I just replace that sentence with "People who actually spend their entire lives looking at pictures in books, paintings, computer displays and TV's in 2D will not be used to looking at a 3D world".

It all makes sense now.

It strains the eyes because the eyes get an unnatural and impossible task: first to keep track of the real-world 3D environment around the 3DS screen and at the same time look at a screen that sends a different picture to each eye.

So in total the eyes must keep adjusting their focus much more frequently than if you were watching a 2D screen.

Dont worry dude
youll get used to it, just keep using it

I always play with 3D on at max.

Never had any problems, not now, not in the beginning. It does has to do something with each individual's eyes though, my mother and one of my cousins can only see it at half way otherwise the screen blurs for them, while my father and another cousin can see it just as well as I can.

Personally, I only have problems when playing outside, or in a very light environment. The screen starts to reflect everything around you so my eyes don't know what to focus on anymore. That's when I start seeing double, but I still don't get headaches.

As somebody who suffers from frequent migraines...
The 3D doesn't bother me at all...

My sister and all my friends said their eyes hurt, and I feel the same. Played Ocarina of Time 3D a few times but I could never get used to it. The 3DS' screen looks a lot smoother with it off anyway.

"iamfanboy"

Endthread/

I had this probleme at first. I remember my first game on the system was OoT and at first I wouldnt say it did hurt my eyes but atleast I felt an awkward pressure and sometimes I saw the screen blurry. The more I played, the longer I was able to play before I started to feel these symptomes. Now I'm totaly used to it and I can play for over an hour before I start feeling pressure on my eyes or a headache.

thye hurt mine but thats why when i go in a store i only have the 3D on very very low! still is cool and doesn't hurt :D
when i get a new job I'm coming for that 3DSXL

When I first saw the 3D on the 3DS, it didn't bother me but it didn't impress me, either. When I bought one, I could only play for a couple of hours and it felt like my eyes were being strained. Now, I don't like to play anything without the 3D and I've considered getting an XL because I want the 3D effect to be even more powerful.