Although photochromic lenses are more commonly referred to as transitional lenses today, the correct term is photochromic or photochromatic. Photochromic sunglasses are commonly referred to as transitional sunglasses because of their transition from dark when outdoors to light when indoors. The definition of photochromic is capable of changing color on exposure to radiant energy and of, relating to, or utilizing the change of color shown by a photochromic substance. You may ask yourself, “How does this happen?”.
Photochromic lenses have many molecules embedded in them. These molecules are transparent to visible light when in the absence of UV light, so the lenses will be light. When in the presence of UV rays, the molecules react and change shape. When this happens the molecules absorb some of the visible light causing the lens to darken. The brighter the sunlight the darker the lens.
Photochromic lenses are great for those that wear eyeglasses, who can not wear sunglasses unless they are prescription. If you wear eyeglasses and wear sunglasses when outside, you are forced to carry two pair of eyewear. For most people this is a hassle. You either break the pair you are carrying or lose them. If you choose to wear photochromics, you can wear them for eyeglasses and sunglasses. You simply buy the photochromic sunglasses, be sure they are Rx ready and take them to your local eye doctor.
Photochromic sunglasses are great for motorcycle riding sunglasses as well. So many motorcyclists are forced to carry two or even three pairs of sunglasses or goggles or interchangeable lens kits with clear, charcoal and amber color lenses. With photochromic lenses you can buy and carry just one pair of sunglasses or goggles for all day and even night riding. With photochromic lenses you do not have to pull off the side of the interstate endangering your life and maybe others to change your sunglasses or goggles. You can ride from morning to night without ever having to change your eyewear.
When purchasing photochromic lenses be aware of the money you are spending. If you buy cheap photochromic sunglasses or goggles the lenses tend to change at a much slower pace and usually do not get dark enough. They tend to darken to a grey/smoke instead of the darker charcoal lens. Some people prefer this, but in our experience most people want the lenses to change quickly and to have the charcoal lens when outdoors instead of the lighter grey lens. A lot of this will depend on how sensitive your eyes are to the sunlight. If you notice that you squint a lot when outdoors, your eyes are more sensitive to light which means you should spend the extra dollar and get a nice pair of photochromics sunglasses or goggles. You’ll be happy you did.