Acanthamoeba keratitis in Iceland from 1996-2021

INTRODUCTION: Acanthamoeba keratitis is a rare but serious eye infection primarily associated with contact lens use. Its diagnosis is often delayed due to treatment challenges, frequent co-infections, and the amoeba's high resistance, leading to significant visual impairment. This study assessed the incidence of Acanthamoeba keratitis in Iceland over 25 years, identified risk factors, diagnostic difficulties, and explored potential improvements. MATERIALS AND METHODS: A retrospective descriptive study including all individuals diagnosed with amoebic corneal infection in Iceland from 1996-2021. Data were retrieved from culture results in Landspitali's Department of Microbiology and patient records. Selected cases were presented in detail. RESULTS: Nine cases were identified, with an incidence of 0.11 per 100,000 individuals over the period. All cases had a history of contact lens use, all but one experienced severe pain, and six were misdiagnosed with herpes viral infection. All patients were treated with diamidines and biguanides, but five received steroid treatment before amoeba diagnosis. Two patients required surgery. The total duration of treatment ranged from 5-24 months, with follow-up periods ranging from 4-110 months. Visual acuity at the last examination was 0-1,25 on the Snellen scale. DISCUSSION: Awareness of environmental amoebas and early diagnosis are key to preventing Acanthamoeba keratitis. Prevention efforts should focus on contact lens users, with targeted education. Diagnostic and treatment guidelines are lacking, and physicians should always consider Acanthamoeba in keratitis cases, particularly in contact lens wearers.