The Benefits of Sunglasses over Transition Lenses
The first downside to photochromic lenses is that they fade back to clear by a thermal process, and therefore become less dark when the weather is particularly hot. This means that in the hottest weather, when you are most likely to have a day requiring sunglasses, your sunglasses will be less efficient than normal. Another problem is that on overcast days the lenses receive less direct UV light due to the clouds, so while it still may be bright outside the lenses will only turn halfway and be kept dim. If you live in an area where overcast weather is common, you may want to consider this effect before buying photochromic lenses. The third, and probably most inconvenient, pitfall of photochromic lenses is that a car windshield has a UV protective coating on it. Therefore the lenses will not darken when you are behind the wheel of a car. Depending on your desired driving conditions, you may have to purchase sunglass clip-ons or prescription sunglasses for driving purposes anyways, at which point the photochromic lenses have not saved you much convenience, and certainly have not saved you any money.
Many people claim that these glasses begin to retain a permanent tint as they get older, which makes it more difficult to see through them indoors. This can also lead to problems if you are in to photography, because looking through the camera lens with tinted glasses can cause you to overexpose the picture. Overall, photochromic lenses cost a great deal more than a pair of prescription sunglasses or clip-ons would. While they are more convenient in one capacity, that of not having multiple pairs of glasses, they are extremely inconvenient in many other ways, and because they do not function while driving you may have to get another pair of glasses anyways. It is important to make sure you get a pair of sunglasses that will work well, and photochromic lenses do not seem to do that when compared to actual sunglasses.
© 2012, Anthony Masiello. All rights reserved.