Dyed lenses may correct colour blindness

London, April 30: Researchers have developed a contact lens that may help correct colour blindness simply by using a low cost dye.

Colour blindness — or colour vision deficiency ( CVD) — is an inherited genetic ocular disorder where some people have difficulty distinguishing certain colours.

“Contact lenses are of interest for colour blindness correction because it is easier to correct the entire field of view,” said Haider Butt from the University of Birmingham in the UK.

“The dye processing we carried out does not need any complex preparation, it is not toxic to the human eye, and our method could be easily used in both glasses and contact lenses at low cost,” said Butt, who led the study published in the journal Advanced Healthcare Materials.

While no cure for this disorder exists, several methods have been used to increase the colour perception of those affected.

However, current products on the market such as colour filtering glasses are expensive, bulky and incompatible with other vision corrective glasses.

Normal colour vision is trichromatic — this means any colour can be created by combining the colours blue, red and green, which are perceived by a cluster of cones at the back of the eye.

These cones are divided into three groups, responsible for short wavelengths ( blue), medium wavelengths ( green) and long wavelengths ( red). In normal vision all three are present.

When any of these cones are missing, the brain receives incorrect information leading to limited ability to identify certain colours in some people.

Several companies are already selling glasses and custom made lenses for colour blindness correction which can be expensive.