IANAD but that sounds serious to me. Visual field distortions are often brain issues. I would go to a neurologist to be sure. Could be a tumor applying pressure to your optic nerve or something.
From a terminology standpoint, usually when people talk about visual field deficits, they are referring to reductions in a visual field, rather than unusual visual phenomena within an otherwise functional visual field.
Anyway, visual field deficits can be brain-lesion-driven, as you say (e.g., the classic bitemporal hemianopsia in pituitary tumors).
No, not necessarily. I've met someone who had a benign brain tumor -- it caused them to have mood swings, but was not in any danger of spreading.
In their case the doctors didn't remove it because the operation would have been more dangerous than the tumor itself, and the symptoms were not too severe. But it's obviously better to be aware of such things.
My wife had a growth removed from her brain a few years ago. Apparently it had quietly sat around since she was a child, not doing anything, until it decided to get its shit together and try to kill her.
ElongatedTowel ought to go to the doctor and deal with a few weeks of feeling like an embarrassed jerk by demanding that they scan his/her brain.
