display - What monitor specifications should be taken into consideration to avoid eye problems?

I spent 8 to 10 hours a day programming on my 13.3" laptop and developed symptoms like red eyes, blurred vision, dry eyes, pain and irritation. To understand the cause of problem I visited a eye specialist and he diagnosed CVS. Now he suggested some exercises, medication, right posture, correct chair height etc. in addition he advice having a bigger Computer display (for bigger font size.)

Buying a bigger screen was on my card for sometime and doctor's advice made it a immediate priority. So I started googling trying to understand what should I consider before buying a monitor.

I could only zero down on the size (20") and LED.

I am looking for suggestions from fellow programmers who spend considerable time in front of their screens what factors like resolution, pixel density, panel technology, display colors and so forth they have taken into consideration before making their choices.

P.S

1. I am not looking for advice on CVS.
2. I am looking for answers focused on best display technology (computer monitor) for programmers (people having prolonged exposure to display screen)

Well, here are a few points to consider:

1. How big do I want my screen to be?
   Up to 17" is good for single tasks. More is usually when you do CAD or if you use multiple programs at the same time. E.g. have a programming environment open + the relevant manual pages next to it.

2. Do I want one screen or two? This is mostly a personal choice. People who tend to put applications full screen usually want two monitors so they can work with two programs. People who know the advanced skill of resizing a window might be better off with a single big screen.

3. How fine do I want my screen content to be? (In pixels per inch).

4. What vertical resolution do I want? (Alternative: How much do I want to avoid scrolling. Personally I always go for 1200 pixels vertical resolution on 24" screens).

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5. How well does it need to display colours?

6. From which angle will I look at the display and will I rotate the screen a quarter?

   There are three ways of building a modern display panel. All three have different patterns matching the above three questions.

   There are TN panels. These are relative cheap to build. They refresh quickly (good for games and movies). They also have relative poor viewing angles. Neither of these matter if you sit behind one and use it for coding. It you put a TN monitor to the side (e.g. as a second monitor containing documentation) or if you rotate it (or both to get a A4/paper format monitor next to you) then it gets harder to read.

   Other panels on the market are based on IPS. This is more expensive, but yields good colours (important in design) and has excellent viewing angles.

   A third panel method is PVA. I do not know enough of this technology and I rarely see them on the market.

   Summary: think about points 5 and 6. Then decide on TN or IPS based displays.

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7. Monitor features: Does to monitor have a stand which allows it to change height?

8. Monitor features: Does to monitor have a stand which allows it to rotate?

9. Connectivity: (Ancient VGA? DVI? Display port? HDMI)?

   • VGA: VGA is old: Do not bother with this on any modern monitor.
   • DVI: Replaced VGA. Works up to resolutions of 1920x1200. Check carefully if you use higher resolutions than that.
   • DisplayPort: Current interface: Replaced DVI. Works perfectly.
   • HDMI: Basically DVI+sound+DRM. Sometimes the DRM kicks in, which is why I prefer displayport over HDMI. Both should be the same qua performance.
     
   • Thunderport: DisplayPort and an external PCIe line in one. Very cool stuff, but rather new, still rare and still expensive. (People reading this after 2012 will probably laugh and smile and say prices went down over time).

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10. LED or Fluorescent?
    There are a few small lamps in the rear of your monitor. Usually these are small TL tubes. Some modern ones use LEDs. These LEDs use less power, but can only be turned on or off. To effectively dim them they are rapidly powered on and off via a method called pulse width modulation. This pulsing is said to irritate some people. For more information on that, see this site. (It is way too much text to paste here).

11. Last but not least: Price. How much do you want to spend?

I am sure there are a few more points which I missed. But this is a start. :)

Instead of buying a new monitor, there are a few things that you can do right now to improve comfort, just through configuring your environment and monitor settings. I've done combinations of these things both for my own self (I'm a verification engineer and am staring at computer screens all day, myself), and my parents (my mother has eye problems and can't see small details very easily).

Things you can do:

1. Change the brightness of the elements on your screen. If you're working in a text editor a lot, chances are that you're staring at a big block of mostly white for many hours in the day. This tires your eyes out quite easily. It's better to keep most things (like the background) dim and only highlight the things you need to see. That means choose a dark scheme for the programs you're using often, desktop background, and window borders. Less stimulation of your optical nerves mean they can relax more and are able to work more efficiently when actually needed. It's similar in concept to how after a while you stop recognizing a smell if it's persistent, because the nerves are being constantly stimulated and accomodate, to expend less energy. Similarly, try raising/lowering the brightness of your monitor until you reach a comfortable level. If your ambient light is dim, then you want to dim the computer monitor accordingly. If it's bright, then raise the brightness. Bring the contrast up too only enough that you can easily distinguish details on your screen. You don't want to be squinting or staring too hard to see what you need. But you also don't want to have the equivalent of a lightbulb shining directly at your face. With lots of very bright small details on a very dark background, your eyes have difficulty adjusting, which can lead to eyestrain.

2. Change the color balance of your screen You can do this through Windows, to a degree, but this is best configured on the monitor itself. It is much easier for your eyes to distinguish colors closer to the red-orange-yellow side of the spectrum, than blues. This is simply because you have more receptors in your eyes for yellow than blue. This can be demonstrated by using a cell phone in a very dark room that illuminates the keypad with blue LEDs, and comparing it to one that uses a different color. The blues are harder to focus on. So, try changing your monitor color profile to "warm" or something that has less blue and more orange/yellow. Similarly, avoid using blues a lot on your screen when configuring your environment's color schemes. This actually cuts down on eye fatigue quite a bit.

3. Change the size of your on-screen elements Many people will just lower the resolution, but I prefer to use the OS settings to change text and on-screen element size. This way, you will still see things zoomed in, but you won't get the blockiness that comes with zooming in pixels individually. Curves and text will be larger and remain crisp, so details will be more distinguishable.

4. Don't sit too close to the screen If you can, put your monitor as far away as is comfortable. When it's close, your eyes have to work harder to focus on it. This can aggravate conditions like near-sightedness and contributes to eyestrain, as well.

5. Increase your refresh rate Eyestrain due to low refresh rate is more easily apparant in CRT displays, because the flicker was more noticeable due to the way they operate. However, it still is something that can play a role even in LCD displays. The refresh rate controls how quickly the image on your screen refreshes, or updates. On a CRT display, 60 Hz was considered the bare minimum, though at that point you would also begin seeing flicker. I usually would recommend bumping it up to at least 75 or 85 Hz on a CRT monitor. LCD displays are a bit more forgiving, as there isn't flicker so much as "choppiness" in the image as it moves. The default in most monitors is 60 Hz, and usually you can't go higher than that. However, if you can, try and put it to 120 Hz. Movement on the screen is much smoother and more natural. Your eyes will thank you for it.

6. Enable desktop composition By this, I am referring to things like Aero in Windows 7, or Compiz on Linux. I believe Mac OSX has it on by default, all the time (I'm not sure, however, since I don't own one). Aside from giving you eye candy, it makes changes on the screen due to window movement and opening/closing dialogs and windows smoother. Both Aero and Compiz can have opening/closing windows and other screen elements fade in and out instead of just popping in and out instantly. This is less of a shock to your eyes, especially if you have a dark screen and a white window suddenly opens. Also, because you're using your GPU to draw the screen instead of the CPU, screen elements will draw more smoothly and you won't get things like image tearing or partial renders.

7. Take occasional breaks! You don't want to be staring at the same thing for too long. Look around often, get up and walk a bit. This is good for you for multiple reasons, but getting away from the computer and letting your eyes relax and focus on objects at various distances can help keep them from getting tired and strained.