CNET reader Jerry asks:
I recently bought a 40-inch LED LCD. I like it a lot, but over the past few months I've noticed my eyes hurt after watching the TV. Mostly it seems to happen at night. This can't be normal, right? Before I spend money on an eye doctor (I've never been), I figured I'd ask if there was something about the TV that was causing it. I never had this problem with my old TV.An interesting, and surprisingly common question.
Let me say, up front, I am not a doctor. I have, however, talked to doctors. Most are very nice, and in the case of this article, very helpful.
Eye strain while watching TV is pretty common, but if you're experiencing it you should absolutely talk to a eye doctor to make sure there's nothing else wrong. Presuming your eyes and head are fine, that leaves the TV.
One of the most common causes of eye strain is watching a small, bright object in an otherwise dark room. Because the room is otherwise dark, your irises are wide open, allowing lots of light to enter. The TV, being a small percentage of your overall field of view, doesn't cause your irises to close as much as they should. To put it another way, if everything in the room was radiating 80 foot-lamberts, your irises would be much more closed then when the room is totally dark and only the TV is radiating 80 foot-lamberts. That "pinpoint" of light in the darkness can be causing your eye/headaches. It can also lead to viewer fatigue, where there isn't sharp pain, just a overall tiredness of the eyes.
Other possible factors, like focusing too strongly on one spot, is less easy to fix. All I can do, as a Not-a-Doctor, is help with the TV. Hopefully one of the ideas below will give you some relief.
Stage 1: Easy
Nearly all LCDs have a backlight adjustment. You can lower the overall light output by reducing the backlight control. If you've never adjusted this setting, as set from the factory, it's probably at or near the top of its range. Reducing this at night will make the TV far easier to watch. It will also improve the black levels, making the picture look a little better as an added bonus (note, this doesn't actually increase the contrast ratio).
If your TV doesn't have a backlight control, you'll have to move on to Stage 2.
If you're having eye strain and have a plasma TV, try lowering the Contrast control. In terms of light output, this control does next to nothing for LCDs, but will make a plasma dimmer. On newer Samsung plasma TVs, there's a control called Cell Light, which acts similar to a backlight control, lowering (or increasing) total light output.
Stage 2: Less easy
The most obvious way to combat the kind of eye strain/eye fatigue we're talking about is leaving the room lights on. I mention this as a Stage 2 option for two reasons: One, I like watching TV in the dark, and two, sometimes due to the placement of room lights, you can get reflections. Check out my article How to rid your HDTV of reflections.
A less severe option is buying or building a bias light. This is a neutral gray light that you place behind the television. It increases the average light in the room by a small amount, but does so without affecting the apparent color accuracy of your television. There are a bunch of how-tos on the Web for building your own, or you can get one from CinemaQuest.
Stage 3: Least easy/most fun
You need to go bigger. This may seem counterintuitive, but a larger screen helps by taking up much more of your field of view. It's also likely that a larger television will be a higher end model that will have a backlight control, or be a plasma which likely won't be as bright. Either way, your eyes won't be as unhappy with the difference between the dark background and the TV. For one thing, there's less "background." This is especially true if you go with my last recommendation:
Get a front projector! As I discuss in my Don't buy a jumbo LCD TV, buy a projector article, projectors aren't that expensive, and can be installed in most rooms. If you're worried about being able to see the screen during the day, you can keep your current LED LCD, and install a drop-down screen for nighttime watching.
This is, of course, the option to consider last. Or first, if you don't mind the idea of a 100-inch TV screen...
Got a question for Geoff? Click "Geoffrey Morrison" below then click the E-mail link in the upper right to e-mail, wait for it...Geoffrey Morrison! If it's witty, amusing, and/or a good question, you may just see it in a post just like this one. No, I won't tell you what TV to buy. Yes, I'll probably truncate and/or clean up your e-mail. You can also send me a message on Twitter: @TechWriterGeoff.