When you buy sunglasses, you must remember that they are not an accessory but, first of all, a means of UV-protection for your eyes. Ultraviolet radiation is not something you want.
You have to rely on the quality of the lens for UV protection. And it is not the only thing that is important. A bad lens, even if it does come with adequate protection, may distort what you see, which will eventually affect your vision in a bed way. Buying sunglasses from street vendors may be particularly dangerous. It’s one thing to buy a fake Rollex watch. It’s still a watch and it does what all watches do, even though it’s luxurious at all, only a fake.
Fake sunglasses, on the other hand, will trick your brain into believing there’s not enough light, and your dilated pupils will let even more UV radiation into your eyes.
It is quite possible that none of the several hundreds of sunglasses that street vendors sell for $10 does not meet the industry standards, and the bright stickers that claim "100% UV protection" are nothing more than fiction. The best budget sunglasses are still worth twice as more, and that’s in the best case.
Savings money on buying proper sunglasses are can lead to visual impairment, cataracts, corneal or retina burns, and other consequences caused by ultraviolet radiation exposure. Low-quality sunglasses do not alleviate risks even in the slightest! They are the risk factor. It is better to not wear any sunglasses at all. At least, that way, you will know when the sunlight is too intense for your eyes.
Remember, dilated pupils lead to increased UV exposure. Any sunglasses must have a UV filter. If they lack it, they are not sunglasses.
I only recommend buying sunglasses in trusted stores or from opticians. It doesn’t even have to be something expensive as long as it’s simply high-quality.
The color itself has no correlation to UV-protection. However, color matters a lot. The color of the tint defines how comfortable the sunglasses will be. I strongly recommend choosing one of the more neutral tints: gray, gray-brown or gray-green.
Pink, blue, orange and yellow sunglasses all have their own uses. However, it’s a bad idea to wear them for a long time, as your eyes will quickly get tired. Such colors may overexcite the retina and cause optical stress. They are perfect for specific goals and activities, but are very ill-suited for casual wearing. If you need yellow or amber sunglasses for contrast enhancement, try lighter tints first. They may not be quite as effective, but they also cause less stress.
Size also matters!
The larger the lens size, the better the sunglasses will protect your eyes and the skin around them from UV radiation. That makes large, massive sunglasses the best choice possible. Sunglasses with massive sides offer additional UV protection from the side light. This is especially important when you are driving or simply enjoy the fresh air in very sunny conditions, such as in the mountains or at the sea.