staring at anything for long periods of time can cause eye fatigue but not necessarily eye damage. i remember my own parents in the mid-1950's telling me that if i sat too close to the television that it would damage my eyes and i would need glasses (of course i did end up with glasses but not from the television). i don't believe there are going to be any adverse health hazards including vision damage from 3d gaming but as a parent i would advise you to limit the amount of time that kids spend in front of the computer screen. set the parameters up front and stick to it. children need to spend time playing outside playing with friends playing sports reading and using their active imaginations. video games sort of take that away. and finally carefully monitor the type of games the children are playing. play with them in order to see what you have just bought. games filled with violence killing high-speed car crashes raises their adrenalin levels and causes stress. they also do not set good or real examples of the world outside.
my 8 yr. old son wants a nintendo 3ds. i have heard that the 3d games are not good for children's eyes. is that true?