Peripheral Choroidal Response to Localized Defocus Blur: Influence of Native Peripheral Aberrations.

Purpose: This study aims to examine the short-term peripheral choroidal thickness (PChT) response to signed defocus blur, both with and without native peripheral aberrations. This examination will provide insights into the role of peripheral aberration in detecting signs of defocus. Methods: The peripheral retina (temporal 15°) of the right eye was exposed to a localized video stimulus in 11 young adults. An adaptive optics system induced 2D myopic or hyperopic defocus onto the stimulus, with or without correcting native peripheral ocular aberrations (adaptive optics [AO] or NoAO defocus conditions). Choroidal scans were captured using Heidelberg Spectralis OCT at baseline, exposure (10, 20, and 30 minutes), and recovery phases (4, 8, and 15 minutes). Neural network-based automated MATLAB segmentation program measured PChT changes from OCT scans, and statistical analysis evaluated the effects of different optical conditions over time. Results: During the exposure phase, NoAO myopic and hyperopic defocus conditions exhibited distinct bidirectional PChT alterations, showing average thickening (10.0 ± 5.3 µm) and thinning (-9.1 ± 5.5 µm), respectively. In contrast, induced AO defocus conditions did not demonstrate a significant change from baseline. PChT recovery to baseline occurred for all conditions. The unexposed fovea did not show any significant ChT change, indicating a localized ChT response to retinal blur. Conclusions: We discovered that the PChT response serves as a marker for detecting peripheral retinal myopic and hyperopic defocus blur, especially in the presence of peripheral aberrations. These findings highlight the significant role of peripheral oriented blur in cueing peripheral defocus sign detection.

Widefield OCT Imaging for Quantifying Inner Retinal Thickness in the Nonhuman Primate.

Purpose: To determine the agreement and repeatability of inner retinal thickness measures from widefield imaging compared to standard scans in healthy nonhuman primates. Methods: Optical coherence tomography (OCT) scans were acquired from 30 healthy rhesus monkeys, with 11 animals scanned at multiple visits. The scan protocol included 20° × 20° raster scans centered on the macula and optic nerve head (ONH), a 12° diameter circular scan centered on the ONH, and a 55 × 45° widefield raster scan. Each scan was segmented using custom neural network-based algorithms. Bland-Altman analysis were used for comparing average circumpapillary retinal nerve fiber layer (RNFL) thickness and ganglion cell inner plexiform layer (GCIPL) thickness for a 16° diameter region. Comparisons were also made for similar 1° × 1° superpixels from the raster scans. Results: Average circumpapillary RNFL thickness from the circular scan was 114.2 ± 5.8 µm, and 113.2 ± 7.3 µm for an interpolated scan path from widefield imaging (bias = -1.03 µm, 95% limits of agreement [LOA] -8.6 to 6.5 µm). GCIPL thickness from standard raster scans was 72.7 ± 4.3 µm, and 73.7 ± 3.7 µm from widefield images (bias = 1.0 µm, 95% LOA -2.4 to 4.4 µm). Repeatability for both RNFL and GCIPL standard analysis was less than 5.2 µm. For 1° × 1° superpixels, the 95% limits of agreement were between -13.9 µm and 13.7 µm for RNFL thickness and -2.5 µm and 2.5 µm for GCIPL thickness. Conclusions: Inner retinal thickness measures from widefield imaging have good repeatability and are comparable to those measured using standard scans. Translational Relevance: Monitoring retinal ganglion cell loss in the non-human primate experimental glaucoma model could be enhanced using widefield imaging.