ACANTHAMOEBA KERATITIS: ANALYSIS OF RISK FACTORS, DIAGNOSTIC MODALITIES AND CLINICAL OUTCOMES AT A TERTIARY REFERRAL OPHTHALMIC UNIT

To analyse the risk factors, clinical features and diagnostic tests in acanthamoeba keratitis, and to evaluate clinical outcomes with PHMB 0.06% monotherapy and enable us to improve management and minimise its complications

Department of Cornea and External Diseases, Moorfields Eye Hospital, London, United Kingdom

Retrospective case series of eyes with laboratory-confirmed acanthamoeba keratitis from January 2021 to April 2023. Patients with the phrase “Acanthamoeba keratitis” or “Corneal ulcer: Acanthamoeba” and who were prescribed PHMB in their electronic medical records were identified. Patients who only attended for confocal microscopy and those lost to follow-up were excluded. All patients were investigated with corneal scrapes, PCR and confocal microscopy and treated as per the Trust protocol with 0.06% PMHB monotherapy as initial treatment. Patient demographics, clinical information and microbiology information was collected and analysed.

Of 158 patients, 125 eyes from 119 patients were included. The mean age of our patient cohort was 40.6 years. 91% were contact lens (CL) wearers with the most common risk factor being water contact with CL (62%). The average duration of symptoms before diagnosis was 27.6 days and the most common clinical presentation was punctate epitheliopathy (70.4%). Laboratory results showed 85% were positive for cysts with confocal microscopy, 53% positive with PCR and 11% were positive with culture. 98% of eyes were successfully treated with medical management with 11% of patients having a relapse requiring re-treatment. Mean visual acuity at the point of diagnosis was 0.65 logMAR compared to a final visual acuity of 0.32 logMAR (p<0.001).

Our findings demonstrate the effectiveness of PHMB 0.06% monotherapy for the treatment of acanthamoeba keratitis. Water contact with CL remains the biggest risk factor whilst confocal microscopy is the most sensitive diagnostic test but PCR and cultures remain useful.