The human eye is one of the most complex organisms in the human body – second only to the brain. It is the organ which gives us the sense of sight, allowing us to observe and learn more about the surrounding world than we do with any of the other four senses. We use our eyes in almost every activity we perform, whether reading, working, watching television, writing a letter, driving a car, and in countless other ways. Most people probably would agree that sight is the sense they value more than all the rest. It can distinguish about 10 million colors. The eye allows us to see and interpret the shapes, colors, and dimensions of objects in the world by processing the light they reflect or emit. It is able to detect bright light or dim light, but it cannot sense an object when light is absent. STRUCTURE OF THE EYE
Human eye are situated in the eyes sockets of the skull. The sockets give protection to the eyes. A number of muscles hold the eyes in place, enabling them to move in different directions. The eye is not shaped like a perfect sphere; rather it is a fused two-piece unit. The smaller frontal unit, more curved, called the cornea is linked to the larger unit called the sclera. The cornea and sclera are connected by a ring called the limbus. The dimensions differ among adults by only one or two millimeters. The vertical measure is generally less than the horizontal measure. The typical adult eye has an anterior to posterior diameter of 24 meters, a volume of six cubic centimeters, and mass of 7.5 grams. PARTS OF THE EYE
To understand how the eye operates, it is first necessary to know the names and functions of some of its parts. The white part of eye that surrounds the cornea and protects the inner parts of the eye is called sclera. Cornea is the transparent tissue at the front of the eyes which helps in concentrating light rays onto the retina. Aqueous humor is a clear transparent fluid that fills space between cornea and lens. It also...
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