快猫短视频

INTENSE flashing lights or rapid colour changes on TV can trigger brain
seizures in some people. But a simple light filter could put a stop to such
seizures and might even replace the drugs some severely affected people take to
prevent them.

The harmful effect of flashing lights on TV was dramatically demonstrated in
1997 when an episode of the Japanese cartoon Pok茅mon triggered
seizures in nearly 700 children. A British advertisement in 1993 triggered three
seizures.

A team led by Yukitoshi Takahashi at Gifu Hospital in Japan has since found
that the majority of TV sets that induced seizures in the Pok茅mon
incident emitted unusually bright long-wavelength red light. This prompted them
to investigate filters that block red light at wavelengths longer than 700
nanometres.

They asked people who are susceptible to seizures to watch patterns of
flashing coloured light on a TV. During this time, the researchers monitored
their brain activity for a telltale early sign of seizure known as the
photoparoxysmal response (PPR). One filter that blocked long-wavelength light,
and cut the overall brightness of the images, reduced the occurrence of PPRs by
95 per cent, says Takahashi. Plastic filters could be used to cover TV screens
or made into goggles, he says.

鈥淭here鈥檚 no doubt in my mind that it works,鈥� says Graham Harding, an expert
on photosensitive epilepsy at Aston University in Birmingham. But he points out
that it鈥檚 hard to know in advance who is susceptible. Three-quarters of the
children who had seizures in the Pok茅mon incident had never had one
before. 鈥淵ou can鈥檛 tell the whole population to wear these spectacles the whole
time they鈥檙e watching television,鈥� he says.

But for people already diagnosed with photosensitive epilepsy, the filter
could provide an alternative to drug therapy. The drug most commonly
prescribed鈥攕odium valproate鈥攈as been linked to birth defects and
disruption of ovarian function. That鈥檚 especially bad news, says Harding,
because the population with the highest incidence of photosensitive seizures are
girls and young women between the ages of 7 and 20. Still, the best way to help
people who don鈥檛 know they have photosensitivity is to regulate broadcasts, he
adds.