This was something I had posted a few years ago when someone was asking about 3D movies for her small daughter with lack of depth perception. Thought I would repeat it here:
Here are my thoughts about the 3D shows:
Mickey's Philharmagic at MK - the music is very good and the show would still be enjoyable even if you could not see the pictures. The pictures are also really good and would be worth seeing even without the music. This is the newest movie and has the best pictures and best 3D effects. It includes scenes from Aladdin, Little Mermaid, Beauty and the Beast, Peter Pan, Lion King among others. If she is familiar with any of these movies, she will probably enjoy this. The story line is very simple - Donald Duck put on Mickey's magic hat, which flew off his head and keeps flying away from him. He spends the movie chasing the hat through scenes from different movies.
Bug's Life at AK - I would skip this one too. The audience is shrunk to the size of bugs and gets an introduction to bugs. I have never been in this show without someone carrying a screaming preschooler out. Some of the scary things include a friendly bug that 'sprays' the audience with stink bug scent, a friendly bug that 'sprays' the audience with 'acid', Hopper (the 'evil bug' of the movie) bigger than most kid's dads, and angry bugs 'spraying' the audience with bug spray, swatting with fly swatters, spiders falling from the ceiling and wasps coming to 'sting' the audience.
Muppets 3D at the Studio - I would go to the one at MK first and go to this one if she does well with that. There is more 'talk' in this movie as the Muppet characters explain what they are doing/what's happening. The movie is cute and does have some musical numbers. If she is familiar with the Muppet characters, she will probably enjoy it more.
About the 3D effects; the technology in the movies use polarized lenses. So, viewed thru one eye with the 3D glasses, there will still be a clear image. If you have differing vision in both eyes, cover the eye with the worst vision.
The movie at MK is the newest and does have the clearest movie. On a visit this past March, my oldest DD and her DH were with us. My son in law has MS and was recovering from an MS episode when we went to WDW. One of the effects of his episode was that he had lost most vision in one eye (don't worry, it's almost all back now). The reason I mention it is that he is someone who previously had 3D vision and temporarily did not. He saw all the movies except
Honey I Shrunk the Audience (NOTE: gone for quite a few years) and said none of them gave him a headache.
He said that Mickey's Philharmagic was really well done and did give a 3D appearance, even when viewed with one eye.
He is an artist (specifically, a comic book artist - and specifically in comics, his specialty is inking. The inker emphasizes lines and puts in shadows, highlights (and uses color, in color comics) to give an illusion of some things being farther back and some closer. The drawing artist uses blurred items in the background to make them appear farther away. He explained that they use the same techniques in the 3D movies to make things look 3D. You can even see that in 2D movies like the picture from Buzz Lightyear:
The polarized lenses intensify and complete the effect, but the colors, shadows and art put into making the film in the first place are what gives the start of the 3D 'look' in the first place.