A New Type Of Keratoprosthesis And The Biological Evaluation Of It

Part 1 in vitro study of PHEMA keratoProsthesis.objeetive:To evaluate the eytotoxicity of PHEMA.Methods:AbstractPorous PHEMA and non-porous PHEMA were impregnated in theDMEM-F12 nutrient culture for 24h and flbroblasts were nourished withthe culture. Cytotoxicity test was carried out with cell counting processand a modified Cell Related Growth Rate (RGR test) was mensurated byspectrophotometer. Corneal flbroblasts were seeded onto the PHEMAdiscs with 50-70μm and 80-100μm porous size in vitro.Three dayslater the growth of flbroblasts were observed.Results:The active cell's quantities at 2448and72hours are not significantlydifferent between the groups of PHEMA and the group of contrast(pO.05). There is also no difference between the group of porousPHEMA and non-porous PHEMA(pO.OS). RGRs of the two groups weremore than 85% and the cytotoxicity was first grade. Corneal flbroblastsin PHEMA discs with 50-70 H- m porous size were more than in discswith 80-100μm porous size .Conclusion:PHEMA don't affect the growth of corneal flbroblasts, PHEMA is agood biocompatible material.Part IL in vivo study of PHEMA keratoprosthesis.Objective:To evaluate the inflammation caused by PHEMA discs in rabbits and thepathology ,ultra structure changes, collagen and fibronectineexpression in rabbit cornea caused by PHEMA discs implantation.Methods:Porous and non-porous PHEMA discs were implanted subcutaneously.Inflammation and fibrous connective capsule around the transplants was3Abstractobserved at 1,2 ,4and 8 weeks. Two kinds of PHEMA sponges ,with poresize diameters of 50-70μm and 80-100μm, were implanted in therabbit corneas.The eyes were examined by slit-lamp biomicroscopypostoperatively. Enucleation was performed at 15 days, 1,2,3 and 4months, then the excised implants were examined by light andtransmission electron microscopy. The expression of collagen type I-VIand fibronectine were detected by immunohistochemical methods.Results:There was subinflammation around the subcutaneous implantations.Corneal fibroblasts can easily invaded the PHEMA sponge, andsynthesized collagen and fibronectine in the pore of it. The rate ofcellular ingrowths and collagen deposition was greater in the PHEMAwith 50-70μm pore than 80-100μm pore.Conclusion:PHEMA is a good biocompatible material. Cornea fibroblasts canpenetrate, proliferate, and synthesize collagen in the pore of two kind ofPHEMA. PHEMA with 50-70μm pore diameter is more suitable for theskirt of the keratoprosthesis than 80-100μm pore.