Purpose: To evaluate the efficacy of 0.02% polyhexamethylene biguanide (PHMB) in the treatment of keratoconjunctivitis caused by microsporidia.
Design: Prospective, double-masked, randomized, placebo-controlled clinical trial.
Methods: One hundred forty-five patients in a single-center, institutional setting were recruited. Patients with superficial keratoconjunctivitis and corneal scrapings with positive results for microsporidial spores were included. Patients with any known allergy to PHMB, and clinically suspected bacterial, viral, or fungal infection were excluded from the study. One hundred forty-five patients were treated at 4-hour intervals with either topical 0.02% PHMB (n = 72) or placebo (n = 73). The patients were followed-up on day 3 +/- 1, day 7 +/- 1, and weekly thereafter, until complete resolution of the corneal lesions. Patients with deterioration of clinical symptoms and signs were removed from the study and were treated with PHMB. Main outcome measures included resolution time, cure time, and final visual outcome.
Results: Resolution time was defined as the amount of time until disappearance of corneal epithelial infiltrates. Cure time was defined as the interval until absence of conjunctival congestion, corneal epithelial lesion, and superficial punctate keratitis. Baseline characteristics showed no relevant difference between the groups. The mean resolution time was 4.9 +/- 2.2 days and 4.6 +/- 2.3 days in the PHMB and placebo groups, respectively (P = .49). The mean time for cure was 13.5 +/- 6.6 days and 9.4 +/- 5.1 days in PHMB and placebo groups, respectively (P = .004). There was no significant difference in the final visual outcome between the groups (P = .10). No serious adverse effects were noted.
Conclusions: Treatment of microsporidial keratoconjunctivitis with PHMB does not offer any significant advantage over placebo, suggesting self-limiting nature of the disease.
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