Eyelash

Eyelashes are the curved, fine hairs that grow along the edge of the upper and lower eyelids. They form a protective fringe that helps shield the eyes from dust, debris, and sweat, and they contribute to the reflex blinking that helps protect the eye from irritation.

Anatomy and growth: Each lash grows from a hair follicle located at the eyelid margin. The lash unit includes the hair shaft, follicle, and nearby sebaceous glands that contribute oils to the lid margin and tear film. Eyelashes grow in cycles that include a growth phase (anagen), a transitional phase (catagen), and a resting phase (telogen). The length, thickness, and density of lashes vary among individuals and are typically greater on the upper lid than on the lower lid.

Function: Beyond serving as a physical barrier, eyelashes are richly innervated at their bases, providing sensory feedback that helps trigger a protective blink when they detect contact or nearby irritation. This reflex reduces the likelihood of foreign material reaching the eye.

Care and cosmetics: People commonly use mascara, curling tools, false lashes, or extensions for cosmetic reasons. Proper hygiene is important; makeup should be removed before sleep to prevent irritation or infection, and extensions or recurrent rubbing can damage the lash line. Some products claim to promote growth, including prostaglandin-based formulations used under medical supervision, which can have side effects.

Disorders: Common eyelash-related conditions include blepharitis (lid-margin inflammation), trichiasis (lashes that grow inward and irritate the eye), and madarosis (loss of lashes). Management focuses on treating underlying causes, maintaining lid hygiene, and, if needed, selecting appropriate cosmetic alternatives.