Have you ever wondered what those lights and shapes you see when you close your eyes tightly are?
The eye is a gel-filled sac with a sensitive retina in the back that responds to light, -and to pressure. Closing your eyes and squeezing the eyelids tightly produces a pressure stimuli which causes the retina to send signals to the brain in the form of visual input.
The same thing happens if you have low blood pressure, stand up too quickly or sneeze violently. The pressure in the eyeball momentarily increase and the retina sends this signal to the brain in the form of light. These lights are called “phosphenes“
from two Greek words (”phos” and “phainein“) meaning roughly ‘To show light.’
Other Ways Phosphenes are Created
Strong magnetic fields can also cause these visual sprites. Hallucinogenic narcotics can also produce phosphene although these light shows are dissimilar to bona fide hallucinations which are generated directly within the brain.) Longer term visual deprivation also is know to be a cause of phosphenes. Extended meditative time spent within sensory deprivation tank, or being in a subterranean cave without artificial lights in time cause these visual effects. Certain diseases such as multiple sclerosis
are known to produce various forms of phosphenes (both visual and auditory,) and side effects from medicinal drugs that affect the visual cortex also cause phosphenes.
Deep meditation can also causes this animated colorful light show to appear. These shapes, forms and color splashes are referenced in Buddhist psychology as “nimetta” which denotes the basic data of perception such as colors, shapes, and sounds.
The Prisoner’s Cinema
Prisoners in solitary confinement often experience phosphenes light shows too, often to their amusement and delight. Hours in solitary can be eased by dreaming in the visual light show.
Termed ‘The prisoner’s cinema,’ these light, shape and color shows can to a degree, entertain the sensory-deprived human mind and help to alleviate boredom and even aggressiveness.
Blind from birth or have later lost their eyesight from injury or accident
People whom were born blind do not see phosphenes but instead, are treated to other heightened senses. If the person became blind later in life after a period of sightedness, normal phosphene manifestations are said to occur. Exactly why this is remains a mystery, but it was in the mid 70s that a crude visual prosthesis device was experimented with that though the creation of electrically-produced phosphenes restored a blind person’s basic vision for obstacle avoidance at least.
Refinements of this device though the use of computer technologies and micro-miniaturization of brain-interfacing hardware might someday lead to device which would be surgically attached to the blind patients brain and effectively restore (and perhaps greatly improve) visual sight. Images of on Lt. Geordi LaForge from “Star Trek: The Next Generation” come to mind.