Abstract
Purpose::
A retrospective case control study was conducted at a tertiary referral hospital in Australia to determine the characteristics of and risk factors for contact lens related microbial keratitis.
Methods::
291 cases of microbial keratitis were retrospectively identified at a tertiary referral hospital over a 2-year period. Hospital records were reviewed for a history of contact lens wear, and where identified, these records were further reviewed for lens type and mode of wear, demographic data, clinical characteristics, and visual outcome. 186 contact lens wearing controls were generated in a telephone survey.
Results::
Ninety-nine (99/291, 34%) new cases of microbial keratitis associated with contact lens wear were retrospectively identified. Overnight use of soft lenses was associated with an increased risk of infection compared to daily disposable lens wear (Odds ratio [OR]: 8.03, 95% confidence interval [CI]:1.82-35.46). Compared with older lens wearers (35-64 years), 15-24 year olds had a 3.5 times greater risk of infection (OR, 95% CI:1.7-7.4), and for 25-34 year olds this risk was 2.5 times (OR, 95% CI:1.3-5.0). Of the 84 cases where data were available, 24 (29%) lost two or more lines of best corrected visual acuity. Those who delayed seeking treatment by 49-72 hours had a 4.5 times (OR, 95% CI:1.4-14.9) greater risk of visual loss compared to those who sought treatment early (0-48 hours after initial symptoms). Of the 99 cases of infection, 88 were scraped and 78% (69/88) of these returned a positive culture. 13 lesions were polymicrobial. Gram-positive bacteria were the predominant causative organisms (64/69), followed by Gram-negative bacteria (16/69) and Acanthamoeba (3/69). 17 of the 99 cases had a history of recent travel.
Conclusions::
Overnight use of lenses and youth carry a greater risk of infection. Practitioners should remind their patients of the importance of proper lens care at all times, particularly when traveling. The importance of rapid presentation to appropriate treatment within 48 hours of the onset of adverse symptoms should also be stressed.
Keywords: contact lens • clinical (human) or epidemiologic studies: risk factor assessment • keratitis