Trichiasis is the term used to describe eyelashes which point inwards and irritate or scratch the eye. This causes a little discomfort in mild cases increasing to severe pain, corneal scarring and even perforation of the cornea in severe cases.
Common causes of trichiasis in Europe and the USA are blepharitis, whereby eyelid inflammation causes normal eyelashes to slowly start to grow backwards towards the eye and entropion leading to the whole lower lid rolling inwards.
In Africa the infection Trachoma is a common cause of trichiasis. Trachoma causes inflammation and then scarring of the lining of the eyelids, especially the upper eyelids. The scarred tissue shrinks and so turns the eyelid inwards, leading to the lashes scratching the cornea.
Mild trichiasis can be treated by simply epilating the eyelashes, although they will grow back again. Small clumps of ingrowing lashes can be treated with electrolysis or laser treatment. Larger areas must be treated with cryotherapy or surgery.