Statistical Methods

Descriptive statistics were calculated for year 1 and year 2 cohorts to identify changes in injection frequency and ETDRS letters over time. Paired t tests were performed within cohorts to determine whether the changes in letters over time were significant. Independent t tests assuming unequal variance were used to determine whether differences in changes in ETDRS letters between cohorts were significant. Calculations were performed using Microsoft Excel, and P values < .05 were considered statistically significant.