A thin glycoprotein coating of a synthetic lenticule does not cause nutritional deficiency of the anterior cornea

Purpose. This study investigated whether a glycoprotein coating that will b e used to enhance corneal epithelialization affects in situ nutritional pas sage through a permeable membrane. Methods. Sixteen adult cats were equally divided into two groups. Polycarbo nate membranes with pore size of 0.1 mu m and total pore area (porosity) of 3.1% were used as implant materials. The membranes for Group 1 were coated with a thin layer of Collagen I, while the membranes for Group 2 were unco ated. Each membrane with 8-mm diameter was implanted into an interlamellar pocket of the cornea. The eyes were observed for approximately 35 days to m onitor clinical signs of nutritional deficiency of the cornea, and then 7 m embranes were removed from the eyes. The permeability of the explanted memb ranes to glucose, inulin and albumin was used to predict the in situ differ ence between the coated and uncoated groups in regard to nutritional passag e through the membranes. To investigate the long-term effect of the surface coating on corneal health, two animals from Group 1 were followed for up t o two years and then both eyes of each animal underwent histological examin ation. Results. Clinically, no post-surgical complications associated with nutriti onal deficiency were observed in any of the eyes. Nutritional permeability tests showed no significant differences between the coated and uncoated mem branes. Histologically, the long-term animals showed no abnormal morphology associated with nutritional deficiency in the cornea anterior or posterior to the membranes. Conclusions. A thin glycoprotein coating on a permeable membrane does not a ppear to affect the nutritional supply of the anterior cornea and therefore can be used to enhance epithelialization of synthetic corneal onlays in vi vo.