Keratoprosthesis (artificial cornea)
Transplantation
An
artificial corneal transplant (keratoprosthesis) is a
procedure that is typically performed for patients who have had two or more
traditional corneal transplants that have failed. Patients with a history of previous corneal
transplant failure often require systemic immunosuppression
for a year or longer to decrease the risk of repeat transplant failure, with
all of the risks associated with the use of these medications. Additionally, patients with corneal limbal stem cell failure will also require systemic immunosuppresion for a year or longer if living related or cadaveric donor stem cell transplantation is performed. Even with the use of systemic immunosuppression, the rate of corneal transplant rejection
and failure is high. Thus, the avoidance
of the need for immunosuppression and the increased
chance of restoring long term visual clarity for these patients with a keratoprosthesis versus a repeat corneal transplant makes the keratoprosthesis a better,
safer option for these patients.
Two
artificial corneas have been approved for implantation by the US Food and Drug
Administration, the
Many of the risks associated with Boston keratoprosthesis implantation are the same as those
associated with corneal transplantation (infection in the eye, glaucoma), while
some are avoided (corneal transplant rejection and failure and the risks
associated with systemic immunosuppression) and
others are unique to keratoprostheses (membrane development behind the optic of the
keratoprosthesis, wound leak associated with melting
of corneal tissue adjacent to the stem of the keratoprosthesis). As the incidence of intraocular infection and
corneal melting has decreased dramatically over the last several years with the
use of daily antibiotic drops and modifications in the design of the keratoprosthesis, respectively, these are no longer
considered common causes of vision loss after keratoprosthesis
implantation. Additionally, as membrane
development behind the optic of the keratoprosthesis
can usually be treated easily with an in-office laser treatment, these do not
represent an irreversible cause of vision loss.
Glaucoma does, however, and thus the majority of patients undergoing keratoprosthesis implantation are having glaucoma surgery
performed at the same time, if not performed previously.
Photograph of patient two months after implantation of
the
JSEI Specialists