Photographic assessment of baseline fundus morphologic features in the Comparison of Age-Related Macular Degeneration Treatments Trials

Abstract

Objective: To describe the methods used for assessment of baseline fundus characteristics from color photography and fluorescein angiography (FA) in the Comparison of Age-Related Macular Degeneration Treatments Trials (CATT) and to describe the relationship between these characteristics and visual acuity.

Design: Randomized, masked, multicenter trial.

Participants: This investigation included 1185 participants of the CATT study.

Methods: Baseline stereoscopic color fundus photographs and FAs of participants in the CATT study were assessed at a central fundus photograph reading center by masked readers. Replicate assessments of random samples of photographs were performed to assess intragrader and intergrader agreements. The association of the lesion characteristics with baseline visual acuity was assessed using analyses of variance and correlation coefficients.

Main outcome measures: Intragrader and intergrader reproducibility, visual acuity, and lesion characteristics.

Results: Intragrader and intergrader reproducibility showed agreements ranging from 75% to 100% and weighted κ values ranging from 0.48 to 1.0 for qualitative determinations. The intraclass correlation coefficients were 0.96 to 0.97 for quantitative measurements of choroidal neovascularization (CNV) area and total area of CNV lesion. The mean visual acuity varied by the type of pathologic features in the foveal center: 64.5 letters (standard error, 0.7 letters) for fluid only, 59.0 letters (standard error, 0.5 letters) for CNV, and 58.7 letters (standard error, 1.3 letters) for hemorrhage (P<0.001). Fibrotic or atrophic scar present in the lesion, but not under the center of the fovea, also was associated with a markedly reduced visual acuity of 48.4 letters (standard error, 2.2 letters; P<0.0001). Although total area of CNV lesion was correlated weakly with visual acuity when all participants were assessed (Spearman correlation coefficient, ρ = -0.16; P<0.001), the correlation was stronger within patients with predominantly classic lesions (ρ = -0.42; P<0.001).

Conclusions: These results show that the methodology used for grading CATT fundus images has good reproducibility. As expected, larger total CNV lesion area and pathologic findings such as hemorrhage, fibrosis, and atrophy at baseline are associated with decreased visual acuity.