Abstract
Purpose :
Controversy exists regarding the inclusion of nonexudative age-related macular degeneration (AMD) patients in clinical studies based on structural vs. functional criteria. In a prior analysis, cone contrast testing (CCT) red distinguished intermediate AMD (iAMD) vs. controls at 12 and 24 months. Our goal was to further analyze the longitudinal changes in CCT in normal, early and iAMD participants.
Methods :
As part of the single-site, prospective, observational Duke FEATURE study, 69 participants (16 healthy control, 22 early AMD, 31 iAMD) were evaluated. Study participants were assessed at baseline, 12 and 24 months using CCT red and green, dilated exam, and optical coherence tomography. CCT blue was not included in this analysis due to the potential effect of mild cataract on test performance and lack of longitudinal change over 24 months in a prior analysis.
Results :
At 12 and 24 months, there was a significant difference across the three groups in the proportion of individuals with no functional deficits based on a normative database (CCT score ≥ 80), moderate deficits (score 50-80), or severe deficits (score ≤ 50) for both CCT red (baseline p=0.01; 12 and 24 months p< 0.01 Fisher’s exact test) and green (12 and 24 months p< 0.02). This significant difference between groups was only found at the baseline visit for CCT red (p=0.01) but not for CCT green (p=0.07).
Compared to normal and early AMD participants, those with iAMD were more likely to show a decrease in total CCT score (red + green) of ≥40 points from any prior visit (p< 0.05) throughout the study. Notably, of the control population, 0% had severe CCT red or green, 56% had moderate CCT red and 37% CCT green deficits at baseline. Proportions of control participants with moderate-severe CCT deficits increased over time: 6% progressed to severe and 56% to moderate deficits on CCT red at 24 months, and 6% to severe and 44% to moderate deficits on CCT green at 24 months.
Conclusions :
CCT tests for red and green colors represent early functional measures of disease progression in eyes with early-iAMD. We noted a longitudinal decline in CCT function over 24 months. A subgroup of healthy control participants demonstrated functional deficits on CCT red and green, suggesting that both visual function and structural inclusion criteria should be employed in future clinical trials of nonexudative AMD.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.