Originally Posted by Hyrax
My wife asked me a question about 3D that I thought I'd pass along. She is rather near sighted and wears contact lenses. The power of these lenses makes it hard for her to focus on close objects, so her doctor has given her a prescription that uses her dominant one eye for seeing things at a distance and the other eye for seeing closer things (if I remember correctly, one lens is +9 and the other is +5). The brain mixes the two images so that she can now see both close things and distant things. This means she will not be able to use either active or passive 3D glasses while wearing these contacts, right?
The science behind this is very complex and I don't pretend to even be close to an expert. In fact I may have totally misunderstood, but, here is my understanding and hopefully others will comment.
In the first few years of your life your brain learns the relative size and distance of objects and how to interprete a real 3D life image. This is why even with one eye, we wouldn't bang into things walking around unless we meet objects that are not common or objects and sizes we have not seen before.
For example, you have probably seen the trick with a table that is much smaller than a chair, but is positioned closer to the person than the chair so from the viewer position they look correct again. The brain is easily fooled.
So keeping in mind this "fooling" the brain. Another way of fooling the brain is actually what we are doing with 3D movies. With a 3D movie, your eyes only focus on the distance to the screen. Afterall, the image is only at that distance, and there isn't really any object closer or further away. Both eyes are focussed on that seat to screen distance from beginning to end of the movie. However, because both eyes see a different image, it forces the brain to "re-compute" what it is seeing, and it gets tricked into applying a 3D interpretation of the two 2D images.
Sometimes the brain tries to fight with itself on what it is seeing, because although your eyes are focussed on a distance say 10 feet away, the brain is trying to tell you the object is only 2 feet away. The fight is that your eyes sometimes then try and refocus on where you normally would with an object that distance away. This is what causes people to lose focus sometimes during 3D movies, and/or cause headaches or eye strain.
So, this is a very long winded way of saying, that if your wife can focus correctly on the screen with both eyes (cover each eye and make sure), then 3D movies should work just fine with the contacts in.
I apologise if I am wrong in my understanding here. I read a paper on this a long time ago, and it was written in gibberish. Hopefully someone else can validate what I am saying.