What to expect from an eye test

A regular eye test is not just about getting glasses - it can help detect eye disease before it affects sight. It should be carried out every two years, take about half an hour and include:

Checking sight: reading letters and colours on a chart

Checking the outer and inner eye by shining different lights

Checking the eye muscles

Working out a prescription if needed - looking at letters and colours through special lenses.

Extra tests may be needed for those at higher risk of eye diseases such as glaucoma, including anyone over 40, anyone with a close relative with eye disease, those of Afro-Caribbean origin, and diabetics. The extra tests involve:

A field of vision test, using patterns of lights

An eye pressure test, using eye drops or puffs of air

Dilating eye drops to check the back of the eye

Charges vary widely - the average is about pounds 16. Certain groups qualify for a free test, including the under-16s, those on income support and those with diabetes or glaucoma, or at high risk of eye disease.

For more information, call the Royal National Institute for the Blind on 0345 66 99 99.