Measurement Repeatability of Sublayers of the Retinal Pigment Epithelium (RPE) using Visible Light Optical Coherence Tomography (vis-OCT)

Abstract

Purpose : Multiple sublayers of retinal pigment epithelium (RPE) can be visualized with vis-OCT. Although the detailed anatomical interpretation has not been established yet, consistent measurements of such structures may have a potential to provide clinically useful biomarkers. The purpose of this study was to assess the RPE sublayer thickness measurement repeatability using vis-OCT.

Methods : Nine eyes of nine healthy volunteers were enrolled and scanned three times at the initial visit. Four of them were scanned another set of three scans on the following visits. Raster speckle-reduction scans (3×3×1.2 mm3 sampled with 512×8×1024 voxels in x, y, and z-axis, respectively) were acquired centering at the superior macular region using our prototype Aurora X1 vis-OCT system (Opticent Inc., Evanston, IL). For thickness measurements, four borders delineating the 3 bright RPE sublayers were manually segmented using averaged 15 A-line profile (Figure). Coefficient of variations (CVs) were calculated to assess the measurement repeatability for each of 3 RPE sublayers thickness.

Results : Mean age of the subjects were 44.9 ± 12.7 years old, with visual field mean deviation (MD) range from -1.6 to 1.1 dB, and global mean circumpapillary retinal nerve fiber layer (RNFL) thickness of 97.8 ± 12.5 (um). All sublayers showed high repeatability on both intra- and inter-session assessment (all CVs < 8%) (Table).

Conclusions : Vis-OCT allows us for visualization and quantification of RPE sublayers with high repeatability. RPE sublayer assessment using vis-OCT may provide clinically useful information on eyes with ocular diseases affecting RPE morphology.

This is a 2021 Imaging in the Eye Conference abstract.

 

Figure. RPE Visualization) a) Healthy subject‘s Bscan demonstrating RPE sublayers b) the corresponding average of 15 A-scans from the highlighted location.