They are caused by mechanical and electromagnetic stimulation of retinal cells, which normally only respond to light stimulus. Sir Isaac Newton was one of the first to document phosphenes, which he did by inserting a blunt-ended sewing needle between his eye and his eye socket and jiggling it around until he saw dark and light circles form.
|Diary entry, 06/11/1665: Today, I discovered that if you stick|
a needle into your eye socket at precisely 90 degrees, it is incredibly painful
It's possible that rubbing your eyes hadn't been invented yet, or that "sticking things into your eyeballs" held brief popularity before "the scientific method". Newton's dedication to scientific discovery is laudable, but ill-advised.
Why?Pressure- and magnetically-stimulated retina cells transmit arcs of 'colour' that we can't accurately describe with images or pictures, obviously because pictures and images are conjured in our brains using light. Less well-understood causes of phosphenes are:
- Transcranial magnetic stimulation
- Cosmic radiation: certain types of radiation cause astronauts to experience phosphenes
- Prisoner's cinema: When the eyes are deprived of light for extended periods of time (ie: prison), phosphenes begin to play across the field of vision as your brain grasps for stimuli.
Try at homeRubbing your eyeballs isn't great for your eyesight, but give it a shot some time and see what all the fuss is about. DON'T USE A NEEDLE.
Want to read more about impulsive scientists who needlessly sacrificed themselves for science?
TLDR: your eyes are little sacs of jelly and putting pressure on them is bad and causes phosphenes