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Jason Andrew Alvarez, Mohammad Yazdanie, Wai T Wong, Darby Thompson, Rachel Lipson, Henry Wiley, Emily Y Chew, Frederick Ferris, Catherine Cukras; Longitudinal Study of Dark Adaptation as a Functional Outcome Measure for Age-Related Macular Degeneration. Invest. Ophthalmol. Vis. Sci. 2016;57(12):2654. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
Impairments in dark adaptation (DA) as measured by rod intercept time (RIT) have previously been correlated with age-related macular degeneration (AMD) severity and presence of reticular pseudodrusen (RPD) using cross-sectional, observational data. In this longitudinal analysis, we assess whether RIT changes significantly over 2 years and whether RIT change is correlated with AMD severity.
Participants >50 years of age were assigned into groups based on fundus characteristics: no large drusen (Group 0), unilateral large drusen (Group 1), bilateral large drusen (Group 2), late AMD in one eye with large drusen in contralateral eye (Group 3), presence of RPD regardless of AMD status (Group 4). One study eye per participant underwent DA testing using a prototype AdaptDx device (MacuLogix, Hummelstown, PA) at baseline, 3-, 6-, 12-, 18 months, and 2 years. Wilcoxon tests were used to compare baseline and 2-year RIT across all eyes and per group. Linear regressions were also performed to determine slope of change in each eye. Mann-Whitney tests were used to compare slopes between groups.
Out of 116 participants with measurable baseline RIT under test ceiling (mean age 75.4±9.4, 58% female), 81 participants (mean age 75.3±9.2, 54% female) had 2-year RIT on the same DA protocol (82% focal bleach at 5o). Eyes that underwent cataract extraction/intraocular lens placement during the study (n=5/81) had significant RIT prolongation vs eyes that did not change phakic status (median ΔRIT=7.10 vs 1.15 mins, Mann-Whitney p=0.003) and were thus excluded from analysis. In all remaining participants (n=76/81), RIT increased by a median value of 1.15 min at 2 years (Wilcoxon p<0.0001). RIT at 2 years was not significantly changed from baseline in Group 0 (Wilcoxon p=0.097; n=37/76), but was significantly increased in Groups 1-3 combined (Wilcoxon p=0.0002; n=38/76). Additionally, slope of change was significantly greater in Groups 1-3 vs Group 0 (median slope RIT=0.75 vs 0.27 min/year, Mann-Whitney p=0.036).
Dark adaptation as measured by RIT demonstrated a small but statistically significant prolongation over 2 years in eyes with AMD, not seen in control eyes. Change in phakic status was also associated with delayed DA. Prolongation of dark adaptation may be a useful phenotypic change of visual function in the monitoring of AMD progression.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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