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Matthew Gorski, Alina Genis, Ahmed Awwad, Douglas R Lazzaro; Seasonal Variation as a Risk Factor for Infectious Keratitis. Invest. Ophthalmol. Vis. Sci. 2014;55(13):1507.
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Infectious keratitis is a common etiology with the potential for severe ocular morbidity. Multiple studies have described various risk factors for the development of infectious keratitis. The purpose of this study was to analyze the seasonal variation in the incidence of infectious keratitis, as well as seasonal changes in its etiologies, risk factors, and clinical outcomes.
A retrospective chart review was performed of consecutive patients presenting to the emergency department at our tertiary care urban hospital center who were diagnosed with infectious keratitis from 2008 to 2013. A chi-square analysis was performed to determine whether a significant variation exists between the month, season, frequency of presentation of ulcers as well as other risk factors.
A total of 155 patients—53 male and 102 female—with a mean age of 40 (range 3-97) diagnosed with infectious keratitis were included in the analysis. Sixty-nine (44.5%) ulcers presented in the summer, 19 (12.3%) in the fall, 34 (21.9%) in the winter and 33 (21.3%) in the spring (P <0.0001). A total of 92 ulcers were cultured, of which 53.8% were positive in the summer, 42.9% in the fall, 57.9% in the winter and 40% in the spring (Figure 1). A significant seasonal variation in the frequency of one organism, Pseudomonas aeruginosa was identified (P=<0.0001). Up to 47.6% of culture-positive ulcers in the summer were Pseudomonas positive, while cultures in the remaining seasons were 0, 9.1 and 12.5% positive for this organism.
The summer months have a higher frequency of infectious keratitis and Pseudomonas aeruginosa positivity. Possible factors leading to this increased summer incidence include warmer temperatures and higher humidity. Clinicians should increase their vigilance and education to high risk patients during these time periods and potentially modify empiric treatment regimens.
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