Safety Studies on Collagen Viscoelastic Substance as an Auxiliary Agent in Anterior Segment Surgery: Assays of Anti-collagen Antibodies in Blood and Residual Concentration of Collagen in the Anterior Chamber of Rabbits

Abstract

Alkali-soluble collagen solution was assessed as a possible viscoelastic substance in anterior segment surgery, in terms of its safe applicability by assaying antigenicity, disappearance rate of collagen from the anterior chamber, and histopathological effect on the corneal tissue. The aqueous humor of rabbits was replaced with collagen solution three times. Then, follow-up clinical examinations with hand-slitlamp-microscopy, tonometry, pachymetry, and specular microscopy as well as ophthalmic histopathological examination were performed. Remaining collagen concentration in the aqueous humor at 1, 3, 5, 8, 24 and 72 hours after injection was determined to evaluate the disappearance rate of collagen from the aqueous humor with time. In vivo effects of chemical modification of collagen and buffer concentration on the corneal tissue were further studied by using transmission electron microscope (TEM) to find an optimum condition for collagen application. Neither anti-collagen antibody formation, nor inflammatory responses in the anterior segment and systemic symptoms were observed even after 3 injections of collagen solution, except for 1 case which showed corneal opacity. As much as 97.4% of the collagen injected into the anterior chamber disappeared from the eyeball. On the basis of TEM findings, succinylated collagen in diluted phosphate buffer seems to be superior to alkali soluble collagen in terms of corneal tissue protection. Collagen specifically prepared for this study showed no antigenecity and disappeared promptly from the anterior chamber. The optimal form of collagen in terms of corneal protection was discussed.