The analysis of bacterial flora in dry eye patients

• Main Author: Graham, Joanna E.
• Published: University of Ulster 2006
• Subjects: 617.71
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.554196

Dry Eye is recognised as one of the most common ocular surface disorders presenting to eye specialists today. The relationship between ocular surface bacteria, tear film function and ocular surface inflammation has been incompletely investigated. Within this study a varied approach to investigate the possible role of ocular surface bacteria in the pathogenesis of DE was undertaken. The research detailed in this thesis was divided into four main areas: diagnosis of normal healthy subjects or DE subjects was established; conjunctival bacterial flora of all subjects was investigated; commensal bacterial interaction with ocular surface cells in vitro was examined; finally, levels of IL-l ~ mRNA expression was investigated in normal and DE subjects. A number of objective and subjective measurements were performed to establish a diagnosis of DE or not. Statistical analysis demonstrated a lack of inter-tear function test correlation and between subjective dry eye assessment measurements. Based on these findings a new diagnostic algorithm was devised to classify study subjects as dry eye or non dry eye. A diagnosis was based on the composite results of four clinical tests and of the 91 subjects recruited, 34 were considered to be DE subjects while the remaining 57 were classified as normal. This study assessed conjunctival flora using routine culture and 16S rDNA PCR with DNA sequencing. Several bacterial species were detected in a number of samples through sequencing while remaining undetectable by culture. A wide variation in the quantity and genus of bacteria was detected between individual dry eye and normal subjects as determined by 16S rDNA PCR and DNA sequencing and routine culture. A number of potentially clinically significant bacteria, not normally associated with the normal ocular surface flora, were identified in both normal and dry eye subjects, including Rhodococcus erythropolis and Klebsiella sp. In vitro model systems of conjunctival epithelial and primary goblet cells were exposed to Staphylococcus epidermidis to assess bacterial invasion and cellular proliferation. Internalisation of S. epidermidis isolated from normal and dry eye subjects by conjunctival epithelial cell line and primary conjunctival goblet cells was demonstrated. Overall, a general decrease in conjunctival epithelial and goblet cell.