The risk of microbial keratitis with daily‐wear and extended‐wear use of disposable lenses

Abstract

SummaryA pilot case‐control study indicated an excess risk of microbial keratitis (MK) with disposable soft contact lenses (DSCL). A larger case‐control study was conducted to separate the risks associated with daily‐wear (DW) and extended‐wear (EW) use of DSCL, and to determine whether there is an excess risk associated with the lenses after controlling for other variables.Contact lens (CL) wearers presenting as new patients to Moorfields Eye Hospital Casualty over 12 months completed a questionnaire detailing CL use and hygiene practices. Cases were patients with presumed MK, according to established clinical criteria. Controls were patients attending with disorders unrelated to CL wear. Relative risks were calculated using conventional soft lenses (SCL) as the referent, and multivariable analysis was performed. DW and EW patients were analysed separately.Among SCL wearers there were 89 cases, and 566 controls. Multivariable analysis confirmed a statistically significant increased risk with DSCL among both DW (×3.5) and EW patients (×4.8).This study shows that, despite the proven reduction in less serious complications with the disposable regimen, there is an increased risk of MK with both DW and EW DSCL, even after controlling for other variables. Although patient and practitioner factors may contribute to these risks, it is likely that properties of some DSCL are partly responsible and require further investigation.