Daily wear contact lens users at greater risk of Acanthamoeba keratitis

Users of daily wear (DW) reusable contact lens (CL) have a more than threefold increased risk of developing Acanthamoeba keratitis (AK) than those using daily disposable (DD) CL, a study has shown.

This case-control study recruited participants from an Accident and Emergency Department serving South-East England. Cases included new CL users with AK retrospectively recruited from January 2011 to February 2013 and prospectively thereafter until August 2014. Controls were prospectively recruited from February 2014 to June 2015.

The authors conducted an analysis of self-administered questionnaires to determine the independent risk factors and population attributable risk percentage (PAR%) for AK.

Eighty-three AK patients and 122 controls were analysed. Twenty patients (24 percent) and 66 (54 percent) controls reported using DD lenses.

Multivariable analyses adjusted for potential confounders showed a higher probability of AK for DW reusable soft lenses (odds ratio [OR], 3.84, 95 percent confidence interval [CI], 1.75‒8.43) and rigid lenses (OR, 4.56, 95 percent CI, 1.03‒20.19) relative to DD lenses.

Among DD-using participants, AK correlated with less frequent professional follow-up visits (OR, 10.12, 95 percent CI, 5.01‒20.46), showering lenses (OR, 3.29, 95 percent CI, 1.17‒9.23), lens reuse (OR, 5.41, 95 percent CI, 1.55‒18.89), and overnight wear (OR, 3.93, 95 percent CI, 1.15‒13.46).

Based on PAR%, an estimated 30 percent to 62 percent of AK cases could be prevented if users would switch from reusable soft lens to DD lens.

“AK risks for DD lens users can be minimized by adherence to safe use guidelines (no reuse, overnight wear, or contamination by water),” the authors said. “Safe CL use can be improved by increasing the prominence of risk avoidance information from manufacturers and regulators.”