Why wear sunglasses?
Sunglasses eliminate solar ultraviolet radiation (UVR), in particular the more-damaging UVB radiation. As the eye cannot see UVR, good quality sunglasses have an important function in blocking UVR. Not being visible, excessive exposure over a long period can damage eyesight, accelerate the development of a cataract and cause premature skin ageing. High quality sunglasses will filter out both UVA (a good way of looking at the 'A' is for ageing) and UVB (a good way of looking at the 'B' is for burning). The latter is responsible for causing sunburn and can damage eye tissue with prolonged and unprotected exposure.
Superior quality sunglasses should meet the industry standard UV400 rating and all the sunglasses we sell meet this standard (except a clear lens supplied as part of an interchangeable model). They will, therefore, provide the eye with substantial protection against solar UVR, and reducing the amount of UVR that the eye is exposed to over a person's lifetime will be beneficial.
When to wear sunglasses?
• Outdoors, especially during summer when the level of UVR at noon is about three times as high as that for winter. More importantly, the levels of UVB can be as much as ten times higher.
• In open spaces (typically when you are taking part in your sport), for example when boating. In such situations, where there might be little or no shade, you are exposed to direct and scattered radiation from the whole sky. A flat surface like the sea reflects 20% of UVA and UVB, which causes high glare.
• Skiing at high altitude. The harmful effects of Solar UVR increase every 1000m and at 2000m can be 30% higher than at sea level. The high reflection of snow increases the problem.
What does polarisation mean?
We all experience glare from the sun interfering with our vision. Technically, glare is a way of describing light wave transmission, reflected or refracted, that is aligned into a directional plane. Light is referred to as "polarised" when aligned in this way. A polarised lens will filter direct light and eliminates polarised light. The result is the ability to see light in its pure state. Objects will appear more defined, sharper and naturally coloured. Instead of squinting to minimise glare, a polarised lens will allow your eyes to see colours with true clarity.
Because polarised lenses eliminate glare off a flat surface they are the popular choice for activities like sailing, boating, skiing and fishing. When used for fishing a polarised lens means you will be able to see down below the surface of the water.
Frequently Asked Questions (FAQs)
What does ultraviolet (UV) mean?
Ultraviolet is simply one type of energy that is emitted from the sun. At school we learned about light and the electromagnetic spectrum. The ultraviolet rays are simply a component of that spectrum. Other rays that are emitted include microwaves and visible light.
Why can't we see UV rays?
The only rays of the spectrum we see are visible light. Our eyes simply cannot detect the other rays due to their frequency. However just because we cannot see them does not mean we cannot feel or sense them.
Why is UV protection important?
We are surrounded by UV radiation all the time. The quantity depends on the conditions outside such as direct sun and the clouds. UV rays can be reflected.
What is a nanometer?
A nanometer is simply a unit of measurement. It is equal to one-millionth of a millimetre. Light rays move with a wavelength small enough that this is the most applicable way of measuring them.
Why do we need UV protection for our eyes?
The depletion of the earth's ozone layer has made the need for protection from any of the sun's rays even more important. It is believed, but not proven, that ultraviolet rays cause photokeratitis, which is cancer of the eye.
What do UVA, UVB and UVC mean?
This is a further breakdown of ultraviolet rays within their component of the electromagnetic spectrum. Ultraviolet rays travel with a wavelength of 10 to 400nm. UVA has a wavelength of 320 to 400nm and causes sunburning, UVB travels in the range of 280 to 320nm, causes sunburn and kills bacteria. UVC is from 100 to 280nm and is usually filtered out by the ozone layer.
What does UV400 mean?
This is an optical industry standard. It means that the lenses are made to protect your eyes against UV rays up to 400 nanometers in wavelength.
How do my lenses protect my eyes from UV rays?
A special clear coating is applied to the lenses. This is either on the front or back of the lens, or sometimes both. Obviously this is a transparent coating and can be applied to any colour of lens including clear.
