Volumic deformation of human cornea under pressure

TL;DR

This study uses OCT to observe the full-thickness deformation of the human cornea under pressure, revealing complex, depth-dependent, and anisotropic mechanical behaviors that are crucial for understanding corneal biomechanics.

Contribution

First comprehensive observation of human corneal deformation throughout its entire thickness during inflation testing using OCT, highlighting depth-dependent heterogeneity and anisotropy.

Findings

Posterior cornea is softer than anterior.

Rapid swelling in the central cornea possibly due to osmotic effects.

Distinct deformation regions indicating complex biomechanical behavior.

Abstract

The cornea, as the outer element of the human eye, plays a pivotal role in vision. Any defects in its shape can result in visual impairments. Mechanical defect manifest as shape defects, as the cornea is under to pressure. Our study presents the first comprehensive observation of human corneal deformation throughout its entire thickness during an inflation test, through Optical Coherence Tomography (OCT). Horizontal deformation reveals depth-dependent heterogeneity, suggesting that the cornea's posterior part is softer than the anterior part. Vertical deformation was observed at levels significantly higher than expected and exhibited depth-dependent heterogeneity, delineating three distinct regions. The central region of the cornea initially experienced rapid swelling, possibly due to osmotic effects, followed by increasing compressions as pressure rose. Conversely, the anterior and posterior regions showed no sign of swelling, and a difference in the compressive response, possibly due to difference in stiffness. Our study shows the complexity of human corneal mechanics, highlighting strong anisotropy and depth-dependent behavior, and implicating osmotic and poroelastic properties.