Short-term Interim Results of Clinical Outcomes and Complications After Implantation of Boston Keratoprosthesis in Japanese Patients

Keratoprosthesis is used for corneal transplantation in high-risk patients who require penetrating keratoplasty (PKP). Boston keratoprosthesis (BKpro) is a representative type of keratoprosthesis used worldwide. In Japan, the first BKpro was implanted in an eye after multiple corneal graft failures in 2008, but its use remains limited. A recent patient survey revealed that among the Japanese patients who had previously undergone multiple PKPs, the retention rate of BKpro was significantly higher than that of PKP at 5 years postoperatively (100% vs. 26%; P < 0.01). Patients with implanted BKpro also had better best corrected visual acuity of 20/200 or higher than those with PKP at 5 years postoperatively (80.0% vs. 17.6%; P = 0.03). Regarding the postoperative complications, retroprosthetic membrane formation was observed in 88.9%, infectious keratitis in 33.3%, and glaucoma progression in 11.1% of cases. Another retrospective analysis showed that fungal keratitis occurred in 0.09 patients per year and severely affected visual acuity. Furthermore, because it is difficult to accurately examine intraocular pressure after BKpro implantation, the intraocular pressure of patients with implanted BKpro was prospectively estimated using a transpalpebral tonometer (Diaton). In conclusion, BKpro implantation is effective and safe for Japanese patients, given the reported improvements in visual acuity and low rates of complications.