Comparison of the biocompatibility of gatifloxacin 0.3% and moxifloxacin 0.5%

PURPOSE: To compare the ocular biocompatibility of the commercially available ophthalmic solutions of the fourth-generation fluoroquinolones gatifloxacin 0.3% (Zymar; Allergan, Irvine, CA) and moxifloxacin 0.5% (Vigamox; Alcon Laboratories, Fort Worth, TX). METHODS: Pretreatment visual acuity and pupil size were measured in all 14 subjects. In a double-masked design, subjects received drops from masked bottles of gatifloxacin ophthalmic solution 0.3% and moxifloxacin ophthalmic solution 0.5%, which were placed in either the right or left eye in a randomized fashion at 1-minute intervals. After 5 minutes with their eyes closed, subjects graded discomfort on a scale of 1 to 10. In each eye, visual acuity was measured, conjunctival injection was graded on a scale of 1 to 4, pupil size was measured, individual punctate areas of fluorescein staining were counted (using nonpreserved fluorescein), and corneal epithelial cell dropout was determined with in vivo confocal microscopy. RESULTS: Moxifloxacin 0.5% was associated with a statistically significantly greater degree of conjunctival injection (2.8 vs. 1.2, P ≤ 0.05), discomfort (1 vs. 0.4, P ≤ 0.05), and corneal epithelial cell dropout per high-power field (8.7 vs. 2.6, P ≤ 0.05) than the gatifloxacin 0.3% group at 5 minutes. There was no statistically significant change in pupil size or visual acuity between the 2 treatment groups. CONCLUSIONS: Gatifloxacin 0.3% showed statistically significantly greater ocular biocompatibility than moxifloxacin 0.5%, using a frequent dosing interval.