The cleanest part of the human body is often considered to be the eye because of its abilities to clean itself. The eyelid opens and shuts several times every minute in order to keep the eye clean and moist.
The eye also protects itself through the production of tears. Tears are secreted from the lacrimal gland on each eye and helps to wash away dirt, germs or other foreign particles, such as dust. The lacrimal gland can be found above the outer corner of each eye.
The eyelids also have good reflex control so they are able to help prevent damage to the eye. An example of the eye's reflex control is when eyelids shut automatically whenever the eye is exposed to bright light from dim light or when an object comes to close to the eye. Eyelashes also help to keep eyes clean by keeping dirt away.
The eye has many parts that make it possible to detect light allowing humans to see. The sensitive tissue lining around the inner surface of the eye is known as the retina. There are cone cells in the retina that help to detect color and rod cells that help to detect low light contrasts. The central opening of the eye around the pupil is the iris and it controls the size of the pupil. The iris is also the colored part of the eye and is where a person will have brown, blue, green or hazel eyes.