DISPOSABLE CONTACT-LENS USE AS A RISK FACTOR FOR MICROBIAL KERATITIS

Aims-A case-control study was performed to evaluate soft contact lens (SCL) wear modality as a risk factor for microbial keratitis. Methods- Contact lens wearers presenting as new patients to Moorfields Eye Hosp ital accident and emergency department during a 12 month period comple ted a self administered questionnaire detailing demographic data and c ontact lens use habits. Cases were patients with a clinical diagnosis of SCL related microbial keratitis. Controls were SCL users attending with disorders unrelated to contact lens wear. Odds ratios (estimates of relative risks) and 95% confidence Limits (CL) were calculated thro ugh multivariable logistic regression analysis. Results-There were 89 cases and 566 controls. A substantially increased risk with 1-4 weekly disposable SCL compared with non-disposable SCL was identified among both daily wear (DW) (odds ratio =3.51, 95% CL 1.60-7.66, p=0.002) and extended wear (odds ratio 4.76, 95% CL 1.52-14.87, p=0.007) users aft er adjustment for demographic, lens use and hygiene variables. Other s ignificant factors among DW users were ''occasional'' overnight use, u se of chlorine based (as opposed to other chemical) systems in combina tion with poor storage case hygiene, and irregular disinfection. Concl usion-Properties of some disposable SCL may be partly responsible for these excess risks. It is also possible, however, that this finding is largely a reflection of widespread complacency among patients and pra ctitioners with respect to disposable SCL fitting and use.