So come rain or shine, everyone is encouraged to sport a pair of sunnies to raise money to help provide support for the blind and partially sighted.

The day is the brainwave of The Guide Dogs for the Blind Association, and bosses and headteachers are urged to allow their employees or pupils to wear sunglasses in exchange for a £1 donation.

As well as raising funds for Guide Dogs, National Shades Day is part of the charity's overall aim to raise awareness about eye health issues.

People need to be more aware of the damage the sun can do to their eyes if they are not protected.

Although most view sunglasses as a summer fashion accessory, it is just as important for keeping the sun's dangerous UV rays away from the eye .

Managing dispensing optician at The Oculist, in Westgate Arcade, Peterborough, Emma Woolner, said sunglasses are crucial for healthy eyes.

She said: "All sunglasses should have a UV protection of 400. UV light can damage cells which could lead to problems such as cataracts so I would advise people to wear sunglasses.

"Wearing a pair of good-quality sunglasses can block between 99 and 100 per cent of UV radiation."

Guide Dogs director of public policy and development Tom Pey said: "Educating people on how to protect their sight is important.

"If you are outside and the light is so bright that you have to squint or turn your head away then you should put on your shades."

But most people wear sunglasses for their fashion value – big and chunky is the style this season.

June Smith, who has been selling sunglasses at John Lewis, in Queensgate, for three years, said: "We have so many brands ranging from the likes of Ted Baker and Gucci to John Lewis's own brand, which are currently the most popular.

"Chanel is another popular brand and if people can't afford the handbags then the sunglasses are a good alternative if you want to wear designer stuff. Our most expensive pair costs £257."

n to find out more visit www.shadesday.org.

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