Trachoma is a disease of the eye caused by infection with the bacterium Chlamydia trachomatis. Infection spreads through personal contact (via hands, clothes or bedding) and by flies that have been in contact with discharge from the eyes or nose of an infected person. Blindness from trachoma is irreversible. With repeated episodes of infection over many years, the eyelashes may be drawn in so that they rub on the surface of the eye, with pain and discomfort and permanent damage to the cornea. To stop blindness from occurring, the upper eyelid is horizontally cut open and stitched in a manner that positions the eyelashes away from the eye and prevents damage to the eye.