Abstract
Purpose :
Optical coherence tomography (OCT) inner retinal thickness measures of the macula and circumpapillary regions are important for determining onset and progression of experimental glaucoma in the non-human primate (NHP). Standard raster and circumpapillary scans have excellent repeatability but sample a limited region of the posterior pole. The purpose of this experiment was to determine the agreement and repeatability of inner retinal thickness measures from widefield imaging compared to standard scans
Methods :
OCT scans (Spectralis HRA+OCT) were acquired from 30 NHPs with healthy eyes. 11 of these animals were imaged on at least 4 separate days to assess repeatability. Standard scans included a 20x20° raster scan centered on the macula, and a 12° diameter circular scan centered on the optic nerve head. Widefield imaging protocol included a 217 line, 55x45° raster scan centered on the macula. Scans were imported into MATLAB, and the inner retinal borders were delineated using a neural network-based image segmentation algorithm. For comparison, retinal nerve fiber layer (RNFL) thickness was determined from an interpolated 12° scan path from widefield thickness maps. For both standard and widefield scans, the ganglion cell inner plexiform layer (GCIPL) thickness was determined for a region of 16 degrees in diameter centered on the fovea.
Results :
The average GCIPL thickness from standard raster scans was 72.7±4.3µm, and 73.7±3.7µm from widefield images (bias = -1.0µm, 95% LOA -4.4 to 2.4µm). Average circumpapillary RNFL thickness from the standard circular scan was 113.2±7.3µm, and 114.2±5.8µm for a similar interpolated path from widefield scans (bias = 1.0µm, 95% LOA -6.5 to 8.6µm). Repeatability (2.77xSw) for GCIPL thickness was 2.7µm and 3.2µm, and for RNFL thickness 5.2µm and 4.5µm, for standard and widefield scans respectively.
Conclusions :
Inner retinal thickness measures from widefield imaging have good repeatability and are comparable to those measured using standard scans. One of the major advantages of using widefield imaging is that it encompasses most of the visual field sampled in perimetry.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.