Purpose:
Microbial keratitis (MK) is a significant health concern for the million wearers of contact lenses (CL) with some potentially modifiable risk factors. Fortunately, MK remains a rare complication of CL wear, but is of interest because it is both a major cause of new cases of MK in the population, and the only sight-threatening complication of an otherwise safe method of vision correction. The aim of the study is to identify risk factors and to put into perspective the individual risk and the societal burden of CL-related MK patients.
Methods:
A prospective multicenter case-control study was conducted in 13 French University Hospitals (Besançon, Bordeaux, Dijon, Fort de France, Grenoble, Limoges, Lyon, Nancy, Nantes, Paris, Marseille, Rouen and Strasbourg) on all lenses wearers presenting with MK between July 2007 and July 2011. Patients had a complete ophthalmological examination and were interviewed by a 51 items anonymous "questionnaire" to determine subject demographics and lenses wear history. The CL related MK subpopulation (Case) was compared to healthy CL wearers (Control).
Results:
Five hundred six patients CL related MK and 499 healthy CL wearers were included. Patients wearing soft contact lenses had a higher risk for MK, as compared as rigid lenses wearers (Relative risk, 2.9 ; p < 0.0001). Among soft lenses, daily disposable CL (RR, 1.8 ; p = 0.01) and 2 weekly replacement CL (RR, 2.1 ; p < 0.0001) had an increased risk of MK than monthly replacement CL, respectively because of some lacks in basic rules of hygiene (absence of hand washing) and the absence of a professional supervision for daily disposable CL and the overtaking of the deadline of renewal for 2 weekly replacement CL.
Conclusions:
Consequently, uninformed CL wearers are experiencing acute vision-threatening infections, leading to a terrible personal and societal cost. With the increasing avaibility of CL, notably through internet or local market, this study serves to highlight the increasingly documented dangers of freely available CL without professional supervision and of the lack of information about the basic rules of hygiene and the basis of CL care and handling.
Keywords: contact lens • keratitis • clinical (human) or epidemiologic studies: risk factor assessment