The Eye: The Purpose Of The Eye And Blindness

The eye is very crucial for our survival, it is one of our five sense being sight. The is the wonderful thing that allows us to see the wonderful world around us. There are many parts to our eyes, a lot more than I thought. Our eye has one main function which is to let us see and there are many things that happen in our eye that gives us sight. Did you know that is many diseases that cause blindness? The eye is a pretty special thing.

There are many parts to the eyeball itself but I'll just be covering the most basic and most needed part.

In this picture you can see the sclera, cornea, pupil, lens, iris, ciliary body, choroid, retina, fovea, and the optic nerve. Each one of these things have essential jobs in the eye. The sclera is the

We all know that the eye gives us our vision but there are many things that happens in our vision. With vision comes the job of seeing actions, two dimensions or three dimensions, light, depth and color. So how do our eyes see in color? Well when you look at a banana, the wavelengths of reflected light determine what color you see. The light waves reflect off the banana's peel and hit the light-sensitive retina at the back of your eye. That's where cones come in. Cones are one type of photoreceptor, the tiny cells in the retina that respond to light. Most of us have 6 to 7 million cones, and almost all of them are concentrated on a 0.3 millimeter spot on the retina called the fovea centralis. Not all of these cones are alike. About 64 percent of them respond most strongly to red light, while about a third are set off the most by green light. Another 2 percent respond strongest to blue light. When light from the banana hits the cones, it stimulates them to varying degrees. The resulting signal is zapped along the optic nerve to the visual cortex of the brain, which processes the information and returns with a color: yellow. Humans, with our three cone types, are better at discerning color than most mammals, but plenty of animals beat us out in the color vision department. Many birds and fish have four types of cones, enabling them to see ultraviolet light, or light with wavelengths shorter than what the human eye can perceive. Lastly we may ask how our eyes see images, the images we see are made up of light reflected from the objects we look at. This light enters the eye through the cornea, which acts like a window at the front of the eye. The amount of light entering the eye is controlled by the pupil, which is surrounded by the iris, the coloured part of the