Simulating Optical Magnification and Receptive Field of Human Fovea using Optical Coherence Tomography

Abstract

Purpose : To simulate optical effects of human fovea pit using optical coherence tomography (OCT) and investigate their roles in retinal diseases.

Methods : A public dataset OCTA-500, containing 300 (N_healthy=91, N_disease=209) 6×6-mm macular OCT scans, as well as private collected 12×12-mm CSCR dataset (N=37) with visual acuity were included in this study. Retinal layer boundaries were automatically segmented using a deep learning network and then manually corrected. To simulate the optical effects, Bruch’s membrane (BM) was first adjusted to fit a hemisphere shape of eyeball with respect to foveal center. The retinal images and other boundaries were aligned according to the BM to reveal the physical retinal curvature. Due to the refractive index mismatch between vitreous humor (n₁=1.336) and retina (n₂=1.375), refraction exists when the light beams hit the retina from vitreous to be detected by photoreceptors. Magnification was calculated as the scale of shift for phototransduction position due to the refraction. The optical receptive field was calculated as the scale of aberration for an ideal point spread function due to refraction. Their correlations with retina morphological pathologies and visual acuity were evaluated.

Results : The curvature of retina was found to be convex within foveola, concave beyond foveola but within fovea, and then convex again in parafovea (Fig. 1 A). Significant magnification and enlarged receptive field were observed in FAZ for the healthy subjects, with values highly correlated to the gradient of retinal curvature (Fig. 1 E-F). The average magnification and optical receptive field within FAZ were decreased in eyes with central serous chorioretinopathy (CSCR) and cystoid macular edema (Fig. 2 A). Magnification was also found to play a role in visual acuity damage in CSCR (Fig. 2 B).

Conclusions : The magnification and optical receptive field of the fovea were successfully simulated using OCT scans and were found to be highly correlated with retinal curvature, morphological changes, and visual acuity.

This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.