• The Cornea - the first thing light hits on entering the eye; it is a round, transparent window which works like a lens; it is made of 5 parts, all of which help protect the eye and assist in proper functioning
• The Sclera - the white of the eye, which is connected to the cornea
• The Uvea - makes up the centre of the eyeball; consists of three parts -
  the choroid (a thin sheet of membrane located between the outer protective sclera and the retina; this layer helps prevent light rays from bouncing off the back of the eye, which would cause confusing images)
  the ciliary body (helps to adjust the shape of the lens) and lastly
  the iris (contains a pigment that gives the eye its color; its muscles can dilate or contract the pupil and thus control the amount of light falling on the retina)
• The Lens - located behind the iris; is elastic and transparent and has less work as compared to the cornea
• The Vitreous Humor - the jelly-like texture that is contained within the interior chamber, behind the lens
• The Retina - forms the entire curved inside of the eyeball and is lined with two types of light-sensitive cells, the rods (sensitive to light of low intensity but not to colors) and cones (sensitive to colors).
• The Optic Nerve - all the rods and cones are connected to the brain by a nerve and all these nerves form a thick cable called the optic nerve. This emerges from the back of the eye, moves through the skull and ends up inside the skull bone, beneath the brain near the pituitary gland. Here it meets its fellow optic nerve coming from the other eye. From here, the nerves pass through the lateral geniculate body, the internal capsule and finally reach the back of the brain. This region is called the Visual Cortex, which is in-charge of receiving information from the eyes and interpreting it.
• As said above, when the eye is focusing on an object, light rays from the object enter the eye, get refracted at the lens to form a smaller, upside-down image on the back of the eye. Depending on the distance of the person from the object, the lens will either become more curved (near objects) or become narrower (far-away objects) to focus the object better.

Process of 'Seeing'
Both the eyes have slightly different fields of vision since they are separated by the nose. Each of these visual fields are divided into the right and left side. The following diagram clearly shows the structure of the human eye and what happens when an object is looked at. Not only do the two eyes see different angles of the object but each individual eye takes in different information, due to the different visual fields. The diagram has given two different colors to the different visual fields to make the process more understandable. Signals from the left visual fields of both eyes are sent to the right visual cortex and vice versa. The information received at one eye is incomplete since only one part of the image is available, therefore both eyes immediately send their information to the brain, so that the information can be combined.

Process of 'Seeing'

Along the way at the optic chiasma, some of the nerves from each optic nerve cross over so that information from both the left visual fields are together; the same goes for the right visual fields. The optic nerve is essentially made up of a bundle of nerve fibers that carry electrical impulses down minute cables. After reaching the optic chiasma, another swapping of information takes place at the cell station or the lateral geniculate body. This connection functions in accordance with the reflexes of the pupils. From here, the nerves spread out on their respective sides around the temporal part of the brain (forming the optic radiation). Finally, they pass through the main exchange (where the body's motor and sensory information is stored) reaching the visual cortex. The images are interpreted at this point.
 

What is so amazing about the eye is that it does all of the above processes in a fraction of a second! This is only a brief outline about the eye and how it works - much more can be learned about this wonderful instrument.