I am a male in my 30s. I was exercising tonight and about 15 minutes into it I noticed a small spot of light that was obscuring my vision in one eye. At first it was small and round, at 9 o'clock in my visual field, but it eventually extended over the entire central visual field; interestingly, it was doughnut-like: it had a small circle in the center of it (which was near the center of my visual field) that was dark. Simultaneously, a different spot in the opposite eye appeared; this one was also off center at around 7 o'clock and did grow larger but not nearly as large as the first spot; it did not extend over the center of my visual field and so it's center was not missing. The best way to describe how these vision-occluding spots looked would be to have you turn out the lights, take a bright flashlight or camera flash and shine it in your eyes, and then see the bright greenish spot that occurs after. The spots were present whether my eyes were opened or closed. I noticed the first spot, and stopped exercising, the second appeared, they both got larger then subsided, the smaller one disappearing first and then the larger one; They were present for a total of about 1 minute to 2 minutes. It was painless; it didn't completely obscure my vision in either eye. It was definitely bilateral - one eye worse than the other. I have no visual deficits now - the spots are gone and my vision does not seem to be affected at all.
I have never had any unusual visual or neurological problems; I don't have a history of headaches or migraines.
I have seen similar spots before - when I was a kid and bored I used to push on my eyes, and I noticed that if I pushed the superior aspect of my eye then I would get a bright spot in the inferior portion of my visual field. I assume that the bright lights I saw as a kid where probably caused by pressure on my retina, and thus the top-bottom inverse relationship. Of course, I haven't pressed on my eyes like that for years.
Anyhow, I am worried that the spots I saw tonight might be related to some type of retinal ischemia. A quick google search on the topic turned up nothing helpful.
As a side-note, I may have hypertension. My left arm systolic blood pressure is about 20 points higher than my right arm, and sometimes my pressure can read up to the 150s in the left arm -- my primary care doc told me I have "white coat" hypertension (although I am not a terribly nervous person) and she didn't want to start me on any anti-hypertensives.
If anyone has experienced something similar, or can point me to some literature describing similar symptoms and their cause(s), I would be grateful.