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K. Edwards, L. Keay, T. Naduvilath, G. Brian, F. Stapleton, Microbial Keratitis Study Group; Risk Factors for Contact Lens Related Microbial Keratitis in Australia . Invest. Ophthalmol. Vis. Sci. 2005;46(13):926.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To establish risk factors for and the relative risk of microbial keratitis (MK) for different contact lens (CL) types in Australia. Methods: New cases of CL related presumed MK were identified in a 12 month prospective study. Cases were interviewed by phone to establish risk factor data. Seven hundred CL wearing controls were identified using a population based telephone survey. CL wearers were grouped as follows: daily wear soft CL (including silicone hydrogel and hydrogel) (DWS), soft extended wear CL (EWS), silicone hydrogel extended wear (EWSH), rigid CL daily wear (RGP), and daily disposable CL (DD). The association of independent risk factors with corneal infection was estimated using odds ratios (OR) and their 95% confidence intervals. Results: 151 cases were reported in the first 6 months with data on CL type and risk factors available in 93 and 70 cases respectively. Males had a higher risk of MK compared to females (OR=1.6, 95% CI=1.01–2.6). The mean age of cases was 33.6±12.8 years, compared with 36.7±12.1 years in controls (p=0.015). Compared to DD wear, the relative risk of MK was 0.2x (95% CI: 0.0–2.4) with RGP, 1.4x (0.4–4.8) with DWS, 24.6x (5.8–103.8) with EWS and 25.5x (7.0–93.1) with EWSH. Behaviours associated with a higher risk of MK included: occasional overnight use of daily wear CL (OR=4.7x, 95% CI=2.1–10.3), not storing CL cases dry (OR=2.4, 95% CI=1.2–5.1), showering in lenses (OR=2.7x, 95% CI=1.2–5.9), smoking (OR=2.5x, 95% CI=1.1–5.5), and inappropriate treatment of CL while swimming (1.3, 95% CI=1.1–1.5). Of the 117 cases where information on final visual outcome was available, there were 7 cases of vision loss of at least 2 lines of best corrected visual acuity: 5 in DWS, 1 in EWS and 1 in EWSH. Conclusions: While the data have yet to be independently reviewed, overnight wear of both hydrogel and silicone hydrogel CLs has a higher risk of MK infection compared to DD, RGP and DWS use. Showering in lenses, smoking, occasional overnight use in DW and inappropriate handling of lenses while swimming are associated with an increased risk of infection.
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