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CF Radford, DC Minassian, JK G Dart; Hardness Of Domestic Water Supply As A Risk Factor For Acanthamoeba Keratitis . Invest. Ophthalmol. Vis. Sci. 2002;43(13):3071.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To evaluate geographical variation in the incidence of Acanthamoeba keratitis (AK) in England and Wales. Methods: AK cases presenting 1.10.97-30.9.99 were identified by the British Ophthalmic Surveillance Unit active reporting system. Clinical and postal patient questionnaire data were analysed. Results: 106 reported cases met study criteria. At least 93/106 (88%) of patients were contact lens (CL) wearers. The annual incidence for CL related AK for the two years was 21.14 and 17.53 per million adult CL wearers. There was marked regional variation in incidence (0 to 85.13 per million), with CL wearers in the South having a nine-fold increased risk of AK compared to those resident in the North (95% confidence limits (c.l.): 2.2-38.9, p<0.0001). There was a threefold increased risk with hard as opposed to soft domestic water supply (95% c.l.: 1.73-6.58, p<0.001). Among soft CL users, one or more previously establised risk factors for AK - including failing to leave CL case to dry (25/55, 45%), irregular disinfection (24/55, 44%), non-sterile rinsing of CL case (20/55, 36%) and swimming while wearing CL (17/55, 31%)- were identified for 50/55 (91%) patients. Conclusion: The geographical variation in incidence appears to be at least partly related to the increase in risk associated with hard domestic water supply. The fact that water quality can have such an effect on the risk of AK suggests that many CL wearers must be letting non sterile water come into contact with their lenses or storage cases. Improved education of CL wearers is indicated.
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