Bacterial keratitis after penetrating keratoplasty - Incidence, microbiological profile, graft survival, and visual outcome

Purpose: To determine the incidence, microbiological profile, graft survival, and factors influencing graft survival after the development of bacterial keratitis after penetrating keratoplasty (PK). Design: Retrospective case series. Participants: One hundred two patients (102 eyes) treated at a single center during a 5-year period. Methods: Retrospective review of the medical records of every patient treated for culture-positive keratitis between January 1, 1998 and December 31, 2002 who previously had undergone penetrating keratoplasty at the King Khaled Eye Specialist Hospital. Main Outcome Measures: Graft survival and visual outcome. Results: There were 2103 PKs performed and 102 (4.9%) cases of culture-positive keratitis during the study period. There were 168 bacterial isolates, of which 140 (83.3%) were gram positive, 28 (16.7%) were gram negative, and 1 (0.6%) was acid fast. Only 38 (37.3%) grafts remained clear after a mean follow-up of 985 days (range, 82-2284). The best graft survival was in eyes with PK for keratoconus (83.7%), whereas the poorest grat survival was for previously failed grafts (5.6%). By Kaplan-Meier analysis, there was an immediate steep decline in graft survival to 54.9%, followed by a slow decline to 47.2% by 1 year and 35.8% after 4 years. Factors associated with an increased risk of graft failure were the surgical indication for PK (P<0.001), increasing patient age (P = 0.004), smaller donor (P = 0.001) and recipient (P = 0.0003) graft size, history of previous microbial keratitis (P = 0.02) or endothelial rejection episodes (P = 0.02), and coexisting glaucoma (P = 0.001). The visual outcome was >= 20/40 in only 8 (8.2%) eyes and better than 20/200 in only 21 (21.6%) eyes. Conclusion: The development of bacterial keratitis after PK is a serious complication that is associated with a high incidence of graft failure and poor visual outcome.