SunticUV and Your Eyes: Protecting Your Sight in the Sun
Sun safety tends to focus on skin, but your eyes are exposed to the same UV and are just as vulnerable to it. Both short bursts and years of accumulated exposure can cause harm, and unlike a sunburn, much of the damage to the eyes is painless until it is advanced. The good news is that protecting them is simple once you know what UV does and what to look for.
How does UV affect the eyes?
UV can damage the eyes over both the short and long term. The American Academy of Ophthalmology links sun exposure to several conditions:
- Photokeratitis, or snow blindness: a painful, temporary sunburn of the cornea from intense short-term UV, often from reflection off snow, water or sand.
- Cataracts: a clouding of the lens that builds over years, with cumulative UV a recognised contributing factor.
- Pterygium, or surfer's eye: a non-cancerous growth on the surface of the eye linked to chronic UV exposure.
- Other long-term risks: including damage at the back of the eye and cancers of the eye and eyelid.
Reflective settings make this worse, since snow, water and sand bounce extra UV up into the eyes. We cover the surface figures in UV reflection from water, snow and sand.
What should you look for in sunglasses?
The single most important feature is UV protection, and it is not the same as how dark the lenses are. Look for sunglasses labelled UV400, or 100 percent protection against UVA and UVB. UV400 simply means the lenses block ultraviolet up to 400 nanometres, which covers effectively all UVA and UVB. A bigger or wraparound style helps further by stopping UV that sneaks in from the sides, and pairs well with a wide-brimmed hat.
Shade and hats do real work
Sunglasses are the front line, but they are not the only layer. A wide-brimmed hat of around 7 centimetres shades the eyes and face and cuts the UV reaching them from above. Shade helps too, though as with skin it is not complete, because UV still scatters and reflects in from the surroundings. Combining sunglasses, a hat and shade covers far more than any single one alone.
A quick heuristic: the shadow rule
You do not always have an instrument to hand, but you can read the sun itself. The shadow rule says that when your shadow is shorter than you are tall, the sun is high and UV is intense, so it is time to protect your eyes and skin and seek shade. When your shadow is longer than you, UV is lower. It is a rough guide that tracks the angle of the sun, and a handy backup when you cannot check a number.
Know when to reach for your sunglasses
Eye protection matters most exactly when UV is strongest, which is not always when it feels brightest or hottest. Suntic shows the live UV index for your location, so you know when to put the sunglasses and hat on, including cold but high-UV days on the water or in the mountains where reflected UV hits the eyes hardest. It is a guide to building better habits, not a substitute for advice from an eye-care professional.
Frequently asked questions
Can the sun damage your eyes?
Yes. UV can cause short-term harm such as photokeratitis, a painful sunburn of the cornea, and contributes over years to cataracts, growths on the eye and other long-term damage. Reflective settings like snow and water raise the risk further.
What does UV400 mean on sunglasses?
UV400 means the lenses block ultraviolet light up to a wavelength of 400 nanometres, which covers effectively all UVA and UVB. It is the same protection as a 100 percent UVA and UVB label, and it is what to look for regardless of how dark the lenses are.
Are dark sunglasses without UV protection bad?
They can be worse than no sunglasses. Dark lenses make your pupils widen, and without a UV rating they then let more UV reach the back of the eye. Always choose sunglasses marked UV400 or 100 percent UVA and UVB protection.
