Current photochromic lenses provide a convenient two-in-one answer for those who need prescription lenses, for both indoors and out, but researchers are working on an even better solution. These special lenses are designed to use the sun’s UV rays to turn the glass from clear to tinted—but the change isn’t instantaneous, so users step outside and squint in the harsh sunlight, or move indoors and have to wait for the lenses to adjust. Most modern car windshields use UV-filtering glass that prevents the lenses from darkening completely. Due to too much ambient UV light at high altitudes causes the lenses to remain darker for longer, even indoors. A group of researchers at the Georgia Institute of Technology in Atlanta has developed a polymer coating for glass that can change the lens colour instantly with a small, user-controlled electrical current. Their work has been published in the American Chemical Society’s Applied Materials & Interfaces.
