Last updated at 1:08 AM on 31st October 2010
They may save you money in the short term but cheap reading glasses could end up costing your eyesight.
The so-called ‘ready readers’, which sell for as little as £1 in high street shops, may leave wearers with eye strain, headaches or even blurred or double vision.
Millions have bought them after baulking at the high cost of buying glasses from an optician.
However, research suggests they could be putting their eyesight and health at risk.
By the age of 50, most adults have problems reading a book or newspaper without spectacles.
So the arrival of the cheap glasses in supermarkets, high street stores and market stalls less than ten years ago has been seen as a saviour for many
A consumer might have to pay more than £100 for a pair of reading glasses from an optician, which might easily be lost or broken.
Instead, many buy several cheap versions to stash around the house so that they can always find a pair.
A researcher at consumer champion Which? checked 14 pairs from seven high street chains.
He found problems with half of them, with those carrying a higher prescription – +3.5 to +4 – considered to cause the most concern. ‘Off-the-peg glasses could cause eye strain, blurred vision, headaches or double vision,’ the Which? researcher said.
‘For people with higher prescriptions, they’re not suitable for walking or other mobile activities.’
They could even ‘cause a nasty accident’, he warned.
The biggest problem is that the centre point of the two lenses might not be aligned.
This means the sight in one eye might be clear while the other is blurred. This was the case in a pair from Poundland – which also had a prescription strength that differed from the +3.5 on the pack – and a £16 pair from fashion eyewear store Sight Station.
‘This could cause eye problems or a head tilt,’ the researcher said.
A £4 pair from Tiger were ‘unwearable’ because the centre point of the lenses did not match, while a £2 pair from Primark had ‘a very large difference’.
A £15 pair from Marks & Spencer were so ‘poorly made’ that the lenses were likely to drop out.
Which? advises people who have a prescription above +2 to test reading glasses for two minutes to check the centre points of each lens are aligned correctly.
Opticians say eye examinations are essential before buying glasses.
As well as ensuring the correct prescription is used, they can detect serious health issues, such as cataracts and brain tumours.