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To be able to see in strong sunlight in a relaxed manner and comfortably, clearly and sharply, without any restrictions or clouding – that’s what sunglasses should allow. They should protect the eyes from the hazards of the sun. To ensure this you need not only the best sun protection lenses but also and above all constant scientific involvement with the subject.
“There are a few but all the more important criteria and factors that distinguish between good and excellent sun protection lenses,” says Rupert Spindelbalker, the Head of Research and Development at Silhouette International. “Sunglasses must permit clear, sharp vision and protect the eye from those rays that might damage it. 100% of UVA, UVB and UVC radiation and 93% of blue light should be filtered out.”
The spectrum of radiation
The human eye perceives light only in the range of wavelengths from about 380 to 780 nm but it is the invisible UV and infrared rays in particular that are dangerous to the eye and can damage it.
The sun’s spectrum is like a rainbow:
Wavelength from 100 to 380 nm: Ultraviolet light (UVA, UVB, UVC)
Wavelength from 380 to 780 nm: Visible light: violet, indigo, blue, green, yellow, orange
Wavelength from 380 to 500 nm: Blue light
Wavelength from 780 to 1 mm: Infrared light
The effect of UV radiation is already familiar from sun protection for the skin. UV A rays tan the skin and are responsible for skin aging, whilst UV B rays cause sunburn and may lead to skin cancer. In the eye, UV B radiation can lead to irritation of the cornea and conjunctiva. UV C light is even more aggressive and dangerous but is mainly filtered out by the ozone layer before it reaches the earth’s surface.
Infrared radiation, like UV rays, is invisible and does not generally give people any problems. It is only if one is exposed to very intense heat sources that it may cause damage to the eye. One familiar example is cataracts.
The complete press release is in the Silhouette Mediabox and available for download.