an outbreak of nocardia keratitis following photorefractive keratectomy

purpose: to report 3 cases of nocardia keratitis following photorefractive keratectomy (prk). report of outbreak: four eyes of 3 patients (2 female and one male) who had undergone prk by a single surgeon at a single center developed nocardia keartitis 3 to 6 weeks postoperatively. mean age was 25 (range 23-28) years and mean onset of corneal manifestations was 29 (range 21-40) days after prk. corneal smear and culture and confocal scan were performed in all eyes. two eyes from the first two patients required lamellar keratectomy to debulk the involved stroma and to obtain specimens for microbiologic and histopathologic evaluation. light microscopic examination disclosed gram-positive and acid-fast filaments of nocardia which were confirmed by the microbiologic results. diagnosis of nocardia keratitis in the third case was not as challenging as the first two cases because of a high index of suspicion. confocal scan in all cases disclosed hyperreflective and slender fibril-like structures in the corneal stroma. all eyes responded favourably to topical amikacin and the infection resolved without recurrence. conclusion: nocardia is a rare cause of keratitis following prk. clinical suspicion along with microbiologic, histopathologic and confocal scanning help to establish the correct diagnosis. the most probable cause of the outbreak was inadequate attention to sterility during surgery.