I am not worried since the situation seems to have resolved itself in half an hour. But I am concerned because this has never happened to me before...

Well, just as the title of this thread implies, I woke up to seeing an odd spot in my left eye's upper-middle field of vision when I tilted (not turned) my head either left or right; tilting forward or backwards seemed not to have affected it. What was odd about it was that I felt no awkward pressure in my eyeball or surrounding area. I did not feel dizzy or nauseas. I did not feel any pain. The spot was simply there when I tilted my head sideways. Also, the more that I tilted my head, the larger the spot became. As for what the spot looked like, all I can say is that it was a dark spot that blocked my vision beyond it.

Any suggestions to point me in the right direction would be greatly appreciated as I am unable to find a satisfactory result through search engines.

Sounds like a standard 'floater' - a bit of debri in the fluid inside the eye that just happens to have moved into your field of view when you tilted your head. If it happens again, you might need to see an ophthalmologist to determine the origin of the debri and whether or not anything can be done to eliminate it.

Thank you for the suggestion, brianmf. But I have always thought of floaters as sort of web-like or worm-like, as if extremely small lint got caught in the eye. The spot I saw seemed like something was pressing into the surface of my eye, though I felt no pressure. The more I tilted my head, the darker and larger the spot became.

Perhaps it is just a floater. But I cannot find any pictures via search engines that look like the spot that I saw.

Floaters vary in shape and size but of course it is possible that this was something else. Rather than speculate, it's best to wait and see if it happens again and, if it does, try to get it checked out immediately.

Hi Fire & Ice,
I have noticed the exact same thing and it first happened to me when I was walking along...I looked up and noticed the odd dark spot very similar to what you have described. It has happened again afew times since, and to be honest i dont know if I should be worrying. I have just had my eyes checked and they are physically fine so I have no idea what it is. My eyesight seems the same and i do also have floaters so I know that two are very different.
It has also happened to me just when I happen to look upwards or sideways just sitting down...
SOrry I have been no help, but wanted you to know of my experience.
Regards,
Appledowns....

I will most definitely follow your sound advice, brianmf, and speak to my doctor if it happens again. To this date, it has not repeated itself.

You are very helpful indeed, Appledowns! At the very least, I am happy that I was able to give a proper enough description that someone else recognized it. I am just sorry to hear that your situation has not resolved. I wish I had more suggestions as to where to look for answers. If I do come across some clues, I will definitely post them on this board. :)