# A transpupillary approach for crosslinking Guinea pig sclera using WST11 and near-infrared light

## TL;DR

This study explores using WST11 and near-infrared light to strengthen the sclera in guinea pigs, finding effective crosslinking parameters that work better in older animals.

## Contribution

The novel contribution is the transpupillary crosslinking method using WST11 and NIR light in guinea pigs, demonstrating age-related efficacy differences.

## Key findings

- Ex vivo treatment with WST-D and NIR light significantly increased scleral thermal stability compared to controls.
- In vivo treatment showed significant crosslinking in both equatorial and posterior scleral regions.
- Crosslinking efficacy was greater in older guinea pigs compared to younger ones.

## Abstract

Crosslinking strengthens the sclera and holds potential as a treatment for myopia. This study aims to identify optimal crosslinking parameters in guinea pigs using WST11 with dextran followed by near-infrared (NIR) illumination. Guinea pig eyes were incubated in WST11 with 2, 5 or 10% dextran, and penetration depth was assessed by fluorescence microscopy. Crosslinking efficacy was measured as thermal stability using a thermal degradation assay, following incubation in WST11 + 10% dextran (WST-D) for 30 min and NIR irradiation at 10 mW/cm2 or 20 mW/cm2 for 10, 20 and 30 min. The optimized parameters were then applied in vivo in 6-month-old guinea pigs. Ex vivo treatment using the optimal crosslinking parameters (WST-D, 30 min; NIR, 10 mW/cm2, 30 min) resulted in the highest thermal degradation midpoint (ΔT50: 6.8), significantly higher than untreated controls (p = 0.0006), with WST-D penetration limited to the sclera. Efficacy was greater in eyes obtained from older compared to younger guinea pigs (p = 0.02). In vivo, WST-D/NIR treatment resulted in significant crosslinking compared to untreated controls (equatorial, ΔT50: 3.7, p < 0.0001; posterior, ΔT50: 3.4, p = 0.01). WST-D/NIR treatment effectively induces scleral crosslinking, with age-related differences suggesting the need for personalized treatment.

The online version contains supplementary material available at 10.1038/s41598-026-36438-w.