system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What is happening when a person rubs their eyelids and momentarily loses vision?

After a person rubs their eyelids, with a bit of force and then re-opens them, their vision appears to come back from total black and then grows in size from a circle of light in the center (this normally only lasts a few seconds). Almost like the vision is re-calibrating or the eyes have some sort of safety measure. Why does this happen?
gpt
rubbing your eyes increases the intraocular pressure by quite a lot.  normal intraocular pressure is between 10-21 but rubbing for eyes can make it go up to 80-100.  if the pressure increases enough then it prevents blood flow to the optic nerve and retina thereby causing loss of vision.  once the blood starts flowing the vision returns.