What is happening when I push on the corner of my eye and “see” a halo?
I do this “for fun” quite a lot, often when I do it accidentally and want to explore more about the phenomenon. I see a black/dark spot surrounded by something like a halo, but I normally would describe it as a black spot.
My general assumption has been that it’s changing the way light is entering your eye such that light coming from certain angles gets redirected in such a way that some parts of your retina receives no input while the surrounding areas are receiving light from multiple angles. Thus your brain determines that a certain area is dark, and the surrounding area is a bit brighter.
Phosphenes
Freaky, aren’t they?
Cool, I’ve been meaning to ask the same question.
Now for the other question: is pressing on your eyes like that liable to cause permanent damage? I like playing with the phosphenes from time to time, but I’ve always been worried that I’m going to end up killing my vision or something.
When I saw them the first time (lying in bed, pitch black), it freaked me out so I made an appt to see my doc. He referred me to a specialist, thinking it was probably nothing but that I might need glasses since I’m forty-something. When I asked the specialist, he said they’re a normal part of aging. My IANADWAG is you’ll be ok.
BTW mine look iridescent, like a jelly fish.
These things also aroused the curiosity of Isaac Newton, who, in trying to figure them out, showed a lot of experimental zeal: he poked around, with a blunt needle, “betwixt my eye & [the] bone as neare to [the] backside of my eye as I could”, essentially performing a circus freak trick in the name of science.
And (to answer a previous question) causing permanent damage to his eyesight in the process. However, he went to extremes, and just poking your eye every now and then isn’t likely to do anything bad. He would do it for hours at a time. He also liked to stare at the sun as long as he could. Interesting guy, that one.