Article

Eyelash

Etymology: The word "eyelash" combines "eye" and "lash" (as in a whip), referencing both the appearance and the stroking motion during blinking.

Eyelashes are short, curved hairs growing on the edges of the upper and lower eyelids. They serve to protect the eye from dust, debris, and small particles, and are highly sensitive to touch, triggering the blink reflex.

Anatomy & Structure

Grow in up to six layers on each eyelid margin.
Each upper eyelid has 90–160 lashes; lower eyelid has 75–80.
Associated glands: Zeis, Moll, and Meibomian glands.
Lashes are not androgenic and do not continually grow like scalp hair.

Lashes develop from the ectoderm between weeks 22–26 of embryonic development. Their color may differ from scalp hair. Lashes are thick at the root and taper at the end. Asian populations have thicker but fewer lashes; Caucasians have more, and often curlier, lashes. Lashes grow to about one-third the width of the eye (7–8 mm upper, 5–6 mm lower), an evolutionary adaptation to reduce evaporation and dust.

Function

Protect the eye from debris and excessive light.
Reduce evaporation of the tear film.
Enhance facial attractiveness; long lashes are often considered a sign of beauty.

Lashes are highly sensitive, with many nerve endings at the roots, triggering the blink reflex even with light touch. They also help shield the conjunctiva from excessive light and UV radiation.

Clinical Significance

Disorders: Madarosis (loss), trichiasis (ingrown), distichiasis (extra row), blepharitis (inflammation), trichomegaly (excessive length).
Eyelash transplant and cosmetic enhancement (extensions, tints, curlers, mascara).

Other conditions:

Trichotillomania: Compulsive pulling of lashes.
Demodex folliculorum: Mites living in follicles, sometimes causing blepharitis.
External hordeolum (stye): Infection of follicles or glands.
Vernal keratoconjunctivitis: Can cause longer lashes due to inflammation.

Eyelash transplants can restore or enhance lashes but require regular trimming. Latisse (bimatoprost) is FDA-approved for eyelash growth.

Cultural Aspects

Long, curled lashes are valued in many cultures and are enhanced with cosmetics.
False eyelashes are iconic within e_girl styling and are common in femboy presentations. See also: F1NN5TER.

Nonverbal communication: Blinking or fluttering lashes is a common flirtatious gesture ("batting eyelashes").

Cosmetics: Kohl has been used since the Bronze Age to darken the lash line. Modern products include mascara, eyelash extensions, tints, perms, and conditioners. Ancient Romans valued long lashes as a sign of chastity. Lashes are enhanced for both beauty and psychological effect.

In animals: Mammals (camels, horses, cows) have prominent lashes. Some birds (hornbills, ostriches) and reptiles (eyelash viper) have lash-like features.