Ofloxacin monotherapy for the primary treatment of microbial keratitis: a double-masked, randomized, controlled trial with conventional dual therapy. The Ofloxacin Study Group

Abstract

Background: Ofloxacin is a potent broad-spectrum fluoroquinolone antibiotic commercially available as a topical ophthalmic preparation. The authors compared ofloxacin (0.3%) as a single therapy with their conventional dual therapy of specially prepared, fortified gentamicin (1.5%) and cefuroxime (5.0%) drops for the treatment of suspected microbial keratitis.

Methods: The authors enrolled 122 patients with a clinical diagnosis of microbial keratitis in a prospective, randomized, controlled, double-masked study to compare the two therapies. The ofloxacin drops were decanted into identical-looking bottles to the conventional treatment and dispensed with a second bottle containing saline only. The initial and subsequent assessments noted any risk factors, the size and location of the ulcer, and any evidence of corneal and conjunctival toxicity. All ulcers were scraped for microbiologic culture, and isolated organisms were tested for sensitivity to the trial antibiotics. For statistical analysis, a "cure" was defined as complete healing of the ulcer (no epithelial defect). A ratio of the two outcome proportions and its confidence limits was used to compare the two treatment groups. Multiple regression analysis using Poisson models was used to adjust for confounding factors that may have modified the outcome ratios.

Results: There was no difference in the treatment success between the two treatments, with 67.9% of the conventional treatment group and 62.1% of the ofloxacin group being cured within 14 days (ratio, 1.09; [95% confidence interval, 0.83-1.43]; P = 0.59). However, there was significantly more toxicity encountered with the conventional treatment group (50.8% vs. 10.2%; ratio, 5.00 [95% confidence interval, 2.25-11.11]; P < 0.0001). Poisson regression with adjustment for confounders did not materially change the ratio proportions for either treatment success or toxicity. There was at least a 90% chance to detect a 30% difference between the groups.

Conclusions: The authors found that the treatment outcomes with ofloxacin monotherapy compared favorably with their conventional therapy and were associated with less toxicity.