# An integrated model of the human cornea as a linear biaxial birefringent medium

## TL;DR

This paper introduces a new model of the human cornea that explains how light bends differently through it based on its structure.

## Contribution

The first model to describe the anisotropic properties of the entire cornea as a biaxial birefringent medium.

## Key findings

- The angle between binormal axes increases from 35° at the center to 83.7° near the limbus.
- The main refractive indices (nx, ny, nz) change in value and order across the cornea.
- The model aligns with existing experimental data on corneal birefringence.

## Abstract

A novel model of human corneal birefringence is presented. The cornea is treated as a homogeneous biaxial linear birefringent medium in which the values of the binormal axes angle and organization of the main refractive indices vary continuously from the apex to the limbus. In its central part, the angle between binormal axes is 35°, and para centrally, it smoothly increases to 83.7°. The values of the main refractive indices (nx, ny, nz) change, as well as their order, from nx < nz < ny to nz < nx < ny. The transition between these two states was described with a normal distribution (μ = 0.45, σ = 0.1). The presented model corresponds with the experimental results presented in the literature. To our knowledge, it is the first model that presents the anisotropic properties’ distributions of the entire cornea. The presented model facilitates a better understanding of the corneal birefringence phenomenon directly related to its lamellar structure.