The actual eye or eyeball is a hollow sphere consisting of many parts. The structure includes the ora serrata retinae, ciliary body, suspensory ligament, cornea, iris, pupil, anterior pole, anterior segment, lens, the scleral venous sinus, the posterior segment, the sclera, the choroid, the treina, the macula lutea, the fovea centralis, the posterior pole, the optic nerve, the central artery and the vein of the retina and the optic disc. Each of these performs a unique function. When abnormalities occur, the result is a vision problem, disease or blindness.

The vascular tunic or uvea is the middle coat of the eyeball. It has three regions called the choroid, ciliary body and the iris. The choroid is a dark brown membrane that provided nutrition to the eye tunics. The ciliary body is a thickened ring of tissue that encircles the lens and consists of muscle bundles. The iris is the colored part of the eye, which is the visible portion seen and referred to as a person's eye color. It is shaped like a flat doughnut and is located between the cornea and the lens. The pupil is the round

The eyebrows are a protective source for the eyes. They keep perspiration from dripping into the eyes and also provide shade from sunlight. The eyebrows are made up of short hairs just above the eyes. The eyelids are thin tissues that cover the eyes. Muscles control eyelids. There are two types of eyelids, upper and lower. The upper eyelid is the larger of the two and the most mobile. Eyelashes, is another protective feature for the eyes. They are located on the eyelids and are made up of hairs. These hairs protect the eyelids and work as a reflex. When touched the eyelashes cause instinctive blinking of the eyelids.

central opening of the iris and allows light to enter the eye. The retina also known as the sensory tunic consists of two layers, a pigmented layer and a neural (nervous) layer. The neural layer of the retina plays a direct role in vision. It is composed of three types of neurons: photoreceptors, bipolar cells and ganglion cells. Rods and cones are found in ural retinas. Rods aid in our dim-light and peripheral vision while cones aid in our bright light and high color vision. There are also various chamber and fluids within the eye, which aid in proper vision and prevention of disease and blindness. The lens is the biconves, transparent, flexible structure of the eye that can change shape and allow precise focusing of the eye.

The conjunctive is a transparent mucous membrane that lines the eyelids. The lacrimal apparatus is within the eye and is visible when the eyelid is inverted. The purpose of the lacrimal apparatus is to provide a constant secr

Some common words found in the essay are:
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Approximate Word count = 1075
Approximate Pages = 4 (250 words per page double spaced)