Sustained scleral stiffening in rats after a single genipin treatment

Abstract

Scleral stiffening has been proposed as a therapy for glaucoma and myopia. Previous <i>in vivo</i> studies have evaluated the efficacy of scleral stiffening after multiple treatments with a natural collagen crosslinker, genipin. However, multiple injections limit clinical translatability. Here, we examined whether scleral stiffening was maintained after four weeks following a single genipin treatment. Eyes from brown Norway rats were treated <i>in vivo</i> with a single 15 mM genipin retrobulbar injection, sham retrobulbar injection, or were left naive. Eyes were enucleated either 1 day or four weeks post-injection and underwent whole globe inflation testing. We assessed first principal Lagrange strain of the posterior sclera using digital image correlation as a proxy for scleral stiffness. Four weeks post-injection, genipin treatment resulted in a 58% reduction in scleral strain as compared to controls (<i>p</i> = 0.005). We conclude that a single <i>in vivo</i> injection of genipin effectively stiffened rat sclera for at least four weeks which motivates further functional studies and possible clinical translation of genipin-induced scleral stiffening.