EyeWorld Asia-Pacific June 2016 Issue

June 2016 58 EWAP CORNEA worsened visual acuity at the study end point were excluded.” Retention In the past, retention of corneal transplant devices has been quite an issue—less than 10% were successfully retained in early KPro trials, Dr. Lee said. This literature review revealed that retention rates have increased to 65% on the low end of the range and 100% on the high end, as reported in 14 of the 22 articles reviewed, which included a followup range of 2 to 47 months. “The challenge remains prevention of infection and thinning at the graft-host junction,” Dr. Lee said. Complications The most common complication reported in the studies was retroprosthetic membrane formation, which occurred in 1% to 65% of patients in the 13 articles reporting this issue over a follow-up range from 6 to 47 months. Glaucoma was the second most common, occurring in 2.4% to 64.0% of eyes in the 12 articles reviewing this complication during a 6- to 47-month follow-up period. Other postoperative complications, to a lesser extent, included corneal melt, infectious keratitis, and scleritis. Lee et al. noted posterior segment complications reported in 16 of the 22 articles reviewed. The most common was endophthalmitis, with 15 of the 22 articles reporting this complication in a range of 0% to 12.5% of patients during a follow-up period ranging from 8.5 to 47 months. Overall takeaway Lee et al. concluded that even though the literature review revealed “reasonable rates of visual recovery after KPro surgery in select patients with corneal opacification, several points of caution were raised in this review.” These points included that the overall outcome and complications were worse over longer follow-up periods and that patients with autoimmune conditions were more susceptible to “severe, devastating complications.” Improvements to the KPro design—holes in the back plate to allow for nutrient diffusion, a threadless design to reduce incidents of tissue melt, and a titanium locking ring to hold all the pieces of the device together— might improve outcomes and reduce complications, but Lee et al. suggested that future research include randomized trials that compare different and newer designs to assess efficacy. “In the right situation, KPro is a great alternative to provide improved vision for patients who do not do well with cadaveric corneal transplants,” said co-author Roni Shtein, MD , associate professor of ophthalmology and visual science, Kellogg Eye Center, University of Michigan, Ann Arbor, Mich. “There are risks associated, and it’s difficult to draw conclusions regarding long-term outcomes given the current data in the peer-reviewed literature.” Other areas of future research could include longer-term studies to better understand possible complications that could occur well after the procedure and also development of a better measure for assessing glaucoma risk in these patients. “We would encourage more studies that continue to follow long-term outcomes of patients with KPro, as well as studies that help us to better understand and combat the complications of KPro,” Dr. Shtein said. “And we recommend future research to continue the quest for a truly biocompatible prosthetic cornea that could integrate with the patient’s existing tissues and reduce the risks of extrusion, infection, inflammation, glaucoma, etc.” EWAP Reference 1. Lee WB, et al. Boston keratoprosthe- Report - from page 57 sis: Outcomes and complications: A report by the American Academy of Ophthalmology. Ophthalmology. 2015;122:1504–1511. Editors’ note: The physicians have no financial interests related to their comments. Contact information Lee: wblee@mac.com Shtein: ronim@med.umich.edu