Why Do We See Patterns With Our Eyes Closed?

 by Nicole Wang

As you settle in for bed, close your eyes and ready to fall asleep, you may notice splashes of colors and light spots appearing on the inside of your closed eyelids. This phenomenon is so-called phosphene 

Everything reflects light and the light comes into our eyes, through the iris, and forms an image on the retina. Inside the retina, millions of tiny cells called rods and cones collect light and convert it into electrical signals which travel through the optic nerve to a part of the brain called the visual cortex. Different cells absorb light of different wavelengths and that is why we can recognise different colours. 

Why can we see patterns with our eyes closed? It must not be the external ordinary light. Instead, it is the light from the inside of your eyes that plays a role, just like fireflies and deep-sea creatures glow in the dark. It is the intrinsic biophotonic light. The ultraweak biophoton emission happens in the cells in the visual pathway. The light becomes conscious if induced or spontaneous biophoton emission exceeds a distinct threshold. In other words, phosphene can be mechanically, electrically, magnetically, ect., induced bioluminescent electromagnetic photons in the visual system as well as random bioluminescent biophoton firings of cells in the visual system. Natural oxidative metabolism of cells is the most source of ultraweak visible biophotons. Biophotons drive mostly from reactions of reactive oxygen species. 

The most common phosphenes are pressure phosphenes, caused by rubbing your eyes. The pressure mechanically stimulates retinal cells. Pressure phosphene can persist shortly after the rubbing stops and the eyes are opened, allowing the phosphene to be seen on the visual scene. Grüsser et al. showed that pressure on the eye results in activation of retinal ganglion cells in a similar way to activation by light. Furthermore, a blow in the head, resulting in the pressure of visual cortex against the inside of the skull, can also elicit phosphene. Both a pressure in the eye or a blow to the head can cause a mitochondrial dysfunction and surprisingly high overproduction of reactive oxygen species. Mechanosensitive ion channels play an important role in transducing physical stresses at the cell membrane into electrical or chemical signals. Under mechanical stretch, mechanosensitive potassium channels alter the membrane potential and cellular oxidative metabolism of cells. The emission of biophotons can be facilitated by a high concentration of potassium ions. 

Direct electrical or transcranial magnetic stimulation can induce brief, reversible disruption in cortical function and the spiking activities of neurons of cortical layers. These stimulations have similar effects on neuronal processes such as: neuronal membrane potential, oxidative processes, neurotransmitter release, etc. Electrical or magnetic stimulations can induce the production of free radicals and excited species can cause a transient increase in biophoton emission in stimulated neuronal tissue. Depending on where a phosphene originated, it can take on a variety of shapes, patterns and colors. Implanting electrodes on the retina or on the visual cortex can make the blind see phosphene, it is also a promising method for making the blind see the world