It’s not exactly your smart phone’s fault. Although several studies indicate prolonged use of mobile or similar stereo 3-D devices leads everything from visual discomfort to headaches to eye fatigue, a new and very preliminary study reveals they aren’t seeing the full picture.
According to a new a new study, The Zone of Comfort: Predicting Visual Discomfort with Stereo Displays published in the Journal of Vision, the root cause of eye fatigue related to mobile and 3-D devices is the demand on our eyes to focus on the screen and simultaneously adjust to the distance of the content. This is scientifically known as vergence-accommodation.
“When watching stereo 3D displays, the eyes must focus — that is, accommodate — to the distance of the screen because that’s where the light comes from,” Martin S. Banks, professor of optometry and vision science at the University of California, Berkeley and author of the study explains. “At the same time, the eyes must converge to the distance of the stereo content, which may be in front or behind the screen.”
The results obtained from a series of experiments on a small pool of test subjects demonstrated that with mobile devices or even desktop displays viewed at a very short distance, stereo content placed in front of the screen and therefore appearing closer to the viewer, even seeming to emerge into the space in the viewer’s environment was less comfortable than content placed behind the screen and seeming farther away from the viewer. When content was viewed at a longer distance, such as a movie theater screen, the opposite effect was observed. In other words, content that emerges from the screen into the audience’s space was a more comfortable viewing experience that content displayed behind the screen.
If these results are replicated in larger studies, the challenge for 3-D producers and technologists is to balance both comfort levels or to focus their efforts on one type of viewing over the other. The authors do propose guidelines be established for the range of disparities presented, especially with the current explosion of stereo 3D imagery across multiple communications fields from entertainment to medical technology.
“Discomfort associated with viewing Stereo 3D is a major problem that may limit use of the technology,” said Banks. “This is an area of research where basic science meets application and we hope that the science can proceed quickly enough to keep pace with the widespread use of the technology.”