Contact lenses provide a number of convenience advantages over glasses, but one they come up short in one area—you can’t get contacts that automatically adjust to the sun’s UV light and darken, like the photochromic lenses many bespectacled people enjoy. But that could soon change: Researchers in Singapore led by Jackie Ying have now created a contact lens that responds to UV light.
Transition lenses for glasses are coated with a dye that is transparent when out of the sun, but responds to UV light by changing shape and darkening. Few previous attempts have been made to design transition contact lenses, largely because it’s difficult to apply dye coatings uniformly to the delicate, soft surface of a contact lens. Ying and her colleagues got around this by developing a contact lens that embeds dyes uniformly throughout the material [Technology Review].
The scientists crafted their contacts with a structure that includes nano-sized tunnels to hold the dye. The lens’ porous structure allows the dye to change shape quickly, which team member Edwin Chow says reduces response time. “When your car suddenly goes into a tunnel, the amount of light is very dim, so you need your lenses to transform back immediately,” says Chow. [Technology Review].
First things first: the team tested its lenses on rabbits to make sure they were bio-compatible, and tests continue test to make sure the lenses don’t leak dye. However, there’s no word yet on whether near-sighted rabbits prefer contacts to glasses.
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Image: Institute for Bioengineering and Nanotechnology