what is photochromic

Photochromic lenses are eyeglass lenses that darken automatically when exposed to UV light from the sun. They are also known as light-adaptive lenses, variable tint lenses, and light intelligent lenses. The lenses contain light- sensitive molecules that shift their structure when exposed to UV light, allowing them to absorb more light and give the lenses a darkened appearance. Once the UV light goes away, the process reverses and the lenses become clear again. Photochromic lenses are ideal for people who need to wear glasses all the time, as they provide the benefits of glasses and sunglasses in a single frame. They are made of plastic or resin and are available in different brands, including Transitions and Acuvue Oasys with Transitions.