Trichiasis

Abstract

Eyelashes play a protective role in keeping foreign material out of the eye. They emanate from the anterior edge of the rectangular lid margin. Each lash has a gently tapering shaft that arches anteriorly and away from the eyelid fissure. The lash follicles are approximately 2 mm deep in the upper lid and 1.75 in the lower lid. If a follicle becomes distorted in shape and/or orientation, the lash will grow with abnormal curvature or direction, defined as trichiasis. Lashes that touch the ocular surface can cause irritation, refl ex epiphora, and abrasions which can lead to ocular surface infections, erosions, and scarring with temporary or permanent visual loss.