With their central position in the human face, spectacle lenses constitute highly exposed surfaces, upon which a high level of viral and bacterial (microbial) contamination can be expected. Learn why it is important to clean eyeglasses hygienically and what new ways exist to reduce germs.
Hygiene and thus prevention against viruses and bacteria have become more important than ever in everyday life. What is often forgotten in daily hygiene is a simple object that millions of people wear directly on their faces: their spectacles. While we regularly wash our hands and occasionally desinfect door handles and surfaces, our eyeglass frames and lenses are often cleaned merely superficially. Instead of hygienically cleaning or disinfecting them like other so-called high-touch surfaces, people often just quickly wipe the lenses with their shirt sleeves or a tissue.
The risk associated with viruses and bacteria on eyeglasses is widely underestimated. In a multi-year cooperation with Germany- based Furtwangen University and its Institute of Precision Medicine, ZEISS Vision Care has issued the most comprehensive studies so far to understand the microbial contamination of spectacle lenses. Professor Markus Egert, microbiologist and health expert from Furtwangen University, and an expert team of researchers conducted vrious studies between 2018 and 2020 showing, for instance, that more than 650 genera of bacteria can be found on eyeglass lenses (found in the 2020 study; the subjects of the study were 30 pairs of glasses). According to another study of the microbiologist and health expert, fifty to eighty percent of the most common microbes found on eyeglass lenses are pathogenic in nature, meaning they can potentially cause disease.
Professor Egert and his research team identified bacteria on different parts of worn spectacles. The most contaminated components were the temple tips and nose pads. A peak value was 660,000 bacteria per square centimeter on a nose pad, including pathogens of eye diseases such as conjunctivitis or endophthalmitis.2
According to Egert, this contamination is not surprising due to the exposed position of spectacles in the center of the human face and their close contact to the human skin, nose and mouth – places where many germs already exist in the natural skin flora. In addition, spectacle lenses are a high-touch surface that people are touching several times a day – often without being aware of it., bringing bacteria and viruses onto the frame and lenses.
It is crucial to recognize eyeglasses as an object that can influence personal hygiene and health. Keeping eyeglasses clean means taking care of health.Prof. Dr. Markus Egert
Interestingly, the study showed that the highest diversity was found on the lenses as compared to the nose pads and temple tips.
According to Professor Egert, the solution to viruses, fungi and bacteria on eyeglass lenses and frames can initially be solved by maintaining proper eyeglass hygiene. This includes thoroughly cleaning the eyeglass lenses and frames at least twice a day. Various methods are suitable for cleaning eyeglasses – from water and cleaning fluid to a cleaning wipe and an ultrasonic bath.
However, cleaning spectacles properly to rid them of viruses and bacteria is only one component of spectacle lens hygiene. There is additional protection against bacteria and viruses: silver. The metal has proven its effectiveness for centuries. It is now applied as a special coating to eyeglass lenses to improve hygiene by deactivating viruses and bacteria on the lens's surface.
Silver (Ag) is well-known as effective antimicrobial agent . The curative properties of silver have been known for more than 2000 years. Hippocrates, Paracelsus, and later Hildegard von Bingen recommended it as an essential agent to protect or maintain health – long before the introduction of antibiotics in the 1940s.
What exactly makes silver so effective against viruses, bacteria and fungi is still subject to on-going research. In most of its applications, silver’s mode of action is presumed to be dependent on silver ions (Ag+) that come into direct contact with the microorganisms, thereby interacting directly with viruses and bacteria.
Today, silver is used in its most refined form as macrosilver, microsilver and nanosilver in numerous everyday products: for example, in products for modern wound care or creams against neurodermatitis.
Silver has not been a preferred admixture in clear ophthalmic lens materials for various technical challenges and product performance reasons. Now, ZEISS scientists combined advanced material science with elaborated vacuum deposition coating processes and developed a novel, innovative and patented silver nanocluster deposition technology. This new process technology allows embedding specified amounts of silver as nano-scale clusters into the anti-reflective stacks.
ZEISS DuraVision AntiVirus Platinum UV is an integrated system of coating layers that have been carefully engineered to deliver excellent anti-reflective properties, cleaning convenience and durability with a new additional feature of antimicrobial efficacy. Independent, accredited external test houses conducted the antimicrobial efficacy testing according to well-established test procedures, including ISO standards.3
All in all, the new coating solution provides some more prevention in everyday life and is a new contribution to ophthalmic lens hygiene.
1 Fritz B., März M., Weis S., Wahl S., Ziemssen F., Egert M. (2020). Site-specific molecular analysis of the bacteriota on worn spectacles. Scientific Reports, 10:5577.
2 Fritz B., Jenner A., Wahl S., Lappe C., Zehender A., Horn C., Blessing F., Kohl M., Ziemssen F., Egert M. (2018). A view to a kill? – Ambient bacterial load of frames and lenses of spectacles and evaluation of different cleaning methods. PLos ONE, 13:e0207238.
3 Tested by ISO 21702:2019(E) for enveloped viruses and tested by ISO 22196:2011(E) for Gram-negative and Gram-positive bacteria. Efficacy proven after 24 hours as defined by ISO.