Corneal ciprofloxacin precipitation during bacterial keratitis

To examine how age affects the risk of developing a white corneal precipitate during ciprofloxacin therapy for bacterial keratitis and to explore the effect of a white precipitate on rates of clinical improvement and cure.

Prospective, multicenter, observational cohort study.

Occurrence of a white precipitate of the corneal surface was recorded among 624 patients with presumed bacterial keratitis who were treated with topical ciprofloxacin 0.3% solution or ointment. Relative risks of corneal precipitation were estimated from logistic regression for age categories and other clinical characteristics. The time-dependent effects of precipitate on rates of infection resolution and corneal reepithelialization were estimated by proportional hazards regression.

Ninety-five (15.2%) patients developed a white corneal precipitate during ciprofloxacin therapy; 72 (75.8%) began within the first 3 days of treatment. Compared with those younger than 40 years old, patients aged 60 to 69 years had 2.8 (95% confidence limits [CL], 1.9, 3.9) times the risk of ciprofloxacin precipitation; patients 70 years and older had 3.7 (95% CL, 2.6, 5.0) times the risk. Median duration of the visible corneal precipitate was 8.5 days (90% decile, 32 days). Presence of ciprofloxacin precipitation did not significantly affect the time until therapeutic improvement (P =.09) but slowed the time until reepithelialization by 55% (95% CL 32%, 70%).

Older patients treated with topical ciprofloxacin for bacterial keratitis have a higher risk of corneal deposition. A white precipitate apparently does not interfere with antibacterial therapeutic response but may delay epithelial healing of ulcerative keratitis.