<p>Boston Type 1 Keratoprosthesis: Updated Perspectives</p>

Abstract

The use of Boston type 1 keratoprosthesis (BKPro) has significantly increased worldwide. It is no longer considered a procedure of last resort but a reasonable option for patients with otherwise poor prognosis for a traditional penetrating keratoplasty. BKPro was approved by the Food and Drug Administration in 1992 for bilateral severe corneal blindness due to multiple corneal transplant failure. Over the years, indications have extended beyond recurrent immunologic rejection to include other conditions such as chemical injury and other causes of bilateral limbal stem cell deficiency, extensive corneal neovascularization, neurotrophic corneas and hypotony, among others. Numerous advances in the design of the BKPro, improvement of preoperative, intraoperative and postoperative management have resulted in favorable outcomes and a reduction in postoperative complications. Accordingly, many studies have shown that implantation of this device is highly effective in restoring vision with very good short-term outcomes. However, due to the lifetime risk of sight-threatening complications after BKPro implantation, a longer follow-up period should provide outcomes that are more realistic. In this review, the authors examined only the results of publications with an average of at least 2 years of follow-up. The overall intermediate to long-term visual outcomes and retention rate in BKPro seem to be favorable. However, autoimmune diseases and cicatrizing conditions continue to show a higher incidence of postoperative complications that require further management.

Artificial Cornea: Past, Current, and Future Directions

“…The Boston KPro consists of a PMMA front plate with a central diameter between 3.5 and 3.7 mm and a backplate made of PMMA or titanium. A titanium locking ring was also added to secure the backplate ( 42 ). Donor corneal tissue acts as a carrier and is placed between the front and backplate.…”

“…Currently, the backplate is 8.5 mm with 16 holes for nutritional support. This led to a decrease in keratolysis from 50 to 10% following transplantation ( 42 ). Wearing a large diameter soft or contour contact lens and long-term use of topical antibiotics also decreased sterile keratolysis ( 14 ).…”

“…Titanium is well-tolerated by the surrounding tissue and is highly resistant to corrosion and is both light and strong. As it is not magnetic, patients can undergo magnetic resonance imaging ( 42 ). Moreover, the titanium backplate can be coloured blue or brown by electrochemical anodisation to help with the cosmetic appeal of the device ( 55 ).…”

“…It was aimed at avoiding damage to the corneal graft associated with the screwing action during surgery and thus possibly reduce RPM formation ( 59 ). This newer stem was both easier to use and less expensive to produce as the device was produced by moulding as opposed to machine-made ( 42 ). Al Arfaj and Hantera investigated four eyes that underwent Boston type 1 threadless KPro implantation and found no RPM developed at the time of follow-up (i.e., up to 11 months) ( 60 ).…”

Eye Banks: Future Perspectives

“…Nevertheless, examples from the field of keratoprostheses (KPro) are illuminating. The Boston Type 1 Keratoprosthesis (KPro) has undergone several modifications to its optics and mounting system since its introduction in 1970 [24]. The system continues to employ a human donor cornea as a carrier.…”