"Doctor, why do we see coloured lights moving inside the eye when we keep a torch on our closed eyes ?"
Her curiosity amazed me and here is a video simulating the colours seen and the mystery behind this.......
Itz called The Entoptic Phenomenon......
Entoptic phenomena are visual effects whose source is within the eye itself. Under suitable conditions light falling on the eye may render visible certain objects within the eye itself. These perceptions are called entoptical.
When a torch is placed on the closed eye it illuminates the inside of the eye and the blood flowing in the vessels and the liquid inside the eye is visible as different colours.
Phosphene
A phosphene is an entoptic phenomenon characterized by the experience of seeing light without light actually entering the eye. The word phosphene comes from the Greek words phos (light) and phainein (to show).[1] Phosphenes can be directly induced by mechanical, electrical, or magnetic stimulation of the retina or visual cortex as well as by random firing of cells in the visual system. Phosphenes have also been reported by meditators,[2] people who go for long periods without visual stimulation (also known as the prisoner's cinema) or who are under the influence of drugs, especially a hallucinogen.
The most common phosphenes are pressure phosphenes, caused by rubbing the closed eyes. They have been known since antiquity, and described by the Greeks.[3] The pressure mechanically stimulates the cells of the retina. Experiences include a darkening of the visual field that moves against the rubbing, a diffuse colored patch that also moves against the rubbing, a scintillating and ever-changing and deforming light grid with occasional dark spots (like a crumpling fly-spotted flyscreen), and a sparse field of intense blue points of light.
The name "phosphene" was coined by JBH Savigny, better known as the ship's surgeon of the wrecked Medusa.[7] It was first employed by Serre d'Uzes to test retinal function prior to cataract surgery.[8]
Most vision researchers believe that phosphenes result from the normal activity of the visual system after stimulation of one of its parts from some stimulus other than light.
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