As cosmetic as sunglass shopping at first tends to seem, there are some technical aspects that must be considered. The first is, of course, the level and type of UV protection but the color, materials and even shape of the lenses play a vital role.
Buying a pair of sunglasses before boarding that plane or cruise ship since most of the sunniest places on earth also have a shortage of shopping centers and pharmacies. There’s a lot of things that are vital to travel like passports and local currency not to mention the ever present English to whatever dictionary. Don’t forget the basics of surviving the climate though since a severe sunburn or damaged retinas will be just as painful as being detained at a border somewhere. This advice can apply to domestic destinations like that southwestern dude ranch too by the way.
A quick consideration of ultraviolet must be mentioned. This is not so much of a problem as it once was though since even very low end sunglasses purchased from dollar stores will generally provide UV protection. Say no, though, if finding a batch that doesn’t have this feature. Over a long period of time overexposure to UV contributes to the development of cataracts. There are two types of ultraviolet to consider: UVA rays and UVB rays when exposed to the sun. Of the two, UVB is the more potentially harmful to human eyes. Sunscreens need to protect from both.
On this topic it needs to be considered that even clear polycarbonate lenses protect against UV rays. That’s a very good argument in favor of wearing corrective lenses! Another aspect to consider is the amount of light leak that enters the eye area when lenses sit too far away from the face. This light is just as damaging as the light that enters the eye directly. This means that for those in very sunny areas sunglasses that are curved and have wide plastic frames will protect the eyes and surrounding tissue better. These also result in less eye strain which can result in facial muscle fatigue or headache. Squinting all day causes an overall feeling of discomfort.