Abstract
Purpose :
A major hurdle in development of novel therapeutics for dry age-related macular degeneration (AMD) is the lack of sensitive endpoints to identify visual dysfunction at early stages of the disease. This study was designed to evaluate a series of reading tests, developed using an electronic tablet, as potential endpoints for early dry AMD.
Methods :
Nine subjects diagnosed with early dry AMD (mean age: 73.7±7.8 years) and thirteen normal subjects (75.4±5.2 years) were included. All subjects had visual acuity (VA) of 20/30 or better on potential acuity meter and ETDRS VA of 0.2 logMAR (20/32) or better for both distance and near with best spectacle correction. Reading tests were performed using an electronic tablet under high contrast high luminance (HCHL) and different challenge conditions; low luminance (LL) (<1% transmittance), low contrast, crowding, pepper words and vanishing optotypes. Time taken to read accurately was calculated in words per minute (wpm). To account for differences in individual reading speed, each subject’s performance under challenge conditions were normalized to their performance under HCHL (wpm ratio). Wilcoxon Rank Sum Test was used to compare between the AMD and normal groups.
Results :
There was no significant difference in ETDRS VA between the early AMD subjects (mean VA: 0.1±0.1 logMAR) and normals (0.0±0.1 logMAR) (p=0.15). Under HCHL reading there was no significant difference in reading speed between the early AMD subjects (142.7±36.4 wpm) and normals (171.8±34.2 wpm) (p=0.10). Under LL, 5/9 AMD and 1/13 normal subjects failed (i.e. were unable to perceive anything to read). Among the subjects for whom reading speed could be assessed, reading under LL was significantly worse for AMD subjects (26.4±7.6 wpm) compared to normals (77.9±44.4 wpm, p=0.002). When normalized to HCHL (wpm ratio), reading speed under LL was 6.5 times worse in the early AMD group as compared to only 2.9 times worse in normals (p=0.001). None of the other challenges showed significant difference between the two groups (p>0.05 for all).
Conclusions :
While there was no significant difference in ETDRS VA between the normal and early AMD groups, our low luminance reading test was able to identify significant visual dysfunction in AMD subjects when compared to age-matched normals. Our tablet-based reading tests shows promise as a potential endpoint in patients with early dry AMD and good VA.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.