Trachoma is the world's leading infectious cause of blindness and a neglected tropical disease affecting the poorest and most marginalized communities. It is largely eliminated in high-income countries thanks to improved socio-economic and sanitary infrastructure. An estimated 1.9 million people are blind or visually impaired as a result of the blinding stage of trachoma. It is caused by the bacterium Chlamydia trachomatis, which is spread by contact and flies. Repeated infection in childhood leads to chronic inflammation of the inner eyelid, scarring, and trachomatous trichiasis, in which the eyelashes roll inward and scratch the eye. Trachomatous trichiasis disproportionately affects women and causes functional limitations in their lifestyle. Global productivity loss due to trachoma is estimated at $8 billion annually.