Investigation On In-situ Endocapsular Gelation Of Copolyacrylamides

Abstract

Abstract: : Purpose: The realization of a lenticular presbyopia like accommodating intra-ocular lens requires the synthesis of an appropriate polymer and a triggering mechanism for gelling the material in the capsular bag. In this abstract we evaluate a procedure for obtaining a non-degradable biocompatible polymeric material having no toxic monomers, which could be injected into, and gelled within an evacuated capsular bag. Methods: Fresh pig eyes from a local abattoir were used. The cornea was removed and a capsulorhexis on the lens of ∼1 mm in diameter was performed using an Ellmen surgitron, set on a power of 1-2. The capsular bag was then evacuated with a Storz phacofrag instrument. Polymeric hydrogels were prepared using acrylamide, crosslinker, ammonium persulfate (APS) and tetramethylethylenediamine (TEMED) as redox initiator. The hydrogels were allowed to swell and were exhaustively washed in water to remove the unreacted potentially neurotoxic monomers. Subsequently, the hydrogels were reversed to a copolymer by breaking the crosslinks and were then characterized. The above polymers of varying copolymer composition and concentration were injected into various molds as well as into pre-evacuated lens capsular bags. Gelation process was triggered by varying the pH just prior to injection. Results: We successfully performed the capsulorhexis and injected the polymer solution into the capsular bag where it gelled in less than five minutes. The elastic and shear modulus of the hydrogel was a function of composition and crosslink density as expected. The hydrogels were optically clear, mechanically soft, and objects seen through the endo-capsular lens appeared undistorted and similar to the natural porcine lens. Conclusion: The surgical technique and the polymeric materials used are helpful for us in the continuing search of obtaining an accommodating intra-ocular lens. Such materials may also serve to probe the mechanism of lenticular presbyopia.

Keywords: 310 aging: visual performance • 304 accommodation • 338 cataract