Eye Parts And Their Functions

Eyes are the windows through which the soul of an individual speaks. Whatever may be the color of the eyes it is used as a diagnostic tool by the doctors to have an overview of one’s health conditions. It is the most important sense a human possesses which gives us vision. This particular sense permits us to comprehend, observe and learn from our surroundings in a way no other sense does. The eyes are an essential part of all our activities like working, writing, reading, seeing etc. It is one of the most valued organs of the human body.

The basic function of the eye is to focus the light entering the eye to the back of the eyes where the sensory receptors convert light energy in to neural signals. These signals then travel to the brain which interprets these signals into images and objects. Cones are a part of the eye which permits colored vision and allows the eye to function under high intensity light. Rods permit functioning under dim light and monochrome vision. Electromagnetic radiation is given out by each and every object but our eyes can only take up a very small range of these radiations. It is known as the visible spectrum. It is difficult to see at night or in dark because absence of light does not allow items to reflect light reducing vision. Rods thus facilitate vision at night. Depth perception is another important function of the eye. Both the eyes are located symmetrically and closely on the human face. This allows the eyes to see an object from a different view known as stereo vision. This is very helpful in throwing, driving and catching.

Balance is another important function of the eye, its loss can lead to serious problems. The vestibular system is the balance system of human body and eye is a part of it. The inner ear provides the vestibular system with the required information but the visual system helps to transmit the information to the different parts of the body. Thus, if the balance is correct all objects will seem upright. This information helps the body to relate its position to the horizon. Balance can be lost if vision is lost.

All the parts of the eye are equally important for the eye to carry out its functions smoothly. The reflecting light enters the eye via a tiny hole known as the Pupil and focuses the light on the Retina. The focusing lens focuses the images on the retina from various distances. The colored ring is known as the Iris which controls the quantity of light entering the eyes. Sclera is a tough white sheet covering the outside of eye. Cornea is the transparent sheet in front of the sclera to permit the entry of light into the eye. There are ciliary muscles which control the lens from focused light. Nutrition to the parts of the eye is provided by a vascular layer formed by Choroid. The formed image is sent out to the brain by the Optic nerve. The important parts of eye and their functions are mentioned here.

Anterior Chamber

It is the frontal area of the eye filled with aqueous fluid bound by the lens and iris on the back and cornea in the front.

  • Aqueous Humor: It is the transparent liquid present in the posterior and anterior chamber of the eye and is chemically composed. It serves the cornea and it is continuously manufactured by choroid tissues. It keeps the eye firm and provides nutrition to the lens.
  • Choroid: It supplies nutrition to all the parts of the eye and is found beneath the sclera. It is composed of melanin which provides the black color of the choroid and traps light.
  • Ciliary body and Crystalline lens: The lens is transparent as it has no blood vessels. It is made up of fibrous cells. The lens functions by focusing the light to form the image. The ciliary body adjusts to the lens shape and helps in seeing objects near to the eye clearly.
  • Ciliary Nerves: Ciliary nerves are sensory fibers running under the endothelium. They belong to the large sensory nerve found in the head.
  • Conjunctiva: A thin and transparent membrane lines the opening of the eye from one lid to another. It does not allow any foreign objects to enter the eyes. The lacrimal glands keep it moist and let’s out tears when a foreign object strikes the eye and washes it away.
  • Cornea: The outer surface of the eye which helps in focusing is the cornea. It comprises of the outer epithelium, Bowman’s membrane, Descemet’s membrane, Stroma and the inner epithelium.
  • Eyelids: Eyelids protect the eye from any kind of mechanical injuries. A layer made of orbital fats surrounds the eyeball to provide it with cushioning allowing the eyeball to rotate smoothly.
  • Iris: The iris overlies the lens and controls the quantity of light which enters the eye. It is composed of tissues which are thin and elastic surrounded by a sphincter. Iris is the colored part of the eye.
  • Nerves: The nerves of the eye transmit the information to the brain from the retina where the information is processed and the image formed. The optic nerve transmits the electrical impulses to the optic chiasm from the eyes so that they can be processed further.
  • Pupil: The black portion of the eye is the pupil and regulates the quantity of light which enters the eye via the iris. Pupils expand when the light is dim so that more light can enter the eye and contract when the light is intense to reduce the quantity of light entering the eye.
  • Retina: It is a nervous tissue referred to as a screen made of photoreceptor cells. It converts the light of the physical image into electrical impulses and sends to the brain. Cells known as cones and rods make up the retina and have around ten layers. They absorb the light striking the retina. The pigments that make up the rods and cones are known as rhodopsin which enables vision in dim light.

The eyes are the most vital organ and need to be cared for well to keep the brain fresh and healthy. Blindness or poor vision can have adverse effects on one’s life.