Inverted eyelashes are a common external eye disease in children, adolescents and the elderly, mainly due to the abnormal growth direction of the eyelashes. Eyelashes that grow in an abnormal direction, especially those that grow backward toward the corneal surface, not only often rub against the corneal epithelium, causing a foreign body sensation, photophobia, and tearing, but also cause eye congestion, conjunctivitis, corneal epithelial detachment, keratitis, corneal cataracts, corneal ulcers, and corneal leukoplakia, which in turn affects the eyesight. Trichiasis is an abnormal condition in which the eyelashes grow backward to touch the eyeball. Normal eyelashes grow on the anterior lip of the eyelid margin and develop from the surface ectodermal epithelium and are arranged in two to three rows of short, curved, thick hairs. Eyelashes have the function of avoiding light, blocking dust, preventing foreign objects from entering the eye and eye beauty, and long, thin, black, upturned eyelashes play an important role in modifying the beauty of people’s appearance. The upper eyelid eyelashes are more numerous, 100 to 150, the length of an average of 8 to 12 millimeters, the upper eyelid eyelashes open the eyes when looking at the angle of 110$€゜$€゜$€゜$€゜$€゜$€゜$€゜$€゜$€゜$€゜$€゜$€゜$€゜$€゜$€゜$€゜$€゜$€゜$€゜$€゜$€゜$€゜$€゜$€゜$€゜$€゜$€゜$€゜$€゜$€゜$€゜$€゜$€゜$€゜$€゜$€゜$€゜$€゜$€゜$€゜$€゜$€゜$€゜$€゜$€゜$€゜ when the eyes are open and flat. The hairy roots of the eyelashes reside deep within the connective tissue and muscle, where there are perverted sweat and sebaceous glands whose ducts open into the eyelash follicles. The posterior lip of the lid margin of the eyelid has most of the small holes arranged in a row; these holes are the openings for the ducts of the meibomian glands, which themselves are located within the lid. Abnormalities in the angle of inclination of the eyelashes can be caused by changes in the angle of growth of the eyelashes or by diseases of the eyelids.