The primary function of a pair of sunglasses is to protect the wearer’s eyes from the sun’s UV rays. Depending on the material from which the lenses are made, the filters applied and the potential coating on the lenses, sunglasses can filter out UV radiation before it reaches the eyes. A good pair of sunglasses will filter out 99 to 100% of UV rays.
Types of UV radiation
The human eye can detect light with a wavelength between 380 and 780 nm. However: damaging light that we cannot distinguish with our eyes exists outside this range as well. This light is mostly made up of UVC, UVB and UVA rays.
- UVC: this is radiation with a wavelength up to 280 nm that is unable to penetrate the Earth’s atmosphere.
- UVB: radiation with a short wavelength (between 280 and 315 nm) that causes sunburn and can inflict damage on eyes.
- UVC: this type of radiation is what gives you a suntan, but it also accelerates the ageing of the skin and damages your eyesight.
All sunglasses in our collection offer 100% protection against harmful UVC, UVB and UVA rays. This can be seen on the label for each pair as well. The label indicates how much radiation is filtered with the letters UV followed by a number. UV400, for instance, means that the sunglasses filter out all radiation with a wavelength up to 400 nm. This complies with European legislation, which requires that all radiation with a wavelength up to 380 nm be filtered.
Every pair of sunglasses is equipped with a CE mark that makes it clear whether they meet the European standards for filter quality. The digit between 0 and 4 after the ‘CE’ tells you the category of the lenses’ colour intensity: in other words, how effectively the sunglasses will prevent your eyes from being dazzled by glare. Sunglasses in category 0 absorb 0 to 20 per cent of the light, while category 4 sunglasses absorb 92 to 97 per cent.
- Category 0: these sunglasses offer virtually no protection and are suitable only for wearing on overcast days.
- Category 1: these sunglasses are suitable for wearing in indirect sunlight.
- Category 2: when the sun is moderately bright, these sunglasses are appropriate to wear. This category is the minimum recommendation for daytime activities at a central European latitude.
- Category 3: these sunglasses provide adequate protection in sunny weather, including at the seaside or in the mountains. This category is recommended for a day at the beach.
- Category 4: sunglasses in this category are recommended for use in circumstances of exceptionally bright sunlight, such as at high elevation (winter sports in the mountains).
All our sunglasses have earned at minimum a CE3 mark.
Colour of the lenses
The idea that the colour of the lenses corresponds to the degree of UV protection offered by a pair of sunglasses is a myth. Sunlight consists of a visible portion (light) and an invisible portion (UV radiation). The darker the lenses, the more visible light is filtered out and the lower the chances of being dazzled by glare. The degree to which the eyes are protected from UV radiation, on the other hand, is indicated by the solar filter rating (for example: UV400), as previously described on this page.
Still, the colour of the lenses does have some significance and every colour has its own distinct properties.
- Grey lenses: this colour is the most neutral option and is recommended for far-sighted individuals in particular These lenses reduce the intensity of visible sunlight without altering colours.
- Brown lenses: brown-tinted lenses distort actual colours, which some wearers may find irritating. They do, however, increase contrast which makes lenses of this colour especially suitable for short-sighted eyes.
- Yellow lenses: the yellow hue of the lenses results in sharper vision because it reduces the haze of blue sunlight; this colour is ideal when driving.
- Green lenses: this colour increases contrast, allowing you to distinguish between objects more effectively. However, lenses of this colour are not recommended for individuals who are colour-blind.
- Pink lenses: the pink hue heightens contrast against a blue or green background. This makes sunglasses with pink lenses ideal for those who participate in water sports.
When light reflects off a smooth surface (such as water, glass or a slick road), vertical and horizontal light waves are created. This radiation simply passes through the lenses of ‘regular’ eyeglasses – but polarized lenses filter out the horizontal light waves. That yields a clear image that is higher in contrast because the effect of the reflection has been eliminated. Polarized lenses also provide protection from UV radiation, of course.
Sunglasses with polarized lenses are especially useful for people who spend a great deal of time driving or on or near water, those who are near or far-sighted, older individuals and people who have had eye surgery.
Size of the lenses
Ideally, the lenses of the sunglasses should be large enough to prevent the sun’s rays from entering the wearer’s eyes at any angle. This is especially crucial in situations with a great deal of reflected light, such as near snow or water. The perfect pair of sunglasses should extend from the middle of the wearer’s nose to above their eyebrows.