The word “eye,” like telescopes, is a convenient word used to designate a complex system of parts that all functions to allow you to see. When you look at your eyes in the mirror, you’ll see a number of different colors and exposed parts of your eye. Behind your eyelids and in the back of your head, there are even more parts that connect your eyes to your body and allow you to see.
The eye’s main responsibility is to take light and turn it into electrochemical signals that can be read by your brain and nervous system in the process of vision. Light has to travel from the front to the back of your eyeball to do this. Let’s follow the journey of light as a way of talking about all the parts of the eye!
Light travels through the cornea and pupil, through the vitreous humor, into the retina where it is transformed. Other parts of the eye have muscles and protective tissues to protect the eye and prevent damage from exterior objects and light itself.
Parts of the Eye
Light’s journey doesn’t actually begin with the pupil, it begins with the cornea!
Your iris and pupil aren’t actually exposed to the outside air, they are both covered by a protective sheath and refractive surface known as the cornea. The cornea is a clear surface, bulging over the iris and pupil. It has nerve fibers that are sensitive to the air and receive nutrition from tears to remain clear.
Starting at the center of your eye, the pupil is the black hole that light passes through. This part of the eye dilates and contracts to regulate the light received, preventing you from being blinded by sunlight and helping you see better in the dark.
The lens is a transparent part of the eye composed of proteins and water which sits directly behind the pupil and iris. The pupil dilates and contracts to allow light into the lens
In the popularity contest of the eye, the iris wins. As the colored part of your eye and the part people refer to when they ask for your eye color, the iris gets the most play of any part of the eye. The iris is composed of the stroma which connects to a sphincter muscle which dilates and contracts your pupils. The iris also contains a beautiful pigment which scatters in the light. The color of the pigment is dependent on melanin amount and distribution.
The sclera is what’s known as the “whites of their eyes.” The exterior part of the sclera is generally smoother and whiter, while the interior section is rougher and brown. The scleras support the cornea and irises, so they are durable and flexible. It has tendons attached that you move when you move your eyes to look around.
Other Connecting Parts of the Eye
Many parts of the eye are used to help other parts connect to each other:
The anterior chamber lies between cornea and iris while the posterior chamber lies between the iris and lens. The chambers hold a small amount of mercury which provides pressure, maintains the form of the eye, and spaces elements.
The choroid sits between the sclera and retina, and the ciliary body is between the choroid and iris. The choroid helps connect the retina (which forms around the whole back of the eyeball) to the sclera, which is the whites of the eyes in front of the vitreous humor. The choroid, sclera, and retina form the parts around the edges of the eyeball.
6. Vitreous Humor
The vitreous humor lies between the retina and lens. By volume, it is by far the biggest part of the eye: the transparent, gelatinous center of the eye. It helps maintain eye shape and guides light back to the optic nerve.
The vitreous humor is the massive part of the eyeball that light passes through between its entry from the pupil and its transformation in the retina.
The retina lies at the back of the eyeball, past the pupil, lens, and vitreous humor. Light passes through all these onion layers before finally getting to the photoreceptors in the retina, which change light into electrochemical signals in a process called “transduction.” In transduction, the light that bounces into your eyeball becomes signals that the nervous system can read.
The macula lies at the center of the retina and helps you see details in objects–aging can deteriorate the macula.
The retina is the “camera” part of your eye, and the parts in front of it are the lens!
8. Optic Nerve
Once transduction occurs and light has become electrochemical signals, the optic nerve sends the signals backward to your nervous system.
And that’s how light becomes vision! Our eyeballs refract light through different parts of the eye until it becomes electrochemical signals that we register as sight. I hope that this article was helpful. If you are interested, visit the health facts page!