Photochemically Induced Crosslinking of Tarsal Collagen as a Treatment for Eyelid Laxity: Assessing Potentiality in Animal Tissue

Purpose: An experimental study to demonstrate in animal eyelids that the controlled exposure of excised tarsal plate to ultraviolet-A radiation can induce a rigidification effect due to photochemical crosslinking of the constitutive collagen. Methods: Excised strips of sheep tarsus were irradiated with ultraviolet-A rays (wavelength 365 nm) at low and high irradiances, in the presence of riboflavin as a photosensitizer, using radiation sources available for corneal collagen crosslinking procedure. The tensile strength and Young's modulus (stiffness) of irradiated and control samples were measured in a mechanical tester and analyzed statistically. Histologic examination of the specimens was carried out to evaluate the effect of radiation on the meibomian glands and collagen organization. Results: Mechanical evaluation showed that irradiation induced both stiffening and strengthening of the tarsal plate specimens, and this effect was enhanced at the higher levels of irradiance. The changes in mechanical properties can be attributed to a process of photochemically induced crosslinking of tarsal collagen. Histology revealed no changes in the meibomian glands or in the fibrous collagen system of the tarsus. Conclusions: These findings indicate that irradiation of tarsal collagen leading to tissue stiffening could be a safe procedure for treating lax eyelid conditions in human patients. Accepted for publication December 5, 2017. Supported by an unrestricted grant from the Queensland Eye Institute Foundation, South Brisbane, Queensland, Australia. The funders had no role in the concept, design, and conduct of the study; neither in the preparation, review, or approval of manuscript for publication. Australian Provisional Patent Application No. 2017900561 has been filed on February 21, 2017, and assigned to the Queensland Eye Institute Foundation, by the authors Tai M. Smith, Brendan G. Cronin, Shuko Suzuki, and Traian V. Chirila as inventors. Address correspondence and reprint requests to Traian V. Chirila, B.Eng., Ph.D., F.R.A.C.I., F.R.S.C., Queensland Eye Institute, 140 Melbourne Street, South Brisbane, QLD 4101, Australia. E-mail: traian.chirila@qei.org.au. © 2018 by The American Society of Ophthalmic Plastic and Reconstructive Surgery, Inc., All rights reserved.