2013-01-03 10:15:47
Recent years have seen the rapid development of new audiovisual technologies in three stereoscopic dimensions (3Ds, often referred to as “3D”). Television manufacturers have supported the offering of products allowing the viewing of programs (fiction films, sporting and cultural events, etc.) in three dimensions using processes which may or may not require the wearing of special glasses. In March 2011, the Nintendo company launched the “Nintendo 3DS” games console on the European market, which for the first time allows the user to perceive 3D images without requiring the wearing of specific glasses.
The development of these “3D” technologies, however, raises the question of their impact on vision. Nintendo also accompanied the marketing of the “Nintendo 3DS” console with a prevention message displayed in particular on the external packaging of the product:“Use of the 3D display by a child six years of age or younger might damage their eyesight. Therefore please observe the following recommendations:
- only children over six years old can use the 3D display;
- If the console is likely to be used by a child six years of age or younger, the 3D display must be blocked by a parent or guardian using the parental controls feature. »
In this context, the Agency was contacted in January 2011 by the “Robin des Bois” association with a request for expertise and opinions concerning the use of a “3D” games console.
Lack of available scientific data
To respond to this request, a bibliographic analysis as exhaustive as possible was carried out by the Agency. The analysis of the scientific literature collected was submitted to experts in ophthalmology, orthoptics and cognitive sciences. In May 2011, the Agency also held a hearing with the company Nintendo so that its representatives might present the scientific elements which supported their warnings relating to the use of the “Nintendo 3DS” games console. Nintendo provided during this hearing complete documentation on the warnings relating to the use of this console, as well as the scientific articles which enabled it to establish the risk analysis underlying these warnings.
In its opinion published in July 2011, the Agency then highlighted the lack of available data on the potential health effects of “3D” game consoles for children. Moreover,the opinion highlights the difficulty in determining the age from which the visual system has reached maturitythe ages cited in the scientific literature vary from 6 to 10 years.
Consequently, ANSES estimated that it was not possible to comment on the health risks relating to the use of “3D” game consoles for children and to determine a precise age from which exposure to “3D” images of game consoles would not affect the child’s visual development.
However, some scientific studies suggest that when viewing images in “3D”, the visual fatigue seems to appear faster and more intensely than with two-dimensional images. Furthermore, “3D” technologies are constantly evolving and the supply of “3D” audiovisual equipment on the market, particularly for domestic use, is growing rapidly. The populations that can be exposed to different “3D” technologies are very diverse (children, general population, workers, etc.). These technologies are in fact accessible to children whose visual system is still developing.
In this context, ANSES took action in 2011 to broaden the field of investigation and conduct an assessment of the health risks linked to all “3D” audiovisual technologies.
The analysis of the scientific literature carried out since 2011 has made it possible to identify various symptoms that may be linked to exposure to “3D” audiovisual interfaces, and which result from visual fatigue due to the “accommodation-vergence conflict”. Indeed, in the real world, to perceive depth and relief, the eyes converge (i.e. are oriented towards the same object) and accommodate (the lens of each eye deforms to obtain clear vision) at the same distance, that is to say at the distance of the observed object. The “3D” restitution technique does not allow this physiological principle to be respected. Accommodation (on a screen for example) and vergence of the eyes (on an object located in front or in the background of this screen) are therefore not carried out at the same distance.
Visual fatigue during exposure to “3D” audio-visual interfaces can result, for example, in: fatigue and periocular pain, the feeling of dry eyes, vision problems (double vision, sensitivity reduced to spatial contrasts, reduction in visual acuity and speed of perception), extra-ocular disorders (headaches, neck pain, back and shoulder pain, reduced performance in mental activities, loss of concentration).
Other symptoms may appear, in particular effects linked to postural balance (dizziness) or effects linked to the appreciation of reality (alteration of perception of the environment). However, these effects remain poorly studied, but might generate a one-off accidental risk linked to dizziness.
In children, particularly before the age of 6, more marked health effects might appear linked to the “accommodation-vergence conflict” of the eyes, due to the active development of the visual system during this period (accommodation, vergence, maturation visual pathways, etc.), all the more so since the quality of 3D content, in terms of visual comfort, turns out to be very heterogeneous, despite the existence of technical recommendations.
The Agency’s recommendations
In this context, ANSES recommends in its opinions and report:
- of advise once morest exposure to “3D” technologies for children under 6 years old ;
- that children under 13 have a moderate use “3D” technologies, and that they, as well as their parents, are attentive to possible induced symptoms ;
- that people subject to certain visual disorders (accommodation, vergence, etc.) and balance disorders limit their exposure to these technologies, particularly in professional exposure contexts.
Given the lack of data concerning the population’s exposure to 3D technologies, ANSES recommends identifying the uses of “3D” as well as the populations concerned, better characterizing the exposures of different populations (adults, children and adolescents, professional users) and to set up exposure monitoring.
The Agency also provides a series of practical recommendations in order to limit visual fatigue or other symptoms in users of this type of technology. She therefore recommends:
- to people experiencing symptoms upon exposure to “3D” interfaces of limit their exposure time and of consult an ophthalmologist in order to detect possible pathologies;
- of do not position yourself too close to the screen : in fact, the further away the spectator is, the less constraints he experiences on his visual system;
- of follow the manufacturers’ instructions “3D” devices;
- of keep your optical corrections while viewing “3D” content;
- and that creators of “3D” content limit the effects produced by respecting existing technical recommendations aimed at producing quality content;
Finally, ANSES encourages awareness of early childhood medical and paramedical professionals and ophthalmologists on the mechanisms involved when viewing “3D” interfaces. In this way, they will be able to inform parents of the symptoms and potential risks but also of ways to remedy them.
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