TIL What Those Lights Are That You See When You Rub Your Eyes Hard

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We can see them when we close our eyes and give them a good rub, little ‘stars’, random patterns, flashes or floating specks of light – a fuzzy fireworks show! They can even remain in our vision for a short while after we open our eyes. I’m not talking about afterimages that occur if you stare into a light source, but lights you see even in a completely dark room.

They are called phosphenes.

The word comes from the Greek phos-light- and phainein-to show- and is a phenomenon that means to see light without light entering the eye. Your eyes are still working even when you close your eyelids and without a bunch of information to take in the inherent impulses from your retina show up as these random patterns of light.

Specifically the type we see when we rub our eyes is pressure (mechanical) phosphenes, but there are also electrical, magnetic, radiation, and by diseases or even use of hallucinogenic drugs as ways to stimulate them as well.

By rubbing our eyes we are applying pressure to our retina and that pressure stimulates it to generate the phosphenes and the light show. You can try it anytime you want to, just be gentle with your eyes. It is the same effect as ‘seeing stars’ after a hit on the head, a big sneeze, or standing up too quickly when you have low blood pressure.

A phosphene effect called “prisoner’s cinema” happens to some people who are put into a dark room for a long time. It is thought that the lack of outside stimulation causes them to occur.

Percentage of pattern appearances. Phosphene colors varying from blue, to yellow, or white for foreground and from black, to red, blue, or yellow for background.

Blind people cannot see pressure phosphenes, but are able to see them when their visual cortex is electrically stimulated. This is being studied to help develop ways to give them artificial sight.

Experiments with intense magnetic fields have created phosphenes in test subjects.

Astronauts have reported seeing phosphenes from space radiation.

It is thought that some Upper Paleolithic art is actually depictions of phosphenes, possibly enhanced by the use of drugs.

Some diseases can cause phosphenes to occur without any of these stimuli. If this is happening to you, go get checked out by an eye doctor.

While I am on this subject, what about “floaters” that some people occasionally see? Those are just bit of solid matter floating in your normally clear eye fluid. Nothing to worry about unless you are suddenly seeing them in large numbers, again go see an eye doctor if this is happening to you.

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Sources:

• What Are the Lights and Patterns I See When I Close My Eyes?
• Why Do I See Patterns When I Close My Eyes?
• Phosphene
• Pictures: Pixabay & 1