Contact lenses featuring gold nanoparticles could correct colour blindness

Some daily activities, such as determining if a banana is ripe, selecting matching clothes or stopping at a red light, can be difficult for those with colour blindness.

Most people with this genetic disorder have difficulty discriminating red and green shades, and red-tinted glasses can make those colours more prominent and easier to see. However, such lenses are bulky and experts cannot make the lens material to fix vision problems.

Because of this, researchers turned to the development of specially tinted contact lenses. And although the prototype hot-pink dyed lenses improved red-green colour perception in clinical trials, they leached dye, which led to concerns about their safety.

In a quest to find an alternative, researchers Ahmed Salih, Haider Butt, and their colleagues at Khalifa University wanted to see whether incorporating gold nanoparticles into contact lens material instead of dye could improve red-green contrast safely and effectively. Gold nanocomposites are non-toxic and have been used for centuries to produce 'cranberry glass' because of the way they scatter light.

To make the contact lenses, the researchers evenly mixed gold nanoparticles into a hydrogel polymer, producing rose-tinted gels that filtered light within 520-580nm, the wavelengths where red and green overlap.

They found the most effective contact lenses were those with 40nm-wide gold nanoparticles because, in tests, these particles did not clump or filter more colour than necessary. In addition, these lenses had water-retention properties similar to those of commercial ones and were not toxic to cells growing in petri dishes in the lab, according to the researchers.

The researchers then directly compared their new material to two commercially available pairs of tinted glasses and their previously developed hot-pink dyed contact lens. Here, they found that gold nanocomposite lenses were more selective in the wavelengths they blocked than the glasses.

The new lenses matched the wavelength range of the dyed contact lenses, the team concluded, suggesting the gold nanocomposite ones would be suitable for people with red-green colour issues without the potential safety concerns.

The team, which also includes Ali Yetisen from the Department of Chemical Engineering at Imperial College London, said that the next step is to conduct clinical trials with human patients to assess comfort.

The research paper, ‘Gold Nanocomposite Contact Lenses for Color Blindness Management’, is available on ACS Nano.

In January, an international team developed a multifunctional ultra-thin sensor using a new manufacturing process – an innovation that could pave the way for the production of smart contact lenses.