Aim To compare the aqueous humour penetration of moxifloxacin 0.5% and gatifloxacin 0.3% eye drops administered in two different dosing regimens during phacoemulsification surgery.

Methods This prospective, randomised study included 97 patients. The patients were randomly divided into two treatment groups to receive either moxifloxacin or gatifloxacin. All patients received the topical antibiotics four times per day for 2 days prior to surgery. Patients in each group were further subdivided to receive additional doses of antibiotic drops as two drops 30 min apart (subgroup 1) versus four drops 10 min apart (subgroup 2) 1 h prior to the surgery. At the beginning of surgery, 0.1 ml of aqueous humour was aspirated, and the concentrations of moxifloxacin and gatifloxacin were analysed by high-performance liquid chromatography.

Results The mean concentrations of moxifloxacin and gatifloxacin in the aqueous humour were 0.72±0.40 μg/ml and 0.47±0.29 μg/ml, respectively, in the first subgroup, and 1.95±1.05 μg/ml and 0.77±0.52 μg/ml, respectively, in the second subgroup. Both the inter-group (p=0.006 and p=0.000, respectively) and the intra-group (p=0.000 and p=0.035, respectively) differences between the aqueous humour concentrations of moxifloxacin and gatifloxacin subgroups were statistically significant.

Conclusion Moxifloxacin, given in the same dosage, penetrated the aqueous humour better then gatifloxacin during cataract surgery. The penetration of both antibiotics increased significantly when the dosage of the agent was doubled.