Boston Keratoprosthesis
The Boston Keratoprosthesis has been under development since the 1960s and has gradually been perfected. It received FDA clearance in 1992. About 600 implantations have been performed. It is the most commonly used keratoprosthesis in the United States.
The keratoprosthesis is made of clear plastic with excellent tissue tolerance and optical properties. It consists of two parts but when fully assembled, it has the shape of a collar button. (See picture above.) The device is inserted into a corneal graft, which is then sutured into the patient’s cloudy cornea. If the natural lens is in place, it is also removed. Finally, your physician may recommend that a soft contact lens may be applied to the surface.
from Massachusetts Eye & Ear Infirmary for Boston Keratoprosthesis