Trachoma: A chronic inflammatory disease of the eye and the leading cause of blindness. Trachoma is due to infection with the bacterium Chlamydia trachomatis. Transmission occurs mainly among children and from children to women caring for them. Key risk factors include inadequate supplies of water and low socioeconomic status. Trachoma affects millions of people worldwide, primarily in rural communities of the developing world and in the arid areas of tropical and subtropical zones. Australia is the only developed country where trachoma is still a significant health problem. The disease goes by a number of names, such as sandy blight.