Clinical Outcomes in Acanthamoeba Keratitis Treated with Polyhexamethylene Biguanide as Monotherapy

Purpose: To assess the efficacy of polyhexamethylene biguanide (PHMB) in treating Acanthamoeba keratitis (AK) and also to identify related factors affecting final visual outcome in AK patients treated with PHMB Methods: In these interventional case series study, 27 eyes of 25 patients with AK received PHMB 0.02% and divided into two groups according to the final visual acuity (VA); VA equal to or greater than 20/25 and VA less than 20/25. Two groups were evaluated for the effectiveness of PHMB in treatment of AK. Results: Before treatment, more than 85% of the eyes had VA of less than 20/25 whilst after treatment final VA was 20/25 or better in 66.7% of eyes. VA regressed in 14.8% of the eyes during follow-up and improved or remained the same in more than 85% of eyes. Patients with deep stromal keratitis or a ring infiltrate had more than a 28-fold increase in the odds of a visual outcome worse than 20/ 25 [odd ratio (OR), 28.0; 95% CI, 3.3-240.8, p=0.001]. Patients with Initial VA<20/40 had a 9-fold increase in the odds of a visual outcome worse than 20/25 (OR, 8.6; 95% CI, 1.2-59.8, p=0.003). Longer duration of symptoms (≥ 3 weeks) or the medication used prior the first visit were not associated with poorer final VA (p>0.05). Five eyes (18.5%) finally required keratoplasty. Conclusion: Initial stage of corneal involvement at presentation was the most predictive factor for final visual outcome in AK. Although PHMB, even as monotherapy, is effective in treatment of AK, a remarkable proportion of patients still suffer a final grim visual outcome which requires aggressive treatments.