Trachoma is the leading infectious cause of blindness and preventable blindness worldwide. It is a chronic eye infection caused by Chlamydia trachomatis.Globally, active trachoma affects an estimated 150 million people, most of them children. About 5.5 million people are blind or at risk of blindness as a consequence of trachoma.

Repeated episodes of re-infection within a family causes chronic inflammation under the eyelids (active trachoma). This leads to scarring which causes the eyelashes to turn inwards and scratch the front of the eye (the cornea).

This is very painful and eventually the cornea becomes scarred causing blindness.