Health: Colour blindness-correcting CONTACT LENSES use gold nanoparticles to filter light

Contact lenses containing gold nanoparticles have been developed that filter light to help correct red–green colour-blindness.

Colour blindness is a condition in which certain hues can appear muted or hard to distinguish from each other — making some daily activities difficult.

Unlike existing tinted glasses for red–green colour blindness, the lenses created by a team from the UAE and the UK can also be made to correct other vision issues.

And because they use non-toxic materials, they do not have the potential health issues that have been flagged with previous prototype lenses that used red dyes.

Before the lenses can reach the commercial market, however, they will need to be assessed in clinical trials, a study says.

The study was undertaken by mechanical engineer Ahmed Salih, of Abu Dhabi’s Khalifa University, and his colleagues. 

‘Colour vision deficiency is an ocular congenital disorder that affects 8 per cent of men and 0.5 per cent of women,’ the researchers explained in their paper.

The most common forms of the disorder are protanopia and deuteranopia — collectively referred to as ‘red–green colour blindness’ — in which people have difficulty distinguishing, as the name implies, between greens and reds.

‘Since there is no cure for this disorder, patients opt for wearables that aid in enhancing their colour perception,’ the researchers added.

Specifically, patients with red–green colour blindness wear red-tinted glasses which can make these colours easier to see — but these spectacles tend to be bulky and they can’t be used to correct other vision problems at the same time.

Because of these limitations, researchers have recently turned to experimenting with specially-tinted contact lenses instead.

Unfortunately, while the prototype lenses — which were dyed hot pink — did improve the wearer’s red–green colour perception in clinical trials, they all leached dye, leading to concerns about their safety and durability.

Colour blindness is a condition in which colours can appear muted or hard to distinguish from each other. Pictured: coloured objects as seen through the different forms of colour-blindness

Instead, Mr Salih and colleagues turned to tiny particles of gold. These are nontoxic, and have been used for centuries to produce rose-tinted ‘cranberry glass’ because of the manner in which they scatter light.

To make their contact lenses, the researchers mixed gold nanoparticles into a hydrogel, a special material made from a network of cross-linked polymers.

This produced a red-tinted gel that filers wavelengths of light between 520–580 nanometres, the part of the spectrum in which red and green overlap.

The most effective contact lenses were those made with 40 nanometre-wide gold particles, which neither clumped together nor filtered more light than needed, the researchers reported. 

Mr Salih and colleagues turned to tiny particles of gold, which are nontoxic and have been used for centuries to produce rose-tinted ‘cranberry glass’, as pictured

To make their contact lenses, the researchers mixed gold nanoparticles into a hydrogel. This produced a rose-tinted gel that filers wavelengths of light between 520–580 nanometres, the part of the spectrum in which red and green overlap

The gold nanoparticle lenses also had water retention properties similar to those of regular, commercially available ones.

With their initial study complete, the researchers are now looking to conduct clinical trials in order to determine how comfortable the new contact lenses are to wear.

The full findings of the study were published in the journal ACS Nano.