Contrary to popular opinion, the ideal position for your computer monitor is not at or below eye level. This is not a normal position for your neck.
The long term effects of abnormal posture can be devastating. The impact of spinal degeneration on your ability to function normally at work, at play or even in your relationships with others can be a significant limitation. 
In severe cases it can stop you from performing at all.
Position your monitor at a height where the middle of the screen is slightly above eye level.
This will allow your head and neck to be positioned at or near the ideal position the majority of the time.
Not only will this allow you to concentrate better, and to focus on the task at hand, but it will minimize the stress and strain upon all of your spinal tissues and reduce abnormal stress and strain upon the neck and shoulder muscles.
Make sure your spine rests firmly against the back rest and your legs are at right angles to the floor. Your feet should be able to touch to floor.
Normalizing your spinal posture while working on your computer is just one more way to improve your overall health.
Studies have shown that this will help your abnormal spinal position improve more rapidly, and will enable you to reduce stress on your spine, and therefore avoid a re-occurrence of postural spinal subluxation.
Avoidance of any abnormal spinal positions is most important to optimize your body function.
Remember, optimal posture is a major part of optimal health. Optimal health keeps all of your options open in life.
Complete Chiropractic St Albans, First Floor, 15 High Street, St Albans   Herts AL3 4EH  Ph. 01727 848 481