LED Cat's eyes trigger epileptic fits

**Stuart** · 03-01-2007, 11:10

New, solar powered LED cats eyes can possibly cause epileptic fits.

The LEDS flash about 100 times a second, and it may be this that causes the fits.

The Highways Agency was alerted by Rebecca Jasiczak that she suffered a mild siezure while driving along the A12 in Essex, and has suspended new installations while it investigates the potential effect on Epilepsy sufferers.

http://www.theregister.co.uk/2007/01/03/led_cats_eyes/

danielf · 03-01-2007, 11:19

Seems a bit strange, as generally the frequency range that triggers fits is quite a bit lower than 100 Hz. 100 Hz is quite a bit. Twice the frequency of AC current...

Quote:

What frequency of flashing light is most likely to trigger a seizure?

This varies from person to person. Generally, it is between 5 and 30 flashes per second (hertz). While some people are sensitive at higher frequencies, it is uncommon to have photosensitivity below 5 hertz.

http://www.epilepsynse.org.uk/pages/...oto.cfm#lights

Mind you, it could just be a coincidence that this woman had a near fit.

**Hugh** · 03-01-2007, 11:49

Quote:

Originally Posted by Stuart C

New, solar powered LED cats eyes can possibly cause epileptic fits.

The LEDS flash about 100 times a second, and it may be this that causes the fits.

The Highways Agency was alerted by Rebecca Jasiczak that she suffered a mild siezure while driving along the A12 in Essex, and has suspended new installations while it investigates the potential effect on Epilepsy sufferers.

http://www.theregister.co.uk/2007/01/03/led_cats_eyes/

In fact, it says "she "narrowly avoided a seizure" - so the new cats-eyes may have nearly caused a fit?

Another link linky - the article above makes it sound as if she was driving, but this article states she was a passenger.
"Sue Jasiczak, 51, complained that driving past the new lights on the A12 at Witham, Essex, produced a strobe effect, which almost triggered her 17-year-old daughter Rebecca's epilepsy. She said: 'We were driving home one night when she suddenly looked away and closed her eyes. 'She said the white lights had a strobing effect and she could sense her eyes beginning to be affected. She is very aware of the warning signs and this was definitely the case in this instance."

altis · 03-01-2007, 11:57

There's some on the A590 near Newby Bridge in the lakes. If you turn your headlights off they carry on flashing for a while. The flashing is quite noticable and I'd guess it's much slower than 100Hz.

I remember reading about these in a Microchip newsletter - they have a PIC microcontroller inside. They are solar powered and, to save power, turn the LEDs off when there are no cars about. They can even change the colour when conditions are icy. I imagine they flash so they can talk to each other to say a car is coming.

**Stuart** · 03-01-2007, 12:05

Quote:

Originally Posted by danielf

Seems a bit strange, as generally the frequency range that triggers fits is quite a bit lower than 100 Hz. 100 Hz is quite a bit. Twice the frequency of AC current...

http://www.epilepsynse.org.uk/pages/...oto.cfm#lights

Mind you, it could just be a coincidence that this woman had a near fit.

True. Flashing at 100Hz should be barely noticable for most people. I suppose it is possible that some people are sensitve to higher frequencies.

Paul · 03-01-2007, 12:14

Or the near seizure was induced another way? Who knows what happened but hopefully the Highways agency will fully investigate it before continuing.... at the very least it will cut down the number of cones on the road for a while

Wicked_and_Crazy · 03-01-2007, 12:20

given that a lot monitors run at between 60-80 Hz i wouldnt have thought 100 Hz would be a problem

danielf · 03-01-2007, 12:27

Quote:

Originally Posted by Wicked_and_Crazy

given that a lot monitors run at between 60-80 Hz i wouldnt have thought 100 Hz would be a problem

In the link I posted earlier there are some tips for preventing photosensitive type fits as well. One of them is to buy a 100Hz telly rather than the standard 50Hz ones...

However, others have mentioned the flashing is noticeable, so perhaps the 100 Hz claim isn't accurate. But also, the near fit reported may be completely unrelated to the lights.

Escapee · 03-01-2007, 19:05

Quote:

Originally Posted by Stuart C

True. Flashing at 100Hz should be barely noticable for most people. I suppose it is possible that some people are sensitve to higher frequencies.

I know that (before my time) my grandfather lived in a small village not far from where I live in Pontypool, I guess it was back in the late 40's or 50's, and they had their power supplied from the colliery generator.

The generator was 25Hz (cycles in those days

) and he said after spending a few days at relatives in other areas, he would come home and feel sick because the light was constantly flashing for a few hours. (I know it would probably be more prominent at 50-25Hz as opposed to 100-50Hz)

So I guess it is possible that we get used to the 50Hz flash, the same as my grandfather was used to the 25Hz flash. Could it just be that people who suffer epilepsy do not have the ability to get used to the flashing?

makes me feel sorry for that poor ntl customer I put a stop to who was getting free service because the picture was causing him epelectic fits, funny though he was quite happy to watch it for free and CS were stupid enough to give him free service.