You only have two eyes and people need to take care of them

Anita Lightstone, RNIB

Children can get glasses for free, but for adults, they cost around �150 on average.

Although the test is free for certain people, including under 16s and over 60s, most people pay between �15 and �25.

In a bid to encourage people to get their vision checked, supermarket chain Asda has announced it is cutting the price of eye tests by �10 to �5 until mid-July.

It will decide then whether to make the price cut permanent.

Health check

People should have a routine eye test every two years.

But people over 40 should have a yearly check, according to the RNIB.

The risks of not having a test include missing early signs of eye disease.

Anita Lightstone warns people need regular eye checks

Glaucoma and diabetic eye disease are particularly common in older people and can cause blindness if left undetected.

Eye tests can also pick up indications of general health problems such as high-blood pressure, diabetes and even eye tumours.

Diabetes is the leading cause of sight loss in the UK's working population.

Anita Lightstone of the RNIB said: "You only have two eyes and people need to take care of them.

"Most of the eye diseases come on very gently and very gradually.

"Things like glaucoma - you yourself would not notice any signs until it was very advanced. But an eye test, the early signs can be picked up very quickly."