Fibrovascular ingrowth in porous ocular implants: The effect of material composition, porosity, growth factors, and coatings

Purpose: Fibrovascular ingrowth into various porous ocular implants as a function of implant material composition, porosity, growth factors, and coatings was investigated in a pilot study in an animal model. Methods: Eighty-one New Zealand white rabbits underwent unilateral enucleation and implantation with ocular implants composed of the following materials: coralline hydroxyapatite (HA) with 200-mu m pores (HA200) or 500-mu m pores (HA500), synthetic HA (synHA), and high-density porous polyethylene (PP). The HA200, HA500, and PP implants were implanted untreated or after treatment with recombinant human basic fibroblast growth factor (Rh-bFGF). Nine HA500 implants were implanted after coating with calcium sulfate (plaster of Paris) to provide a smooth outer surface. Implants were harvested at 1-, 2-, 4-, or 8-week intervals and were examined histologically. Results: A significant difference was found between untreated HA500 and PP, with PP showing better ingrowth. There was no significant difference between unheated HA and PP, nor between untreated HA500 and synHA. Significant increases in ingrowth were found in HA200 compared with HA500, and in Rh-bFGF-treated implants compared with unheated controls. The calcium sulfate-coated implants showed less vascularization compared with the uncoated implants, although the difference was not significant. Conclusions: Fibrovascular ingrowth occurred earlier in HA200 implants than in HA500 implants, and was enhanced when implants were treated with Rh-bFGF.