I think the writer of the warning article, Wayde Robson, is sloppy with his use of the word 'trick'. Early on he writes stereopsis "is being tricked every time we watch a 3D movie." Later on he likens treating strabismus to "re-teach[ing] the optic nerves the trick of binocular vision." So which is the trick - healthy binocular vision or "modern digital 3D effect using glasses"? After the debacle over the misunderstood use of the word "trick" in the climate gate email scandal, science writers need to exercise more effort to achieve clarity when using this word.

Robson writes that the results of Stanford Research Institute studies have been published, but he doesn't point to them. The DSTO link offers the most substantive relevant information, but it doesn't necessary support the argument made by the article. Side Effects of Virtual Environments: A Review of the Literature (pdf). This was published in 2004. Searching it for the word "strabismus" leads to this: "Because attention to the physiological oculomotor changes has been so recent, no studies to date have investigated the issue of who is most at risk. Also, there have been no investigations carried out on the oculomotor effects of prolonged VE exposure." (page 21) The question is whether "oculomotor effects" can produce strabismus in adults. The answer is still awaiting research, at least as of 2004. Again, on page 26:

"While some investigations have been carried out on HMDs, there are no studies currently in the literature of the oculomotor effects of screen-based stereoscopic displays. It could reasonably be expected that there might be changes in heterophoria following exposure to a VE stereoscopically displayed on a wide screen, but neither this nor the effects of the system calibration for effective ocular separation have yet been examined."

The phrase "ocular separation" sounds a lot like strabismus.

I'm not convinced. Perhaps the SRI studies present new findings.

Quoting from elsewhere (highlights are mine):

Quote: Problems of stress on the visual system have been most obvious in HMDs. While poor engineering design or incorrect calibration for the user can be a source of visual stress, a problem less easy to avoid is the challenge to the accommodation-vergence cross-links. Current stereoscopic VR displays provide an illusion of depth by providing each eye with a separate 2D image on a fixed focal plane. The mechanisms of binocular vision fuse the images to give the 3D illusion. Because there is no image blur, the eyes must make a constant accommodative effort. But at the same time the images stimulate a changing vergence angle with changes in apparent depth, so that the normal cross-linked relationship between the systems is disrupted [Mon-Williams & Wann 1998]. The problem is not limited to HMDs as ANY stereoscopic display, from a stereoscopic desktop to immersive systems such as the CAVE, uses the same display method [Wann & Mon-Williams 1997]. Within certain limits the visual system can adapt, as shown by results of orthoptic exercises and of adaptation to different prisms placed in front of each eye. However, whether the changes are long term or whether there can be dual adaptation to both the real and virtual environments has not been established [Rushton & Riddell 1999].

What has been shown in SEVERAL STUDIES is that short-term exposure to VEs with stereoscopic displays has produced changes in heterophoria (latent squint), where the visual axes of the eyes deviate from their usual position. The resting vergence angle of the eyes may be altered either in the direction of exophoria (turning outwards of the eyes) or esophoria (turning inwards of the eyes). Some decrements in visual acuity have also been reported. These objective changes, which must be assessed using orthoptic instruments, are associated with reports of subjective symptoms such as blurred vision, headaches, eyestrain or momentary diplopia (double vision). The degree of objective change and the symptomatology also depended upon the VR system or VE being evaluated [Costello & Howarth 1996; Mon-Williams & Wann 1998; Mon-Williams et al. 1993]. The reported changes in heterophoria could account at least in part for the subjective symptoms as well as reduced visual acuity and reduced perception of depth when relying on stereopsis. These changes are similar to those reported with the use of NVGs and thought responsible for the reduced depth perception [Sheehy & Wilkinson 1989]....Certainly longer exposures in flight simulators result in greater severity of symptoms overall [Kennedy, Stanney, & Dunlap 2000].

http://dspace.dsto.defence.gov.au/dspace/bitstream/1947/4079/1/DSTO-TR-1419%20PR.pdf

This settles it--stereo 3D cannot be considered safe unless detailed new studies are performed that prove it is safe for given usage patterns.

P.S. Also see 3D TV launch flags health concerns

[Edited by - Prune on June 27, 2010 7:05:38 PM]

Quote: Original post by Prune
This settles it

[rolleyes]

I'm not buying this. If getting two images to line up in simulated 3D puts your eyes at a different angle then it does in real life, and this causes your eyes to adapt to the simulated environment with normal usage, then why shouldn't your eyes adapt right back as soon as you're not looking at a simulation for exactly the same reason? You haven't made a case for why this wouldn't be the case.

In fact, it looks like you just took some random text and then highlighted things out of context to make it look like the evidence is firmly on your side and then asserted your absolute correctness.

The fact is, you might be right. But when you say things like "period," "that settles it," and "are ALL DANGEROUS TO YOUR HEALTH" it makes it seem like either you have some ulterior agenda or that you jump to conclusions far too quickly. Either way, it's hard to take you seriously.

Quote: Original post by cowsarenotevil
I'm not buying this. If getting two images to line up in simulated 3D puts your eyes at a different angle then it does in real life, and this causes your eyes to adapt to the simulated environment with normal usage, then why shouldn't your eyes adapt right back as soon as you're not looking at a simulation for exactly the same reason?

Are you kidding me? Because, as it's clearly addressed in the posts above, its not the angle (convergence) by itself but the mismatch between the angle the stereo forces and the angle that the eye naturally assumes because of accommodation (focus). In real world 3D vision these two angles are always the same are the same. This would have been clear to anyone that actually has read the thread.

Quote: Original post by Prune
...both work by forcing the eye muscle to a different default convergence. This is very, very basic logic here, and I'm flabbergasted that I have to explain this. A perfect analogy is bending an arrow sign. The treatment is equivalent to bending it to point to the right direction when it was wrong before. In prolonged stereo 3D exposure without matching focus, it's equivalent to bending it from the correct direction to another one.

Another analogy would be that it's like the top button on that pair of jeans thats a bit too small.
The treatment is like when you squeeze and pull both sides together until the button does up properly, and then once it's there, it stays in place.
Watching 3d movies is like undoing the button so your undies are visible, but you can quickly do it back up again whenever you want because you've learned what it feels like to have your jeans done up or undone.

In other words, perhaps there's a difference between the right/wrong muscle tendencies that this treatment treats. Perhaps the brain can tell when it's being taught a 'good' muscle configuation and a 'bad' one. The treatment works because the eyes want to reach a good configuration, but 3d entertainment isn't (permanently) damaging because the brain easily forgets the 'bad' muscle configuration and goes back to the last known 'good' config. Like system restore ;)

Of course I've no evidence or even any research to say any of this is true, it's just an idea. But your idea that 'anti-treatment' is just as effective and long-term as 'treatment' needs some work too.

Quote: Original post by Prune

Quote: Original post by cowsarenotevil
I'm not buying this. If getting two images to line up in simulated 3D puts your eyes at a different angle then it does in real life, and this causes your eyes to adapt to the simulated environment with normal usage, then why shouldn't your eyes adapt right back as soon as you're not looking at a simulation for exactly the same reason?

Are you kidding me? Because, as it's clearly addressed in the posts above, its not the angle (convergence) by itself but the mismatch between the angle the stereo forces and the angle that the eye naturally assumes because of accommodation (focus). In real world 3D vision these two angles are always the same are the same. This would have been clear to anyone that actually has read the thread.

his point is why would your eyes not adapt back after you are finished. Our eyes have been doing it the right way a lot longer than the hour and a half they'd do it the wrong way watching a 3D movie.

You're taking a very alarmist view of this, and it hurts your credibility. I'd agree it's worth researching more, but the extremism of your stance and tone makes me less than sympathetic to your cause.

Quote: Original post by Prune

Quote: Original post by cowsarenotevil
I'm not buying this. If getting two images to line up in simulated 3D puts your eyes at a different angle then it does in real life, and this causes your eyes to adapt to the simulated environment with normal usage, then why shouldn't your eyes adapt right back as soon as you're not looking at a simulation for exactly the same reason?

Are you kidding me? Because, as it's clearly addressed in the posts above, its not the angle (convergence) by itself but the mismatch between the angle the stereo forces and the angle that the eye naturally assumes because of accommodation (focus). In real world 3D vision these two angles are always the same are the same. This would have been clear to anyone that actually has read the thread.

Yes, I realize this, and nothing in my post contradicts this, either. However, this doesn't change the fact that your claim is that your eyes will adapt to the simulated version but for some reason won't correctly adapt back to real life, but you don't provide any justification for this. This is what I was pointing out in my post, and you ignored it.

Also, I'd like to point out that plenty of other things, such as wearing glasses, adjust the accommodation of one's eyes (though by a constant factor relative to what is expected from stereopsis) without, obviously, any effect on the convergence of one's eyes. Clearly you're not arguing that wearing glasses or being nearsighted causes people to become cross-eyed. How do you explain this?

Once again, you might well be right, but, as numerous people have said, you haven't made your case nearly well enough to justify your being as patronizing and antagonistic as you are. Actually, being patronizing and antagonistic is not something I like even from people who do make airtight arguments.

If 3D stereoscopic technology was so damaging to peoples eyes sight it would have become apparent by the many users of such technologies ages ago. This technology isn't new its been around for nearly 30 years. 10s of thousands of scientists, engineers and professionals use 3D stereoscopic displays for everything from 3d chemical modeling to remote surgery, at exposure times measured in hours per day.

The paper does make a point that extremely young people shouldn't be using these displays since their "wiring" is still in the process of learning, but that still need more study as it's just extrapolating other studies themselves.

The total number of people exposed to 3D stereoscopic displays just jumped like 100x fold from the recent advances of 3D movies. The only issue so far has been it has help identify some people who have eye conditions preventing them form having full stereoscopic vision (ie lazy eye). Sure I think more study needs to be done, but from the preponderance of evidence so far, stereoscopic display technology doesn't impair normal vision for adults as far as i can see.

-ddn

Quote: Original post by ddn3stereoscopic display technology doesn't impair normal vision for adults as far as i can see.

Lol.

Quote: Original post by Hodgman
Of course I've no evidence or even any research to say any of this is true, it's just an idea. But your idea that 'anti-treatment' is just as effective and long-term as 'treatment' needs some work too.

I submit that your analogy lacks the physiological symmetry of displacing the eye muscles' convergence set point for a given detected focal distance by either strabismus eye training exercises or stereoscopy without matching accommodation.