VOA标准英语2010年-Research Shows 3-D Movies, TV Can Caus（在线收听）

Three dimensional movies, like Avatar, are wowing us with their visual display. The science fiction epic Avatar won best drama and top director for filmmaker James Cameron at this year's Golden Globe awards.  But a study at the University of California Berkeley found that 3-D movies can cause eye strain. 

Normally, when we look at things nearby, our eyes converge. They do the opposite when we look at things in the distance.  Martin Banks, a professor of optometry at Berkeley, says 3-D doesn't allow our eyes to follow the rules because we're focusing on things both far and near at the same time.  That's called "vergence accommodation conflict."

"You have to concentrate your eyes to something near, but focus your eyes on something far," said Banks.  "So you have to break that normal coupling between avergence and accommodation."

And it can lead to headaches and blurred vision.

"You're taking that normal relationship which has been coupled in the brain for years and you're changing it. And what we showed is that can cause fatigue," he added.

Banks says younger viewers are more vulnerable.

"When you hit your 50s and 60s, we think that concern is going to be reduced," noted Banks.  "So that is probably more problematic for young adults, teenagers, et cetera."

Banks tells VOA he has spoken with movie producers and they are receptive and willing to make adjustments to reduce the fatigue. But he says while adjustments can minimize the problem, they will not eliminate it.

No matter, 3-D is here to stay. Experts predict that 3-D television will be a major trend in about five years.