Pathology of corneal hydrogel alloplastic implants.

Hydrogel keratophakia is a new form of lamellar refractive surgery which, in theory, can deal with almost all forms of refractive error. We examined the histopathological effects of several types of hydrogel materials on the cornea of non-human primates. With the exception of one type of hydrogel material, which was associated with endothelial cell degeneration, only minor histopathologic changes were seen up to a maximum of one year of observation, including thinning of the epithelium and decreased population of stromal keratocytes. These changes did not correlate with any clinical abnormalities. Additional extensive preclinical testing and eventual human clinical trials will determine the safety and efficacy of this procedure.