Parts of the Eye
The human eye is often compared to a digital camera, but it is much more complex. Delicate structures controlled by tiny muscle fibers bend and focus light that is being reflected from the objects in our visual field. This light is concentrated onto specialized cells in the back of the eye that convert it to electric signals that travel from the optic nerve deep into the brain. Our brains then process the image, allowing us to recognize objects and interact with our environment using our sense of vision.
Cornea: The cornea is the clear, outer layer of the eye. Though the cornea is very thin, it is composed of five layers. The outer layer, the epithelium, is made up of cells that quickly regenerate and heal the scratches and nicks caused by irritants in the environment. Light first enters the cornea and is focused into the eye
Iris: The iris is the colored part the eye. It is controlled by muscle fibers that cause it to open and close to allow light into the pupil
Pupil: The pupil isn’t a structure, it’s an opening that allows light to travel from the front of the eye to the back
Lens: Light that enters the eye through the pupil passes through the lens. The lens is controlled by the tiny ciliary muscles that bend light at an angle and focus it toward the retina
Retina: The retina is located in the back of the eye. It is made up of specialized photoreceptor cells that change light into electric signals that travel along the optic nerve into the visual cortex. Cone cells are concentrated in the center of the retina and allow for visual acuity and color vision. Rod cells are located along the length of the retina and help with night vision and peripheral vision
No “Body” is Perfect. What is an Astigmatism?
The human eye is a sphere filled with vitreous humor, a gel-like substance that allows light to travel from the front of the eye onto the retina. Many of us have eyes that aren’t perfectly round but are slightly misshaped. This is known as astigmatism. When this occurs, light is bent at wrong angles and doesn’t land correctly on the photoreceptor cells on the retina. As a result, our vision is blurred.
Near-sightedness, or myopia, is when the eyeball is misshaped lengthwise. This causes the lens to be too curved and objects close up will be blurry.
Far-sightedness, or hyperopia, occurs when the eye has a misshaped height. This causes a lengthening of the lens that causes objects far away in the distance to appear blurry.
All of these conditions are diagnosed with an eye exam and corrected with prescription glasses or contact lenses.