Vision in stereo

I have fairly idiosyncratic eyesight. While it's not terribly bad, one eye is long-sighted (the left) and the other is short-sighted (the right). My left eye, due to increasing age, as become more short-sighted as time has gone on, and is almost normal. Unfortunately, my short-sighted right eye is extremely dominant, which means I need to wear glasses. I can read a book with average print-size without my glasses on, although doing it for extended periods nauseates me.

However, I can't go cross-eyed, and I have never been able to see the 3-d images in those "magic eye" pictures. This evening I thought I'd check out what the problem might be, and I found this site on checking your "3-d vision". And, for the life of me, I can't make it work. In fact, I have now got a stunning headache at the back of my head (I never get headaches, even when I have left my glasses off for a while), which is at least consistent - vision is processed at the back of the brain - and I feel as crook as hell. I found a couple of other tests and I had the same problem with them too.

Now, the funny thing is that I haven't considered much to be wrong with my depth perception. Ok, I have problems trying to sink a straight shot at pool - in fact, I can't do it if the ball is at the other end of the table from the white one. I can estimate distance reasonably well, but again, it's much easier if the object to be measured is horizontal to me, or at an angle. I don't think relative ease of estimation from an angle is that unusual, tho'. I'm fine at catching things and hitting things.

Hm, I might have this investigated the next time I go to the optometrist. It's bugged me somewhat that while my eyesight is only somewhat bad in one eye, I can't really do without my glasses. If there is a lack of stereoscopic vision, and my left eye is effectively doing nothing, that would explain a lot.

Now I'm going to see if this goddamned headache can be fixed with a sweet cuppa. Blech.