Daniel E, et al. - Researchers here delineated the risk factors for scar formation and changes to fibrotic scar through 5 years in the Comparison of Age-related Macular Degeneration Treatments Trials (CATT). In this study, scar formation was observed in association with several morphologic features, including classic choroidal neovascularization (CNV) and large hemorrhage. After 2 years, a decline in rate of new scar formation was observed. Over time, visual acuity (VA) reduced as a result of an expansion of most fibrotic scars and accompanying macular atrophy.

Methods

• Researchers performed a multicenter, prospective cohort study; participants were 1,061 subjects in CATT.
• They evaluated color photographic and fluorescein angiographic images from baseline and 1, 2, and 5 years.
• Kaplan–Meier curves were used to determine incidence of scar formation.
• Cox regression models were utilized to assess the risk factors.
• Scar formation, fibrotic scar area, and macular atrophy associated with fibrotic scar (“atrophy”) were the main outcome measures.

Results

• At years 1, 2, and 5, cumulative proportion of eyes with scar was 32%, 46%, and 56%, respectively.
• In this study, baseline factors correlated with higher risk (adjusted hazards ratio [aHR] and 95% confidence interval [CI]) were classic CNV (aHR, 4.49; 95% CI, 3.34–6.04) vs occult, hemorrhage >1 disc area (DA) (aHR, 2.28; 95% CI, 1.49–3.47) vs no hemorrhage, retinal thickness >212 μm (aHR, 2.58; 95% CI, 1.69–3.94) vs <120 μm, subretinal tissue complex thickness >275 μm (aHR, 2.64; 95% CI, 1.81–3.84) vs ≤75 μm, subretinal fluid thickness >25 μm (aHR, 1.31; 95% CI, 0.97–1.75) vs no fluid, visual acuity (VA) in fellow eye 20/20 (aHR, 1.72; 95% CI, 1.25–2.36) vs 20/50 or worse, retinal pigment epithelium elevation absence (aHR, 1.71; 95% CI, 1.21–2.41), and subretinal hyperreflective material (aHR, 1.72; 95% CI, 1.25–2.36).
• VA reduced by a mean of additional 13 letters between years 1 and 5 among 68 eyes that developed fibrotic scar at year 1.
• At 1, 2, and 5 years, mean scar area was 1.2, 1.2, and 1.9 DA, respectively.
• In 18%, 24%, and 54% of these eyes, atrophy was present at 1, 2, and 5 years, respectively; the mean areas were 1.6, 2.0, and 3.1 DA, respectively.
• In 8 eyes, atrophy replaced fibrotic scar at year 5.
• Scar growth and atrophy growth showed no significant correlation.
• The clinical trial and observation periods showed similar rate of growth for both.