Have you ever seen geometric shapes or blobs of color when you close or rub your eyes? Have you ever seen stars, colors or other amorphous flashes of light when you stand up too fast?

Well, there's a term for these seemingly odd, random flashes of light and color. They're called phosphenes and can basically be defined as impressions of light that occur without actual light entering the eye.

Phosphenes and biophotons

The light we perceive when we see phosphenes is caused by biophotons. Biophotons are photons of light produced by a biological system, such as the light that emits from fireflies.

Research conducted by Hungarian neuroscientist Istvan Bokkon suggests that phosphenes occur when biophotons in our eyes are triggered. So think of a phosphene as a phantom light that occurs when certain stimuli (like rubbing your eyes) generate biophotons within the visual system.

Tricking the visual system

Our visual system consists of:

  • The retina, a membrane that lines the back of the eye and senses light
  • The optic nerve, which connects the eye to the brain
  • The occipital lobe, the part of the brain that sorts visual stimulation

When one of these three parts of the visual system is manipulated or “tricked” in some way, we can experience the sensation of phosphenes. Our visual system can be manipulated by either electrical stimulation or mechanical stimulation.

In the case of electrical stimulation, placing electrodes near your optic nerve can cause you to see phosphenes. Placing an electromagnet near your occipital lobe also can produce the same effect.

Mechanical stimulation would be due to pressure — rubbing your eyes or gently pressing on the side your eyes. When the eye experiences this sort of pressure, the eye perceives the pressure in the same way it would the stimulus of light. Because of this, the central nervous system can't tell if it experiences light from outside or inside the eye.

Pressure phosphenes are actually the most common form of phosphenes. A blow to the head, sneezing hard and standing up too fast (which causes blood pressure to drop) can also cause the sensation of phosphenes.

Phosphenes, migraines and multiple sclerosis

Phosphenes are harmless on their own, but they can occur as the result of certain medical conditions.

Phosphenes are a symptom of the aura phase of a migraine. When a migraine causes vision problems in addition to pain and/or nausea, it's called an ocular migraine.

Phosphenes are also tied to multiple sclerosis. One potential and common symptom of multiple sclerosis is optic neuritis. Optic neuritis occurs when the optic nerve becomes inflamed, which may cause phosphenes.

If you experience phosphenes on a consistent basis without trying to create the sensation, you may want to consider contacting your doctor.

Otherwise, go ahead and rub your eyes for a bit and make your own personal light show.

There's a name for those odd flashes of light you sometimes see with your eyes closed
Those odd, random flashes of light and colors you sometimes see when you rub your eyes are called phosphenes. Here's why they happen.