Eyelashes are the clump of hairs that grow at the base of the eyelid. They are extremely sensitive and protect the eyes from any floating debris or insects that may come in contact with the eye area. When debris such as dust mites come too close to the eye, the lashes close reflexively to prevent pain and infection. Eyelashes often fall out on their own after completing their cycle, much like the hairs on one's head or anywhere else on the body.
Human eyelashes reach their full level of growth during the seventh or eighth week of an embryo's development. Thus, a human's eyelashes are fully grown at birth. Eyelash regrowth usually takes about 8 weeks if they are pulled out or fall out naturally. The colour of the eyelashes often corresponds to the natural colour of a person's hair. Since eyelashes do not grow past a certain length like the hair on one's head, many women and some men try to lengthen their lashes with cosmetics. Mascara, false eyelashes and even eyelash extensions are all methods of making lashes appear temporarily longer and fuller.
Just like any other part of the human body, eyelashes are prone to health disorders. Some of the most prominent conditions include madarosis (loss of eyelashes), trichiasis (ingrown lashes), blepharitis (eyelids become itchy/eyelashes fall out) and sty (inflammation of the eyelid). These conditions are best treated by a dermatologist or ophthalmologist to prevent any long-lasting adverse effects to the lashes and entire eye area.