Risk factors, demographics and clinical profile of Acanthamoeba keratitis in Melbourne: an 18-year retrospective study

Purpose To assess incidence, risk factors, presentation and final visual outcome of patients with Acanthamoebakeratitis (AK) treated at the Royal Victorian Eye and Ear Hospital (RVEEH), Melbourne, Australia, over an 18-year period. Methods A retrospective review of all cases of AK managed at RVEEH between January 1998 and May 2016 was performed. Data collected included age, gender, affected eye, signs and symptoms, time between symptoms and diagnosis, risk factors, presenting and final visual acuity (VA), investigations, medical treatment, surgical interventions and length of follow-up. Results A total of 36 eyes affected by AK in 34 patients were identified. There were 26 cases diagnosed early (<30 days) and 10 were diagnosed late (>= 30 days). There were 31 (86.1%) cases associated with contact lens (CL). Signs associated with early AK included epithelial infiltrates, while signs of late AK included uveitis, ring infiltrate, endothelial plaque and corneal thinning (p<0.05). Surgical treatment was required in seven cases (19.4%). There were 29 (80.6%) cases that reported improved VA. Median best corrected final VA was worse in patients with late diagnosis (logarithm of minimal angle of resolution (logMAR) 0.5, IQR: 0.2-0.8), compared with patients with early diagnosis (logMAR 0.0, IQR: 0.0-0.3; p=0.01). Late diagnosis was associated with a prolonged disease period. Conclusion AK was an uncommon cause of severe keratitis and was associated commonly with CL. Patients with late diagnosis had worse presenting and final VAs as well as a prolonged disease period, indicating need for early recognition and management.