It's clear, all glasses protect your eyes

ANNA PEARSON
Last updated 05:00 03/02/2014
Pterygium
SUPPLIED

REAL DANGER: Pterygium – an eye disease caused by sunlight exposure.

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A pair of clear glasses can protect your eyes from UV damage just as much as a pair of tinted sunnies, according to Christchurch specialists, and you need not spend a week's wages on an expensive pair.

Southern Eye Specialists ophthalmologist Dr James Borthwick says most sunglasses filter close to 100 per cent of harmful UV rays, regardless of price.

The Press found sunglasses for $14.95 at Cotton On in Westfield Riccarton, or two pairs for $20, and ones for upwards of $800 at the Sunglass Hut in the same mall.

Borthwick says most glasses sold in New Zealand should adhere to the Australian and New Zealand standards for sunglasses. A label on the sunglasses at Cotton On said they complied.

Exposure to sunlight can lead to diseases such as pterygium, an overgrowth of tissue from the white of the eye onto the cornea.

There is also "a strong association" between sunlight exposure and cataract formation.

"Between the cornea and the lens of the eye, only 1-2 per cent of harmful ultra violet radiation reaches the retina, however, because the cornea and lens absorb these wave lengths, they are associated with disease such as pterygium on the cornea and cataract formation of the lens."

Borthwick says sunglasses not only protect people's eyes, but the risk of skin cancer to the eyelid is also increased with UV exposure.

Most clear polycarbonate lenses remove close to 100 per cent of ultraviolet light, even without tinting.

"A clear lens will be giving you protection, but obviously people are also wearing sunglasses for reduction of glare and for comfort."

A Consumer NZ report on sunglasses in 2011 concluded people did not have to spend "big bucks" to buy good protection against UV.

Consumer NZ adviser Maggie Edwards says it tested sunglasses in 2007 in "a real effort to find glasses that would be likely to be dodgy - from $2 Shops and the like - and tested them to the Australian/New Zealand standard".

All of the glasses it tested provided adequate protection against UV, but some were not suitable for driving due to lens distortions. Edwards says the tint of some sunglasses might also affect colour perception in people who are colour blind.

"It is easy to find cheap sunglasses that are labelled as complying with the standard and are perfectly suitable for people with normal vision," she says.

Borthwick says when buying expensive designer sunglasses, people are "paying for the brand".

"You are often paying for the look - the name and the frame, but not always high quality lenses. Buying a reputable brand manufactured by a company that has a history of sunglass manufacturing should guarantee high quality optical lenses with a guarantee of good light filtering."

Borthwick says "in theory" sunglasses bought at a market on the street, "should not be any different". However, it is "a bit like buying DVDs in a market - you cannot rely on the quality".

"I am not sure that wearing cheap glasses can cause more damage, but it is fair to say that fashion spectacles - particularly those that are graduated tint - may offer less protection."

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Christchurch optometrist John Veale, of Merivale Optical, says a climbing experience 20 years ago "confirmed to me the protection of clear optical plastic lenses".

Veale says he and a friend left Christchurch to climb Mt Rolleston on a cloudy day and did not pack sunglasses. After about three or four hours climbing, they found themselves above the cloud and surrounded by highly-reflective snow.

"I had my ordinary, clear spectacles on and my climbing companion had nothing. We climbed the mountain, which took another three or four hours, and came back down. He had snow blindness and I did not.

"Snow blindness is just sunburn of the epithelium - the thin skin on the front of your cornea," he says.

In saying that, Veale has a pair of $2 sunnies, which he leaves in his car, "and the optical quality is s . . . ".

"They blur my vision. The more you pay, the better quality of the optics."

- The Press

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