The use of a conjunctival flap with pediatric Boston keratoprosthesis (KPro) may decrease short-term postoperative complications and improve visual acuity, according to research results published in Cornea. 

Data shows that the Boston type 1 KPro is successful due to its ease of use; the device has a 95% retention rate for an average 8.5-month follow-up period and a 67% retention rate at 84 months in adults. The KPro, however, has not been studied in children or infants, and the limited data available provide mixed reviews. 

In 2014, the Flaum Eye Institute at the University of Rochester Medical Center in Rochester, New York, implemented a modified procedure using the near-complete conjunctival flap to cover the KPro device following implantation. In the current study, the researchers conducted a retrospective chart review of pediatric patients who underwent primary KPro implantation during the 3-year period before and the 3-year period after conjunctival flap incorporation (2011 to 2014 and 2014 to 2017). 


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Investigators examined the incidence of KPro-related complications that required surgical intervention within a 1-year follow-up period in both groups, with complications defined as “vision threatening complications that required reoperation” such as retroprosthetic membrane formation, corneal melt, retinal detachment, exposure keratopathy, recurring conjunctival cysts, and endophthalmitis

Eyes with 1 year minimum of follow-up or the occurrence of melt within 1 year postoperatively were included in the study, for a total cohort of 21 eyes from 16 patients. 

In the nonconjunctival flap group (n=10), median age at implantation was 18.5 months (60% girls); 80% of eyes had Peters anomaly, which was the primary indication for KPro implantation. Two patients required bilateral KPro implantation. In the conjunctival flap group (n=11), median age at implantation was 4 months (55% girls). All eyes in this group had Peters anomaly, and 3 patients required bilateral KPro implantation. 

In the conjunctival flap group, participants required fewer KPro-related reoperations, compared with 90% of eyes that required 16 surgeries due to KPro-related complications within 1 year. These 16 surgeries were performed for 21 complications: 6 related to the posterior segment and 15 related to the anterior segment. Comparatively, 27% of eyes in the conjunctival flap group required 5 surgeries due to complications, all related to the anterior segment. This group also experienced 7 additional surgeries for prophylactic conjunctival flap revision in 45% of eyes.

Four eyes and 1 eye in the nonflap and flap groups, respectively, experienced corneal melt, while endophthalmitis was seen in 1 eye and 0 eyes in each group. 

At 1-year follow-up, investigators found decreased visual acuity in 3 of 10 eyes and 1 of 11 eyes in the nonflap and flap groups, with improved visual acuity in 5 of 10 and 9 of 11 eyes in each group, respectively. 

Study limitations include the lack of long-term follow-up data, which will ultimately be critical in understanding device retention, the presentation of visual acuity data, which is difficult to assess in infants, and the difference in median ages between the study groups. 

“Currently, the outcomes and complications of Boston KPro type 1 implantation in children remain less favorable than those seen in adults,” the study explains. “Implementation of a conjunctival flap has herein been shown to lead to lower implant extrusion rates and improved visual outcomes for recipients.” 

“In addition, further investigation of the role of the conjunctival flap used in this study is needed to better understand its role in preserving the health of the KPro implant during long-term follow-up.” 

Reference

Bawany MH, Kudla C, Khan FA, Chung MM, Aquavella JV. Short-term outcomes of pediatric keratoprosthesis with the near-complete conjunctival flap. Cornea. 2021;40(6):679-684. doi:10.1097/ICO.0000000000002685