Posted on August 31 2015
The human eye is an incredible organ that is very intricate. Everyone knows that the eye is responsible for vision, but vision is also quite multifaceted. It concerns shapes as well as detail, motion, distance, color, texture and shading. For us to be able to see in such varied ways, the eye must have many, complex parts. So let’s talk about the different parts of the eye and why they’re essential.
From a basic perspective, we can start with the five parts of the eye with which most people are familiar: the cornea, iris, lens, retina and optic nerve. The cornea is the covering of the eye that we see through. It is transparent and helps direct and focus light as it first enters the eye. Behind the cornea is the iris. When we say that someone has blue or brown eyes, we are referring to the pigment in the iris. The iris is also responsible for controlling the amount of light that enters the eye. On a bright, sunny day, the iris will contract, limiting the light that enters the eye, so it doesn’t become overwhelmed. The black part of the eye, inside the iris, is called the pupil. After the iris, we find the lens (also called the crystalline lens), which functions very similar to how a lens works in a camera. It is adjusted to focus the light that is entering our eyes. The lens is actually quite soft and comprises a great deal of our eye power. At the back of the eyeball is the retina. This is where light waves are translated into nerve signals that are sent to our brain. The macular area, which is part of the retina, is also responsible for peripheral vision. After light has been converted to nerve signals, it leaves the eye through the optic nerve. The optic nerve allows this nerve signal to travel to the brain, where it is reconstituted into our vision.
The retina is one of the most important areas of the eye, and the fovea is a key part of the retina. The fovea is a tiny section (about one and a half millimeters) of the macular region of the retina. It is crucial to vision clarity because the fovea is the section of the eye where our vision will focus. Without the fovea, we would not be able to see clearly enough to have workable sight. Also, the fovea handles color recognition. The fovea is made up of neurons called cones that are sensitive to light. The other type of photoreceptor neurons in the retina is called rods. Rods, which are outside the fovea, are very sensitive although they do not respond to color. The fovea is nourished by the blood in the middle layer of the eye, called the choroid.
n the next article, we will discuss some of the other, lesser-known though still crucial parts of the eye.