I actually find that eyes burning and watering is more of a problem with prolonged exposure to stereograms, although I get that with 3D movies using glasses too

I actually find that eyes burning and watering is more of a problem with prolonged exposure to stereograms, although I get that with 3D movies using glasses too. A while back, I watched Captain America in side by side mode on my computer. Only problem was that in SBS they put the left eye on the left and the right on the right. To view that as a stereogram would require "wall-eyed" vergence, which is basically impossible to do beyond a certain angular distance - I'd have had to watch it all tiny. So as an experiment in perceptual adaptation, I watched the whole movie cross-eyed, so that I perceived the depth as inverted. It wasn't really enough time for full perceptual adaptation, although by the end of it, I basically found that my brain had stopped paying attention to dept whatsoever unless I consciously thought about it. Anyway the point is that at the end, I let my eyes slide back into their normal state, and they burned for a while after like they were dry, but they didn't ache at all. That said, I have spent a ludicrous amount of time in my life setting my vergence to values outside of the manufacturer's recommended range. So my results may not be typical.