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Dexamethasone Diffusion Across Contact Lenses Is Inhibited by Staphylococcus epidermidis Biofilms in Vitro

Brothers, Kimberly M. PhD*; Nau, Amy C. OD; Romanowski, Eric G. MS*; Shanks, Robert M. Q. PhD*

doi: 10.1097/ICO.0000000000000196
Basic Investigation

Purpose: This study was designed to measure the impact of bacterial biofilms on diffusion of an ocular therapeutic through silicone hydrogel bandage lenses in vitro.

Methods: An assay was designed to study the passage of a commonly used steroid, dexamethasone, through silicone hydrogel soft contact lenses. Diffused dexamethasone was measured using a spectrophotometer over a period of 18 hours and quantified using a standard curve. This assay was performed with control and Staphylococcus epidermidis biofilm-coated contact lenses comprised of lotrafilcon A and methafilcon. Biofilms were formed in brain heart infusion broth supplemented with D-glucose.

Results: The presented data validate a simple in vitro model that can be used to measure the penetration of a topical therapeutic through silicone hydrogel soft contact lenses. Using this model, we measured a reduction in dexamethasone diffusion up to 88% through S. epidermidis biofilm-coated silicone hydrogel lenses compared with control lenses.

Conclusions: The results of this in vitro study demonstrate that bacterial biofilms impede dexamethasone diffusion through silicone hydrogel contact lenses and warrant future studies regarding the clinical benefit of using ocular therapeutics in the setting of bandage contact lens use for corneal epithelial defects.

*Department of Ophthalmology (OVSRC), Charles T. Campbell Ophthalmic Microbiology Laboratory, UPMC Eye Center, Ophthalmology and Visual Sciences Research Center, University of Pittsburgh School of Medicine, Pittsburgh, PA; and

Department of Ophthalmology, Fox Center for Vision Restoration, University of Pittsburgh School of Medicine, Pittsburgh, PA.

Reprints: Robert M. Q. Shanks, PhD, Department of Ophthalmology, EEI 1020, 203 Lothrop St, Pittsburgh, PA 15213 (e-mail:

Supported by unrestricted funds from Research to Prevent Blindness, the Eye and Ear Foundation of Pittsburgh, and National Institute of Health grants AI085570 and EY08098.

The authors have no conflicts of interest to disclose.

Received March 28, 2014

Received in revised form May 14, 2014

Accepted May 29, 2014

© 2014 by Lippincott Williams & Wilkins.