To people who say your eyes hurt, try checking the calibration settings or something. Unless you have very sensitive eyes, you're probably doing it wrong.
Not really. Its well known that our eyes cannot handle the 3D effect due to how the eyes having to process the images we are receiving at a very fast and changing pace in a scale that is larger than we were born to be able to perceive. There are warnings on 3D TVs, systems, games, and movies that say people are supposed to take breaks from interacting and over exposure could cause irreversible consequences.
I cannot see 3D effects, but I still suffer from the draw backs because, even though I cannot see them, my eyes still try to process the images the way they are meant to be processed and it puts a lot of strain on my eyes.
If you can do the 3D effect, having your slider up at all times, and not suffer from anything that means your eyes are just more accustomed to something it shouldn't be accustomed to at all. Means in this one instance your eyes are better than most people's.
Yes, however, where I live it is also well known that looking at a computer screen for too long would give you square eyes, so I tend to take those kind of statements with a grain of salt.
Granted I see some people do get irritated from the 3D function, but relating to myself I can't figure out why.
That said, the moment I move my 3DS out of it's "perfect position", my eyes get teary because the 3D effect becomes irritating - I can clearly see an overlay of the same two pictures. This is where my previous statement came from.
Therein lies the issue (at least for me). Do you have a regular 3DS or an XL? I hear it's a bit trickier to stay within the "3D zone" on the XL, which is why I never have it enabled for long periods. It's not the 3D that eventually gives me a headache, it's the fact that my eyes are constantly going in and out of "focus."