The Eyes essays

The Eyes essays The eye houses 70% of all sensory receptors of the body. At first glance, the eye seems to be a simple structure, but it is very complex. 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 persons eye color. It is shaped like a flat doughnut and is located between the cornea and the lens. The pupil is the round 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 ...