Self-moisturising contact lenses

Chemical engineering researchers at McMaster University in Canada have shown that a common fluid found in our bodies can be used as a natural moisturising agent in contact lenses.

The research from McMaster showed that the fluid - hyaluronic acid - can be entrapped in existing contact lens material without affecting optical properties.

It was also found that using hyaluronic acid considerably reduces the build up of proteins which can cloudy contact lens material, the cause of up to 30 per cent of all after-care visits by contact lens wearers to optometrists.

Hyaluronic acid is a natural polymer that acts to reduce friction. An average person weighing 70kg has about 15g of hyaluronic acid in their body, one third of which is turned over daily.

The body uses hyaluronic acid to repair skin, provide resiliency in cartilage, and contribute to the growth and movement of cells, among other things. It is also used by the medical profession to treat patients with dry eyes, in cataract surgery, and for other eye-related procedures.

While manufacturers have not yet produced contact lenses with hyaluronic acid, the researchers remain hopeful.

'We've shown that the process works,' said Heather Sheardown, a professor of chemical engineering at McMaster and a member of the McMaster School of Biomedical Engineering, who was involved in the research. 'We're optimistic that a manufacturer will see the benefits of using this naturally based technology to provide contact lens wearers with greater comfort and convenience.'

The current wave of self-moisturising contact lenses still use synthetic materials as a wetting agent to prevent eye dryness and increase wearer comfort.