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UV400 sunglasses: what to look for

By Anwar Optical, Karachi. Updated .

Part of our guide: sunglasses buying guide.

Sunglasses should protect your eyes from ultraviolet (UV) light, not just make things darker. This guide explains the labels so you can choose with confidence. Our UV protection guide goes into more detail.

UVA, UVB and UV400

Sunlight contains two kinds of UV that reach the ground: UVA and UVB. Too much UV over the years is linked to eye problems such as cataracts, and to sunburn of the eyelids and the surface of the eye. UV400 means the lens blocks light up to 400 nanometres, which covers both UVA and UVB. It is the label to look for.

Dark lenses are not the same as UV protection

A dark tint reduces brightness, but it does not tell you how much UV the lens blocks. A dark lens without a UV filter is worse than no sunglasses, because your pupils open wider in the shade of the lens and let in more UV. Check for UV400 on the label or tag, and ask the shop if it is not shown.

Polarized is a different feature

Polarized lenses cut glare reflected from flat surfaces such as roads and water. They make bright light more comfortable, but polarizing does not mean UV protection. Look for both. See polarized lenses.

Lens darkness categories

Sunglasses are rated for how much visible light they block, from category 0 (very light) to category 4 (very dark). Category 2 and 3 suit most everyday use. Category 4 is for extreme glare, such as snow or high mountains, and is not suitable for driving.

Check the frame as well

  • Larger or wraparound frames block more light from the sides and top.
  • Choose a size that sits close to your face. See how to find your frame size.
  • Children need UV protection too. Look for UV400 in their sunglasses, and a light, comfortable frame.

If you wear glasses

You can have your prescription made into sunglasses. See prescription sunglasses. Photochromic lenses darken outdoors and clear indoors, see photochromic lenses.

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