Hygiene & Bacteria
Contact Lenses vs. Glasses: Why the Infection Risk Is So Different
Dirty glasses are a hygiene topic (see the Furtwangen studies), but not a direct infection vector for the eye, since they rest externally on skin and nose. Contact lenses, according to the German Ophthalmological Society (DOG), are a 'foreign body in the eye' with a significantly higher, well-documented infection risk when hygiene is lacking.
An important clarification up front
In the scientific and ophthalmological literature we reviewed for this article, the documented link between hygiene and eye infections relates almost exclusively to contact lenses – not to glasses. We're deliberately setting the record straight here, rather than equating the two topics without evidence.
Why contact lenses pose a different risk
According to Prof. Dr. Gerd Geerling (Director of the Department of Ophthalmology, University Hospital Düsseldorf) and the German Ophthalmological Society (DOG), a contact lens is always a 'foreign body in the eye' that alters the oxygen supply and moisture of the eye's surface. Pathogens that reach the eye via the lens aren't wiped away by blinking, as they would be with a bare eye – instead, they get trapped underneath the lens.
At least 3.4 million people in Germany wear contact lenses (DOG). With poor hygiene, DOG warns of sometimes serious corneal infections from bacteria, fungi, or – in around 5% of cases – Acanthamoeba (parasites), which in the worst case can threaten eyesight.
What ophthalmologists specifically recommend for contact lens wearers
- Wash your hands before touching your lenses.
- Never use tap water – neither for rinsing nor in the case, since it can contain Acanthamoeba.
- Disinfect the lens case regularly and replace it completely every three to six months.
- See an eye doctor immediately if you experience redness, pain, blurred vision or discharge.
And what about glasses?
Glasses rest externally on the nose and ears, not on the sensitive surface of the eye itself. The documented bacterial colonisation of glasses (see How many bacteria live on a pair of glasses?) is therefore primarily a general skin-contact and hygiene topic, not a directly documented risk factor for eye infections the way it is with contact lenses. Anyone who switches between both still benefits from clean glasses – if only to avoid transferring germs between glasses and lenses when touching them.
Frequently asked questions
Can I clean my contact lens case in an ultrasonic cleaner?+
An empty, rinsed-out plastic case can benefit from an additional ultrasonic clean of its outer surfaces – but this doesn't replace the mandatory daily disinfection with the contact lens solution recommended by the manufacturer. According to ophthalmologists, that remains essential.
Sources
- DOG (Deutsche Ophthalmologische Gesellschaft): 'Gefahr der Augeninfektion – Kontaktlinsenbehälter sind Bakterienfallen' – Prof. Dr. Gerd Geerling, Universitätsklinikum Düsseldorf
- Apotheken Umschau: 'Kontaktlinsen: Darum ist Hygiene Pflicht' – Berufsverband der Augenärzte Deutschlands (BVA)
- mgo medizin: 'Warum die Hygiene bei Kontaktlinsen so wichtig ist' – DOG-Jahreskongress 2023
Author: Moritz Weinert, Gründer NURO Labs · Last updated on 8 September 2026