I have these. I've had them for about four years now. I have been diagnosed with classic ocular migraines after having a CT Scan and MRI. Mines happen in one eye, my right eye and I loose vision in it for about a minute, not long at all. I am still able to see out of my other eye during these episodes. I just had one last night actually.
I know when its going to happen. I feel a funny "brain buzz", I can't explain it, its just a funny feeling where I know its coming.
Slowly my right eye vision becomes cloudy, like I've been staring at a flashing camera and the lights have burned into my vision. This is followed by sparkles, very bright, where it almost looks like I'm looking into my brain because the sparkles look like glowing bright veins or something. Really weird stuff. Then my vision slowly returns.
Some times its worse than other times. I get this after I've had a migraine buy they can be triggered by bright light, straining my vision and PMS. Basically the same things that would trigger a migraine. The event itself is painless and not followed by painful migraine.
I have always known them to be called ocular migraines and they can happen in just one eye. They are usually pain free. Basically its a type of migraine with aura. Its harmless but some people can have one happen for 30 minutes or more. I have heard people call them retinal migraines before as well. My neurologist never mentioned them being dangerous or causing permanent damage. The only issue they can cause is a higher risk of stroke.
I don't want to know if they are dangerous and stuff. My anxiety levels have been higher than usual these days and dang it, the last thing I want to think about is going blind along with everything else I got going on.