The five senses that humans experience are all vital to overall health, well-being, and a basic understanding of the physical world. Vision is usually the first way a person observes their environment. Images are interpreted by the brain, allowing people to understand the difference between colors, textures, and movement.
Light is essential to eyesight, so the retina and pupil play a very important part in seeing images. The pupil is a tiny pinhole in the cornea that allows light to enter. Once light enters the eye, it reaches the retina and is either refracted or reflected. When the light is bent, the image is bent as well, and this allows the eye to focus on the thing it is looking at. The cornea, which is the clear front covering of the eye, also allows light to be bent so people can see clearly.
Every eye is shaped slightly different and has a different length. Depending on the length of the eye, there can be some vision problems. This is also due to how the retina and cornea receive, bend, and reflect or refract light. For people who are nearsighted, the eye is too long. For those who are farsighted, the eye is too short, and for people with astigmatism the eye has an unusual or oddly shaped curvature. All three of these eyesight issues can affect how images appear, but can usually be corrected through prescription lenses or, in some cases, surgery.
The optic nerve plays the most integral part in how the eyes work. This nerve is a conduit between the retina and the brain. It receives signals from the retina, and sends them to the brain for interpretation and memory storage. If the optic nerve is damaged, people can experience difficulty seeing images, or even blindness. The optic nerve contains a vast network of blood vessels, which keep it nourished.
At the back of the eye sits the optic disk, which is positioned right at the front of the optic nerve. All of the retina’s tiny blood vessels connect to this disk. Cells called rods and cones are what allow colors to be seen. Babies’ rods and cones are not fully formed, so babies see everything in black and white until the rods and cones have matured.
When light goes through the cornea, it is crossed, so images we see are actually transmitted upside down. The brain then turns the image right side up so that the things people see are actually as they are. All of the elements of eyes work together, to form an intricate network of nerves, cells, and blood vessels that allow people to see more than just basic outlines, but detailed, vivid images.