Polymicrobial keratitis after a collagen cross-linking procedure with postoperative use of a contact lens

PURPOSE: To report a case of polymicrobial keratitis caused by Streptococcus salivarius, Streptococcus oralis, and coagulase-negative Staphylococcus sp. in a patient who underwent collagen cross-linking for keratoconus. METHOD: Case report. RESULT: A 32-year-old male presented with a 1-day history of a painful red eye, occurring 3 days after he had undergone a collagen cross-linking with riboflavin and UV-A on his left eye for keratoconus. He admitted to removing his bandage contact lens and cleaning it in his mouth before reapplying it in his eye. On presentation, a severe keratitis with an 8-mm epithelial defect and 360-degree ring infiltrate was found. Culture results from his contact lens were positive for S. salivarius and S. oralis, and coagulase-negative Staphylococcus sp. were grown from his corneal scrapings. CONCLUSIONS: Collagen cross-linking is a promising procedure for the treatment of progressive keratoconus with minimal reported side effects. However, the possibility of a secondary infection after the procedure exists because the patient is subjected to epithelial debridement and the application of a soft contact lens. The role of the UV light on the immune mechanisms of the cornea and its effect on corneal wound healing warrant further investigation.