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#71904 - 08/24/06 04:30 AM Do "cool" lights hurt your eyes?
Ors Offline
Namu (Giant Tree)

Registered: 09/16/05
Posts: 663
Loc: Florida, USA
A couple of weeks ago I was thrilled to find compact flourescent bulbs that emit white light. I've had incandescent bulbs that emit white light, and I really like the way the colors contrast with these lights.

That night, I put one of the new bulbs in the reading lamp beside my bed and read with it. After a while, my eyes started to hurt. I ended up putting one in the bathroom too, and replaced one of three lights in our bedroom ceiling fan. When I put one in the living room lamp, again, my eyes hurt.

DW said it hurt her eyes too, and asked for them to change them back.

After a while, my eyes didn't hurt any more. I still haven't changed any other bulbs for fear of the eye strain again.

Has anything like this happened to anyone else? Any ideas why it happens?
Memento mori
Vulnerant omnes, ultima necat (They all wound, the last kills)

#71905 - 08/24/06 04:38 AM Re: Do "cool" lights hurt your eyes?
ironraven Offline
Cranky Geek
Carpal Tunnel

Registered: 09/08/05
Posts: 4642
Loc: Vermont
Florescents flicker. It's very fast, most people's brains just filter it out, but even if you don't "see" it, your eye does.

When a man dare not speak without malice for fear of giving insult, that is when truth starts to die. Truth is the truest freedom.

#71906 - 08/24/06 05:34 AM Re: Do "cool" lights hurt your eyes?
anotherinkling Offline

Registered: 03/09/05
Posts: 109
Loc: Chicago
It's referred to as photo-pattern sensitivity, pattern sensitivity or a form of photosensitivity. I have it too. Fluorescents drive me a little batty after a while. My neurologist says it's fairly common in epileptics and affects about 5% of the general population. You can buy switches for fluorescents that keep them from flickering (not sure of the exact technology there), but they are very pricey (as in hundreds). I find that it's worse if the flourescent's the only light in the room. If there's a bit of sunshine coming in the windows, it's not nearly so bad.

#71907 - 08/24/06 08:25 AM Re: Do "cool" lights hurt your eyes?
pteron Offline

Registered: 10/01/01
Posts: 59
Loc: UK
Standard fluorescent lights flicker at 2 times the mains frequency, so 100Hz here, 120Hz there. The little battery powered ones will flicker at whatever frequency the inverter that drives them is running at. One theory is that people get headaches from them because the muscles of the iris are able to follow the flickering.

Some companies now make high frequency fuorescent drivers, often 20kHz or more - these are much better on the eyes.

#71908 - 08/24/06 10:32 AM Re: Do "cool" lights hurt your eyes?
redflare Offline

Registered: 12/25/05
Posts: 647
Loc: SF Bay Area, CA
I use "full spectrum" incandecent lights in all the rooms I spend a lot of time in (living, dining, bedroom). They provide this more "natural" light.
I put fluorescent into bathrooms and kitchen, since I am only there for a short period each day.

#71909 - 08/24/06 05:07 PM Re: Do "cool" lights hurt your eyes?
Simon Offline

Registered: 04/24/06
Posts: 398
Loc: Tennessee
The photosensitivity takes both eyes being used to take effect. It has to do with the optic nerve. Close one eye or use an eye patch and it could be alleviated. This is a pain in the butt though and is too annoying. I have photosensitive epilepsy and have the same problem with computer monitor flicker. About 3 % of persons with epilepsy experience this. Gee, my luck. I have gone the route (which is also cheaper) of using a video-out card and use a tv for a monitor to alleviate the flicker problem. Regular computer monitors will give me simple-partial seizures within five minutes of when I start using them.

This is not limited to just flourescent lights and computer monitors though. NBA basketball, 3D video game commercials on tv, backwards "spinning wheels" on people's cars nowadays. There are numerous things that trigger it for me.
Me, a vegetarian? My set of teeth came with canines.

#71910 - 08/24/06 07:39 PM Re: Do "cool" lights hurt your eyes?
massacre Offline
Old Hand

Registered: 12/07/05
Posts: 781
Loc: Central Illinois
Try LCDs instead of CRTs. You can watch TV on them as well. No flicker. In my office, I use a lamp stand that directs the light to the ceiling and then it's reflected down. Those are fluorescent bulbs and casting them off a surface seems to help a bit. They do this in some buildings instead of aiming the long bulbs directly down on your desk. If it hits different surfaces and has a diffuser it doesn't "seem" to flicker as much.
Experience is a hard teacher because she gives the test first, the lesson afterwards.

#71911 - 08/25/06 12:39 AM Re: Do "cool" lights hurt your eyes?
Simon Offline

Registered: 04/24/06
Posts: 398
Loc: Tennessee
Yep, its in the long-term budget planning {Simon rubs his thumb against his fingers and rolls his eyeballs and sighs--and wishes--and sighs again}
Me, a vegetarian? My set of teeth came with canines.


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