1. Monitor should be arms length away. 2. Brightness should conform to the light in the room. 3. Try to get a good bit of ambient light from the side (via a lamp or window). 4. Keep eyes at a 10-15° downward angle on the monitor. 5. Take a break every hour and let your eyes rest for a second. 6. If you have glasses, wear them.
Those six principles will go a long way toward keeping your eyes happy!
When nobody is around I swap the glasses for a pair of geeky plastic amber lab protection, which block more blue light than any other solution. Sure, the OS or flux, for example, can block some, but a physical solution is reliable.
The glasses are "hit and miss" with the blue blocking. I don't know if the process is partially manual, but the amount of blue light that gets blocked is not always the same between two pair from the same manufacturer. Different manufacturers use different technologies to block the blue, some of which block almost nothing.
Once I got a pair that blocked enough blue light, though, I really noticed a difference in eye-strain and length of time I could look at the monitor. The cheapest and best, strangely, is the plastic amber lab eye covering. Those block far more than any other pair of glasses and work the best for me.
Make sure to also sit up straight, not hunched or slouched, with the keyboard near the torso (the close side maybe half a foot from the belly), and upper arms hanging loosely at the sides. The palms/forearms should be free floating, not resting on any surface. At all costs keep the wrists as straight as possible. Typing should be light and springy.
Adjust the tilt of the keyboard so that its surface is approximately parallel with the forearms. A split keyboard which is tented even a little bit upward toward the middle and turned a bit so that the far side points inward relieves quite a bit of strain by reducing wrist pronation, but is not strictly necessary.
Unfortunately there hasn’t really been very much large-scale, carefully scoped and controlled, properly conducted/analyzed, anatomically motivated study of keyboard ergonomics. That is, there have been a large number of research studies but almost all of them were garbage for one reason or another. As a result many of the most important conclusions about proper typing style can best be discovered by reading directly about anatomy, investigating proper technique for other tools, and doing careful personal experimentation/analysis. Reading keyboard-specific ergonomics literature does not necessarily lead to healthy recommendations or physical keyboard designs.
Maybe this is because I wear glasses and don't move my eyes much (tend to move whole head when shifting gaze because looking through center of glasses works best), but when my monitor is low, it eventually causes strain on my neck and shoulders. It also causes me to slouch a lot as I try to fix the positioning subconsciously.
Before I had a monitor with a riseable base, I used to put my monitor on a book or two.
Put the display on an VESA mount attached to an articulating arm and put the bottom of the display bezel directly on the table or slightly above. Maybe if you have a 40 inch display it starts getting tough.
Up-down, I move my head almost immediately.
My understanding is that glasses have an optimal viewing angle centered around your pupils where your perscription is perfect. As you start looking through different parts of the lens, it gets less perfect. At extreme angles you start seeing the frames themselves and it's annoying.
Lenses: Essilor “Eyezen+ 0” CR-39 lens+AR is ~$120 online or Zeiss Individual SV ~$300. If you have prescription with sphere stronger than -3, the improvement in peripheral vision can be useful for large or multiple monitors.
Is that for people who need glasses but don't wear them, or wear corrective lenses (of some sort) all the time but really should use glasses because there somehow better?
Seriously, I want to know, being the latter part.
You want to avoid focus-locking the eyes to a single distance. It’s better to have the monitor further away so there are other objects in your field of vision, preferably more distant than the monitor.