Normal Variation of Photoreceptor Outer Segment Volume With Age, Gender, Refractive Error, and Vitreomacular Adhesion

BACKGROUND AND OBJECTIVE: Thickness and volume changes of the photoreceptor outer segment (PROS) layer on spectral-domain optical coherence tomography (SD-OCT) images are associated with various disease states. However, there are limited data on normal anatomical variation. This study evaluates the correlation of PROS volume with age, gender, refractive error, and presence of vitreomacular adhesion (VMA) in healthy subjects. PATIENTS AND METHODS: SD-OCT scans of 68 normal eyes were analyzed. The ellipsoid zone and the apical retinal pigment epithelium boundary were segmented using an automated algorithm. The PROS volume was calculated as the region bounded by these two layers within a 6-mm diameter circle centered at the fovea. A general linear model was used for statistical analysis. RESULTS: PROS volume increased with age to a significant degree (P=.013). Gender, refractive error, and presence of VMA were insignificant factors. CONCLUSION: PROS volume, as measured on routine SD-OCT, increases with age in healthy subjects, after adjusting for gender, refractive error, and VMA.