Anatomy of the eye

An eye consists of several parts that work together to see well.

Eyelids: Eyelids protect our eyes from drying out, dirt, and bright light. Every day we blink about 20,000 times. Blinking keeps our eyes moist, this prevents dehydration. Blinking we do, like squeezing shut in a reflex.

White of the eye: The white of the eye provides the firmness of the eye. The white of the eye is the outer layer of the eye and passes into the cornea.

Cornea: The cornea is the transparent part at the front of the eye. Light enters our eye through the cornea. The cornea acts like a lens. The cornea contains no blood vessels so there is no supply of oxygen and nutrients. Because the cornea does need oxygen, it gets it from the outside air. Therefore, it is important for people with contact lenses that the lenses allow enough oxygen to pass through.

Iris: The iris ensures that the right amount of light enters the eye. The iris is a sphincter that can enlarge (in low light) or diminish (in high light) the pupil. In addition, the iris (also called the rainbow membrane) determines the color of the eye.

Pupil: The pupil is the opening in the iris where light enters. When there is a lot of (bright) light, the pupil gets smaller. In lower light, the pupil enlarges.

Eye lens: Behind the pupil is the lens of the eye. The eye lens and cornea work together to project incoming light rays onto the retina. This is necessary for sharp vision. To see well both near and far, the lens adjusts the convexity.

Anterior and posterior eye chambers: The eye chambers are located between the cornea and the iris (anterior eye chamber) and behind the iris near the lens (posterior eye chamber). Both chambers are filled with ocular fluid. Ocular fluid supplies oxygen and nutrients.

Vitreous humor: Behind the lens of the eye is a cavity filled with vitreous. Vitreous fluid ensures that the eye maintains its round shape. This is important for proper refraction of light (and thus for good vision).

Retina: The retina converts projected images into electrical signals. These signals are transmitted to the brain via the optic nerve.

Vascular membrane: The choroid is located between the retina and the white of the eye. This membrane consists of small blood vessels that supply nutrition to the eye. The choroid passes into the iris.

The yellow spot: The yellow spot (macula) is located on the retina and allows us to see fine details. How well we can do this is expressed in visual acuity.

Optic nerve: The optic nerve (a collection of nerve fibers) is located at the back of the eyeball. The nerve fibers send a signal that is transmitted to the brain via the optic nerve pathway.

Tear Gland: The tear glands are located on the outside above the eye. Tear glands produce tear fluid. This fluid is spread over the eye when we blink. This protects our eyes from drying out.