Forget a healthy sex drive or even being able to walk, given the choice most of us would sacrifice both of those if it meant we didn't lose our ability to see, according to the latest research.

It's the sense we apparently value above all others, yet looking after our sight seems to be a hit-and-miss affair, with half the population mistakenly thinking that not sitting too close to the TV, reading in a good light, and wearing an eye mask at night is enough to protect their eyes, according to a survey by eye care manufacturers Bausch & Lomb.

In reality, a regular eye test is one of the most effective safeguards, particularly as we get older when we are more at risk of eye conditions such as glaucoma and AMD (age-related macular degeneration).

Iain Anderson, chairman of The Eyecare Trust, which is promoting the benefits of eye tests for the elderly, points out: "Research figures suggest that more than four million OAPs miss out on vital sight tests every year - despite the fact that eye examinations for the over 60s have been free on the NHS for eight years."

Dr Susan Blakeney, optometric advisor for The College Of Optometrists, says research shows that more than one in 10 people have never had their eyes tested.

She says: "The eyes are one of the most amazing parts of the body. They can process 36,000 bits of information every hour, and in a normal life span the eye will generate almost 24 million images of the world around us.

"Yet people often underestimate how important it is to look after them."

She warns: "Many wrongly assume that because they can apparently see clearly there cannot be anything wrong with their eyes.

"While that is a good sign, it doesn't necessarily mean your eyes are absolutely healthy, as in the early stages some eye conditions may have symptoms that can only be detected by an optometrist."

She recommends that in general people have their eyes tested at least once every two years, or more often if advised by an optometrist.

"Wearing sunglasses even in winter to protect the eyes from UV rays, giving up smoking which can more than double the risk of some eye conditions such as AMD, and having a balanced diet, which includes leafy green vegetables, are all key ways to protect eyes."

Follow our guide, with advice from the experts, to eye health

Eating for eyes

Prof Ian Grierson, head of the ophthalmology unit at Liverpool University, recommends a rocket, pear and cheese salad as one meal to help boost eye health. It's a recipe from his book, Vegetables for Vision - Nature's Supplements for Eye Health (Indigo Creative Marketing, £14.50).

The salad serves two, and uses: 100g (4oz) washed rocket or mixed leaves, three pears (any type), one lemon, 15ml (1tbsp) walnut oil or virgin olive oil, 35g (1 1/2oz) Edam, Stilton or Danish Blue, 10ml (2tsp) sesame seeds.

Spread salad leaves in a bowl, peel and core pears and slice. Cover with lemon juice and add oil. Sprinkle cheese and sesame seeds on the top and a good pinch of pepper. Add fresh figs if in season.

Eye exercise

"Keep eye muscles in good shape by holding a pencil three inches from your face and focus on the tip," says Dr John Hill, senior eye surgeon at Optimax, which specialises in laser surgery.

"Move it away to arm's length and then bring it forward again." Exercises can sometimes help to alleviate eyestrain from too much reading or computer work, but do take regular screen breaks.

Eye conditions

Age-related Macular Degeneration may not have as much public recognition as conditions such as glaucoma or cataracts but Andrew Lotery, professor of ophthalmology at Southampton University, believes it is "a hidden epidemic".

He says: "It's the commonest cause of vision loss in the western world for those over 60, and is thought to affect more than three million people in the UK."

There are two forms, wet and dry, and women are more likely to suffer than men. Distortion of central vision, fuzzy lines and shapes, and sensitivity to light can all be symptoms that the macula is beginning to deteriorate.

There may be a dark spot in the centre of the vision and you may see shapes and lights that are not really there.

Prof Lotery advises: "Those who have problems with their eyesight, or sudden changes such as reduced vision that doesn't clear up within a day or so, should consult a specialist urgently."