The purpose of this study is to assess the concentration of besifloxacin compared to gatifloxacin and moxifloxacin in human conjunctival tissue, following a single drop of the drug instilled topically into the study eye. Conjunctival biopsies will be performed at specified time points, followed by the use of loteprednol etabonate/tobramycin ophthalmic suspension four times a day for 5 days.