The general instruction to be followed at computer work are noted below
If the chair height is right for your leg to reach, a leg ret is not needed.
Always sit back in the chair to give full spine and shoulder support.
The armrest of the chair should be close to the body.
Ensure you have a lower back support when you are seated at the monitor.
The leg should not be folded behind the base of the chair.
The keyboard height should not be raised(the wrist angle should be kept in mind).
A keypad and mouse rest will be comfortable for wrist position.
Maintain a distance of at least 60cm from the monitor for comfortable eye functioning.
Glare due to reflected light on the monitor or on the eye should be eliminated.
Indirect lighting is the best for computer workrooms as glare is minimal
Glare in your screen will spoil your eyes.
Blinking of eyes: 15 time / min
Break: 1 minute for every 20 min work