PERIOPERATIVE OFLOXACIN VS TOBRAMYCIN - EFFICACY IN EXTERNAL OCULAR ADNEXAL STERILIZATION AND ANTERIOR-CHAMBER PENETRATION

Objective: To compare the efficacy of two treatment regimens, tobramyc in drops-erythromycin ointment and ofloxacin drops-placebo ointment, i n sterilizing the external ocular adnexa when given perioperatively. A second objective was to determine the aqueous humour concentration of ofloxacin and tobramycin. Design: Randomized double-blinded clinical trial. Setting: University-affiliated hospital. Patients: Patients age d 18 years or more scheduled to undergo planned cataract surgery who w ere judged likely to complete the trial. Numbers: Of 55 patients enrol led 6 were disqualified and 49 completed the trial. Interventions: Pre operative instillation of 10 drops of a 0.3% solution of ofloxacin (26 eyes) or tobramycin (23 eyes) in the operative eye, starting the even ing before surgery, Tobramycin-treated eyes received erythromycin oint ment after surgery; ofloxacin treated eyes received petrolatum ointmen t, Lid and conjunctival swabs were obtained from both eyes on the day before surgery (visit 1), at surgery (visit 2) and on the first postop erative day (visit 3), Aqueous humour samples were obtained from the s tudy eyes at surgery. Main outcome measures: Threshold growth of bacte ria on culture, aqueous humour concentration of ofloxacin or tobramyci n. Results: At visit 1, 96% of all eyes had positive cultures; this re sult persisted at visits 2 and 3 for the control eyes. For the treated eyes the incidence of positive cultures decreased from visit to visit , By visit 3 lid cultures were positive for 7 (27%) of the ofloxacin-t reated eyes and 7 (30%) of the tobramycin-treated eyes; conjunctival c ultures were positive for 0 (0%) of the ofloxacin-treated eyes and 1 ( 4%) of the tobramycin-treated eyes, No significant differences were se en in culture positivity between the treatment groups at any visit. Th e mean aqueous humour concentration of ofloxacin was Significantly hig her than that of tobramycin (0.4084 vs. 0.0279 mu g/mL) (p < 0.001). C onclusions: Both ofloxacin-placebo treatment and tobramycin-erythromyc in treatment were more effective than no treatment in sterilizing the external ocular adnexa, The two treatments were equally efficacious in eliminating bacteria, more successfully in the conjunctiva than the l ids. Topically administered ofloxacin demonstrated significantly great er anterior chamber penetration than topically administered tobramycin .