Ocular Microbiology and Immunology Group
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2014 OMIG Abstract 7

Diffusion of Antimicrobials Across Silicone Hydrogel Contact Lenses
Kristin M. Hunt, BS; Alison M. Zambelli, MD; Kimberly Z. Brothers, PhD; Eric G. Romanowski, MS;
Amy C. Nau, OD; Deepinder K. Dhaliwal, MD, LAc; Robert M.Q. Shanks, PhD.
The Charles T. Campbell Ophthalmic Microbiology Laboratory, UPMC Eye Center,
University of Pittsburgh, Pittsburgh, PA.

Purpose: To assess passage of moxifloxacin, amphotericin B, and polyhexamethylene biguanide (PHMB) through silicone hydrogel (SH) contact lenses in vitro. Anti-infectives like these are frequently used in concordance with SH bandage contact lenses to treat a variety of ocular issues without clear knowledge of drug permeability through SH lenses.

Methods: Antimicrobial compounds diffused through SH contact lenses (lotrafilcon A) were measured using a spectrophotometer for four hours and quantified using a standard curve. A biological assay was performed to validate the diffusion assay by testing antimicrobial activity of diffused material against lawns of susceptible microorganisms (Staphylococcus epidermidis and Saccharomyces cerevisiae). Experiments were repeated at least two times with a total of at least 4 independent replicates.

Results: Our data show detectable diffusion of moxifloxacin and PHMB through SH contact lenses at 30 minutes, while amphotericin B diffusion remained below the limit of detection within the 4 hour experimental period. At four hours, 10.6 ± 4.1% of the moxifloxacin, 5.1 ± 1.5% of the PHMB, and <0.1% of the amphotericin B diffused through the contact lens. There was no statistically significant difference between the percentage of moxifloxacin and PHMB passing through the lens at this time point (p = 0.21, 2-tailed, unpaired Student’s T-test). In the biological assay, diffused moxifloxacin demonstrated microbial killing starting at 20 minutes on bacterial lawns, PHMB produced a faint zone of inhibition after diffusion for 60 minutes, and amphotericin B failed to demonstrate killing on microbial lawns over the course of the 60 minute experiment.

Conclusions: In vitro diffusion assays demonstrate limited penetration of certain anti-infective agents through silicone hydrogel contact lenses. Further studies regarding the clinical benefit of using these agents along with bandage contact lens use for corneal pathology are warranted.

Disclosure code: S=NIH grants: A1085570, EY08098, EY017271, Eye and Ear Institute of Pittsburgh, Research to Prevent Blindness

2014 Agenda and Abstracts | < Previous | Next >