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Kimberly Brothers, Amy C Nau, Robert M Q Shanks; A Model System for Testing the Effect of Biofilms on Drug Diffusion Through Contact Lenses. Invest. Ophthalmol. Vis. Sci. 2014;55(13):4644.
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Topical therapeutics such as antibiotics and steroids are frequently administered to patients using soft bandage lenses, and must pass through the contact lens to reach the cornea. Bandage lenses are widely used when the epithelial surface of the cornea is compromised in cases of corneal abrasions, ulcers, penetrating corneal trauma, after anterior segment surgery, corneal prostheses and when pain relief is needed, as in Thygeson’s punctate keratitis. Our goal was to measure the impact of microbial biofilms on drug delivery through contact lenses using an in vitro diffusion model.
Staphylococcus epidermidis (ATCC 35984) biofilms were grown overnight on lotrafilcon A (Air Optix Aqua), and methafilcon A (Kontur Precision Sphere) lenses in brain heart infusion medium containing 0.2% glucose to an average of 3x105 colony forming units per lens. Lenses were placed upright onto a 0.45 μm filter insert that remained hydrated with 1 ml phosphate buffered saline (PBS) below the filter insert. Dexamethasone (40 µl of 6 mM) was used as test therapeutics. Diffusion of therapeutics through lenses (+/- biofilms) into PBS was measured after 24 h at room temperature. Diffused therapeutics were measured by absorbance or fluorescence and quantified using a standard curve.
S. epidermidis biofilms impeded passage of dexamethasone through both Air Optix and Kontur lenses by 53% and 60% respectively, (p<0.05, Student’s T-test).
We have developed a model to quantify diffusion of therapeutics through contact lenses. Using this model, it was shown that biofilms obstruct passage of a clinically relevant drug through two different contact lens types. These results highlight potential complications regarding the dosing of corticosteroids in patients who are wearing bandage contact lenses.
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