Abstract
Purpose :
Contrast sensitivity is a critical visual function task for maintaining quality of life in aging and AMD particuarly under low lighting conditions. However, in clinical trials, visual acuity remains the pivotal endpoint despite the existence of contrast sensitivity-based endpoints such as the Pelli-Robson chart. Although useful in a clinical setting, these methods lack sufficient sensitivity to detect early disease or easily show a treatment effect. In this study, we test a static three alternative forced choice contrast test method presented on a Windows tablet using touch screen input. The test is designed to increase the sensitivity of the test in early to intermediate age-related macular degeneration patients and healthy controls. The subject is asked to identify the location of a disk of mesopic luminous intensity in one of three locations. Threshold is determined by an adaptive procedure based on the method of constant stimulus and takes approximately 6 minutes to complete per eye.
Methods :
Eight subjects with non-advanced AMD (AREDS grade 1-4 on simplified scale) and ten age-matched controls (AREDS grade 0) were included in this pilot study. All subjects had baseline VA of 20/25 or better using ETDRS chart in the study eye. To visualize the results of the Ora CST, the two groups were plotted overlain with boxplots. To test the hypotheses that the Ora CST differs between normal and AMD subjects, we conducted a two-sample t-test and a Wilcoxon rank sum test.
Results :
The mean value of the Ora CST was 1.842 (SD = 0.131) for the AMD group and 1.9725 (SD = 0.134) for the normal group. [p=0.01445 Wilcoxon Signed Rank Test]. Though the sample size is small, the data is trending to show a separation between the AMD and normal groups, with higher values indicating a more favorable clinical outcome.
Conclusions :
In this pilot study with a small sample size, the novel Ora CST shows a trend to differentiate eyes with early to intermediate AMD from age- and vision-matched healthy subjects. Ongoing data collection may help support its use in clinical trials to detect treatment effects.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.