Seeing red on sunnies that don't see blue

If the proposals are adopted, warning labels that deem many sunglasses with deep red, yellow and brown tints as unsuitable for driving, would have to be dropped.

Stephen Dain, a University of NSW professor and former head of the School of Optometry and Vision Science, has vowed to resist the changes.

Under Australian standards, sunglasses that block more than 30 per cent of blue light from reaching the eye must be labelled as unsuitable for driving.

The reason, Professor Dain said, was that green traffic signals are green-blue - because blue is easier for "colour-deficient" motorists to recognise.

"Roughly 8 per cent of the male population has some colour deficiency," he said. About one in 200 women has problems.

However deeper red-, yellow- and brown-tinted glasses, popular because they block glare from blue skies, also absorb the blue light in green traffic signals.

For five years a working group of the international body that sets standards has been debating new sunglass guidelines.

European countries, Professor Dain said, out to avoid imposing restrictions on manufacturers that could hamper sales, want an international standard allowing sunglasses transparent to just 60 per cent of blue light to be sold without warning labels.

However, Australia's delegation is refusing to accept anything less than the existing national standard. "We think we have it right," the professor said.

He has published research suggesting that even the local standards are too low.

In his study 49 colour-deficient males and 20 with normal vision were given various tinted sunglasses and asked to identify colours of simulated traffic lights.

About 20 per cent of colour-deficient subjects wearing tinted glasses could not correctly identify the lights.

His report notes that "response times for colour-deficient people were slower than colour normals for red and yellow" lights.