Intrasession repeatability of optical coherence tomography measures in active neovascular age-related macular degeneration

Objectives: To determine the repeatability of Stratus optical coherence tomography fast macular thickness map analysis in patients with active neovascular age-related macular degeneration (nAMD). Methods: Consecutive pairs of scans from 112 eyes of 112 consecutive patients with active nAMD were analyzed. The Bland-Altman coefficient of repeatability (CR) was calculated for each retinal thickness or volume measure. Results: The CR for the central 1 mm macular subfield was 59 mu m (18% of retinal thickness) and did not exceed 69 mu m in any subfield. There was much poorer repeatability for the center-point thickness (CPT) measure (CR of 78 mu m; 24%). However, in the subgroup of 38 patients with no Stratus software low analysis confidence message on either analysis map, the revised CR (42 mu m) for the CPT measure and the A1 subfield (40 mu m) were similar. Conclusion: Optical coherence tomography-derived retinal thickness measurements are subject to measurement variability in patients with active nAMD. The results suggest a change criterion of more than 59 mu m in central 1 mm (A1) subfield macular thickness is necessary to distinguish true clinical change from measurement variability in these patients.