Trichiasis: refers to the abnormal condition that eyelashes grow backward to touch the eyeball. Trichiasis is a common external eye disease in children, adolescents and the elderly, mainly because of the abnormal growth direction of eyelashes. Eyelashes with abnormal growth direction, especially those growing backward to the corneal surface, not only often rub the corneal epithelium, causing foreign body sensation, fear of light, tears and other symptoms, but also cause eyeball congestion, conjunctivitis, corneal epithelial shedding, keratitis, corneal pannus, corneal ulcer, corneal leukoplakia and so on, further affecting vision.

Normal eyelashes grow in the front lip of eyelid margin, developed from the surface ectodermal epithelium, and arranged in 2 ~ 3 rows, showing short and curved coarse hair. Eyelashes have the functions of avoiding light, shielding dust, preventing foreign objects from entering the eyes and beautifying the eyes. Slender, black and upturned eyelashes play an important role in modifying people's appearance beauty.

References:

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2. Lin Maochang. Modern eye plastic surgery. Xi 'an: World Book Publishing Company:1997,326-334.

3. Xu Naijiang, Zhu Huimin, Yang Li. Practical eye plastic surgery. Zhengzhou: Zhengzhou University Press, 2003, 73-99.

4. Jack J Kanski (translated by Xu Guoxing). Clinical ophthalmology. Fuzhou: Fujian Science and Technology Press, March 4, 2006.

5. Li Meiyu, Wang Ningli. Ophthalmology and clinic. Beijing: Peking University Medical Press, 2003, 62-63.