I don't know whether this question will be allowed on here or not. Just to be clear, I'm not asking for a diagnosis of myself. I am curious and wanting to know what can happen.
I made the mistake of holding the built-in flash of my DSLR to my eye and taking a photo in a very dark environment. I think I've done this before (never in a very dark environment, however). It was stupid of me. That area of my eye was not working for a while, but within an hour, everything was normal.
My question is, does doing this have the capacity to cause permanent damage to your eye? I did a bit of googling, and apparently, you need prolonged exposure to a very bright source of light for it to be harmful (for example, more than a few seconds at the sun). The camera flash is very, very brief. A fraction of a second.
PS. I'm not planning on doing this again anyhow. I'm just curious.