Diffuse lamellar keratitis related to endotoxins released from sterilizer reservoir biofilms

Objective: To investigate the risk factors and control mechanisms used to c ontrol the outbreak of diffuse lamellar keratitis (DLK) associated with las er in situ keratomileusis (LASIK) and examine the relationship between DLK and endotoxins released from sterilizer biofilm reservoirs. Design: Clinic-based cohort and laboratory study. Participants: All patients undergoing LASIK at our clinic from October 7, 1 998 through August 31, 1999. The case definition was a diffuse infiltrate i n the interface developing within the first week after surgery. Interventions: Biofilm control in the sterilizer, changes in sterilizer, di stilled water, instruments, and irrigating fluids. Main Outcome Measures: The incidence of DLK after LASIK surgery. Results: There were 983 evaluable patients, with three whose DLK status was not recorded, There were 52 cases of DLK. Burkholderia pickettii was isola ted from the sterilizer reservoir. Potential risk factors and associations, for which there was no significant difference, included age and sex of the patients, surgeon, operating suite temperature or humidity, drapes used, s aline solutions used, time of day the surgery was performed, and microkerat ome use. Sterilizers 1 and 2, before biofilm control, were compared with st erilizer 3, after control. The relative risk was 9.4 (confidence limits [CL ], 7.5-11.8) for sterilizer 1 versus 3 and 18.7 (CL, 11-32) for sterilizer 2 versus 3. Three cases occurred after biofilm control, but were sporadic i n nature and associated with epithelial defects. Conclusions: Clusters of DLK may be related to endotoxins released from gra m-negative biofilms in sterilizer reservoirs. We experienced an outbreak of DLK affecting 52 patients and isolated B. pickettii from the sterilizer re servoir. Epidemiologic investigation showed that biofilm control in the ste rilizer reservoirs was associated with a significant reduction in the devel opment of DLK. We encourage any clinics that experience a cluster of DLK to consider microbiologic and epidemiologic investigation for the effectivene ss of sterilizer biofilm control. (C) 2000 by the American Academy of Ophth almology.