3D technologies and eyesight

The last ten years have seen the rapid development of new audiovisual technologies in stereoscopic 3D. TV manufacturers have boosted the offer of products for viewing programmes in three dimensions (feature films, sports and cultural events, etc.) with processes that can be used either with or without special glasses. In March 2011, Nintendo placed the "Nintendo 3DS" video games console on the European market, which, for the first time, allows users to "see" images in 3D without needing to wear special glasses.

However, the development of these 3D technologies raises the question of their effect on eyesight. Indeed, Nintendo includes a warning notice, placed on the outside of the product's packaging, as a part of its presentation of the "Nintendo 3DS" console: "The use of the 3D feature by children aged six and under may cause vision damage. Therefore it is recommended that:

• only children over six should use the system in 3D mode;
• if children aged six and under have access to the system, parents or legal guardians should restrict the display of 3D images using the Parental Controls feature."

In this context, the Agency was requested in January 2011 by the French consumer protection association "Robin des Bois" to conduct an expert assessment and produce an Opinion concerning the use of a specific 3D games console.

Lack of available scientific data

To respond to this request, the Agency carried out the most comprehensive bibliographic analysis possible. An analysis of the scientific literature collected was submitted to experts in ophthalmology and orthoptics and in the cognitive sciences. In May 2011, the Agency also interviewed representatives of Nintendo to learn the scientific background for the warnings given by the company related to the use of the Nintendo 3DS games console. During this hearing, Nintendo provided a complete set of documents concerning the warnings related to the use of this console, as well as the scientific articles on which the risk analysis behind these warnings was based.

In its Opinion published in July 2011, the Agency highlighted the lack of available data on the potential health effects of 3D games consoles for children. In addition, the Opinion stressed the difficulty in determining the age at which the visual system reaches maturity, as the ages cited in the scientific literature range from 6 to 10 years.

Accordingly, ANSES deemed that it was not possible to reach a decision on the health risks related to the use of 3D game consoles for children or to determine a precise age above which exposure to 3D images on games consoles might no longer affect a child's visual development.

However, some scientific studies suggest that when viewing images in 3D, visual fatigue seems to occur earlier and more intensely than with two-dimensional images. Furthermore, 3D technologies are constantly developing and the 3D audiovisual equipment available on the market, especially for domestic use, is increasing rapidly. The populations that may be exposed to the various 3D technologies are very diversified (children, general population, workers, etc.). These technologies are therefore accessible to children whose visual system is still developing.

Against this background, ANSES issued an internal request in 2011 to broaden the scope of investigation and undertake an expert assessment of the potential health risks related to the use of all 3D audiovisual technologies.

An analysis of the scientific literature since 2011 identified different symptoms potentially related to exposure to 3D audiovisual interfaces, resulting from the visual fatigue due to "vergence-accommodation conflict". In the real world, to perceive depth and relief, the eyes converge (i.e. they are directed at the same object) and accommodate (the lens of each eye changes shape to obtain clear vision) at the same distance, i.e. the distance to the object being observed. The technique of stereoplotting (3D) makes it impossible for the eye to practice this physiological principle. The eyes' accommodation (to a screen, for example) and vergence (on an object located in the foreground or background of this screen) can therefore not occur at the same distance.

Visual fatigue during exposure to 3D audiovisual interfaces can take the form of: fatigue and pain around the eyes, a sensation of dry eyes, visual disorders (double vision, reduced sensitivity to spatial contrasts, reduced visual acuity and speed of perception), and extra-ocular disorders (headache, neck pain, aching in the back and shoulders, poorer performance in mental activities, loss of concentration).

Other symptoms may potentially appear, including effects linked to postural balance (dizziness) or to the appreciation of reality (altered perception of one's surroundings). Although these effects have not yet been sufficiently studied, they could generate a short-term risk of accidents related to dizziness.

In children, especially before the age of six, more severe health effects related to "vergence-accommodation conflict" in the eyes may occur, as a result of the active development of the visual system during this period (accommodation, vergence, maturing of visual paths, etc.), especially as the quality of 3D content is proving to be very mixed in terms of visual comfort, despite the existence of technical recommendations.

The Agency's recommendations

Against this background, in its Opinion and Report, ANSES recommends that:

• children under the age of six should not be exposed to 3D technologies;
• children under the age of 13 should only use 3D technologies in moderation, and that both they and their parents should be vigilant concerning any resulting symptoms;
• persons subject to certain visual disorders (disorders of accommodation, vergence, etc.) and problems with balance should limit their exposure to these technologies, including in the context of occupational exposure.

In view of the lack of data concerning the exposure of the population to 3D technologies, ANSES recommends identifying the various uses of 3D as well as the populations concerned, better characterising the exposure of different populations (adults, children and adolescents, professional users) and setting up a system for monitoring exposure.

In addition, the Agency provides a series of practical recommendations for limiting visual fatigue or other symptoms among users of this type of technology. ANSES thus recommends:

• that people experiencing symptoms during exposure to 3D interfaces limit their exposure time and consult an ophthalmologist in order to identify possible pathologies;
• not sitting or standing too close to the screen: this is because the greater the distance from the screen, the weaker the constraints on the visual system;
• complying with the instructions of manufacturers of 3D devices;
• continuing to wear eyeglasses or contact lenses when watching 3D content;
• and that creators of 3D content should limit the effects produced, by observing existing technical recommendations promoting the production of quality content.

Lastly, ANSES strongly suggests that medical and paramedical professionals who deal with young children and also ophthalmologists should be made aware of the mechanisms brought into play when viewing 3D interfaces. They will thus be in a position to inform parents of the symptoms and the potential risks and also of the means to avoid them.