Epilepsy — certain light frequencies can trigger an epileptic seizure.
I wanted to buy LED torches ( home use) for someone,who has an epilpetic kid . Is there some specifications I should look for whle buying them ??
Also , is it safe to buy a cordless phone ( base + handset) for the same household ??
Indian
This page claims that seizures are most likely to be caused by flashing between 5 and 30 Hz, so you should be fine buying an LED torch so long as it doesn’t come with a “strobe” mode.
Edit: The section 508 guidelines recommend that you avoid frequencies between 2 and 55 Hz, but that still wouldn’t affect the choice of torch as long as it’s non-strobing.
Some LED lights include circuitry that drives the LEDs with brief, high-current pulses - in order to get better performance out of the batteries - I think the frequency of these tends to be rather higher than 50Hz, but I might be wrong about that.
Correct.
LEDs have a maximum current rating. If you go above that rating, the LED burns out. However, you can go above the max current rating if you pulse the LED, provided that the average current of the pulses does not exceed the maximum current of the LED. Even though the average current is the same, the light output appears brighter to the human eye.
In other words, it’s better performance for the same amount of battery life (or better battery life for the same light output, if you want to think of it that way).
Persistence of vision is around 10 to 20 Hz for most folks, so you need to pulse the LED quicker than that or it will noticeably flicker. I can’t speak for every device out there, but most of them pulse at a frequency much higher than 30 Hz.
The cordless phone itself works on radio waves which have no effect at all on epilepsy. My cordless phone has an LED that flashes at a couple of Hz when the phone rings, so that you can tell it’s ringing if the audible ringer is turned off. I don’t know how sensitive an epileptic is going to be to a small LED, but it’s in the right frequency range that you probably should avoid it. Pick out a phone that doesn’t flash and you’ll be fine.
I don’t know how common these are, but I have an LED torch that has an energy saving mode that actually strobes the light, I’d say at around 5 Hz or so.
Will a cellphone have any negative effect on epileptic people ??
IANAN(neurologist) but no, I can’t see why a cellphone would have an effect on epileptics. They certainly don’t bother my wife.
It might cause them to talk loudly in public places.
Actually, it might just be best to ask the household what known triggers their kid has instead of checking with a message board.
Not all people with seizure disorders are photosensitive for example. I’m not. I’m just more likely to have a seizure if I’m off my medication + stressed + tired, but that’s not 100%.
Epilepsy.com has an overview of what provokes seizures, if you want more information. The left column has a list of common triggers that you can read up on, as well.
Thanx for all the inputs . I will check out the website…