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Optische Strahlung

UV eye protection

Ultraviolet (UV-) radiation can cause permanent damage to both the skin and eyes. It is therefore strongly recommended not only to observe the sun protection rules but also to effectively protect the eyes from the sun.

Sun glasses are absolutely essential not only to protect our eyes against glare but also to stop UV-radiation entering our eyes. However, not all sunglasses will provide sufficient UV-protection. In contrast to glare reduction which can be tested by the customer himself, one cannot tell the UV-protective effect of sun glasses.

UV-filtering effect

Measurements have shown that the manufacturers’ information is relatively reliable. For instance "UV-400", or "100 per cent UV-protection" means that the sunglasses filter out all of the UV-radiation up to 400 Nanometres (nm), which is sufficient to fulfil the UV-filtering requirements on lens quality of sunglasses. It is therefore vital to pay attention to the corresponding designation when buying sunglasses.

Please note: UV-protection provided by sunglasses lenses with vision correction may be insufficient as a result of lens processing!

Lens tint/shading

As to the level of lens tint, sunglasses lenses should fall within category rating number 2 or 3. This information is mostly found on a tag or label attached to the eyeglass or to the temple arm (e.g. "cat2"). Tint category 1 scarcely protects against glare, tint category 4 is too dark to permit good sight and is, for instance, not road legal. For extreme exposure conditions such as on snow in the high mountain range, it is advisable to choose appropriate cat4-glacier goggles with side protection which in addition filter out all of the blue light.

Lens colouring

Appropriate colourings are brown or grey. These colourings are ideal for good sight. Blue and red colourings interfere with contrast rendition and visual acuity.

Side coverage

Since UV-radiation scatters strongly, sunglasses should be chosen considering good side protection (either by the lens size or by the sunglasses’ design). This is easily to be judged by the customer.

Choice of material

Since UV-protective coating is specifically applied by the manufacturer, the choice between genuine glass and synthetic material is irrelevant for the UV-filtering effect. The former recommendation to use genuine glass dates back from 15 years ago when low-price sunglasses made of polystyrene were manufactured without additional UV-protection which involved indeed a serious hazard to the eyes.

State of 2018.04.13

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