3D is not perceived by some people, it is not an eye matter but more to do with how the brain resolves the stereoscopic image being presented to it. The brain is tricked into believing it is seeing 3D when in fact it really isn't. Some brains work it out and do not resolve, or perhaps like Hecatae's wife the brain has trouble working it out and so makes stuff up - the blurry image. Yet others overload quickly and suffer intense discomfort, headaches, nausea, anxiety even!

This 3D stuff is amazingly complex and the human condition is directly linked. It has a way to go yet to perfection, 3D TV is about where 625 lines replacing 405 lines were back in the 1960s. It is very very new. For the vast majority of people 3D appears to work just fine. But there appear to be significant numbers for who the technology, as it is today, is wholly unsuitable.