UV-responsive contact lenses developed by Singapore researchers
Transition lenses have long been on the market for nearly 40 years. But only eyeglass lenses are available. These eyeglass lenses would automatically darken in response to bright sunlight and restore their normal brightness once sunlight is removed. The basic principle of these transition sunglasses is to use millions of molecules of photochromic dyes. These dyes can absorb UV light, which leads to a shape change. As a result, the lenses will darken. Once UV light disappears, the molecules will restore their normal shape and maintain transparent.
This flexibility has never been successfully adapted to contact lenses. But now, researchers in Singapore are addressing this challenge. They have partially succeeded in developing UV-responsive contact lenses that offer similar functions as photochromic sunglass lenses. Under the Institute for Bioengineering and Nanotechnology (IBN), researches led by Jackie Ying have successfully developed their photochromic contact lenses and plan to test them in animals.
The most important factor that assesses the success of their UV-responsive contact lenses is to see whether the dyes are contained within the lenses stably. In fact, the most difficult task is to fill the dyes that are responsible for brightness change in the lenses. Jackie Ying and his colleagues use a novel polymer laced with an intricate network of nano-sized tunnels to “store” the dyes. This most challenging task of applying dye coatings to the lens surface has been solved. In other words, photochromic contact lenses developed by these researchers embed dyes uniformly throughout the lens material. In this way, more dye molecules can be packed into the lens material.
Speed of transition is the most critical factor for both photochromic eyeglass lenses and UV-responsive contact lenses. For instance, a car suddenly going into a tunnel requires immediate brightness change in the driver’s lenses. Thanks to the special design from IBN, their photochromic contact lenses have greater sensitivity to light and offer a faster response. According to Ying, their UV-responsive contact lenses take only 10 to 20 seconds to darken or brighten.