Nintendo, Sony, Toshiba have all issued warnings on the development of eyesight in younger children when watching stereoscopic 3D images. Here is a link to a BBC story about the recent Nintendo announcement. Their announcement basically said: "There is a possibility that 3-D images which send different images to the left and right eye could affect the development of vision in small children".
Small children obviously have a smaller inter-occular distance (i.e. distance between eyes) and hopefully we now all realise that this means that 3D has a much greater effect of them. Now, as a parent I have often seen my children when they were toddlers wander up to the screen and kiss it or look very intently at one of the characters on screen. In 2D it's not that much of a problem - just a messy screen that needs a wipe - but for small children 3D is a problem.
When looking at 3D, their eyes are forced to look outward rather than being parallel or convergent (which is the norm) and it could be damaging to them. With the upcoming release of the 3DS from Nintendo (no glasses required ) I can see a lot of small children getting their hands on one when they should not.
It's bad enough when you see games rated 16 being played by children as young as 6 or 7 due mainly to parents not paying enough attention to what their children are consuming. By putting a warning on a website and possibly in the instructions (who reads them?) are we really protecting children? Let's face it, many parents won't understand the finer intricacies of the 3D revolution.
If 3D has the power to affect adults who fall outside of the norm and have smaller or larger inter-occular distance (big or little people), causing headaches and nausea, we can only guess at what it is doing to a child's brain and wiring at such a young age. Don't get me wrong I think when used well, 3D can look awesome, but there's a lot of parameters that need to be taken into consideration when viewing it to get the best out of it. But kids who are upside down on the couch at some weird angle aren't really getting the optimal view point... are they? Who knows what that would do to their eyes and brains.