Trichiasis is a medical term for abnormally positioned eyelashes that grow backwards to eye causing irritation of conjunctiva and cornea. Its causes are as follows Repeated cases of trachoma Infection Inflammation Autoimmune Congenital defects agenesis of lids Trauma severe burns or trauma to lids Trichiasis is a leading cause of blindness in the world  post misdirection of normal lashes frequently affects l lids Share your opinion.