The first hot summer days attract countless light hungry people outside. This again starts the season of sunglasses. In addition to their protective function against UV radiation, sunglasses have long since made the step towards fashion accessories. But the qualitative differences in the variety of models offered are very large. Many features of the sunglasses are not recognizable by the consumer himself. That's why qualified opticians are in demand. The following 12 tips and information will help you to understand what to look for when buying sunglasses.
1. Dark glasses are dangerous
Glasses must protect against ultraviolet radiation (UV radiation). Such ultraviolet radiation is invisible. However, it can lead to painful inflammation of the connective and cornea in the corresponding intensity.
Sunglasses that only attenuate the visible light, therefore harm more than they are useful. They override the natural protective mechanism of the eye, whose pupil normally automatically decreases in brightness and thus allows less radiation to penetrate.
The filtering of the UV radiation takes place in the spectacle lens and therefore does not depend on the degree of tinting. It's not the darkest colored glasses that are the best protection, but the sunglasses that are made of high quality material with a built-in UV filter.
2. UV protection: What is the name "UV 400"?
The term "UV 400" indicates the wavelength below which the ultraviolet light is blocked by the glass. A pair of glasses with this mark filters UV-A, UV-B and UV-C rays because their wavelength is below 400 nanometers. Visible light has a wavelength of up to 780 nanometers and therefore penetrates through such sunglasses.
Make sure the sunglasses are labeled "UV 400". This value is usually sufficient when used in normal everyday life. At the sea or in the mountains even more protection may be needed. Let us advise you!
3. Light reduction: What is absorption?
The absorption characteristic of colored lenses depends on the light reduction. This is the amount of light that is removed by the glass and thus does not get into the eye. With a light reduction of 65 percent, only 35 percent of the incident light gets into the eye, 65 percent are removed by absorption and reflection.
In Central Europe, reduction values between 50 and 75 percent are used. In a very bright environment, for example, on the beach or in a snowy landscape, you should use higher reduction levels of up to 85 percent.
4. The color of the glasses also plays a role
Brown and gray glasses falsify the color of the visual impressions the least. For all other glass tints, the eye needs a certain amount of reaction time to neutralize the color again.
According to DIN standards, the lens color must not affect the visibility of the traffic lights and the blue light of emergency vehicles. The color has no effect on the UV protection.
5. How to check the quality of sun protection lenses
Use the following criteria to check the quality of the sunblinds:
- High quality glasses have no streaks, bubbles or inclusions.
- At a slight pressure of the finger, the glass must not yield.
- An object fixed by a solar control glass should not warp or distort when turning the glasses back and forth.
6. The size of the glasses must be right
Glasses should be large enough to protect the eyes from the side, from the top or - by reflection - from the sun's rays.
7. Is the CE mark available?
Since 1 July 1995 sunglasses may only be marketed if they bear the CE mark. This allows the sales of sunglasses in all states of the European Union, it is attached by the manufacturer or importer. The CE mark guarantees a minimum of quality standard.
8. Sunglasses and driving
If you drive a lot, you should make sure that the socket and bracket are as narrow as possible so that they do not restrict the field of vision.
Sunglasses are not meant to be worn at dusk or night. Motorists endanger themselves and others if they wear absorbent glasses when lighting is inadequate.
9. Choose your sunglasses according to the activity
When winter sports you need different glasses than on the beach, while sailing or surfing. Snow and white sand, for example, reflect more than 90 percent of the sun's rays (which is also the reason why you can get sunburn under a parasol).
10. The socket must fit
Every head is different. Therefore, the version of the head shape must be customized. The optician considers with great care:
- head shape
- temporal width
- Distance of the eyes
- Position of the ears
11. How to care for sunglasses
Like any pair of glasses you should also clean your sunglasses regularly. To care for the sunglasses take a special cleaning cloth, which is available from the optician, or a dishwashing detergent and rinsed with clear water.
Sunglasses lenses that are contaminated with sun oil or cream residues should not be cleaned with wet wipes, but first with clean water.
12. Let us advise you
If you want to know more about quality features when buying sunglasses, it is best to contact your local optician.