Epidemiological analysis of an outbreak of diffuse lamellar keratitis.

PURPOSE: To describe the incidence, causes, risk factors, and preventive strategies regarding an outbreak of diffuse lamellar keratitis (DLK).

METHODS

Between March and October 2007, an epidemic of DLK was detected in one center. During this period, 6 surgeons performed 1161 LASIK or flap lift procedures. From March to August 2007, data were retrospectively collected corresponding to pre- and postoperative clinical findings and environmental risk factors related to the operating room, auxiliary staff, sterilization, and surgical equipment (phase 1). Incidence and distribution of cases are described. From August to October 2007, a prospective epidemiological study was completed, analyzing the clinical and intraoperative variables associated with the outbreak (phase 2). A plan of action was applied covering a wide range of possible causes.

RESULTS

During phase 1, 25.79% of eyes developed DLK. A greater incidence was found in eyes operated on Mondays and a smaller incidence was found when povidone-iodine was used for disinfection of the instruments. Actions taken by the staff to stop the outbreak had no effect, and epidemiologists designed a strategy aimed at addressing all possible weak points and the prospective study for detecting causes. The incidence decreased to 1.87% and a weak significant association was found for sex, atopy, drug allergies, spherical equivalent refraction, and mechanical microkeratome.

CONCLUSIONS

Strategies aimed at addressing all possible etiological factors can stop an epidemic of DLK even when a single cause has not been isolated.