Sunglasses and UV: How to Tell Real Protection From a Dark Tint
A dark lens makes your pupil open wider. If that lens does not block UV, it is letting more ultraviolet into your eye than if you wore nothing.
Egypt sits in a high-UV band for most of the year, and the ultraviolet load does not drop on cloudy days or in winter the way people assume. Cumulative UV exposure is linked to cataracts, pterygium — the fleshy growth across the white of the eye that is notably common in sunny, dusty climates — and skin cancers on the eyelids.
The counterintuitive part
Your pupil sizes itself to visible brightness, not to ultraviolet — which you cannot see. Put a dark lens in front of your eye and the pupil opens up. If that lens has no UV filter, the wider pupil now admits more UV than a bare eye squinting in daylight would. This is why a cheap unbranded pair is not simply "not helping": it is actively worse.
What the labels mean
| Label | What it tells you |
|---|---|
| UV400 | Blocks wavelengths up to 400 nm — that is all UVA and UVB. This is the one that matters. |
| 100% UV protection | Equivalent to UV400 when it comes from a real manufacturer. |
| CE / EN ISO 12312-1 | The European standard for sunglasses. A meaningful mark on a genuine product. |
| Category 0–4 | Tint darkness only, not protection. Cat 3 is normal daylight; Cat 4 is for mountains and is not legal for driving. |
| Polarised | Cuts glare reflected off flat surfaces. A comfort feature — it says nothing about UV. |
Checking a pair before you buy
- Look for a permanent UV400 or CE marking on the lens or temple — a stick-on label that peels off proves nothing.
- Hold the lenses up and look through them at a straight line, such as a door frame. Move them around. If the line bends or wobbles, the optical quality is poor and they will give you headaches.
- To test polarisation, look at a phone screen through one lens and rotate the glasses 90 degrees. Polarised lenses will darken the screen dramatically at one angle.
- Ask any optician to put them through a UV meter. It takes seconds and any reputable shop will do it, including for glasses you did not buy from them.
Choosing a lens tint
- Grey — neutral, keeps colours true. The safest all-purpose choice, and the best for driving.
- Brown / amber — lifts contrast, helpful in haze and dust. Slightly warms colours.
- Green — a middle ground: good contrast with fairly natural colour.
- Mirror coatings — reduce the light reaching the lens surface, useful on water and open desert.
Every sunglass lens we sell is UV400, and any of them can be fitted with your prescription.
Shop sunglassesFrequently asked questions
Are dark sunglasses without UV protection dangerous?
Yes. A dark tint makes your pupils dilate, and a dilated pupil behind a lens with no UV filter lets more ultraviolet reach the retina than an unshaded eye would. Wearing no sunglasses is safer than wearing unprotective dark ones.
What is the difference between polarised and UV protection?
They solve different problems. UV protection is a filter that blocks invisible ultraviolet radiation and protects eye health. Polarisation is a filter that blocks horizontally reflected light, cutting glare from roads, water and car bonnets — it is about comfort and clarity, not protection.
Do I need sunglasses on cloudy days in Egypt?
Yes. Cloud cover reduces visible brightness far more than it reduces ultraviolet, so a large share of UV still reaches your eyes on an overcast day. Dust and haze scatter light rather than absorb UV, which makes the eyes work harder without offering protection.
Can I get prescription sunglasses?
Yes — almost any sunglass frame can be fitted with tinted prescription lenses, including polarised and UV400 versions. It is the better option for anyone who drives, because photochromic lenses stay too light behind a windscreen.