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Alison M Binns, Laura Edwards, Deanna Taylor, David Crabb; Determining optimal test parameters for assessing dark adaptation in people with intermediate age-related macular degeneration. Invest. Ophthalmol. Vis. Sci. 2018;59(9):2425.
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© ARVO (1962-2015); The Authors (2016-present)
AdaptDx (Maculogix, PA) measures time taken for a seeing threshold to reach a criterion level (the rod intercept time; RIT) after a substantial photopigment bleach. We aim to determine optimal test conditions for evaluating intermediate age-related macular degeneration (iAMD) in order to minimise test time whilst maintaining diagnostic sensitivity. A secondary aim was to determine whether any test condition reflected self-reported visual difficulty.
People with iAMD and age-similar controls were recruited (aged >55years). RIT was assessed under 5 test conditions over 2 visits: 76%, 70% and 65% rhodopsin bleach at 5 degrees eccentricity and 76% and 70% bleach at 12 degrees. Test order was randomised and a 30-minute washout added between tests. Self-reported visual difficulty was assessed using the low luminance questionnaire (LLQ; Ophthalmol Vis Sci. 2006;47:528–35). Results were compared between groups (independent samples t-test), receiver operating characteristics (ROC) curves were constructed, and associations between RIT and LLQ scores assessed (Pearson’s correlation).
Fourteen people with iAMD (mean age 72 years+/-7SD) and 10 controls (69 years+/-8.SD) attended for 2 visits. Seven others (5 AMD, 2 controls) were excluded due to inability to carry out the repeated testing. RIT only varied significantly between groups when 76% of pigment was bleached and recovery tested at 5 degrees (18.4 mins+/-10.6SD [AMD], 7.9 mins+/-6.3SD [controls]; p=0.009). Difference between groups was smaller for 76% at 12 degrees (8.7 mins+/-7.2SD[AMD], 4.5 mins+/-2.1SD[controls]; p=0.1). The area under the ROC curves was 0.82 and 0.77 for these two test conditions, respectively. Six (43%) of the AMD group had RITs >20 mins for 76% bleach at 5 degrees, but only one (7%) for 76% bleach at 12 degrees. There was no significant correlation between RIT and LLQ scores apart from 65% bleach at 5 degrees (LLQ total p=0.05, Pearson’s r = -0.58).
Nearly half of the participants with iAMD produced an unacceptably long recovery time (>20mins) using a 76% bleach at 5 degrees eccentricity. The 76% bleach at 12 degrees provided almost equivalent separation between iAMD and normal (ROC area under curve) but recovery was achieved within 20 minutes for almost all participants. The RIT did not reflect the patient experience according to the LLQ for most conditions.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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