Non-porous implants include PMMA and silicone. For evisceration, many surgeons advocate silicone or PMMA implants. Non-porous implants can occasionally migrate after enucleation, but are less prone to exposure.
Porous implants allow for tissue ingrowth and less potential for migration in patients who have enucleation. Examples of porous implants include hydroxyapatient (coral), porous polyethylene (Medpor) and bioceramic (aluminum oxide). The main “advantage” of porous implants was that they could be coupled to a prosthesis with a peg to enhance motility. The peg is inserted about a year after eye removal. However most surgeons in North America no longer peg their porous implants due to the greater risk of complications including chronic discharge and higher risk of exposure of the implant. Porous implants are about 20 times more expensive than non-porous implants.