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  • Risk of Acanthamoeba Keratitis in Contact Lens Users

    By Lynda Seminara
    Selected by Russell N. Van Gelder, MD, PhD
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    Journal Highlights

    Ophthalmology, January 2023

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    Acanthamoeba keratitis (AK) is a vision-threatening condition that occurs mainly in contact lens (CL) wearers whose eyes are healthy. Carnt et al. con­ducted a case-control study to compare AK rates between wearers of single-use daily disposable (DD) lenses and reus­able daily wear (DW) lenses. They also explored risk factors for AK among DD lens users. They found a higher risk of AK in the DW group, and they identi­fied several modifiable factors that can decrease this risk, including removing lenses before showering.

    The case and control participants of the study were recruited from an emergency ophthalmology department that serves South-East England. All wore DD or DW lenses. Those in the case group (n = 83) presented with keratitis, and those in the control group (n = 122) had a disorder thought to be unrelated to CL wear. Patients in both groups received a 48-item question­naire, and the case group was given 15 additional questions. Domains includ­ed demographics, history of CL wear, disinfection solutions, environment of CL use, and frequency of eye care. Responses were compiled and analyzed. Outcomes of interest were independent risk factors and the population-attrib­utable risk percentage (PAR%) for AK.

    Among the study population, 24% of the case group and 54% of the controls used DD lenses; the others wore DW lenses. Multi-variable analyses, adjusted for potential con­founders, showed that AK risk was higher with reusable soft DW lenses (OR, 3.84) and rigid gas-permeable DW lenses (OR, 4.56) than with DD lenses. Among DD users with AK, several modifiable risk factors were identified: lower frequency of professional follow-up visits (OR, 10.12), showering with lenses in place (OR, 3.29), reusing lenses (OR, 5.41), and wearing them overnight (OR, 3.93). PAR% findings demonstrated that 30% to 62% of AK cases could be prevented by switching to DD lenses.

    Although AK risk is about threefold higher with DW lenses, this can be lowered by improving CL hygiene and increasing the frequency of follow-up care, as noted in this study. Given that AK accounts for half of the severe keratitis cases in CL users, these safety measures are expected to benefit public health, said the authors, who empha­sized the importance of identifying modifiable risk factors for AK. “Unlike bacterial keratitis in CL users, 90% of cases are associated with avoidable risks.” The data may encourage more CL wearers to switch to DD lenses and avoid lens reuse, overnight wear, or contamination by water. They believe that manufacturers could help to improve safety by including clear risk-avoidance infor­mation on CL packaging.

    The original article can be found here.