Trends in contact lens microbial keratitis 1999 to 2015: a retrospective clinical review

Importance Contact lens microbial keratitis (CLMK) is the most common cause of microbial keratitis in our community. Background Define the trend in rate of CLMK and define patient demographics/culture results that may have a predictive value in patients with CLMK. Design Retrospective review of clinical records of patients with MK. Participants All patients with positive corneal scraping between 1999 and 2015 at the Princess Alexandra Hospital, Brisbane, Queensland identified through local microbiology database. Methods Trend in CLMK tested with chi-squared test of peak 3 years vs other years and Poisson regression of interrupted time series. Patient characteristics predictive of CLMK were defined by creating a polynomial regression model by stepwise variable selection. Main Outcome Measures Yearly rate of CLMK. Results Records of 895 episodes of MK were included. The most common: risk factor was contact lens wear (324, 36.2%), isolated organism was Pseudomonas aeruginosa (P. aeruginosa 181, 55.9%) and treatment was monotherapy with a fluoroquinolone 172, 53%). CLMK was most common between 2009 and 2011 (49.5% vs other years 32%, P < 0.001). Poisson regression of the interrupted time series showed there was a significant decrease in the rate over time after 2010 (P < 0.001). Independent factors predictive of CLMK in multivariate regression were young age (15-49 years) and corneal culture positive for P. aeruginosa Conclusions and Relevance The rate of CLMK in our community ranged between 32% and 50% and the rate of disease appears to have peaked during 2009 to 2011 and subsequently declined.