Abstract
Purpose: :
The purpose of this study was to develop and test unique in situ polymerizing collagen-based compositions for sealing limbal corneal incisions and injection tunnels resulting from needle sclerotomies.
Methods: :
Soluble, pepsin digested, collagen was purchased from Advanced Biomatrix. In situ polymerizing collagen was prepared by extensive dialysis of salt precipitated collagen against 0.035M EDTA with step-wise increase in pH to 7.5. The final solutions were analyzed for collagen purity and concentration. Collagen solutions were evaluated in the rabbit model following injection into limbal corneal incisions made using a 2.75mm metal keratome and into sclerotomy tunnels formed using a 25 gauge myirigotomy knife. Treated and untreated control eyes were examined by slit-lamp biomicroscopy immediately after treatment and 24 hours after treatment. Sections of treated wounds and untreated tissues were processed for histological examination.
Results: :
SDS-PAGE analysis of in situ polymerizing collagen showed protein bands corresponding to Type I collagen, with no lower molecular weight bands. Collagen concentration ranged from 25-35mg/mL. The kinetics of fibril formation was evaluated spectrophotometrically. Results demonstrated nearly instantaneous formation of fibrils when incubated with salt solution compared to "standard" acid soluble collagen. Gross histology of treated corneal and scleral tissue showed a rapid transition of clear collagen solution to an opaque gel and fibrous mass. Subsequent histological examination confirmed the formation of a stable collagen fibrous structure integrating into the corneal and scleral wounds with negligible tissue reactivity.
Conclusions: :
Novel in situ polymerizing collagen gels were developed, analyzed, and evaluated as corneal wound and scleral tissue sealants. Results demonstrated rapid collagen fibril formation and integration with surrounding tissues. It is proposed that these unique collagen compositions will successfully seal corneal incisions and sclerotomy tunnels. In addition, studies have shown that these same collagen compositions provide sustained release of antibiotics and other active agents.
Keywords: wound healing • cornea: basic science • vitreoretinal surgery