If you're one of the 11million Britons who'll splash out on sunglasses this year, it may be worth thinking about how good they are for your eyes. The eyes are especially susceptible to the sun because of the transparency of the outer tissues. Long-term exposure can speed up ageing of the macula, the most sensitive part of the retina and can also lead to cataracts. Here is the ultimate guide to protecting your eyes in the sun.
Look for sunglasses that meet the European safety standards. This means they will be of good optical quality with break-resistant lenses, providing high levels of protection against ultraviolet light, while not distorting colours. It's worth buying a pair with a dark tint and with plastic rather than glass lenses, for safety reasons. One of the key functions of sunglasses is to reduce the amount of sunlight entering the eye. Look for a pair offering a light reduction of up to 80%,
that is they will allow in only 20% of the sunlight. The size of the lens - the area shielded - affects light admitted.
Recommended makes: Most High Street and designer brands.
All outdoor activities can put your eyes at risk from UV radiation exposure and discomfort associated with squinting and eyestrain. Even on a cloudy day, UV radiation will penetrate the eyes and, in countries such as Australia, where the ozone layer is depleted, there is a high risk of eye damage in any daylight. High-contrast lenses offer good protection while allowing the eye to function normally, without the dulling effect of most other lenses.
Recommended makes: Boots, Rayban, Marcolin, Hobie, Dolce & Gabbana, and Polo Ralph Lauren.
Whether you are playing a round of golf or spending a long day on the cricket field, there are a host of sports sunglasses to protect your eyes. Top companies have spent millions developing sports sunglasses with extra tough frames and lenses to cope with outdoor sports such as tennis, cricket and golf. One company has designed a lens that can pick out the yellow of a tennis ball, making it easier for the player to follow on a bright day; while another company even tests for sturdiness by firing steel bullets at more than 100mph at its sunglasses. Avoid metal frames which can break, and look for poly-carbonate.
Recommended makes: Oakley, Revo.
Varying light conditions and glare can cause drowsiness and reduce concentration. Because the windscreen will take away 40% of the UV risk, this will reduce the effectiveness of photochromic lenses (which darken in sunlight).
The best choice is a high-contrast lens that allows the eye to react naturally to changing light conditions. Polarising lenses will also help as they are specially made to reduce reflective glare off flat road surfaces and relax the eyes.
Also, make sure the sunglasses are in the filter category range of 0-3. A lens carrying a filter category of 4 will be too dark for safe driving. Never wear sunglasses when driving in poor light.
Recommended makes: Revo, Serengeti and any good quality polarising range.
Whether you're windsurfing in Wales or jetskiing in the Bahamas, on a sunny day it is best to wear polarised lenses that reduce reflective glare from the water surface, while polycarbonate material allows lenses to be lightweight and safe and which will not shatter on impact. Wraparound styles help keep out peripheral glare and spray, and when fitted in nylon or other polyamide materials provide excellent safety.
Recommended makes: Bolle, Oakley, Maui Jim.
Like adults, children's delicate eyes need protecting from the sun. From birth, it is a good idea to protect a baby's eyes with a sunhat, umbrella or just by sitting them in the shade. As soon as possible, they should be wearing sunglasses made with tough polycarbonate lenses that will not damage their eyes if they break.
Recommended makes: Boots, Bolle, Disney brands. Look for the CE and British Standard marks and make sure the sunglasses have plastic lenses.
What to look for
* Expensive sometimes means better, but not necessarily. What really counts is the degree to which the lenses filter out harmful UV rays. Look for the CE mark, which proves they conform to the European Community Standard. They should also satisfy British Standard BSEN1836, meaning they will provide high levels of protection against damaging ultraviolet light.
* Do not confuse the shade of the lenses with their ability to filter UV rays. Dark sunglasses may still allow UV rays to enter the eye. Sunglasses are marked with a filter category from 0-4, where 4 is the darkest lens.
* UV protection has nothing to do with lens colour. It has everything to do with blasting radiation that can damage your eyes. The best makes will block 100% of UV-A, UV-B and harmful blue light.
* Buy a pair offering a 'light reduction' of up to 80% - they will allow in only 20% of sunlight.
* Polarising lenses will reduce reflective glare from water and land surfaces, making them particularly good at improving vision in bright or hazy driving conditions.
* Anti-reflective coatings eliminate glare.
* Photocromic lenses go darker in the sunlight and are good UV absorbers.
* Impact-resistant lenses are essential for a sporty or active lifestyle as they are made from polycarbonate or toughened glass.
* High-contrast lenses work like a graphic equaliser on a stereo: they balance pitches of light, helping the wearer to see things more naturally.
* Wraparound styles further protect the eyes by helping to keep out peripheral glare.