Trachoma is the leading preventable cause of blindness worldwide. Most trachoma cases occur in poor areas of Africa, where 85% of people with active disease reside. In areas where trachoma is prevalent, infection rates among children under 5 can be 60% or more. Early treatment may help prevent trachoma complications.
https://www.mayoclinic.org/diseases-conditions/trachoma/symptoms-causes/syc-20378505