Bodily Oddities

Phosphenes

Also called: Pressure phosphenes · "Seeing stars"

The flashes, rings, and patterns of light you see when you rub or press your closed eyes, or after a knock on the head. The retina fires from pressure instead of light.

Eyes Brain Involuntary Involuntary
Try it Illusion

How common

Everyone Universal · ~100%

Does this happen to you?

These are answers from visitors, not a study.

How it works

The retina turns light into nerve signals2. It also responds to other things: mechanical pressure, electric current, magnetic fields, and radiation1. The brain does not know the difference. Any signal from the retina is seen as light.

Pressure phosphenes are the everyday kind. Press gently on a closed eye and the pressure bends the retina. Its cells fire. You see a ring, a spot, or a spreading patch of colour, usually on the side of the visual field opposite the pressure1. Flick phosphenes appear in darkness during quick eye movements1. The faint drifting patterns you see with eyes closed and no pressure are a related effect3. A blow to the head makes you “see stars” because the sudden movement of the eye’s jelly pulls on the retina1. Astronauts on the Apollo missions reported flashes with their eyes closed. These came from cosmic rays passing through the retina or the visual part of the brain1.

Electric stimulation of the visual cortex, the back of the brain, also produces phosphenes. Researchers use this to design artificial vision for blind people1.

Try it

  1. Close your eyes.
  2. Press very gently on the outer corner of one eye, through the eyelid, with a fingertip.
  3. Watch for a spot or ring of light on the side away from your finger.
  4. Release. The spot fades in a few seconds.

Gentle pressure is safe. Hard pressure is not. Skip this if you have any eye condition or recent eye surgery.

History and culture

Isaac Newton recorded coloured circles after pressing on his own eye with a blunt needle, an experiment nobody should repeat1. The word phosphene comes from the Greek for “light” and “to show”.

Sources and further material

  1. Encyclopedia Phosphene
  2. Encyclopedia Retina
  3. Encyclopedia Closed-eye hallucination Related patterns seen with eyes closed and no pressure.
  4. Video Phosphenes demonstration YouTube search.
Eyes Perception

Closed-eye hallucinations

Close your eyes and you do not see nothing. You see speckle, drifting colour, and, as you fall asleep, moving patterns and even scenes. Everyone has them. Almost nobody talks about them.

Everyone
Heart Involuntary

Seeing stars when standing up

You stand up fast, your vision goes grey or sparkly, and your head feels light for a few seconds. Blood has briefly pooled in your legs. It passes on its own.

Almost everyone, at some time
Eyes Involuntary

Floaters

Small grey threads, dots, or cobwebs that drift across your vision and dart away when you look at them. They are shadows of tiny clumps inside the eye. They are common and usually harmless.

About 70% of people, at some point
Eyes Perception

Blue field entoptic phenomenon

Tiny bright dots that dart along wiggly paths when you look at a clear blue sky. They are your own white blood cells moving through the capillaries of the retina.

Everyone