Light-Initiated Bonding of Amniotic Membrane to Cornea

Abstract

Suturing amniotic membrane to cornea during surgery is time consuming, and sutures may further damage the eye. The authors introduce a novel sutureless, light-activated technique that securely attaches amnion to cornea through protein-protein crosslinks. Cryopreserved human amniotic membrane, stained with Rose Bengal (RB), was placed over a full-thickness wound in deepithelialized rabbit cornea and was treated with green laser. The intraocular pressure that broke the seal (IOP(L)) was measured, and adhesion was measured with a peel test. The influences on bonding strength of fluence, irradiance, RB concentration, and amnion surface bonded were measured. Epithelial cell migration on treated amnion and keratocyte viability after bonding were also measured. The involvement in the bonding mechanism of oxygen, singlet oxygen, and association of RB with stromal collagen was investigated. Sealing amniotic membrane over cornea using 0.1% RB and 150 J/cm(2) at 532 nm produced an IOP(L) of 261 ± 77 mm Hg ex vivo and 448 mm ± 212 mm Hg in vivo. The ex vivo IOP(L) increased with increasing fluence (50-150 J/cm(2)). Equivalent IOP(L) was produced for bonding basement membrane or stromal amnion surfaces. The bonding treatment was not toxic to keratocytes but slightly reduced the migration of corneal epithelial cells on amnion ex vivo. Mechanism studies indicated that RB forms two complexes with amnion stromal collagen, that bonding requires oxygen, and that singlet oxygen mediates protein crosslinking. A rapid, light-activated technique produces strong, immediate bonding between amnion and cornea and merits further evaluation for ocular surface surgeries.