How cheap sunglasses can leave you with double vision and headaches

Uh-oh! We know sunglasses are one of those cheap accessories but as I said before, they're concerning your eyes, 80% of your knowledge so you can NEVER BARGAIN FOR IT!
Taken fron DailyMail
http://www.dailymail.co.uk/health/article-2027260/How-cheap-sunglasses-leave-double-vision-headaches.html


Cheap sunglasses may look like a bargain, but could leave you seeing double or developing headaches.

Even those costing £5 from high street names such as Tesco and M&S failed some lab tests, breaching British Standard quality markers, according to consumer group Which?

It tested three pairs of sunglasses bought from each of seven stores – Asda, M&S, New Look, Poundland, Primark, Sainsbury’s and Tesco – all costing between £1 and £5.

Fifteen pairs failed key tests and only the three from New Look passed everything.
All three pairs from Poundland had what opticians call a vertical prism in the lenses.
Present in some prescription glasses, it has the effect of bending light and can cause double vision or headaches in some wearers.

One pair was labelled good for driving when the lenses were too dark for such use.

A £1 pair from Primark had lenses containing optical power – in other words acting like prescription lenses – and each lens let in different amounts of light.
The Primark glasses could make vision problems such as astigmatism worse, said Which?
A pair of £5 sunglasses from Tesco and one from Asda had one lens different to the other, while several sunglasses let in different amounts of light in each lens.

Which? health expert Joanna Pearl said: ‘While these problems would not cause long-term vision damage, they are not pleasant, and glasses must comply with the British Standard they claim to meet.’

Those buying sunglasses should check for the CE mark, which is mandatory on products approved for sale within the EU, and the British Standard number 1836:2005.

Asda, M&S, Sainsbury’s and Tesco insisted their sunglasses were tested to British Standards, with the latter three disputing the Which? findings.
Asda and Poundland said they would be investigating immediately while Primark declined to comment.

A second probe by Which? found those with the most serious eye conditions received the worst service from opticians.
Of 40 branches of chains and some small independents visited, a third were judged not up to scratch.