Introduction to the use of the Boston keratoprosthesis

Abstract

The Boston keratoprosthesis (KPro) is one of several types of artificial cornea manufactured worldwide that are being implanted in increasing numbers in patients with severe corneal diseases and graft failures. The prognosis for long-term success varies greatly between diseases, with autoimmune conditions, such as ocular cicatricial pemphigoid and Stevens–Johnson syndrome, and severe chemical burns remaining difficult. In the potentially much larger cohort with little preoperative inflammation, retention is excellent, complications are manageable and outcome is usually very good. Early implantation in congenital corneal opacities to offset amblyopia shows promise. The Boston KPro uses a ‘collar button’ design of polymethyl methacrylate that is sturdy and easily machined and polished, giving excellent vision if the remainder of the eye is healthy. This is implanted into a carrier corneal graft or into the patient’s own cornea. Holes in the back plate allow nutrition from the aqueous humor to reach the graft and long-term use of around-the-clock soft contact lenses protects the ocular surface from excessive dehydration. In nonautoimmune diseases, these measures have virtually eliminated necrosis and melt of the corneal tissue holding the device. Postoperative prophylactic antibiotics can now fully protect eyes from infection.