How Sunglasses Protect Your Eyes

They come in all shapes and sizes. Some are made for fashion rather than function. You probably have a favorite pair. Sunglasses make it easier for you to see on a bright day. The right ones can protect your eyes for years, but the wrong kind can do more harm than good.

Why You Need to Protect Your Eyes

Step outside and the sun's rays beam down on you, even on a cloudy day. When you're outdoors, you should protect your eyes from the sun's ultraviolet (UV) radiation.

One type of UV radiation -- UVA rays -- harm something in the back of your eye called the macula. It helps you see detail clearly. It's part of the retina, which sends signals to your brain to translate light into images. The blue and violet parts of the sun's rays can also hurt your retina.

The front part of your eye, where your cornea and lens are, can get damaged by another type of UV radiation called UVB rays. The lens of your eye lets in light and works with the cornea to focus it on the retina.

Welding machines, tanning beds, and lasers can expose you to man-made UV rays that can also be bad for your eyes.

Very dark sunglasses that don't block any UV rays can harm your eyes more than not wearing sunglasses at all. That's because the dark lenses cause your pupils to open wider and allow more light into your eyes than would come in without sunglasses.

Diseases Caused by UV Damage

Even if it's for a short amount of time, UV rays that hit your eyes can raise the odds that you'll get certain conditions and diseases.

Photokeratitis. This condition is like a sunburn of the eye. It's caused by a large amount of eye contact with UV rays in a short time.

The sun's rays can bounce off sand, snow, water, and ice. Be careful with light reflecting off pools or the ocean. You can also get a type of photokeratitis called "snow blindness" while outside in a snowy and icy place.

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Symptoms include:

  • Pain
  • Redness
  • Blurriness
  • Eyes tearing up
  • Gritty feeling in your eyes
  • Sensitivity to bright light
  • Seeing halos

Your symptoms may get more intense the longer your eyes are hit by UV rays. But the problems typically go away and don't permanently damage your eyes.

Cataracts. Many years of being out in the sun with UV rays hitting your eyes can cause this disease that makes the lenses in your eyes cloudy.

Symptoms can include:

  • Blurriness
  • Seeing two images instead of one
  • Sensitivity to bright light
  • Hard to see well at night, or needing more light to read
  • Bright colors looking faded or yellow

The only way to remove cataracts is with surgery.

Macular degeneration. Like cataracts, you're more likely to get this disease if your eyes are hit by UV ray over long periods of time. It is also genetic.

Macular degeneration comes in two types -- wet and dry. It breaks down the macula and makes you lose your central vision. Dry macular degeneration is more common, and wet macular degeneration always starts as the dry kind.

Symptoms of macular degeneration include:

  • Straight lines that look wavy or bent
  • Trouble seeing for the first few minutes after entering a dark place
  • Difficulty reading words on a page that has a similar color

Pterygium. UV rays, wind, and dust can cause this growth on the clear coating (conjunctiva) on the white part of your eye. It can begin as pinguecula, a yellowish growth in your eye on the side by your nose, or can build on its own. The growth can be small or get so big that it makes it hard for you to see.

Symptoms of pterygium and pinguecula include:

  • Red or swollen conjunctiva as the growth gets bigger
  • Yellow spot or bump on the white part of your eye
  • Gritty feeling in your eye or eyes that are dry, itchy, and burn
  • Blurriness

Pterygium and pinguecula don't usually need treatment. Your doctor may give you drops to put in your eyes to make them feel better. If the pterygium causes too many problems, you may need surgery to get rid of it.

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Skin cancer around the eyes. Your upper and lower eyelids are made of thin skin that makes it easier for UV rays to damage them. This can make you more likely to get nonmelanoma skin cancers on and near your eyelids.

Basal cell carcinoma is the most common type of cancer around the eyes, but squamous cell carcinoma can also develop.

Melanoma is also a type of skin cancer that can grow near your eyes and in them, but that's rare. Researchers aren't sure if UV rays make eye cancer more likely.

Symptoms of basal cell carcinoma include:

  • Bump that looks waxy or pearly
  • Flat growth that is skin colored or brown and looks like a scar
  • Sore that bleeds and scabs, then heals and comes back

Basal cell carcinoma usually forms on your face, neck, and other parts of your body that are in the sun.

Symptoms of squamous cell carcinoma can include:

  • Lump that is hard and red
  • Flat growth that is crusty and scaly

Squamous cell carcinoma also develops on parts of the body that are in the sun. People with darker skin may get it on body parts that don't usually get sunlight.

Treatment for skin cancer and precancerous growths depends on their size, type, depth, and location.

What to Look for in Sunglasses and When to Wear Them

Baseball caps and hats with a wide brim only block about half of the sun's UV rays. And polarized lenses don't block them, though you can get some with a special UV-blocking material.

Sunglasses that block 99% to 100% of UVA and UVB rays can properly protect your eyes. You should also look for these things when shopping for sunglasses:

  • Stop 75% to 90% of visible light
  • Lenses with the same level of darkness. If the lenses go from light to dark, the darkest part should be on top and the change should be slow.
  • Lenses that don't change your view so that it's unnatural
  • Lenses that are gray, so you can see colors correctly
  • A frame that is close to your eyes and fits the shape of your face well

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If you do outdoor sports or work that could be dangerous for your eyes, you should have lenses that resist impact and are made from polycarbonate or material that goes by the brand name Trivex. You should also get sunglasses that wrap around your face to protect against wind and UV rays that come from the side.

Children and teens need the right sunglasses, too. Kids can get up to 80% of a lifetime of sun exposure before they turn 20.

If possible, avoid the sun from 8 to 10 a.m. and 2 to 4 p.m. Those are peak hours for UV rays to damage your eyes.

WebMD Medical Reference Reviewed by Whitney Seltman on July 14, 2020

Sources

SOURCES:

American Optometric Association: "Protecting your eyes from solar radiation," "Sunglasses: Healthy Eyes are Always in Style," "Take a Closer Look When Buying Sunglasses This Season," "Do Your Sunglasses Really Protect Your Eyes from the Sun?" "When It Comes to Sunglasses, Looks Aren't Everything."

Prevent Blindness: "Protect Your Eyes from the Sun."

YouTube: "Peripheral Vision and Central Vision in the Retina," EyeSmart -- American Academy of Ophthalmology.

National Keratoconus Foundation: "How Does The Human Eye Work?"

University of Utah Health: "How to Tell If Your Sunglasses are Really Protecting Your Eyes."

American Academy of Ophthalmology: "What is Photokeratitis -- Including Snow Blindness?" "What Are Cataracts?" "Cataract Diagnosis and Treatment," "What Is a Pinguecula and a Pterygium (Surfer's Eye)?" "Pinguecula and Pterygium (Surfer's Eye) Symptoms," "Pinguecula and Pterygium (Surfer's Eye) Treatment."

Mayo Clinic: "Wet macular degeneration," "Skin cancer."

BrightFocus Foundation: "Symptoms of Dry Age-Related Macular Degeneration (AMD)."

American Macular Degeneration Foundation: "What is Macular Degeneration?"

Skin Cancer Foundation: "Focus on Eyelid Skin Cancers: Early Detection and Treatment."

American Cancer Society: "Risk Factors for Eye Cancer."

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