Eyes!

The eyes are an amazing thing. They are the very thing you use to read this piece of text. But do you wonder how eyes work? The eye has 6 main points; The cornea, pupil, iris, lens, retina and optic nerve. The cornea is the front part of the eye. It is tough, transparent and convex. The job of the cornea is to refract light as it enters the eye. The next important part of the eye is the pupil. It is the black part in the center of your eye. The job of the pupil is to let the light into your eye. Surrounding the pupil is the iris. The iris is the coloured part of your eye and it's job is to control how much light gets in. Once thought the iris and pupil, the next part is the lens. The lens in a bi-convex, transparent, flexible disk and the job of the lens is to focus the light onto the retina. Now we get to the retina. The retina is a layer of cells which connect directly to the optic nerve. Retina is a really important part of seeing. What happens is once the light passes through the iris, pupil, lens and onto the retina, the retina changes those light waves into electrical waves. These waves then get sent into to optic never which goes straight to the brain. The brain revive these electrical waves and changed them into images which is how we see.

At science we did a cows eye dissection to take a closer look at eyes. We started by removing any excess fat and muscle surrounding the eye. Both the pupil and iris had clouded over and was just a misty blue colour. Next we got surgical scissors and gently cut the eye open. Inside the eye humor leaked out. Within the humor we could the lens lying about. If the cow were to still be alive and living the lens would be very flexible and soft. But since it was dead it was hard. At the back was a lining of the retina. On the other side of it was what once used to be an optic nerve. Underneath the retina was a blueish colour along the edge. This is what allows cows to see in the dark. 

The reason our irises come in different colours are due to the amount of melanin we have. People with less melanin are more likely to have blue or green coloured eyes whereas people with more melanin are more likely to have darker colours such as brown. This is all to do genes and the amount of pigment you have. For example, people with lighter skin are more likely to have lighters eyes and vice versa. The colour of your iris doesn't affect your vision.