Function and Anatomy of the Human Eye
Function and Anatomy of the Human Eye
The human eye is a wonderful thing. It lets us view things. They can give us another eye color, or we could just use them to simply view things. But it’s not that simple you see. Some people aren’t that lucky, and have impaired vision. This includes near-sightedness and far-sightedness. To begin though we must understand how the eye works, and why it works that way.
First is the cornea, which is a clear dome that covers the front of the eye. The cornea accomplishes the majority, which is about 70%, of the bending of light rays.
The crystalline lens finishes the rest of the 30% of focusing of light. It helps to "fine tune" vision, and it has the ability to change shape so that it focuses on one thing, normally near. When it becomes cloudy, it is called a cataract. Sometimes age has some thing to do with cataract. Unlike the cornea, the lens can be made to change its shape (and, therefore, its refractive power) often and however many times it pleases. Using its ability to change shape, the lens allows the eye to change its focal point. Changes in the shape of the lens will allow a normal eye to focus on near objects.
Then there is the iris, which really doesn’t do anything except give the eye color, which I guess is pretty cool. It would be weird if everyone had black eyes, or brown eyes, so variety is good.
The pupil is the little opening in the middle of the iris. It can change shape, as it controls the amount of light that enters an eye. When it is bright the iris will shrink, therefore not letting in as much light. When it is dim the iris will grow, therefore letting in more light.
In the back of the eye there is nerve tissue that senses light and is called the retina. “Specialized cells called rods and cones convert light energy into nerve signals that travel through the optic nerve to the brain” I quoted that from Grolier encyclopedia 1996, simply because it was the best way to put it.
Now that the basic knowledge has been taught, we move on to the next part, near-sightedness.
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