Shades keep eyes on the road

PUBLISHED : Friday, 15 October, 2010, 12:00am
UPDATED : Friday, 15 October, 2010, 12:00am

Hong Kong drivers are already shading their eyes from the winter sun as the days get shorter. Tomorrow's sunrise will be at 6.20am and sunset will be at 5.58pm, according to the Hong Kong Observatory. Next Saturday, the sun will rise three minutes later and set six minutes earlier, and that means over the next few weeks you could commute to and from work when the sun's dazzle is at its meanest: low over your dashboard, into your eyes and affecting your traffic judgment.

Sunglasses help combat that rush-hour glare. The best are designed to reduce the light reaching the eye and protect it from ultraviolet (UV) light which causes damage to the cornea, lens and retina, says Dr Henry Chan, chief of the Optometry Clinic at the Polytechnic University's school of optometry. The lenses should 'minimise glare, and provide drivers with comfortable vision and good colour discrimination', he says.

Polarised glasses reduce the sun's glare and block much of the reflected dazzle from the road, skyscraper glass and other cars. Mirrored lenses reflect light from the eyes, while impact-resistant lenses are less likely to be shattered by road grit, an insect at high speed or a crash.

'In a collision, the glasses may be broken resulting in eye injuries,' says pathologist Dr Mong Hoi-keung, chairman of the Institute of Advanced Motorists in Hong Kong. 'It pays to invest in a pair of shatter-proof glasses just like when you play squash.'

Drivers 'should choose sunglasses with lenses dark enough [about 70 per cent or higher] to block unwanted light; the lenses should also block UV [light]', says optometrist Tony Chung, of the Hong Kong Optometric Services. Sunglasses also have to fit properly to prevent them from slipping and to minimise light bypassing around the lenses.

Go for a comfortable fit, Chung says, adding wraparound lenses can counter stray light or glare from the sides. But thick, logo-laden frames could create peripheral blind spots wherever you look. And lens colours are important. 'On sunny days, brown or grey are the best [because they] cause the least colour distortion' and yellow tints could enhance contrast in mist, Chung says.

Sunglass makers Bolle, Gargoyles, Maui Jim and Serengeti have lines just for drivers, and Austrian shades maker Estede launched an Euro11,500 (HK$124,572) platinum pair for Bentley at this month's Paris Motor Show. Local Porsche, BMW and Mercedes-Benz dealers also offer driving sunglasses, and you can purchase pairs online from firms such as

Some online services offer glasses for night driving, but Chan advises against their use. 'Wearing sunglasses for night driving would reduce the sensitivity of our visual system and slow drivers' response times,' he says. 'This would cause an accident.'