Health effects of 3D
Some viewers have（1）of headaches and eyestrain after watching 3D films. Motion sickness, in addition to other health concerns, are more easily induced by 3D presentations. One published study shows that of those who watch 3D films, nearly 55% experience varying levels of headaches, nausea and disorientation.
There are two primary effects of 3D film that are（2）for human vision: crosstalk between the eyes, caused by imperfect image separation, and the（3）between convergence and accommodation, caused by the difference between an object's perceived position in front of or behind the screen and the real origin of that light on the screen.
It is believed that approximately 12% of people are unable to properly see3D（4） due to a variety of medical conditions. According to another experiment up to 30% of people have very weak stereoscopic vision preventing them（5）depth perception based on stereo disparity. This nullifies or greatly decreases immersion effects of digital stereo to them.
