Patients will be assigned to 1 of 4 commercially available antibiotics at the initial study visit: ofloxacin 0.3% (Ocuflox, Akorn Inc., Somerset, NJ), azithromycin 1% (AzaSite, Inspire Pharmaceuticals, Inc. Durham, NC), gatifloxacin 0.3%, or moxifloxacin 0.5% and will use only their assigned antibiotic during and after all injections for the entire duration of the study.