Useless fact
What are the spots you see when you rub your eyes?
The visual sensations of light, spots, or patterns produced when you rub your closed eyes are known as phosphenes.
The phenomenon of phosphenes has been recognized since antiquity. Ancient Greek writers and early scientists, including Isaac Newton, documented seeing colors and flashes of light after applying pressure to their own eyes. Modern scientific understanding established that phosphenes are caused by mechanical stimulation of the retina. When you press on your closed eyelids, the physical pressure stimulates the cells of the retina in a way that mimics the effect of light, causing them to send electrical signals to the brain. The brain's visual cortex interprets these signals as actual visual patterns, which often appear as swirling colors, grids, or geometric shapes. An adjacent detail of this phenomenon is that phosphenes can also be induced by other non-visual stimuli, such as electrical currents, intense magnetic fields, or sudden changes in motion, which astronauts frequently report experiencing while traveling through cosmic radiation in space.
Why this is true — The term 'phosphene' is the accepted scientific name for the phenomenon of seeing light without light actually entering the eye, commonly experienced by pressing on the eyelids.
Sources
- What Are Phosphenes? American Academy of Ophthalmology