibility of employing LLVA, MAIA microperimetry and CCT in early dry AMD. These tests were well tolerated and had high test-retest repeatability in this population. The AREDS3 AMD group exhibited visual dysfunction on LLVA, microperimetry and on red and blue CCT, in the presence of normal visual acuity. These data suggest that these visual function measures can be employed as alternative clinical trial endpoints for future proof-of-concept studies in dry AMD. A larger prospective study investigating the natural history of alternative visual function measures in early and intermediate dry AMD is warranted.
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