Developed through a collaboration between the Academy and Bloomberg School of Public Health at Johns Hopkins University, Global Ophthalmology courses review critical issues in global eye health and prepare US ophthalmologists to conduct mission work in the developing world. Dr. Alfred Sommer presents a four-part lecture on the major causes of preventable blindness: mature cataract, onchocerciasis, xerophthalmia, and trachoma. This course is part of the Academy's Global Ophthalmology (GO) Guide.