Sometimes, when you shut your eyes tightly or are in a pitch black room, your eyes decide it’s time for a light show. Random, psychedelic-like patterns and flashes of color will dance around your field of vision like it’s 1969. While you can appreciate the entertainment, in the back of your mind you wonder what is causing the phenomena.
Are these flashes and patterns of light and colors indicative of a health problem? Are they something that can be treated or cured? Or are they completely normal? Today we’re going to crash the party in your eyes and find out what’s going on.
Light Need Not Apply
One common misconception about a human’s vision is that our eyes require light (photons) to be stimulated. Even in the absence of photons, the neurons in our visual system are always active. The thalamus (part of the brain responsible for relaying sensory signals), your visual cortex, and your retina are in an “always on” state – even while you sleep. The neurons in these visual systems are continuously relaying signals and information.
This continuous activity is sometimes referred to as background activity. It’s this background activity that is responsible for your trippy visuals and interesting patterns in the absence of light. The technical term for this phenomena is a “Phosphene“.
