Anatomy of the Eye 201: The Unsung Heroes of Eyesight

Previously, we took a tour of the eye to see how it functions. We followed a light wave as it enters the eye and travels through the cornea, lens and vitreous body, onto the retina. There, the rod and cone cells gather data from the light wave and send it to the optic nerve, which translates the information into images. As you read this, light waves are traveling the same path through your eyes now.

The basic anatomy of the eye is miraculous enough, but there are also a few characters in supporting roles that you should know about. Without them, the light waves would not reach their final destination, and we wouldn’t have our precious eyesight.

Conjunctiva

The conjunctiva is a thin tissue that covers the white portion of your eye and the inside of your eyelid. Since it’s transparent, you cannot see it, but if you look closely in the mirror you might be able to observe the tiny blood vessels which keep the conjunctiva’s cells nourished. Its job is to protect the eye and assist in keeping it lubricated. It’s not uncommon for the conjunctiva to become inflamed as a response to bacteria, viral infections, or allergens. You may be familiar with this condition, known as conjunctivitis, or “pink eye.”

Tears

You may think tears are a pretty simple element, but a closer look can further your appreciation. Tears are made by small glands surrounding the eye. The moist film known as tears is really a series of layers: the outermost is oil (which prevents evaporation), the middle is water (to keep things lubricated and clean), and the base layer is mucous (which adheres the other layers to the eye). Your tear film plays an important role in your vision.

Iris

The iris is the beautifully colored ring that surrounds (actually forms) the pupil. Situated between the cornea and the lens, your iris is flecked with a unique arrangement of colored melanin cells. Its muscles contract and dilate to adjust for your environment, letting in more or less light as needed to see.

Sclera

The word “sclera” comes from the Greek root “skleros”, which means “hard”, or “tough.” Your eye’s sclera is indeed tough, and thank goodness too, because its main job is to protect. It’s the white part of the eye, to which your 6 extraocular muscles are attached. You may only be able to see the white part, but its presence extends around the eye’s globe to the optic nerve, and even blends with the optic nerve’s covering, or dural sheath. In fact, it has been called an extension of the dura mater, which is the brain’s outer covering.

Orbit

Your eye socket is your eye’s first line of defense against physical injuries. Known as the orbit, the bony structure is actually a group of 7 bones arranged in a cone shape. It is within this protective cone that your eye is able to perform all of its functions.

If hindsight is 20/20, then hopefully this new knowledge on the anatomy of the eye will sharpen your foresight. There are many elements working to make your eyesight a success, and the more you know, the more you’ll value these unsung heroes.

For questions or comments, contact Woodham’s Eye Clinic.

Image Source: Flickr

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