Ocular pathogen or commensal: a PCR-based study of surface bacterial flora in normal and dry eyes.

Purpose: To compare the bacterial population of the ocular surface of normal and dry eye subjects using conventional culture and 16S rDNA PCR.

Methods: Ninety-one subjects were classified as normal (n = 57) or dry eye (n = 34) by using tear break-up time, McMonnies survey, goblet cell density, and meibomian gland assessment. Conventional bacterial culture and broad-range 16S rDNA PCR, cloning, and DNA sequencing were used for bacterial identification.