Quantitative Subanalysis of Cystoid Spaces and Outer Nuclear Layer Using Optical Coherence Tomography in Age-Related Macular Degeneration

Abstract

To use optical coherence tomography (OCT) to quantify intraretinal cystoid spaces (ICSs) and the outer nuclear layer (ONL) in patients with neovascular age-related macular degeneration (AMD) and to investigate the correlation of these parameters with visual acuity. StratusOCT (Carl Zeiss Meditec, Inc., Dublin, CA) images were collected from 53 patients receiving their initial treatment with intravitreous ranibizumab. Images were analyzed with custom software (OCTOR) that allows accurate manual segmentation of OCT B-scans and provides thickness/volume measurements of ICS, ONL, neurosensory retina, pigment epithelial detachments (PEDs), subretinal fluid (SRF), and subretinal tissue (SRT). Univariate and multivariate analyses were used to correlate OCT parameters with best corrected Snellen visual acuity. Reproducibility was assessed with weighted kappa statistics and intraclass correlation coefficients. A multivariate linear regression model with adjusted R(2) showed that ONL volume and SRT thickness significantly correlated with Snellen visual acuity (R(2) = 0.15, P = 0.002 and R(2) = 0.19, P = 0.001, respectively) with an overall model R(2) of 0.34. Adjustment of ONL volume for ICS did not improve correlation with visual acuity, and ICS volume did not independently correlate with visual acuity. Weighted kappa statistics showed excellent intergrader agreement for both ICS and ONL measurements. The results suggest that an increased total volume of the ONL is associated with decreased visual acuity in neovascular AMD and that the total volume of ICS does not correlate with visual acuity. Although the correlations detected in this study are modest, quantitative subanalysis of OCT images may be of greater clinical relevance in the context of more advanced OCT technology.