Following is the link on the above subject appeared in The Hindu news paper y'day. Sitting in front of computer (desktop/laptop/tablet/smart phone, etc) lead to different kinds of health problems like neck pain, back pain, wrist pain, finger pain, joints pain, shoulder pain, headache, tears from eyes, numbness in bottom limbs, etc.
Some tips on ergonomics issues are provided in the article including taking breaks for every 30-60 minutes for five minutes, looking at distance for every 10 seconds, closing the eyes for 5 minutes for every hour work, etc.
http://www.thehindu.com/features/magazine/boot-up-your-health/article4541693.ece