Test-retest variability of reading performance metrics using MNREAD in patients with age-related macular degeneration.

Purpose: To determine the test-retest variability of reading ability using the MNREAD charts in patients with stable age-related macular degeneration (AMD).

Methods: In this prospective study, reading ability was measured at two visits in 124 nontreated eyes of 124 patients with AMD, who were enrolled in an ongoing clinical trial using a standardized MNREAD protocol. Only patients with stable AMD who could perform the reading test at 40 cm at both visits were included in the analysis. Different scoring rules were applied to calculate critical print size and maximum reading speed.

Results: Data from the 59 patients with a mean (SD) age of 78 (7.6) years who met the study criteria were analyzed at a mean (SD) interval of 43 (6) days between measurements. The 95% coefficient of repeatability (CR) was 0.30 logMAR for reading acuity. The CR for critical print size and maximum reading speed varied depending on the analysis method applied.

Conclusions: This is a report of estimates of the intersession test-retest variability of reading performance metrics in patients with stable AMD. The results are helpful both in defining end points in clinical trials for AMD and in distinguishing clinical change from measurement variability in clinical practice.