Important Causes of Visual Impairment in the World Today

VISUAL IMPAIRMENT, WHICH may be defined as blindness (best vision of 20/200 in the better eye in the United States and 20/400 by the World Health Organization WHO definition) or low vision ( 20/40 in the United States and 20/60 according to WHO), is one of the most common disabilities: an estimated 40 million people worldwide were blind nearly a decade ago, the time of the last accurate assessment, and 110 million people had low vision. Among persons older than 40 years in the United States, 937000 people were blind and 2.4 million people had low vision in 2002. Figures for the developing world, where approximately 90% of world blindness exists, and the developed world are expected to increase significantly during the next decades as the world’s population ages.