PMMA (POLYMETHYLMETHACRYLATE) ORBITAL IMPLANT
PMMA Orbital Implant was very common in the past but today is still preferred by some surgeons because of the almost total absence of contraindications and its very low cost. It’s used only in primary enucleation since the material hardness and its unwanted movement inside scleral shell make it unsuitable for evisceration. It offers a moderate filling of the anophthalmic socket but a limited movement to the prosthesis.

SILICONE ORBITAL IMPLANT
Silicone orbital implant is very similar to PMMA implant and it differs only for its flexibility and a less smooth surface. These features guarantee a minor trauma on cover tissues and also a poor sliding of the implant. For these reasons the silicone implant is suitable to be contained in scleral shell after evisceration of the bulb.
Due to its low cost and good versatility, it is still chosen today over more expensive and perfected implants. It is well tolerated and expulsion is unlikely. In evisceration offers excellent motility, otherwise only achievable with porous implants.