Purpose: To determine the repeatability of Stratus optical coherence tomography (OCT) measures of retinal thickness and volume in patients with neovascular age-related macular degeneration (nAMD) METHOD: Fifty-one eyes of 51 consecutive patients with nAMD underwent an OCT imaging session in which two fast macular thickness map (FMTM) protocol scans sets were acquired by a single experienced operator certified for clinical trials work. Coefficients of repeatability for each of nine Early Treatment of Diabetic Retinopathy Study (ETDRS)-like regions, foveolar center-point retinal thickness (CPT) and total macular volume (TMV), were calculated. Scans were analyzed retrospectively for errors in retinal boundary placement by two observers, with revised coefficients of repeatability calculated after excluding any scan sets with significant segmentation error.
Results: The coefficient of repeatability for the central 1-mm macular subfield was 67 mum (23%) and was less than 75 mum for all macular subfields. There was much larger variability in the center-point thickness measure, with a coefficient of repeatability of 88 mum (32%) for the automated center-point thickness (ACPT). After excluding nine scan set pairs with significant segmentation error, the coefficient of repeatability for the central 1-mm macular subfield was reduced to 50 mum (19%).
Conclusions: OCT-derived retinal thickness measurements are subject to considerable measurement variability in patients with nAMD. Changes in central macular thickness of more than 50 mum may better reflect true clinical change in scan sets without significant segmentation error and may be used to guide the retreatment of patients with nAMD in clinical trials and clinical practice.