Q: I have usually had my glasses made with those lenses that turn dark automatically in the sun, but my husband generally gets separate sunglasses made in his prescription. Which is better?
A: This is a common question in our office too. There are important differences that may help you decide which is better for your lifestyle.
First, the lenses that darken automatically we generically refer to as photochromatic lenses. This means a chemical in the lenses, when triggered by certain amounts of light, turn dark in less than a minute. This is faster, and actually now much darker than was the case a few years ago. It is still true that these lenses only turn fully dark in direct sunlight, meaning they are only partially darkened inside your vehicle. While there are several good brands of these photochromatic lenses, you may often hear them called “Transition” lenses, a brand that has captured the general title — like saying “Kleenex” instead of “tissue.” These are very popular for general use, because you need not carry two pairs of glasses with you or change every time to step outdoors.
The major advantage of separate prescription sunglasses is the fact that can use “polarized” lenses in them. Polarized lenses are designed to block out, or absorb, virtually all reflected light. This most commonly refers to reflected light from the highway, other cars, and water — what we would call “glare.” This is actually very important, as a high percentage of auto accidents every year are caused by “blinding glare,” meaning the driver could not see something in the road due to glare from the sun off the road. Polarized lenses come in both dark gray and brown colors, and are always dark — they do not change as do Transitions.
Many people use both, with Transitions being their general purpose or all around eyewear, but switching to polarized lenses for safer and more comfortable driving. Likely most people know that fishermen love polarized lenses to allow better vision in the water, by erasing the glare on the surface. But in reality, driving is the most common activity where erasing glare improves performance and comfort.
Lastly, some patients will choose to use Transition lenses in their eyewear, but have polarized clip-ons made to snap on for outdoors use. This combination works fine, but does add a little more weight to your glasses. And some clip-ons can scratch your lenses over time. So your choices are varied, and your decision should be based on what activities your lifestyle includes. I would add that one last consideration should be the protection of your eyelids and delicate skin around your eyes , where about 11 percent of all skin cancers occur, from UV radiation. Here is a good example where separate polarized sunglasses in a larger wrap-around design can provide better protection than just your indoor glasses.
Choose your outdoors glasses and sun protection based on these key facts, and not on fashion or designer names on the frames. There is no regulation of over-the-counter sunglasses and their labels of UV protection, so best to consult your eye doctor or optician for recommendations you can rely upon.
DR. THOMAS STOUT, OD, FAAO is an eye physician in private practice at Morgantown Eye Associates. Info: MorgantownEye.com.
