Choosing sunglasses

To help choose your sunglasses here are a few things you must know.
- At altitude in the mountains sun rays are less filtered by the atmosphere and UV exposure increases 4% every 300m.
- Snow reflects up to 85% of UV.
Proper fitting sunglasses offer protection against the sun and wind.

 

Lenses

Lenses have different UV protection rates set by the European Union ranging from 1 to 4 depending on how much light is filtered out.
- UV1 used in foggy conditions these lenses filter between 20 and 40% of light.
- UV2 in mixed conditions these lenses filter between 47 and 82% of light.
- UV3 in bright and sunny conditions these lenses filter between 82 and 92% of light.
- UV4 in very bright and sunny conditions mainly in spring these screens filter over 92% of light.

Note : All sunglasses maybe used for everyday life the only exception being UV4 lenses which should not be used for driving.

- Photochromic lenses : highly versatile, the lenses adapt to light exposure and can be used in all weather conditions.
- Polarised lenses : these lenses absorb reflections and amplify contrast.

Lens materials

Filtering lenses can be made out of different materials such as :
- Mineral : silica based, the only lens that offers natural resistance to scratches, it is however slightly heavier (9 g against 5 g for polycarbonate)
- Polycarbonate : lightweight and shock resistant.
- Organic : slightly heavier than polycarbonate but equally shock resistant and cheaper.