Sun and your eyes: how to choose sunglasses that really protect
By See Better · Updated · 5 min read
The short answer
Choose sunglasses labelled UV400 or 100% UV protection, which block both UVA and UVB rays. The darkness of the lens tells you nothing about protection, and polarised lenses reduce glare but are not automatically UV-protective. Large or wraparound frames and a wide-brimmed hat add more protection. Children need sunglasses too.
Key points
- Look for UV400 or 100% UVA and UVB on the label. Nothing else guarantees protection.
- Dark lenses without a UV filter are worse than no sunglasses at all.
- Polarised lenses cut glare. They are a comfort feature, not UV protection.
- South Africa's UV levels are high for most of the year, in winter as well.
Why the South African sun is hard on eyes
South Africa has some of the highest ultraviolet (UV) levels in the world. In summer the UV index regularly reaches "very high" and "extreme" across the country, and on the Highveld the altitude adds to it: the higher you are, the less atmosphere there is to filter the rays. UV is also reflected back at you by water, sand, concrete and car bonnets, and it passes through cloud.
You cannot see or feel UV. Eyes do not warn you the way hot skin does.
What UV does to your eyes
In the short term, a heavy dose of UV can burn the surface of the eye, exactly as it burns skin. This is called photokeratitis. Some hours after a long day on the water or at the beach, the eyes become painful, red, watery and very sensitive to light. It heals in a day or two, but it is a clear sign of overexposure.
Over the years, damage adds up:
- Cataracts. UV speeds up the clouding of the lens. See cataracts: early symptoms and treatment.
- Pterygium. A fleshy, wedge-shaped growth that spreads from the white of the eye onto the cornea. It is common in sunny, dusty climates and among people who work outdoors, and it can distort vision and need surgery.
- Pinguecula. A yellowish raised spot on the white of the eye.
- Skin cancer of the eyelids. The thin skin around the eyes is a common site.
- Macular degeneration. Long-term light exposure may contribute to it.
The damage is cumulative and begins in childhood.
How to choose sunglasses that protect
1. Check the UV label
Look for UV400 or 100% UV protection (UVA and UVB). UV400 means the lens blocks rays up to 400 nanometres, which covers the whole UV range. If there is no UV label, do not assume there is any protection.
2. Ignore how dark the lens is
Tint and UV protection are separate things. A clear lens can block 100% of UV, and a very dark lens can block almost none. Dark lenses without a UV filter are worse than nothing. They make your pupils open wider, which lets more UV into the eye.
3. Understand what polarised means
Polarised lenses block the horizontal glare that bounces off flat surfaces such as roads, water and bonnets. They make driving and fishing far more comfortable. Polarisation is not UV protection, though. Most good polarised sunglasses have both, but check the label for each.
4. Go bigger
UV reaches your eyes from the sides, from above and from below. Large lenses, close-fitting frames and wraparound styles protect far better than small, flat fashion frames.
5. Pick a lens colour for comfort
- Grey: natural colours, and good for general use and driving.
- Brown or amber: more contrast, and good in changing light.
- Green: a balance of the two.
Colour does not affect UV protection.
Are cheap sunglasses safe?
Price is not a reliable guide. An inexpensive pair with genuine UV400 lenses protects your eyes as well as a designer pair. The risk lies with unlabelled sunglasses from informal sellers, where a UV claim cannot be verified, and with lenses of such poor optical quality that they distort your vision. Buy from a retailer that states the UV rating. If you are unsure about a pair you already own, an optometrist with a UV meter can check it.
Sunglasses for children
Children spend more time outdoors than adults do, and the young lens lets more UV through to the retina. A large share of a person's lifetime UV exposure happens in childhood. Give children UV400 sunglasses with impact-resistant lenses and a comfortable, flexible frame, and add a wide-brimmed hat. A hat alone cuts the UV reaching the eyes roughly in half.
There is one balance to strike. Time outdoors helps to protect children against short-sightedness. The answer is not to keep them inside, but to send them out with a hat and sunglasses. See short-sightedness in children.
If you wear prescription glasses
You have several options:
- prescription sunglasses, which are ideal for driving
- photochromic lenses that darken outdoors
- a fixed tint on your everyday lenses
- clip-on or fit-over sunglasses
Photochromic or tinted lenses? compares them. Many modern clear lens materials block most UV as well. See Better's glasses packages include tinted lenses and start at R1199 with the eye test and frame.
Everyday sun habits
- Wear sunglasses whenever you are outdoors in daylight, not only on hot days. UV is high on cool, bright winter days too.
- Take extra care between 10:00 and 15:00, near water and at high altitude.
- Wear a wide-brimmed hat.
- Never look directly at the sun, including during an eclipse. Ordinary sunglasses do not make that safe.
- Use proper eye protection for welding and sunbeds.
Frequently asked questions
What does UV400 mean?
It means the lenses block ultraviolet light with wavelengths up to 400 nanometres, which covers all UVA and UVB rays. It is the same as 100% UV protection.
Are polarised sunglasses better for your eyes?
They are better for comfort and safety in glare, particularly when driving and on water. They are not automatically better for eye health. UV protection is what protects your eyes, and it is a separate feature.
Do I need sunglasses in winter or on cloudy days?
Yes. UV passes through cloud, and in South Africa UV levels remain significant in winter, particularly at altitude and around midday.
Can sun damage to the eyes be reversed?
Sunburn of the eye surface heals within days. Long-term damage, such as cataracts and pterygium, does not reverse without treatment, which is why protection from childhood matters.
This article is general information and is not a diagnosis or a substitute for an eye examination. If you are worried about your eyes or your sight, see an optometrist or a doctor. Sudden loss of vision, eye injuries and severe eye pain are emergencies.
