Ora tablet based contrast sensitivity test results in patients with non-advanced AMD and age matched controls.

Abstract

Purpose : Contrast sensitivity is a critical visual function task for maintaining quality of life in aging and AMD particularly 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. While acuity measurement proves valuable in a clinical setting, it lacks the sensitivity to identify early-stage diseases or readily demonstrate treatment effects. This study involved a comparison of two contrast sensitivity tests utilizing an electronic tablet device that can be conveniently deployed for multi-site clinical trials involving subjects with AMD and normal controls. The first test is the Ora Vanishing Optotypes test; a reading test with an equiluminant font causing a vanishing effect at low contrasts. The second test is the Ora Variable Contrast Flicker test, a flickering stimulus-based contrast sensitivity test.

Methods : Eighteen subjects with non-advanced AMD (AREDS grade 1-4 on simplified scale) and seventeen age-matched controls (AREDS grade 0) were included in this pilot study. All subjects were then tested for ETDRS BCVA, variable contrast flicker (VCF) sensitivity, and Ora vanishing optotypes reading test. All subjects had baseline VA of 20/40 or better using ETDRS chart in the study eye. T-tests were performed for each test and results from the two tests were fit to a logistic regression model and an ROC curve was generated.

Results : Ora Vanishing Optotypes tests results showed trending significance at both maximum contrast optotypes (p=0.0528) and lower contrast optotypes (p=0.0591) where 1 AMD subject and 1 Normal subject were unable to complete. Ora Variable Contrast Flicker test showed a significant difference p= 0.0458 (mean threshold AMD 0.245 StDev 0.31, Normal 0.09 StDev 0.23). When applying an ROC curve to the logistic regression model the AUC was 0.89 with 100% sensitivity and 86% specificity.

Conclusions : In this study, the Ora Vanishing Optotypes test shows a trending significant difference between the AMD and control group based on reading speed. The Ora Variable Contrast Flicker test shows a significant difference between both groups. By weighting the two tests to maximize sensitivity and specificity we are better able to determine the differences between early AMD subjects and age matched controls.

This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.