Sportspersons could soon be looking at their game through amber, yellow and rose tinted lenses with coloured contacts set to become the latest must-have sporting accessory -- as commonplace as air-cushioned trainers and tinted shades.

The lenses are being tested by sporting accessories giant Nike which believes they can help players see the ball better, particularly in bright sunlight.

If the trial is successful and players sponsored by Nike - such as footballers Wayne Rooney, Robbie Keane and Ronaldo - are seen with red or yellow eyes, it would almost certainly spark a lucrative new sportswear trend, reports the Scottish daily Scotsman.

The tinted lenses, under development for seven years, could be used in Britain this year. Nike is working on a contact with lens company Bausch and Lomb to sell them through opticians.

According to optometrist Karen Sparrow, red and yellow are effective because of their position in the rainbow. "They are also much lighter than the tint used in sunglasses."

Red-tinted lenses improve vision by filtering out some colours and creating sharper contrast, she explained. "It would be much easier to see a white ball against the pitch or the sky on a sunny day. Amber would be good for baseball players as it filters blue colours, helping to see the ball against the sky."

Tony Chipote, a marketing field manager for Nike, said: "We want our athletes to continue to see their game better and better for longer and longer. As soon as you start to lose your eyesight, the rest of your body will start to suffer."

Nike also has signed up tennis star Roger Federer and golfer Justin Leonard to test the lenses. It claims that while the red lenses are ideal for fast-moving sports such as football, grey lenses are the key to golfers being able to discern the lay of the land on a putting green.

Said Brian Roberts, of US basketball team Baltimore Orioles, who has tested the lenses: "They're like wearing sunglasses without wearing sunglasses. I could see such a huge difference right away."

The colour of the lenses has been designed to ensure the wearer does not actually see a red tint, and bright sunlight is filtered out. It is hoped that by wearing them during sunny matches, wearers could prolong their playing careers.

There could also be medical advantages in wearing the lenses. While light can leak through sunglasses - through the opening between the frame and the eyes - performance-enhancing contacts sit on the pupils and better protect them from the sun.

However, top optometrists warn that use of the lenses will need to be tightly controlled.