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Risk Factors for Microbial Bioburden During Daily Wear of Silicone Hydrogel Contact Lenses

Jiang, Ying M.D.; Jacobs, Michael M.D., Ph.D.; Bajaksouzian, Saralee M.S.; Foster, Altreisha N. Ph.D.; Debanne, Sara M. Ph.D.; Bielefeld, Roger Ph.D.; Garvey, Matt M.S.; Raghupathy, Sangeetha B.S.Optom.; Kern, Jami M.B.A., Ph.D.; Szczotka-Flynn, Loretta B. O.D., Ph.D.

Eye & Contact Lens: Science & Clinical Practice: May 2014 - Volume 40 - Issue 3 - p 148–156
doi: 10.1097/ICL.0000000000000026

Purpose: To assess risk factors associated with substantial microbial bioburden of lids, conjunctivae, contact lenses, and storage cases during daily wear of silicone hydrogel contact lenses.

Methods: Two hundred eighteen patients were fit to lotrafilcon A lenses, randomized to use either a multipurpose solution or a hydrogen peroxide care system, and followed up for 1 year. Lenses, lens transport saline, lids, conjunctivae, and storage cases were cultured and considered to have substantial microbial bioburden when they harbored high levels of commensal or pathogenic organisms. Univariate and multivariate logistic regression analyses were conducted to examine which demographic covariates were associated with significant bioburden at each location while controlling for solution use.

Results: In multivariate analyses, smoking trended toward an association with lens bioburden (odds ratio [OR]=2.15, 95% confidence interval [CI]: 0.95–4.88). Clerical occupations were found to be associated with more frequent overall storage case contamination (OR=3.51, 95% CI: 1.15–10.70) and, specifically, higher gram-positive storage case contamination (OR=5.57, 95% CI: 1.82–17.06). The peroxide system was associated with more frequent storage case contamination (OR=7.6, 95% CI: 3.79–15.19). Coagulase-negative staphylococci (CNS) were the most frequently cultured organisms within storage cases, and in multivariate analyses, CNS were more frequently found in storage cases of peroxide users (OR=6.12, 95% CI: 2.91–13.09).

Conclusions: Clerical occupations were associated with increased microbial bioburden of storage cases during daily wear of silicone hydrogel lenses. Smoking may increase the risk of lens contamination. Storage cases are most frequently contaminated with normal skin flora, and peroxide cases were associated with more frequent contamination. However, the solution type was not associated with lid or lens contamination nor with corneal infiltrative events in this study.

Departments of Epidemiology & Biostatistics (Y.J., S.M.D.), Pathology (M.J., S.B., A.N.F.), Division of Information Technology Services (R.B., M.G.), Case Western Reserve University, Cleveland, OH; Department of Ophthalmology & Visual Sciences (S.R., L.B.S.-F.) and University Hospitals Eye Institute, University Hospitals Case Medical Center, Cleveland, OH; and Alcon Research Ltd. (J.K.), Fort Worth, TX.

Address correspondence to Loretta B. Szczotka-Flynn, O.D., Ph.D., University Hospitals Eye Institute, 11100 Euclid Avenue, Lakeside 4126C, Cleveland, OH 44106; e-mail:

S. M. Debanne is contracted to Johnson and Johnson for data research as a data and safety and monitoring member. L.B. Szczotka-Flynn has disclosures with Alcon, <$5000 for honoraria and consulting. The other authors have no conflicts of interest to disclose.

Supported by Alcon Research, Ltd., with indirect support for laboratories and coordination from the Ohio Lions Eye Research Foundation and Research to Prevent Blindness. The identifier is NCT00937105.

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Accepted January 21, 2014

© 2014 Contact Lens Association of Ophthalmologists, Inc.