Acanthamoeba keratitis: multicentre survey in England 1992-6

Aim - To investigate the frequency, outcomes, and risk factors for acantham oeba keratitis (AK) in England during the past 4 years. Methods - An ophthalmologist in 12 of the 14 regional health authorities (R HAs) coordinated identification of patients in their region presenting with AK between 1 October 1992 and 30 September 1996. Clinical and postal patie nt questionnaire data were analysed. Results - 243 patients (259 eyes) with an AK diagnosis were identified, equ ating to an annualised incidence of 0.14 per 100000 individuals. UK residen t patients for each year numbered 50, 71, 73, and 32 respectively. Among pa tients with sufficient data 170/237 (72%) were diagnosed early (within 30 d ays of presentation), 197/218 (90%) were treated with polyhexamethyl biguan ide and/or chlorhexidine, and 40/243 (16%) underwent surgery. Visual acuiti es of 6/12 or better were achieved by 222/259 (86%) eyes, including 84 eyes of patients under review or lost to follow up. Non-contact lens (CL) weare rs were associated with delayed diagnosis, increased need for surgery and a poorer visual outcome (only 10/18 eyes, 56%, achieved 6/12 acuity). 225/24 3 (93%) patients were CL wearers, and 205/243 (84%) were soft CL (SCL) user s. Among SCL user respondents, previously identified risk factors - swimmin g with CL (47/138, 34%), non-sterile CL rinsing (11/138, 8%), omitted disin fection (85/138, 62%), and chlorine release disinfection (65/138, 47%) - we re identified for 125/138 (91%) patients. Conclusions - Earlier diagnosis and more effective medical therapy have imp roved the prognosis for most AK patients. The study demonstrates the highly preventable nature of the disease: 91% of the SCL wearers could have avoid ed the disease by refraining from inadvisable practices, and a marked fall in frequency was seen after intensive media attention to AK, possibly in co njunction with increasing penetrance of new CL products. Since the frequenc y of AK appears to be largely determined by the ever changing trends in CL use, continued monitoring is indicated.