Risk factors for acquisition and severity of Acanthamoeba and Fusarium keratitis in contact lens users—A case–control and clinical–epidemiological study, 2009–2020

PURPOSE: Since 2015, the uncommon yet severe Acanthamoeba keratitis (AK) and Fusarium keratitis (FK) have increased in the Netherlands, predominantly in contact lens (CL) users. We investigated risk factors for acquisition and severity of AK and FK among CL users. METHODS: For this retrospective case-control study, we approached AK and FK cases diagnosed in 16 cornea reference centres between 2009 and 2019. CL-wearing controls were recruited in 2020 through social media. Besides, we assessed risk factors for treatment failure (corneal transplantation and/or final visual acuity ≤0.25) among cases included in the case-control study. Odds ratios (OR) with 95% confidence intervals (95%CI) were computed in multivariable logistic regression analyses. RESULTS: The case-control study comprised 220 cases (181 AK, 39 FK) and 1020 controls. Identified risk factors were previous eye injury (OR: 16.0, 95%CI: 3.4-76.7), occupational/recreational surface water contact (OR: 9.1, 95%CI: 3.5-23.2), cleaning/rinsing CLs with tap water (OR: 3.3, 95%CI: 1.7-6.4), cigarette smoke exposure (OR: 1.9, 95%CI: 1.1-3.5) and napping in CLs (OR: 1.9, 95%CI: 1.0-3.6). Treatment failure occurred in 85/179 (47%) AK and 23/35 (66%) FK cases. Evisceration or enucleation was performed in 9/179 (5%) AK and 5/35 (14%) FK cases. Age > 42 years (OR: 5.6, 95%CI: 2.3-14.6), hard CL use (OR: 3.3, 95%CI: 1.0-14.0), corticosteroid eye drops prior to diagnosis (OR: 3.8, 95%CI: 1.5-10.5) and a ring infiltrate at diagnosis (OR: 15.3, 95%CI: 4.8-57.4) were associated with AK treatment failure. CONCLUSION: Identified preventable risks warrant enhanced communication between eye care providers and CL wearers promoting healthy CL wear and care practices. Increased awareness among ophthalmologists is needed to prevent corticosteroid treatment prior to AK diagnosis to reduce treatment failure.