How Your Eyes Work

How Your Eyes Work?
The light rays enter the eye through the cornea, which is a thick, transparent protective layer on the surface of your eye. Then the light rays pass through the pupil(the dark circle in the center of your eye and into the lens.
When light rays pass through your pupil, the muscle called the iris (colored ring) makes the size of the pupil changedepending on the amount of light that's available. You may have noticed this with your own eye if you have looked at it closely in a mirror. If there is too much light, your pupil will shrink tolimit the number of light rays that enter. Likewise, if there is very little light available, the pupil will enlarge to let in as many light rays as it can. Just behind the pupil is the lensand it focuses the image through a jelly-like substance called the vitreous humor onto the back surface of the eyeball, called the retina.
The retina, which is the size of your thumbnail,is filled with approximately 150 million light-sensitive cells called rods and cones. Rods identify shapes and work best in dim light. Cones on the other hand, identify color and work bestin bright light. Both of these types of cells then send the information to the brain by way of the optic nerve. The amazing thing is, when they send the image to the brain, the image isupside down! It is the brain's job to turn the image right side up and then tell you what you are looking at. The brain does this in a specific place called the visual cortex.
Once light isconverted into electrical impulses and sent down the optic fiber, it goes all the way to the back of the brain (after making a few stopovers), where the visual cortex is located. In thevisual cortex, a hierarchy of detector cells isolates useful regularities in the visual data, discarding superfluous information. One layer of cells detects things like lines and curves.