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

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.