OCT 10, 2012
This large multicenter study of patients receiving a Boston type 1 keratoprosthesis (Boston KPro) found that eyes undergoing corneal replacement for infectious keratitis or aniridia had the greatest risk of developing retroprosthetic membrane (RPM). Overall, RPM formation was common, occurring in close to one-third of cases.
The study's analysis included 265 patients (265 eyes) who underwent Boston KPro implantation by one of 19 surgeons at 18 medical centers. The mean follow-up was 17.8 months. The majority of patients (85.4 percent) had experienced a failed penetrating keratoplasty before keratoprosthesis implantation.
The RPM formation rate was 31.7 percent. The most significant risk factor for RPM development was infectious keratitis. This is believed to be the first published report of this association. Patients with a history of infectious keratitis were more than twice as likely to develop an RPM (P = 0.002) and developed them faster in comparison to patients with other surgical indications (P = 0.0002). Aniridia also was an independent risk factor for RPM development.
The data also indicated that both chemical injuries and adjuvant intracameral steroids may delay the development of RPM. The authors note that although the protective effect of chemical injuries was not significant on controlled analysis, this finding was significant on univariate analysis, suggesting that its contribution to the development of RPM may be mitigated by other factors.