The human eye sends light through a series of specialized parts to the nerve directly to the brain.
Light-processing parts:cornea, pupil, crystalline lens,retina, and the optic nerve itself.
Each part of the eye has a specific task to help the brain receive signals that it can turned into pictures that we can see.
Movement of the eye is controlled by a series of muscles that is direct to the eye.
The size of the pupil determines how much light enters the eye.
Light enters the eye through a transparent layer, the cornea.
The cornea has no blood supply and receives oxygen directly from the air instead.
It is shaped to begin bend light waves toward the rest of the eye.
A healthy cornea is slightly thicker on the edges than in the centre, but if the cornea is damaged or changes in shape because of disease or injury, light entering the eye is distorted.
The pupil is the next part for see able light.
A reflex called the pupillary light which changes the pupil's size according to how bright the light is.
Next the light goes through a transparent gel-like material — the aqueous humour — that further refracts light waves to reach the crystalline lens.
The crystalline lens is a flexible lens that changes itself according to the distance or size of the object. This is unlike the cornea, which is fixed in its magnification.
Lens thicker = focus short distance
Lens flattens = focus further smaller objects
An image seen through the lens is upside down and backwards because of the nature of light waves. The brain is able to read this upside down image .
Light then travels from the lens to the retina through another clear substance called the vitreous humour. More refraction happens in this substance.
The retina is mainly a group of nerve cells, called photoreceptors, that are able to read a certain range of light waves of the electromagnetic spectrum.
Photoreceptors are mainly of rods and cones. Rods work in dim light and read in black and white. Cones read colour and work in brighter light. The retina also has photoreceptors that help the eye react to bright light. These rare photoreceptors are called photosensitive ganglion cells.
After the retina, light reaches the optic nerve, which then sends the information to the brain.
The brain is able to make out these combinations of light waves so that the human consciousness can understand them.
The retina specifically translates light into electrical signals and sends the signals all the way to the back of the brain.
The retina is actually the part of the brain that is made to serve as a transducer for the changing of patterns of light into neuronal signals.
The lens of the eye focuses light on the photoreceptive cells of the retina, which detects the photons of light and responds by producing neural impulses.
The primary and secondary visual cortex of the brain receives these signals from the lateral geniculate nucleus as they are processed in a hierarchical fashion by these different parts of the brain.
Light travels from Cornea → Pupil → Aqueous Humor → Crystalline Lens → Vitreous Humor → Retina → Optic Nerve → The Brain → Human Consciousness