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S. Katiyar, L. Keay, K. Edwards, T. Naduvilath, F. Stapleton, MK Study Group; Climatic Influence on Contact Lens Related Microbial Keratitis . Invest. Ophthalmol. Vis. Sci. 2006;47(13):5561.
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© ARVO (1962-2015); The Authors (2016-present)
The purpose of this study was to investigate the climatic influences on contact lens related microbial keratitis (MK) in Australia.
Cases were detected via a national surveillance study conducted from October 2003–September 2004 utilizing information from practitioners and patients. Climate zones were divided in six: zone 1– hot humid summer, zone 2– warm humid summer, zone 3– hot dry summer, mild winter, zone 4– hot dry summer, cold winter, zone 5– warm summer, cool winter, and zone 6– mild summer, cold winter. Geographic location at the time of the event was matched to the weather collection stations of the Bureau of Meteorology. Temperature (°C) and humidity (%) data were obtained for the day of onset for cases (n=249). In order to minimize noise and to obtain a smooth trend line, moving averages for temperature and humidity were used for each month. Cases were sorted into months and analyzed as proportion per zone per month.
Temperature and humidity were strongly associated with each other (R2= 0.88, p<0.001). There were 11 cases in zone 1, 48 in zone 2, 1 in zone 3, 2 in zone 4, 167 in zone 5, and 20 in zone 6. Peak seasons for MK occurrence was spring/summer for zone 1 and 2, summer/autumn for zone 5, and autumn/winter for zone 6. Overall, a strong linear association existed between MK and rising temperature (R2= 0.64, p<0.01). Humidity had a moderate positive association with MK occurrence nationwide (R2= 0.52, p<0.01). A strong linear association with temperature existed for zone 1 (R2 =0.67, p<0.001) and for zone 2 (R2=0.80, p<0.001). A strong association existed for the combined effects of temperature and humidity in zone 5 (R2=0.75, p<0.01) and in zone 6 (R2=0.80, p<0.001).
MK occurrence is positively associated with temperature in zones 1 and 2. Both temperature and humidity influence MK occurrence in zones 5 and 6. Additional environmental factors are likely also involved in the development of contact lens related MK.
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