Contact lenses for color blindness correction

ACS Nano 2021, DOI: 10.1021 / acsnano.0c09657 “width =” 472 “height =” 254″/>

Imagine seeing the world in soft shadows – gray sky, gray grass. Some people with color blindness see everything this way, although most cannot see specific colors. Colored glasses may help, but they cannot be used to correct blurred vision. And the dyed contact lenses currently in development for the disease are potentially harmful and unstable. Now in ACS Nano, researchers report infusing contact lenses with gold nanoparticles to create a safer way to see colors.

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 who are color blind. Most people with this genetic disorder have a hard time distinguishing between shades of red and green, and red glasses can make those colors more prominent and easier to see. However, these lenses are bulky and the lens material cannot be made to correct vision problems. Thus, the researchers switched to the development of special colored contact lenses. Although the prototype of lenses dyed in hot pink has improved the perception of the greenish-red color in clinical trials, they leach the ink, which has raised concerns about its safety. Gold nanocomposites are non-toxic and have been used for centuries to produce “cranberry glass” due to the way they spread light. So Ahmed Salih, Haider Butt and their colleagues wanted to see if incorporating gold nanoparticles into contact lens material instead of dye could safely and effectively improve the red-green contrast.

To make contact lenses, the researchers uniformly mixed gold nanoparticles into a hydrogel polymer, producing pink gels that filtered light at 520-580 nm, the wavelengths where red and green overlap. The most effective contact lenses were those with gold nanoparticles 40 nm wide, because in the tests, these particles did not agglutinate or filter more color than necessary. In addition, these lenses had water retention properties similar to those of commercial lenses and were non-toxic to cells growing in Petri dishes in the laboratory. Finally, the researchers directly compared their new material with two pairs of colored glasses available on the market and their previously developed hot pink colored contact lenses. Gold nanocomposite lenses were more selective in the wavelengths they blocked than glasses. The new lenses matched the wavelength range of the dyed contact lenses, suggesting that gold nanocomposites would be suitable for people with red-green color problems without the potential safety concerns. The researchers say the next step is to conduct clinical tests on human patients to assess comfort.