An idiopathic inflammation of the vitreous humor, “sterile vitritis”, has been observed in some keratoprosthesis recipients, typically months to years after implantation. Its etiology is unclear. Potential mechanisms include: (i) local tissue destruction and inflammation around the prosthesis, at the point of contact between cornea donor tissue and the device, (ii) microbial cell wall or nucleic acid triggering inflammation, and (iii) a systemic immune response with ocular manifestations.
One or more of these mechanisms likely contributes to each case of idiopathic vitreous inflammation. Tissue remodeling around the keratoprosthesis may create a dynamic space for inorganic or organic debris to enter the eye. Some cases of vitritis may have an infectious origin, despite negative cultures. Continued studies are needed to assess the clinical significance of corneal tissue loss under the front plate and adjacent to the stem. These areas of tissue “gaps” may provide access for organic and inorganic debris to enter the eye and stimulate inflammation.