It depends on the content ;). We once interviewed experts principle to 3D videos:
By unilateral actions, such as eg. work on the computer is missing the human eye variety, which is given more in a normal, varied work by different local and tele vision. Of the eye muscles, the optic nerve and related brain processes lacking a regular workout. Short-sightedness can be the result.
Watching 3D applications compels the human eye to a different, unusual perception and thereby provokes a change of focus points. These unusual efforts can lead to irritation. Regular use trains the visual organs. The irritation leaves after a short time.