Cheap sunglasses are everywhere. They are a popular free gift from companies that want to appear trendy, and they are on sale at every shop anywhere near a beach, as well as anywhere else that people often go in summer (theme parks, for example). But you should be very, very cautious of cheap sunglasses, because even though it feels like they're helping to keep the sun out of your eyes, they can actually do more harm than good.

The problem is that cheap sunglasses don't protect against ultraviolet rays, the rays that can cause problems like eye cancer and cataracts. Instead, they fool your eyes into thinking that it's dark when it's actually not, which causes the pupils of your eyes to widen, letting in far more UV rays than they normally would. This massively increases the amount of damage that the sun can do to your eyes. While you might be happy to use them to keep the sun from dazzling you, if you do it often you may be significantly damaging your health. If you have a pair of cheap sunglasses - or you're given one for free - the best thing to do, all things considered, is to throw them in the bin.

Of course, the opposite of cheap sunglasses isn't necessarily expensive ones. The sunglasses you want are ones that offer 100% protection from UV rays, but these can actually be very reasonably priced - and as long as you keep track of where you put them at the end of the summer, they can last you for decades to come, which makes them even better value. You should look for some kind of official certification that the sunglasses have passed tests both for UVA and UVB screening, and only buy from a shop that you trust, preferably an established pharmacist.