By Nigel Little 

Vision correction  may become necessary for smartphone users who view 3D content on their devices according to latest research on this rapidly growing phenomenon. The first 3D iPad adverts have recently appeared and, as the latest must-have gadgets, they promise users an exciting entertainment experience. But scientists have warned that using smartphones in 3D could damage your vision and give you headaches due to the demand on our eyes to focus on the screen and simultaneously adjust to the distance of the content. The phenomenon is known as 'vergence-accommodation' and experiments found people suffered discomfort when content from mobile phones and other short distance displays appeared in front of the screen rather than behind it.

Optometrist Professor Martin Banks from the University of California said: '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. At the same time, the eyes must converge to the distance of the stereo content, which may be in front of or behind the screen.' Researchers from the University led by Professor Banks observed whether placing the content in front of the screen or behind it affected 24 adult participants. The results demonstrated that with devices like smartphones that are viewed at close quarters, material appearing nearer the viewer was less comfortable than that placed behind the screen. This gives rise to headaches and the eyesight issues which may lead to a need for vision correction .

More and more businesses are embracing the technology, using 3D for adverts on giant screens and cereal boxes, or by helping consumers pick products through an immersive online 3D experience. TVs, cinemas and more recently digital billboards in airports and bus stops have all been bombarding users with three-dimensional content. But a number of reports published recently have indicated that prolonged viewing of mobile devices and other stereo 3D devices leads to visual discomfort, fatigue and headaches, with a need for vision correction  occurring in certain cases. Professor Banks says: 'Discomfort associated with viewing stereo 3D is a major problem that may limit the use of technology. We hope that our findings will inspire more research in this area.'

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