Simulation of optical coherence tomography to determine refractive indices of retinal layers in different organisms

Optical coherence tomography (OCT) is a non-invasive imaging technique that generates two-dimensional (2D) images or three-dimensional (3D) representations of inhomogeneous biological tissues and is widely used in ophthalmology. This study simulates OCT interferograms to extract the refractive indices of retinal layers in humans, monkeys, cows, and dogs. Using a supergaussian light, the refractive indices of key retinal layers including the nerve fiber layer (NFL), inner plexiform and ganglion cell layers (IPL + GCL), inner nuclear layer (INL), outer plexiform layer (OPL), outer nuclear layer and photoreceptor inner segments (ONL + PIS), and photoreceptor outer segments (POS)—are calculated based on predefined layer thicknesses. The simulation results showed that, for example, the refractive indices of the NFL are 1.376, 1.374, 1.380, and 1.355 for human, monkey, cow and dog, respectively. These values are validated by matching the peak positions in the OCT interferograms to the known physical thicknesses of each retinal layer. The proposed method provides a reliable approach for refractive index determination of samples where experimental data are limited.