Headaches and Nausea
If you have a Strabismus (often called a squint), then you could also struggle to put together a stereoscopic 3D image. Sparrows explains that 'If you have two eyes that don't look in the same direction - in other words you've got an eye that turns out or turns in - then you're not going to get those two images that can be interpreted as a 3D picture.'
She also points out that all humans have eye sockets that point slightly outwards. 'When we go to sleep, our eyes relax and turn out slightly,'
she says. 'That means that the natural position for your eyes sitting in your eye sockets is to just wander out, so all the time that we're awake, our eye muscles are pulling away to keep them straight. Now for some people those eye muscles have to pull harder than others, and they may not notice that normally, but if they're using 3D technology for too long then their eye muscles might get tired. So something that's not normally evident might suddenly become more evident with headaches, eye strain and tired eyes.'
Experiencing undesirable physical symptoms is also a problem people often report after using 3D technology. Aside from eye strain and tired eyes, many people also feel nauseous, while some get migraines and headaches. What's the reason for this?
'We're used to appreciating the real world in all manner of ways,'
says Sparrow, 'and we use all sorts of cues. So, for instance, the song about the Blue Ridge Mountain had some truth in it, in that things are bluer or greyer in the distance, so our brain says that must be further away than something that's big or nearer to us, so our concept of the real world and its full three dimensional nature is based on all sorts of things – colour, size, shape, texture, something moving behind something, parallax – all of these things are taken into account.
Clues such as distant mountains appearing blue or grey enable our brains to perceive 3D in the real-world, but these cues can be ignored when viewing 3D films or games
'So when we have a machine that creates 3D, whether that's a television or a Nintendo 3DS or whatever, you're telling your brain to ignore some of those normal clues and cues. You can then appreciate the 3D effect, but if you carry on ignoring those cues and clues then your eyes have to readjust back to the normal world when you step away from the technology.'
For most people, Sparrow says that this readjustment period is limited or almost non-existent, but for others it can result in feelings of nausea and disorientation, as well as headaches. If this sounds like you, then the Association of Optometrists advises you to have an eye exam, as it may be a symptom of a further problem.
The quick flickering systems used in some stereoscopic 3D setups, most notably 3D televisions or PCs with active shutter glasses, can also cause problems for some people. 'If your brain is receiving images alternating very fast, then that can be tiring for the eyes,'
says Sparrow, 'and for some people any flickering environment makes them more susceptible to migraines, and the headache prior to a migraine.'
This begs another question, though – could using stereoscopic 3D actually damage your health in any way? This is a difficult question to answer, as we currently have very little data. In order to make a strong scientific conclusion on long-term health effects, you need many years' worth of data, and a large number of subjects.
'We haven't really got to that stage yet,'
says Sparrow, 'but the early case studies, which aren't definitive research, are saying that some people are getting headaches, some people are getting dizziness and these effects tend to wear off very quickly, but they can vary from person to person.
Current case studies show that problems such as headaches are only temporary, but optometrists say more research is needed
'At the moment, because all the technologies are all so new, and people are only just starting to use them for any length of time – like a whole movie, or sitting on their games console for several hours - we don't really know what the long term temporary effects or the long term bigger effects might be. There certainly needs to be a lot more research in this area to find out what really happens if you do spend hours and hours looking at a 3DTV or playing on a 3D games console.'
Interestingly, however, stereoscopic 3D could potentially help with correcting and diagnosing problems such as lazy eye. 'I worked a little bit with a company out of Boston that was trying to develop a medical training system with 3D glasses, so that they could correct eye problems,'
says Nvidia's product manager for 3D Vision, Andrew Fear. 'I also did some work with the University of Texas' visual-cognitive department, which studies how the brain perceives depth and motion, and they found that stereoscopic 3D also has benefits when helping to train your brain for corrective vision as well.'
He also notes that 'there are a couple of American Optometric Association programmes out there that talk about eye doctors who want to look at the benefits of 3D. These guys will tell you that the techniques you use to view 3D can actually correct lazy eyes. So if you have a lazy eye, you use glasses with a corrective lens in it, which will try to train your eye to focus back in. Some of them are actually now using stereoscopic 3D to correct eye problems.'
Fear also points out that people with minor discomfort issues with 3D can also vary the depth of the 3D effect using Nvidia's software, which you can also do with the middleware used in AMD's HD3D system.