Darker sunglasses do not mean better. Toop explains that UV protection is an invisible coating applied to lenses. Very inexpensive sunglasses may have lenses that can cause subtle distortions and therefore be unpleasant to wear. Yet other than this, the cost of sunglasses is not important, so long as they provide UV protection. UV protection can also be added to regular prescription glasses, though consumers must usually specify that they would like this extra protection.
Sunglasses are advisable even on overcast summer days, since UV rays can still do damage.
This protection is also important when hiking in the mountains or skiing during the summer, since the sun's reflection off the snow and higher elevation further increases exposure to UV rays. Sunglasses with UV protection are also advisable for children, Toop notes. Of course sun is not the only thing that can damage the eyes. Toop also recommends wearing safety glasses for protection against airborne materials when using lawn mowers or weed trimmers in the yard, sanding or cutting wood in the shop, or taking part in outdoor activities such as biking, and skating.