OUR eyesight, arguably the most precious of the senses, is all too easily strained and fatigued by the long office hours and polluted cities of modern life.

Yet, most of us take our vision completely for granted and our eyes remain among the most neglected parts of the body.

Recent research from The Guide Dogs for the Blind Association has shown that more than a third - 38 per cent - of regular VDU users aren't aware of their right to an eye test paid for by their employer.

And, amazingly, the charity has also found that some people don't realise the importance of wearing sunglasses in bright sunlight to protect their eyes from the harmful effect of ultraviolet rays.

"Fewer than half of those who knew about free eye tests actually claimed them," says Geraldine Peacock, Guide Dogs' chief executive. "Many said they had never got round to it, never thought about it, or weren't bothered.

"But, if people made regular visits to the opticians, there'd be a massive impact on the eye health of the nation's workforce. It's also concerning that the importance of protecting eyes from ultraviolet rays has yet to sink in with young people. Yet UV does the most damage below the age of 18.

"It can increase the risk of developing cataracts and there's evidence that it can hasten the onset of sight degeneration."

Eyes need exercise, rest and nutrition to function at their best. It's accepted that prolonged periods working at computers can cause tired eyes, discomfort or headaches, and at the least make users more aware of visual defects such as short sight.

And as VDUs play an ever more prominent role in daily life of a growing proportion of the national workforce, there is continuing debate over whether they can cause permanent eye damage.

A report published by the University of California's Berkeley School of Optometry claimed that 30 per cent of American schoolchildren were causing stress to their eyes by spending too long on the computer, and said there was a link between premature myopia and computer use.

But in 1995, a Health and Safety Executive commissioned evaluation of the 1992 Health and Safety (Display Screen Equipment) Regulations found there was no evidence it caused disease or permanent damage to eyes.

Nevertheless, under HSE regulations, employers of regular VDU users are still legally obliged to provide a free eye test and to pay for a basic pair of glasses specifically for screen work.

Ray Hutchings, of Specsavers, says there are plenty of measures that VDU users can take to prevent serious eye problems.

"The more natural daylight there is, the better," he advises. "If the artificial lighting's too bright, have it adjusted, and, if it's poor, change workstation or use a desk lamp. Tilt your screen downwards to eliminate glare on the computer screen from the overhead lighting and adjust your monitor so that it's not too dim or too bright.

"Don't strain to see a tiny font on the screen when you can work in bigger characters. An anti-glare screen might help, and it is also worth having your spectacles coated with an anti-glare lens.

"Wearing the correct type of glasses is important, so regular eye tests are very important to see what is appropriate for you.

"For VDU use, spectacles designed to help you to see material 18 to 20in away are ideal. These can be a separate pair to your normal reading glasses.

"When at your screen, take a few minutes break from it once an hour to look around and refocus the eyes. Remember to blink regularly and every 20 minutes or so, look up from your screen and focus on something about 20ft away for 20 seconds."

Employers are legally required to carry out an assessment of staff's workstations to make sure they meet health and safety rules aimed at reducing the most common work-related health problems.

These include musculo-skeletal disorders - such as repetitive strain injury, or RSI, back, neck or hand problems - in addition to eye problems and fatigue.

According to Dr Wendy Doyle of the British Dietetic Association, nutrition is also important for healthy eyes.

"Vitamin A is essential in forming the retinal pigments responsible for vision," she says. "It's plentiful in raw carrots, red peppers and other orange fruit and vegetables. Other active sources include liver, kidney, margarine, egg yolks dark green vegetables and fish liver oils.

"Diets high in the other antioxidants - vitamins C, E and carotene - found in brightly coloured fruit and vegetables also help and zinc, vitamin B2 and iron play a role."