Sunglasses are more than just a fashion accessory. Their main purpose should be to protect your eyes and the sensitive skin surrounding them from the sun's damaging ultraviolet rays.
But not all sunglasses are created equal. There are several factors that go into determining the best type of sunglasses to buy, and whether you should pick up a cheap pair from your local retail store or splurge on a pair of designer frames.
When it comes to your eye health, here's what you need to know before you purchase then throw on those shades:
Expensive doesn't always mean excellent
Fortunately for your wallet, you don't necessarily need the most expensive frames to protect your eyes from UV rays.
"It's a fashion choice for people when it comes to selecting the frame that works for them, as long as the sunglasses have 100 percent UV protection," said Dr Deeba Chaudri, an optometrist at Cosmopolitan Eyecare in New York. "The effectiveness is not related to the price point."
But this isn't to say you should buy sunglasses from just anywhere. You should use caution when purchasing bargain brands, as not all provide 100 percent protection from the sun. Muse Amawi, an optician and the general manager of SEE Eyewear in New York, said you should focus on the glasses' type of lenses.
"The quality of the lens and coatings is what's important, so cheaper frames can be effective as long as you're getting it from an optical or known optical brand and not a fashion brand," Amawi said.
The best way to check if your sunglasses have the proper protection is to take them to your doctor, said Dr Andrea Thau, an optometrist based in New York and a past president of the American Optometric Association.
"You can determine if they are safe by bringing them to your doctor of optometry to have them checked during your annual comprehensive eye examination," she said. "We have methods of testing their UV protection, and unfortunately, you can't tell if they have UV protection from just looking at them."
Optometrists warn about sunglass stickers that say the lenses offer UV protection.
"Some sunglasses potentially have false UV labels," Chaudri said. "You can ask an optician which sunglasses are specifically designed for UV protection and are rated UV400 or higher." She added that UV400 protection means that the glasses protect eyes from all the damaging invisible rays from the sun.
Why you need to deal with it
UV rays are a form of radiation emitted by the sun. If your eyes are exposed to too much of it, you could suffer from some not-so-fun side effects such as vision loss and cataracts. Enter your favourite pair of frames.
"UV rays are the strongest between 10am and 2pm," Chaudri said. "If you live in a city with strongly defined seasons, rays are the strongest during the summer and spring months."
However, you should wear sunglasses not just when the sun is out. Even on cloudy or overcast days, UV rays can penetrate clouds and cause eye damage, Chaudri said. Water, sand and fresh snow can reflect harsh rays, which can be blocked best with polarised sunglasses.
Excessive exposure to ultraviolet radiation in a short period can damage your eyes and sight, according to the American Optometric Association, possibly causing red eyes, the feeling of something being in your eye and extreme sensitivity to light. The good news is that these symptoms are usually temporary and permanent eye damage from brief exposure is uncommon ― as long as you wear proper sunglasses.