Abstract
Purpose :
Changes in choroidal thickness may be associated with macular conditions including age related choroidopathy and pachychoroid. Several studies have reported variation in OCT-derived choroidal thickness measurements in patients with neovascular age related macular degeneration (nAMD) being treated with anti-angiogenic agents. Although this may be a promising structural marker of disease activity, an understanding of its repeatability is required in order to define true clinical change rather than measurement variability alone. The aim of this work was to describe the repeatability of choroidal thickness measurements in nAMD using a commercially available swept-source OCT (SS-OCT) device (DRI-OCT-1, TopCon Inc).
Methods :
39 eyes of 39 patients with nAMD were included in the study. Each patient underwent a 12 x 9mm raster scan using the DRI-OCT-1. The scans were repeated three times in the same imaging session by a clinical trial certified technician. Submacular choroidal thickness measurements were calculated using the on-board segmentation algorithm for each of the nine ETDRS (Early Treatment Diabetic Retinopathy Study) subfields. Coefficients of repeatability were calculated for each of these subfields according to methods described by Bland and Altman.
Results :
Mean (±SD) age of each patient was 73.9 (±7.2) years. There were 24 male and 15 female subjects. This consisted of 21 right and 18 left eyes. The intrasession coefficient of repeatability (CR) of choroidal thickness of the central macular subfield (A1) was 57.2μm with a mean retinal thickness of 181mm (±15.8μm). The CR of the other macular subfields ranged from 38.5μm to 60.3μm.
Conclusions :
This study suggests that variation of more than 57μm in choroidal thickness is necessary to suggest clinical variation due to disease activity rather than measurement alone. This may be useful in the interpretation of studies investigating variation in SS-OCT derived choroidal thickness measurements in nAMD during treatment with anti-angiogenic agents. Further analysis is needed to define SS-OCT derived choroidal thickness measurements as an outcome variable in clinical trials in nAMD.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.