INVISION ContactLensResearchers reveal a promising new approach.

Researchers at the Technical University of Munich say a natural mucus component isolated from pig stomachs has the potential to bring relief to sufferers of dry eye.

Mucins are molecules capable of binding lots of water and thus can act as a natural lubricant. Our tears contain such mucins, which also occur in the mucous layer protecting the stomach and intestines. The tear fluid of patients suffering from dry eyes usually does not contain enough of this molecular lubricant, the mucin MUC5AC.

Lack of MUC5AC can be problematic in particular for those of us who wear contact lenses. Without a protective lubricant film between the eye and the contact lens, the cornea can be injured. 

The scientists had the idea to apply the missing mucin directly to the contact lens and optimized a method for isolating the substance from the stomachs of pigs. The trick was to make sure the molecule didn't lose its lubricant properties through chemical changes during the purification process.

"Most of the commercially available mucins, which are already used e.g. for the treatment of oral dryness, have lost exactly this ability; we were able to demonstrate this in a series of experiments. These commercial mucins are therefore not suitable for treating dry eyes,"  said Oliver Lieleg, professor of biomechanics at the Munich School of BioEngineering.

In animal experiments, the team showed that the lenses caused no tissue damage when they were coated with mucins. Before it is ready for application in humans, the pig stomach mucin will undergo further testing in the lab.

"We showed that the mucin passively adsorbs to the contact lens material and forms a lubricating layer between the contact lens and the cornea," said Benjamin Winkeljann, first author of the study. Thus, in the opinion of the scientists, it should be sufficient to soak the contact lenses overnight in a mucin solution to obtain the protective effect.

Conventional products for treating dry eyes are primarily based on hyaluronic acid. However, in contrast to mucin, this molecule does not occur naturally in the tear fluid. Also, hyaluronic acid has to be applied to the eye in the form of drops, requiring repeated applications throughout the day.

Mucin, on the other hand, adheres directly to the contact lens, thus providing the eye with long-term protection. Before it is ready for application in humans, the pig stomach mucin will undergo further testing in the lab.

Read more at Technical University of Munich

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