Anatomy of the Eye 101

The eye is arguably one of the most complicated organs in our body. Being able to absorb light through the pupil where the internal lens focuses it onto the retina through the vitreous humor and then converting it into electrical signals that are carried to the brain via the optic nerve is anything short of extraordinary. But what are the basic parts of the eyes? What are their respective roles? And how do they function? Let’s dive a little deeper into the eye to gain a basic understanding of it from a high level view.

Sclera: The sclera is the white of the eye, with a smooth exterior and grooved interior. The sheath of the sclera continues with the sheath that covers the optic nerve. The sclera is the housing of the eye and is incredibly flexible and durable. This part of the eye also has tendons attached to it allowing it to be moved.

Cornea: The clear bulging surface in front of the eye is the cornea. It is transparent in nature and is the primary refractive surface of the eye. With its sensitivity to foreign debris and irritants such as chemicals and even cold air it is the eye’s primary defensive. Tears help the cornea maintain water content and oxygen exchange.

Iris: The Iris is heavily pigmented and defines the color of the eye based on the concentration and distribution of these pigments. The iris also has a sphincter muscle that controls the amount of light allowed into the eye through contraction and dilation.

Pupil: The pupil is a hole approximately 3 to 7 millimeters in diameter through which light passes.

Lens: The lens is a transparent body enclosed in an elastic capsule made up of protein and water which can change shapes, however as you get older the ability to shape the lens becomes more difficult causing people to require bifocals. This lens can also become cloudy, the primary cause of cataracts.

Vitreous Humor: This is the gelatinous substance that fills the space between the lens and retina. This fluid help to also maintain the eye shape however debris in the vitreous can create shadows causing floaters within the eye.

Retina: The retina is a layer at the back of the eyeball. It contains cells that are sensitive to light and create electrical nerve impulses to the optic nerve that is then passed to the brain allowing us to see.

OpticNerve: The location where the optic nerve is bundled is known as the optic disk. With no photoreceptors at the optic disk there is a blind spot.

With a better understanding of the eye and its parts it demonstrates its true complexity. Taking sight for granted is easy to do, however, perhaps by promoting a higher understanding of the eye will help underscore the importance of maintaining healthy eyes.