A new study conducted by the University of Waterloo Department of Chemical Engineering and the Centre for Ocular Research & Education (CORE) has determined that human coronaviruses can easily be removed from contact lens surfaces, although regimen matters depending on the type of lens care solution. Most notably, 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) is in press from Contact Lens and Anterior Eye, the peer review journal of the British Contact Lens Association.

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 such.

To assess attachment bonds, researchers 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 eye care community and wearers, as long as proper care occurs,” said Lyndon Jones, PhD, DSc, FCOptom, a paper co-author and CORE’s director. “Practitioners and manufacturers need to continue emphasizing 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 at https://doi.org/10.1016/j.clae.2022.101719. The study was funded by Ophtecs Corp.

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About the Centre for Ocular Research & Education (CORE)

The Centre for Ocular Research & Education (CORE) was established in 1988 at the University of Waterloo’s School of Optometry & Vision Science. Over the next three decades, the organization evolved from a three-person operation into a thriving hub of basic and applied research, collaborating with sponsors, agencies and academia on advanced biosciences, clinical research and education. Its uncompromising independence and results of the highest quality have been at the heart of many of the most prominent advances in eye health. Today, its approximately 50-person team serves a range of ophthalmic sectors, including medical devices, ocular pharmaceuticals, digital technology and others, with a focus on the anterior segment. For more information, please visit core.uwaterloo.ca.