Purpose
Identify risk factors for microbial keratitis in corneal grafts and subsequent outcomes.
Methods
A retrospective analysis of medical records of all patients presenting with a microbial keratitis (excluding herpetic keratitis) in corneal grafts to the Royal Victoria Infirmary, Newcastle upon Tyne, United Kingdom, between January 2003 and July 2014. Demographics, predisposing factors, clinical, microbiological findings and final outcomes were analyzed.
Results
Fifty-eight episodes of microbial keratitis were identified in 40 eyes of 40 patients (38 penetrating keratoplasty and 2 deep anterior lamellar keratoplasty). Eleven (27.5%) patients presented with multiple episodes of infection of which 8 of them had a failed graft. Mean age of patients was 65.9 (± SD 19.6, range 25.0-89.6) years. The median time interval between corneal graft transplantation and the incidence of microbial keratitis was 49.5 months (range 2-158 months). In these eyes, the predisposing factors for a microbial keratitis were failed corneal graft (61.4%), concurrent use of topical glaucoma medication(s) (59.6%) or topical antibiotic (28.1%), history of herpetic eye disease (30.4%), contact lens wear (29.8%), co-existing ocular surface problem such as keratoconjunctivitis sicca (17.5%) or atopic eye disease (8.8%). About 75% of the cases had 2 or more predisposing factors. Corneal scrape culture showed gram-positive organism in 38.3% of cases, gram-negative organism in 23.4%, fungal species in 4.3% and no growth in 34.0%. Four eyes developed failed corneal grafts following the microbial keratitis while 2 eyes were complicated with a perforated ulcer (1 eye had underlying Peter’s anomaly, failed graft and Molteno tube; 1 eye had a large Staphylococcal ulcer in a failed graft). Best-corrected visual acuity at final follow-up visit was 20/40 or better in 12 (20.7%) cases, between 20/40 and 20/200 in 17 (29.3%) cases and worse than 20/200 in 29 (50%) cases. Twelve eyes (30.0%) had lost visual acuity post-keratitis compared to their baseline vision.
Conclusions
Our analysis revealed that the majority of cases presenting with microbial keratitis in a corneal graft have multiple predisposing risk factors; failed graft is a major determinant. The occurrence of microbial keratitis in corneal graft is associated with a high ocular morbidity rate with poor visual outcome.