GEL INJECTION ADJUSTABLE KERATOPLASTY (GI AK(R)) - BIOCOMPATIBILITY OF A GAMMA-RAY CROSS-LINKED POLYETHYLENE OXIDE GEL

Background GIAK is a surgical technique developed for the correction o f myopia. We evaluated the biocompatibility of a gamma ray crosslinked poly(ethylene oxide) gel in two critical situations. Materials and me thods In 3 rabbits, a 5 mm inner diameter annular channel of 1 mm widt h was delaminated at 80 % corneal depth and a sterile gamma ray crossl inked polyethylene oxide gel was injected in the channel. In cornea 1 (control), the annulus was centered on. the corneal apex and the chann el was fully filled with gel. In cor-nea 2, the delamination was purpo sely decentered and the channel was approximately 1 mm from the limbus at ifs closest point. In corrnea 3, the centered channel was purposel y partially filled. After a 6 month follow-up, the rabbits were sacrif iced for histology. Results Histopathology showed the oval channel wal ls to be irregular and a slight thinning of the epithelium located abo ve the implant but no abnormalities in the stromal thickness. No monon uclear, po nuclear cells or other signs of encapsulation or rejection were found around the polymer in any the animals. In cor-nea 3, fibrob lasts were found on the lateral sides of the hydrogel globules. No lim bal neovascularization tvas observed over the 6 month period in any of the animals. Conclusions The injected PEO gel followed intimately the delaminated stromal channel and was well tolerated in the cornea. The fibroblastic reaction found in partially filled channels is caused by the normal wound healing process and not by the hydrogel chemical pro perties.