Abstract
Purpose :
This study aims to characterize the directional reflectance of the cornea using Optical Coherence Tomography (OCT), building on foundational work on retinal reflectance properties (Knighton et al. 1998, 1999). We present a model to describe the mean reflectance characteristics of the cornea, emphasizing the directionality of light scattering in different corneal layers.
Methods :
We conducted a retrospective analysis of OCT scans from normal eyes. Reflectance was analyzed across segmented corneal layers (epithelium, stroma, and endothelium), focusing on mean reflectance characteristics. A model comprising multiple exponential components was developed for each layer, describing reflectance as a function of layer depth and of the angle of incidence. This model quantifies corneal directionality through intensity and decay coefficients. We also calculated the percentage reflectance accounted for by each exponential component, with assessments of model fit using R-square.
Results :
Our model reveals distinct reflectance patterns across corneal layers, as shown in 1A, which plots average reflectance against cornea depth. The anterior and posterior stroma are more reflective than the middle stroma. 1B demonstrates the variation of reflectance with incidence angle, highlighting the directionality in different corneal layers. The epithelium exhibited less directionality compared to the stroma. The anterior and posterior stroma exhibited more directionality than the middle stroma. Fig2 summarizes the directional reflectance components for each corneal layer, detailing the model's intensity and decay coefficients, as well as the percentage reflectance and half-reflectance angles.
Conclusions :
This study advances our understanding of normative corneal properties by providing a detailed model of corneal directional reflectance. Our findings underscore the importance of accounting for incidence angle variability in OCT imaging. While this abstract focuses on mean reflectance characteristics, comprehensive data including the 95th and 99th percentile characteristics will be presented separately, offering a more complete understanding of corneal optics.
This abstract was presented at the 2024 ARVO Imaging in the Eye Conference, held in Seattle, WA, May 4, 2024.