MANY people only think about having their eyes tested if they notice a problem with their eyesight, assuming that if they can see clearly then their eyes must be fine.

Unfortunately this is not always the case. It sounds surprising, but thousands of people in the UK are believed to have eye problems without being aware of it. The bad news is that if you are unlucky enough to have an eye condition, it could get worse if it is left alone and, by the time you notice a change in your vision, it may be difficult to treat.

The most common eye problems which are picked up during a routine sight test are familiar to most of us - short and long sight, astigmatism (irregularly shaped eyeball) and presbyopia (difficulty reading, which first starts to affect people in their mid-40s).

People developing one of these visual problems might notice a gradual blurring of vision, eyestrain, headaches or find themselves holding small print at arm's length to see it clearly. A sight test enables opticians to measure the extent of the problem and explain the options which meet personal requirements. Spectacles, contact lenses or refractive surgery can generally resolve all of these problems.

But there's much more to a simple sight test than you might expect. The optician also checks the health of your eyes. The tests are able to detect more serious eye conditions such as glaucoma, early cataracts and macular degeneration which are some of the most common causes of blindness in the UK today.

The same routine sight test can sometimes pick up early signs of general health problems. Hypertension (high blood pressure), diabetes and high cholesterol can often be detected by an eye examination. The clear front surface of the eye provides a 'window' through which the optometrist - using a hand-held instrument which doesn't touch the eye - can see nerves and blood vessels at the back of your eye. Any changes in the normal appearance of these will alert the optometrist to arrange for you to visit your GP or local hospital for further tests.

So a regular eye examination is an important part of looking after yourself and staying healthy.

Nigel Best is director of Specsavers Opticians in Darlington.