London - Do you find car headlights blinding? Road safety campaigners say the problem has been exacerbated by the arrival of modern headlights, such as xenon or high intensity discharge lights which produce a harsh blue light that is typically twice as bright as the old soft yellow halogen versions.
These have been followed by the newer generation of light-emitting diode lights that started to appear in 2006 and are fitted to a lot of new cars.
Glare may make us wince and inadvertently shut our eyes, and can even cause a pain-like reaction "comparable to the pain signal you get when you suddenly over-strain a joint", according to Dr Peter Heilig, a professor of ophthalmology at the University of Vienna.
In March Britain's Royal Automobile Club warned that the brightness of headlights fitted on some new cars could increase the risk of crashes. An RAC report showed that about 15 percent of drivers polled had been involved in a "near miss" after being dazzled by headlights, and 65 percent said they were often dazzled even when headlights were dipped.
The main problem is light scatter. When bright light is shone through an eye’s lens and cornea, some of it gets scattered around the inside of the eye, making images blurred or blank.
According to University College London professor of ophthalmology John Marshall, the effect of glare from modern lights is greater as we grow older. With age, he says, the lens and cornea become less clear.
"At night your pupil opens wider to let in more light," he explained, "nd when your eye meets a headlamp you get more scatter and can’t see."
Ten-second blind spot
Research has found it can take 10 seconds to recover from the glare of modern headlights - that's 166 metres at 60km/h.
But industry association The Society of Motor Manufacturers and Traders has said there is no evidence that factory-fitted high-power lights distract drivers. Headlight-levelling technology ensures they are safe, it insists, adding that they are important on poorly lit roads.
So what can you as a driver do? Experts suggest wearing clear glasses with a UV-absorbent coating, available from opticians, when driving at night.