I have had very similar experiences to this Op, mine are like a camera flash but much faster. Its happening a few times a week now and started a couple of months ago. Its happened at work but when i looked around nobody seemed to have noticed, Also had one at night in the bedroom, i actually got up to see if somebody was flashing a flashlight across the window outside? very bizarre.
I'm a printer by trade so my eyes are pretty much spot on (no probs) 20-20 vision :/