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L. B. Szczotka-Flynn; Clinical Associations With Contact Lens Microbial Contamination During Extended Wear. Invest. Ophthalmol. Vis. Sci. 2009;50(13):6353.
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Microbial contamination of contact lenses is the greatest risk factor for corneal infection and likely inflammation. This study determined which clinical factors are associated with bacterial contamination of silicone hydrogel contact lenses when worn for continuous wear.
205 patients were enrolled in the LASH Contact Lens Study and were fitted with lotrafilcon A lenses for monthly continuous wear and followed for 1 year. Lenses were aseptically removed after 1 week and 4 months of wear and cultured using an agar sandwich technique. Lids and conjunctiva were routinely cultured at baseline, 1 week, and 4 months. Lenses were considered to have abnormal microbiota when they harbored high levels of normal flora or other pathogenic organisms. Univariate analyses were conducted to examine whether abnormal levels of lid or conjunctival organisms, lid disease, ethnicity, gender, age, history of previous adverse events, previous lens experience, lens deposits, corneal staining, dry eye, or discomfort were associated with lens contamination. Significant variables were entered into a multivariable logistic regression model.
33.3% of patients had sterile lenses in both eyes across multiple visits. 31.7% of patients had significant levels of microbial contamination on at least one lens across multiple visits. 53.7% and 11.2% of patients had significant levels of lid and conjunctival contamination, respectively, and 11.2% complained of discomfort. In univariate analyses, high levels or pathogenic lid and conjunctival biota, Asian ethnicity (protective), and lens discomfort were associated with lens bacterial contamination (p<0.05). In multivariable analysis, high levels or pathogenic lid and conjunctival biota (p=0.0263, p=0.0013, respectively), and lens discomfort (p=0.0199) were associated with abnormal lens microbial contamination. Although blepharitis was associated with lid microbial contamination (p=0.009), it was not associated with lens contamination.
As expected, lid and conjunctival microbiota are significantly associated with and likely the major route for lens contamination. This is the first study to report lens discomfort to also be associated with abnormal levels of bacteria isolated from continuous wear contact lenses.
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