By Geraldine Ling
Watching three-dimensional images on a flat screen can cause eye strain, headaches and seizures.
Viewing movies in 3-D is all the rage now for many movie-goers. With the aid of special 3-D eyewear, viewers see images in three dimensions, including depth. But anecdotes have surfaced about people who suffer from headaches and eye strain after watching 3-D movies.
One South Korean TV maker, Samsung, has piqued interest in 3-D TV's possible health effects. A page on its website, www.samsung.com/au/tv/warning.html, advises viewers to consult a medical specialist before watching 3-D TV if they or others in their family have a history of stroke or epilepsy.
So what exactly goes on behind that 3-D experience and is it safe to watch such shows?
Associate Professor Leonard Ang, medical director of The Eye & Cornea Transplant Centre and The Premium Lasik Surgery Clinic, said the eyes have to make constant adjustments when viewing 3-D images on a flat screen.
When seeing real-life objects, the eyes rotate slightly inwards to look at something near. Conversely, they rotate slightly outwards when looking at something far. The eyes do so to allow the object's image to be projected on the centre of the retinas, thus preventing double vision.
The retina helps the brain to register images. Each eye's lens will also change its shape to focus on the object while maintaining a clear image.
All these typically take place while the person is looking at an object located at a distance.
Watching a 3-D movie or television show breaks this natural relationship. Prof Ang said the eyes are now forced to concentrate on something near - the projected 3-D image. At the same time, they also use the actual onscreen image - which is further away - as their focus.
This constant re-adjustment that the eyes make to see 3-D images may cause eye strain, fatigue and headaches.
Eye strain is more likely to occur while watching 3-D TV at home than watching a 3-D movie.
Prof Ang explained that TV screens tend to be closer to the viewer than cinema screens. The TV's proximity may lead to eye fatigue and strain.
Referring to Samsung's health warning, DrCharles Siow, a consultant neurologist and pain specialist at Siow Neurology Headache and Pain Centre, said people who have photosensitive seizures - triggered by visual stimuli like flashing lights - should be careful when watching 3-D movies or TV shows.
A 3-D show may cause a seizure because there are more visual stimuli, he said.
Prof Ang said that most people are able to watch 3-D movies and TV without experiencing any problems.
Dr Clement Tan, a consultant at the department of ophthalmology at National University Hospital, said there have been no reports of serious or permanent long-term complications from watching 3-D TV shows and movies. Still, Dr Siow said those who start experiencing discomfort while watching 3-D shows should take a break.
Prof Ang said: ' If you do not feel comfortable watching 3-D images, then don't force it.'