A big visual fatigue, potentially toxic blue light: virtual reality headsets, democratizing, have their flaws
Oculus Rift Facebook, Gear VR Samsung Vive Pre HTC or Sony PlayStation RV ... All the heavyweights of virtual reality market their products in 2016. These much-anticipated helmets promise new video game and movie experiences 3D and 360 degree immersing the user in a virtual world, his vision is reduced to a screen placed on his nose.
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Like any technology, these headsets raise questions about their health effects or risks they entail, especially for the eyes. The instructions for the Oculus Rift and suggest taking at least 10 to 15 minute break every hour, and does not recommend the use of helmets for children under 13 years. Samsung has similar recommendations.
But these tips are nothing scientific to speak of. "Everything is going very fast, there is no significant clinical study on the subject," says Pierre-Francois Kaeser, head of the unit strabology and pediatric ophthalmology at Jules Gonin Eye Hospital in Lausanne.
Doctors, however, have a certain perspective on the subject, the first commercial models of virtual reality helmets having arrived on the shelves in mid 1990. In 1997, a team from the University of Loughborough in England already addressed the issue visual disturbances hitting some users.
Squinting to infinity
Today, technology has not really changed, except that the graphics performance and display are more advanced. 3D requires "all warnings related to the use of 3D glasses also apply to virtual reality helmets," warns Pierre-Francois Kaeser. At issue, decoupling between accommodation and convergence. Look at an object close: the lens, our natural lens, makes the development above: it is the accommodation. Simultaneously, both eyes "squint" to the object in order to avoid seeing in duplicate: the convergence. Both phenomena allow us to see a single image, net, even near.
Most times, it is a transient visual discomfort more than a real pathology. And to my knowledge there is no damage in the long term.
In "Avatar" as in games in virtual reality, the process is the same: each eye gets its own track images slightly offset in space, and the brain, fooling rebuilt itself a depth image. This is where the problems begin. When a dinosaur emerges from the screen, the eyes converge on it to follow. They have the reflex to adapt their range of accommodation to keep the focus on the saurian that moves away from the screen and is approaching us. Except that in reality it has never left the screen! Accommodate about his supposed distance would make the whole scene ... blurred. To continue to see the film significantly, eyes operate a decoupling between convergence and accommodation: they aim dinosaur but keep the focus on the screen.Children, an issue
"This non-physiological phenomenon partly explains the nausea that can be felt with the use of a virtual reality helmet, says Pierre-Francois Kaeser. But mostly, it is a transient visual discomfort more than a real pathology. And to my knowledge, there is no damage in the long term. "
And the specialist added that the situation is different in people already suffering from vision problems, including strabismus (which prevents perceive the 3D), and also in children, we imagine fond of this kind of gadgets. The visual system is not mature at birth, better to avoid exposing small before a certain age. Which? Hard to say because we do not know when the visual system completes its development. Still, that "subjecting children to such abnormal stimuli and especially long term may fear the appearance of damage," Dr. Kaeser fears.Blue light, a potential danger to the retina
Scientific Director of the French Society of Ophthalmology, Gilles Renard agrees. He recently warned against another risk to users of virtual reality headsets: to irreversibly damage the retina, because of blue light.
Until recently, most of the daily displays were of the LCD type, ie LCD. In these devices, the light that reaches the eye is emitted from the back of the screen by neon or LED. This white light embraces all colors of the rainbow sky and poses no particular problem.
OLED displays are potentially toxic, especially to children.
But things change in recent years with the arrival of a new display technology: the OLED screens, which equip an increasing number of smartphones, some TVs but also virtually every virtual reality helmets. "OLED displays are potentially toxic, especially to children," warned Gilles Renard.
In these devices, each pixel is an LED can emit any color. Or some shades of blue - situated in a wavelength range of 415-450 nanometers - have a toxic effect to the retina. "This type of light destroys the cells of the retina, located at the back of the eye, with a cumulative effect if repeated exposures," says Gilles Renard. Toxicity is proven in studies in animals. It is quite possible that this is also the case in humans, although it is only a hypothesis. "
The ophthalmologist says further that the effects of blue light are even more toxic than the distance to the screen is reduced and the exposure time is long. Two risk factors are greatly favored by virtual reality helmets where the display is located within 5 cm of the eyes and where the hours tend to spin ...The game nauseum
But the most commonly encountered adverse effect is undoubtedly the "cybersickness" or "bad virtual reality", which causes nausea and vomiting. It is partly related to the visual system and is due to a disorder of the system that can locate in the space. Normally, the brain uses three data sources to inform the agency on its position and movement: the inner ear, muscles and eyes. But once the helmet on the head, "the eyes indicate that you are in a roller coaster, but the inner ear and the muscles say that this is not the case: the inconsistency of sensory information causes nausea," explains Pierre-Francois Kaeser.In conclusion: the importance of common sense
Virtual reality therefore is not really well with the eyes. But nothing to worry about beyond measure, say doctors. Just use common sense: do not allow children to use these headphones without supervision, take regular breaks to rest your eyes, and to try the equipment before purchasing.
Builders are in any case reluctant to communicate on the subject. Facebook said no word of the negative effects, for Samsung, the agency that manages the communication has not responded to our requests for interviews. This does not mean that nothing is done to address these problems on the blue light, software such as F. lux possible for example to reduce exposure to the most harmful wavelengths. Optical filters should also help to accommodate vision myopic and astigmatic, although for this there will probably opt for the higher-end models. As for possible long-term effects, we must be patient to get a clear idea: "They will be monitored, but we will not know anything for fifty years," Gilles Renard slides.
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If the virtual reality helmets can raise questions as to their effect on the eyes, physical accidents may well be the most common, and perhaps the most serious.
Marketed in 2006, the Nintendo Wii has been popularized as much for its excellent games for the numerous accidents in which she was involved. In the heat of the moment, many levers smashed television screens, and many budding athletes have ended up in hospital after breaking bones in parts of sports games.
The virtual reality helmets should resurrect what has sometimes been called "the effect Wii." Once the headgear installed, it sees absolutely nothing of its environment. Furniture, pets, or just the cables connecting the headphones to the computer are transformed into so many obstacles that can cause serious accidents.
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