Early Real-World Outcomes Of Polyhexamethylene Biguanide (Phmb) 0.08% Monotherapy For Acanthamoeba Keratitis

To describe early real-world outcomes, tolerability, and clinical course of topical polyhexamethylene biguanide (PHMB) 0.08% monotherapy in patients with Acanthamoeba keratitis (AK) at a tertiary referral centre.

Moorfields Eye Hospital, London, United Kingdom.

We conducted a retrospective observational series of consecutive patients with AK managed at a tertiary referral centre during a period when compounded PHMB preparations were unavailable. All patients were treated with PHMB 0.08% monotherapy. Demographic data, disease stage, prior anti-amoebic therapy, adjunctive corticosteroid use, tolerability, and early clinical outcomes following initiation of PHMB 0.08% were recorded. Diagnosis of AK was confirmed by in vivo confocal microscopy, polymerase chain reaction (PCR) or culture.

Fifty eyes from 49 patients received PHMB 0.08%. Sixteen eyes were excluded due to insufficient follow-up. Among the remaining 34 eyes, 44.1% (15/34) were contact lens related and 94.1% (32/34) were unilateral. Disease severity included 38.2% stage 1 (13/34), 47.1% stage 2 (16/34), and 14.7% stage 3 (5/34). Prior anti-amoebic therapy with compounded PHMB had been used in 47.1% (16/34). Treatment with PHMB 0.08% was well tolerated, with no discontinuation due to ocular surface toxicity. Adjunctive topical corticosteroids were used in 47.1% (16/34). Clinical resolution occurred in 23.5% (8/34) within the first four months after commencing PHMB 0.08% monotherapy.

PHMB 0.08% monotherapy was well tolerated and provided a practical treatment option when compounded PHMB preparations were unavailable, allowing continuity of care. Early real-world outcomes support its use across the AK disease spectrum. Further follow-up is needed to determine long-term cure rates and comparative effectiveness, but initial experience demonstrates the feasibility and safety of PHMB 0.08% monotherapy in routine clinical practice.