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David Waters-Honcu, Michael J. Byrnes, Patrick Johnston, Sunita Saigal, Gail Torkildsen, Avner Ingerman; Assessment Of Reduced Visual Function In Early-to-Intermediate Dry AMD By Means Of A Macular Recovery Time Test. Invest. Ophthalmol. Vis. Sci. 2011;52(14):4009.
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© ARVO (1962-2015); The Authors (2016-present)
We have previously developed a highly reproducible method for assessing macular recovery time by measuring recovery of L-cone sensitivity after photostress. By this method, recovery time is significantly elevated in older subjects relative to younger. In this study, the MRT of early-to-intermediate dry AMD patients was compared to younger and older control subjects.
MRT after photostress was assessed in 44 eyes of 22 subjects, including 5 younger controls (aged 20-23; BCVA ≥ 20/20 in better eye), 6 older controls (aged 61-75; BCVA ≥ 20/40 in better eye), and 11 patients with early-to-intermediate dry AMD (aged 60-81; BCVA ≥ 20/40 in better eye). Each subject was tested 3 times within 2 weeks to assess reproducibility. After baseline assessment of L-cone threshold using the Roland Consult Dark Adaptometer, a photostress exposure sufficient to bleach 90-95% of cone photopigment was applied with a diffused fluorescent light source. Immediately following exposure, the recovery of L-cone sensitivity was monitored with the dark adaptometer. For each subject and trial, recovery half-life was estimated using an exponential recovery model. The effects of age and disease status on baseline cone threshold and recovery half-life were assessed via an exponential model with fixed effects for age and AMD and random effects for subjects.
Mean ages of young controls, old controls, and AMD patients were 21.6, 64.0, and 70.2. Mean logMAR BCVA of young controls, old controls, and AMD patients were -0.05 (-0.16 - 0.0), 0.07 (-0.04 - 0.16), and 0.11 (-0.06 - 0.28) in their better eyes, and -0.04 (-0.14 - 0.0), 0.1 (0.02 - 0.18), and 0.25 (0.02 - 0.38) in their worse eyes. As described previously, old subjects had longer recovery times than young subjects. A bimodal pattern was observed in the AMD eyes, with a subset of eyes having normal recovery times and a second subset having significantly prolonged recovery times relative to old controls.
These results support our previous observation of longer recovery time in older compared to younger subjects. We note that a subset of early to intermediate dry AMD patients exhibit slower recovery than age-matched controls.
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