Germ colonization: glasses are so unhygienic

Lisa Vogel studied departmental journalism with a focus on medicine and biosciences at Ansbach University and deepened her journalistic knowledge in the master's degree in multimedia information and communication. This was followed by a traineeship in the editorial team. Since September 2020 she has been writing as a freelance journalist for

More posts by Lisa Vogel All content is checked by medical journalists.

Bacteria spinner glasses? Up to 660,000 pathogens cavort per square centimeter. Ear hooks and nose pads in particular are collection points for germs. They can be dangerous for some people.

From the skin to the glasses

Anyone who wears glasses regularly adjusts them or chews thoughtfully on the temple. This is how bacteria get from the surface of the skin and the mucous membranes onto the visual aid. A study by Furtwangen University has now shown how many germs actually live on glasses.

For the investigation, Prof. Markus Engert's team took samples from a total of 31 glasses with sterile cotton swabs.21 belonged to employees of the university, ten came from residents of a retirement home. They examined seven parts of the visual aids, including glasses, frames and nasal pillows.

2000 bacteria per square centimeter

“All the glasses examined were contaminated with bacteria,” says microbiologist Egert. Across all the areas examined, the visual aids of the university employees were colonized with 1,400 bacteria per square centimeter, while the residents of the nursing home collected an average of just over 2,000 germs.

But there were also real hotspots: the scientists were able to find 660,000 germs on a square centimeter on a glasses nose pad - the maximum value measured. "The germ density is strongest in places with direct skin contact," says Egert.

See worse, clean less

The glasses of the residents of the retirement home are slightly more stressed than those of the significantly younger university employees. One explanation: "The age-related poor eyesight promotes germs because those affected are less likely to notice fingerprints or similar contamination," the scientists write. This is why older people rarely clean their glasses.

Danger for immunocompromised

Especially bacteria of the genus staphylococci sit on the glasses. The germs occur on the skin of around a third of all people. They usually do not cause problems for healthy people. But when the immune system is weakened, the bacteria can spread. There is a risk of wound infections, muscle diseases and, in the worst case, blood poisoning.

Eyeglass cleaning cloths eliminate germs

The good news: damp glasses cleaning wipes wipe away 94 to 99 percent of bacteria. Alcohol-free cleaning solutions are similarly effective. Only the dry wiping of the glasses did worse - only 85 to 90 percent of the bacteria had then disappeared. In addition to the glasses, wearers of glasses should regularly clean the highly germ-contaminated areas of the ears and nose particularly thoroughly in order to remove the unwanted lodgers on the glasses.

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