Purpose
To evaluate the growth of geographic atrophy (GA) during anti-VEGF therapy.
Design
Cohort within clinical trial.
Participants
Patients included in the Comparison of Age-related Macular Degeneration (AMD) Treatments Trials (CATT)
Methods
Participants were randomly assigned to injections of ranibizumab or bevacizumab and to a 2-year dosing regimen of monthly or pro re nata (PRN), or to monthly for 1 year and PRN the following year. Digital color photographs and fluorescein angiograms at baseline, 1 and 2 years were evaluated for GA and the total area of GA was measured by two graders masked to treatment; differences were adjudicated. Multivariate linear mixed models of the annual change in the square root of the area included baseline demographic, treatment, and ocular characteristics on imaging as candidate risk factors.
Main outcome measures
GA growth rate.
Results
Among 1185 participants, 86 (7.3%) had GA at baseline, 120 (10.1%) developed GA during year 1 and 36 (3.0%) during year 2. Among 194 eyes evaluable for growth, the rate was 0.43 (standard error [SE]: ±0.03) mm/year. In multivariate analysis, the growth rate was 0.37 mm/year in eyes receiving bevacizumab and 0.49 mm/year in eyes receiving ranibizumab (difference 0.11, 95% Confidence Interval [CI]: (0.01, 0.22); p=0.03). Growth rate did not differ between eyes treated monthly and PRN (p=0.85). Eyes with subfoveal CNV lesions had a lower growth rate than eyes with non-subfoveal CNV lesions (difference 0.12, CI: 0.01, 0.22; p=0.03). Eyes with GA farther from the fovea had higher growth rates by 0.14 (CI: 0.01, 27) mm/year for every mm farther from the fovea. The growth rate was 0.58 mm/year for eyes with predominantly classic lesions, 0.41 mm/year for eyes with minimally classic lesions, and 0.30 mm/year for eyes with occult only lesions (p<0.01). The growth rate in eyes having a fellow eye with GA was higher by 0.13 (CI: 0.01, 0.24; p=0.03) mm/year than in eyes without GA in the fellow eye. Eyes with epiretinal membrane had a higher growth rate than eyes without epiretinal membrane (difference 0.16, CI: (0.03, 0.30; p=0.02).
Conclusion
GA growth depends on several ocular factors. Ranibizumab may accelerate GA growth.