Risk Factors for Microbial Keratitis in Daily Disposable Contact Lens Wear

Abstract

Purpose: : The incidence of microbial keratitis (MK) in daily disposable (DD) contact lens (CL) use is similar to other daily soft lens CLs, although it is lower for severe MK. This study investigates independent risk factors in MK for DD CLs.

Methods: : Cases were DD CL wearers attending Moorfields Eye Hospital with MK between 2003-2005 and those reported through a one-year surveillance study of ophthalmic practitioners in Australia and New Zealand (2003-2004). A population based telephone survey identified DD CL wearing controls. In London, hospital based DD CL wearing controls were also identified. All wearers completed a questionnaire describing CL wear history, hygiene and compliance habits and demographics. The sample analysed was randomly selected in proportion to the CL wearing population at each site. Risk factors were determined using multiple binary logistic regression.

Results: : 68 cases of MK (36 severe) and 372 controls wearing DD CLs were analysed. Independent risk factors were, wearing CLs every day compared with less frequent use (OR 6.0x; 95% CI 2.9-12.3), overnight wear compared with daily use (OR 1.2x; 95% CI 1.0-1.3), less frequent hand washing (OR 3.2x; 95% CI 2.7-3.6), smoking (OR 1.7x; 95% CI 1.5-2.0) and more than 1 year since the last aftercare (OR 1.8x; 95% CI 1.5-2.3). Certain DD CLs (OR 0.2x; 95% CI 0.1-0.2) and youth (OR 0.2x; 95% CI 0.1-0.2) had protective effects.

Conclusions: : Consistent with previous findings in other daily wear modalities, overnight wear, increased exposure in daily wear, smoking and poor hand hygiene are significant risk factors for MK with DD CL. In contrast, younger age and more frequent check ups are protective. As risk varied with CL type, material properties and design may play a role in the aetiology of MK in DD CL wear.

Keywords: contact lens • keratitis • clinical (human) or epidemiologic studies: risk factor assessment