Risk factors, management, and outcomes of Acanthamoeba keratitis: A retrospective analysis of 110 cases

PURPOSE: To evaluate the risk factors, medical and surgical management, and visual outcomes of patients affected by Acanthamoeba keratitis (AK) over a 16-year period. OBSERVATIONS: Records were reviewed retrospectively for all AK patients treated at University of Iowa between 2002 and 2017. Main outcomes measured were risk factors, time to diagnosis, coinfection types, initial and final visual acuities, and treatment outcomes, with failure of medical therapy defined as need for therapeutic keratoplasty (TK). Effects of steroid use on these outcomes were determined. Among all AK cases occurring during the study period (N = 110), the median age of the AK cohort was 31 years (range 8–80 years), and 49.1% were men. Contact lens wear was the primary risk factor for AK (95/100, 86.4%), and the median time to diagnosis was 0.70 (0.23–1.23) months. Forty-four AK patients (40%) failed medical therapy. Vision outcomes were better for AK patients with successful medical therapy compared to those requiring TK (LogMAR 0.00 v. 0.30; p < 0.0001). Corticosteroid use was associated with increased time to diagnosis (1.00 v. 0.50 months; p = 0.002), decreased final vision (LogMAR 0.10 v. 0.00; p < 0.05) and increased need for TK (40/77 v. 4/33; p < 0.001). CONCLUSIONS AND IMPORTANCE: Acanthamoeba keratitis cases have increased over the past two decades at our institution. In this large retrospective study, AK was commonly misdiagnosed with delayed diagnosis and high rates of failed medical therapy. Corticosteroid use before AK diagnosis led to poorer outcomes. Our findings underscore the need for ophthalmologists to suspect Acanthamoeba in the setting of contact lens-associated keratitis before topical steroids are initiated.