Risk Factors for Severe Microbial Keratitis in Daily Wear Contact Lens Users

Abstract

Purpose: : To establish risk factors for severe microbial keratitis amongst daily wearers in Australia.

Methods: : A 12 month national prospective surveillance study identified all new cases of presumed microbial keratitis related to contact lens wear in Australia. Controls were generated using a population based telephone survey. Cases and controls were interviewed by phone to determine details on lens type, wear habits and history, and demographics. A clinical case definition was used and cases were stratified by severity according to the size and position of the lesion, culture result and visual outcome. Risk factors were determined using multiple binary logistic regression.

Results: : 125 eligible cases related to daily wear of contact lenses were reported during the study period, including a subgroup of 90 cases of severe keratitis. 1,090 community controls wearing daily wear contact lenses were identified. Independent risk factors for infection for severe keratitis, while adjusting for age, gender and lens material type included occasional overnight lens use (once a week or more often; 6.5x (95% CI 1.3-31.7)), high socioeconomic status (4.1x (95% CI 1.2-14.4), poor case hygiene (6.4x (95% CI 1.9-21.8)), smoking (3.7x (95% CI 1.1-12.8)), infrequent case replacement 5.4x (95% CI 1.5-18.9) and solution type (7.2x (95% CI 2.3-22.5)).

Conclusions: : Severe microbial keratitis associated with daily use of contact lenses was independently associated with occasional overnight use of contact lenses, storage case hygiene, smoking, solution type and the frequency of storage case replacement. Lens material type and wearer age and gender were not associated with severe disease. Attention to modifiable risk factors may reduce disease severity.

Keywords: cornea: clinical science • contact lens • keratitis