Eyelash

Overview
An eyelash or simply lash is one of the hairs that grow at the edge of the eyelid. Eyelashes protect the eye from debris and perform some of the same function as whiskers do on a cat or a mouse in the sense that they are sensitive to being touched, thus providing a warning that an object (such as an insect or dust mite) is near the eye (which is then closed reflexively).

Human eyelashes
The eyelashes of the embryo develop between the 7th and 8th week. Eyelashes will grow back if they fall out or get pulled out. Eyelashes take about four to eight weeks to grow back. Their color may differ from that of the hair, although they tend to be dark on someone with dark hair and lighter on someone with light hair.

The follicles of eyelashes are associated with a number of glands known as the glands of Zeiss and the glands of Moll.

Cosmetics
Long eyelashes are considered a sign of femininity in most if not all cultures. Accordingly, some women seek to enhance their eyelash length artificially to appear more feminine and sexually desirable. See also eyelash extensions. Kohl has been worn as far back as the Bronze Age to protect and enhance lashes.

Complete eye makeup includes mascara, eyeliner and eye shadow to emphasize the eyes. The twentieth century saw the beginning of convincing-looking false eyelashes, popular in the 1960s.

Health
There are a number of diseases or disorders involving the eyelashes:
 * Madarosis is the loss of eyelashes
 * Blepharitis is the irritation of the lid margin (where eyelashes join the eyelid). Eyelids are red and itching. The skin often becomes flaky. The eyelashes may fall.
 * Distichiasis is the abnormal growth of lashes from certain areas of the eyelid.
 * Trichiasis is ingrown eyelashes
 * Eyelashes may become infested with crab louse parasites
 * An external hordeolum, or stye, is a purulent inflammation of infected eyelash follicles and surrounding sebaceous (Zeis) and apocrine (Moll) glands of the lid margin.
 * Trichotillomania is a disorder that urges the sufferer to pull out scalp hair, eyelashes, etc.
 * Demodex folliculorum (or the demodicid), is a small mite that lives, harmlessly, in eyelash and other hair follicles and around 98% of people have these mites living on them. Occasionally they can cause blepharitis.

Eyelash and eyebrow transplant surgeries may help to reconstruct or thicken lashes or eyebrow hair.

Animals
Lashes, being hair, are found in mammals. Camels' lashes are remarkably long and thick, and giraffe's eyelashes are considered by some to be more beautiful than a human's. Horses, cows, and also ostriches, (vestigial feathers without barbs) feature eyelashes as well.

Inherited eyelash problems are common in some breeds of dogs.

Eyelash vipers show a set of modified scales over the eyes which look much like eyelashes.

Hornbills have prominent feather eyelashes, an uncommon feature in birds.

Mythology and trivia

 * Hera was said to have cow's eyes (Greek boôpis).
 * In Thai art, Buddha is said to have "eyelashes like a cow's".
 * When Ymir (or Aurgelmir) was slaughtered by his grandson Odin, his eyebrows became Midgard, the world of men. The gods set up Ymir's eyelashes to keep the giants at the edges of the earth disk.
 * Porcelain dolls have moving eyelids with detailed eyelashes.
 * Betty Boop is depicted with great eyelashes and eyelid flutter ability.
 * Snoopy’s sister, Belle, looks like him but has long eyelashes.
 * Some believe that finding an eyelash is very good luck
 * Some believe that the same collection of factors that brought about long eyelashes in human females also occurred in other species and that one can tell the sex of some types of mammals (such as cats) by looking at the eyelashes and shape of the brow.
 * It is said that if you happen to find that you lost an eyelash and it is in your hand, you can make a wish by just saying the wish softly and blowing the eyelash out of your hand. It will not work if you pull one.