# Assessing Effects of Riboflavin/UV‐A Cross‐Linking on Aqueous Outflow Facility, Corneal Biomechanics and Their Association With Intraocular Pressure

## TL;DR

This study shows that riboflavin/UV-A cross-linking increases corneal stiffness and decreases fluid outflow in pig eyes, which could help assess treatment effectiveness for keratoconus.

## Contribution

The study provides quantitative evidence of CXL effects on outflow facility and corneal biomechanics across IOP levels using direct and non-contact techniques.

## Key findings

- CXL increased ocular rigidity and reduced outflow facility in ex vivo porcine eyes.
- Corneal elasticity (Young's modulus) increased significantly at all tested IOP levels after CXL.
- Outflow facility and corneal biomechanics may serve as indicators for evaluating CXL effectiveness.

## Abstract

Riboflavin/UV‐A corneal collagen cross‐linking (CXL) is a standard treatment for early‐stage keratoconus. However, quantitative CXL outcomes remain limited. This study evaluated CXL effects on outflow facility and corneal biomechanics at intraocular pressures (IOPs) in ex vivo porcine eyes. Ocular rigidity and outflow facility were derived from pressure–volume and IOP decay curves using a direct manometric technique, while corneal elasticity (Young's modulus) was measured via non‐contact air‐pulse optical coherence elastography. CXL increased ocular rigidity (0.0066 ± 0.0001 μL−1 vs. 0.0060 ± 0.0002 μL−1) and reduced outflow facility from 0.5429 ± 0.0320 to 0.1485 ± 0.0153 μL/min/mmHg (20–40 mmHg), compared to 0.7327 ± 0.0894–0.2210 ± 0.0502 μL/min/mmHg in untreated eyes. Young's modulus increased by 92%, 89%, and 155% at 20, 30, and 40 mmHg. These findings enhance our understanding of flow dynamics at IOP levels, suggesting that outflow facility and corneal biomechanics may serve as potential indicators for evaluating the effectiveness of CXL.

Our study demonstrates that UV cross‐linking (CXL) reduces outflow facility while increasing corneal elasticity across IOP levels of 20–40 mmHg, measured using direct manometry and non‐contact optical coherence elastography. These results highlight both parameters as potential indicators for evaluating CXL effectiveness and monitoring keratoconus treatment outcomes.