Variable tinted lenses, also called photochromic lenses, are clear indoors and become darker outdoors in the sunlight. The lenses darken in reaction to UV (ultraviolet) rays from the sun, but when the lenses are no longer exposed to the UV rays, the tint fades and the lenses become clear again.
What variable tinted lenses treat
Variable tinted lenses can be used to treat anyone who needs glasses for vision correction. Single vision lenses as well as bifocals and progressive lenses are available with a variable tint. The variable tint protects the eyes from harmful UV rays. When exposed to direct sunlight, the lenses will turn a dark shade of either gray or brown, depending on your preference.
Benefits of variable tinted lenses
Variable tinted lenses are especially beneficial to those with large pupils and others whose eyes have a heightened sensitivity to sunlight, as these individuals don't have to worry about switching their glasses when they go outside. Since variable tinted lenses automatically darken when exposed to UV rays, there is no need to carry a separate pair of sunglasses. Having a single pair of glasses for indoor and outdoor use is not only convenient but also more affordable than purchasing sunglasses separately.
Problems with variable tinted lenses
If using variable tinted lenses as a substitute for sunglasses, it is important to note that they may not fully transition while driving. This is because windshields in most cars are treated to block UV rays, which hinders the lenses from tinting completely. Also, it may take a few minutes for the tint to fade after coming in from outdoors. The time needed for the lenses to transition may be particularly irritating for individuals who continually go in and out.
To learn more about variable tinted lenses, or to find out if this option is right for you, contact an experienced eye care professional.