A new study has determined that it is easy to remove human coronaviruses from contact lenses, although regimen matters depending on the type of lens care solution.
Most notably, the researchers from the University of Waterloo Department of Chemical Engineering and the Centre for Ocular Research & Education (CORE) found that ‘rub and rinse’ steps are crucial for non-oxidative systems, while products containing hydrogen peroxide and povidone-iodine removed contaminants through soaking alone.
‘The impact of a rub and rinse regimen on removal of human coronaviruses from contemporary contact lens materials’ (Nogueira C, et al) has recently been published in Contact Lens and Anterior Eye, the peer review journal of the British Contact Lens Association.
The researchers note that while an ocular pathway has not been demonstrated to be a primary route of entry for SARS-CoV-2, the ongoing COVID-19 pandemic has raised awareness about physical virus transmission via hands and fingers.
However, there has been limited data regarding the attachment of viruses, particularly coronaviruses, across lens materials and the ability of contemporary contact lens care products to inactivate them.
To assess attachment bonds, the research team selected two seasonal human coronaviruses, HCoV-229E and HCoV-OC43, as surrogates for SARS-CoV-2, allowing for less pathogenicity while being in the same virus family with similar structures.
Eight soft contact lens materials (including silicone hydrogels and hydrogels) and four RGP contact lens base materials (with and without a hydrophilic coating) were contaminated then soaked in a phosphate-buffered saline.
Although viral particles were recovered when the lenses were removed from the passive saline soak, no detectable virus remained when the lenses were subjected to a single rinse, double rinse, or rub-and-rinse treatments.
Since a simple saline rinse step alone removed both virus types from all materials, two representative soft lens materials (one hydrogel and one silicone hydrogel) were chosen to evaluate care system efficacy for elimination of HCoV-229E.
Investigators selected four representative contact lens care products (two oxidative and two non-oxidative). Both oxidative disinfection systems reduced the number of infectious viral particles that adhered to each material below the limit of quantification through soaking alone. The non-oxidative disinfection systems required a rub and rinse step to do the same.
“Our results indicated that human coronaviruses bind quite loosely to contact lens materials, which should provide peace of mind for the eyecare community and wearers, as long as proper care occurs,” said CORE director and co-author Prof Lyndon Jones said.
“Practitioners and manufacturers need to continue emphasising the importance of following disinfection regimens, especially ensuring that a rub and rise step occurs prior to overnight disinfection when using non-oxidative systems.”
The complete paper and supplementary data are available at no cost from Contact Lens and Anterior Eye here.