Domestic Water Quality and Contact Lens-Related Microbial Keratitis

Abstract

 

Purpose:

 

Environmental bacteria are frequently associated with contact lens (CL)-related microbial keratitis. Since one attribute of domestic water quality is the total (environmental and enteric) coliform count, we hypothesised that poor water quality may be associated with CL-related microbial keratitis. This study examined the relationship between water quality and CL-related microbial keratitis in a population-based study.

 

Methods:

 

New cases of CL-related microbial keratitis (n=287) were detected via a national surveillance study conducted in Australia from October 2003 to September 2004. Controls (n=1,373) were identified using a national telephone survey of 35,914 individuals aged 15-64 years in randomly selected households. Postcode data were used to establish domestic water supply regions and water quality data were obtained from the respective water supplier or local government compliance reports. Water quality was categorised according to the percentage of samples with zero total coliforms; greater than 98% of samples with total coliform count compliance denotes high water quality zones; those with 95-98% compliance are moderate quality zones and below 95%, poor quality zones. Water supply data were available for 156 cases and 937 controls. A Chi-squared test was used to compare the distribution of water quality between cases and controls.

 

Results:

 

See Table 1. There was no statistical significance in association between water quality and CL-related microbial keratitis.

 

Conclusions:

 

Water quality, as reported by the publicly available monitoring data, and using total coliform count as the criterion, was not associated with CL-related microbial keratitis. Causative organisms may be derived from other environmental sources.  

 

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