Researchers are developing contact lenses that darken automatically in sunlight, similar to photochromic lenses available for prescription glasses. The contacts are treated with sun-sensitive dyes that darken when exposed to ultraviolet light, which is harmful to eyes.
Earlier attempts to make photochromic contacts were few and unsuccessful. Now, researchers at the Institute of Bioengineering and Nanotechnology (IBN) in Singapore are making headway by using a contact lens material that contains a network of nano-sized tunnels that can be filled with photosensitive dyes. The structure of the flexible lens material allows the dye to react quickly and uniformly throughout the lens, according to the researchers.
Edwin Chow, IBN senior research scientist, says this technology has a faster response time than photochromic eyeglass lenses (such as Transitions lenses) currently on the market. While photochromic lenses can take minutes to fully react to light, the new photochromic contacts can respond in 10 to 20 seconds, he says.
Next the research team will test the contact lenses in animals. IBN Director Jackie Ying believes the contacts could be available commercially outside the United States within a year. Approval for use in the U.S. may take longer due to safety testing required by the Food and Drug Administration (FDA).
The study was reported this month in Technology Review, published by the Massachusetts Institute of Technology (MIT).
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