ObjectiveTo study the effect of collagen cross-linking induced by riboflavin and ultraviolet A (UVA) on biomechanical properties of the sclera in guinea pigs. Methods The changes of biomechanical properties of the sclera induced by riboflavin and ultraviolet A (UVA)-induced collagen crosslinking were examined in ten guinea pigs and compared with those of ten non-treated guinea pigs. Histological and ultrastructural changes of the sclera were examined to evaluate the side-effects. ResultsAt one month after the UVA plus riboflavin treatment, the ultimate stress increased by 147%, elastic modulus increased by 193%, ultimate strain reduced by 21.9% in the equatorial sclera and significantly changed by 108%, 191%, 40.42% in the posterior sclera, respectively. Light microscopy showed no pathological alterations. Transmission electron microscopy showed active hyperplasia of scleral fibroblasts in the crosslinking area of the sclera in the guinea pigs of the experimental group. ConclusionsThe method using UVA plus riboflavin to induce scleral collagen cross-linking shows effect to improve the biomechanical properties and to enhance the tension and strength of the sclera. Collagen cross-linking may become a new approach of clinical treatment for pathologic myopia.