Blindness is a serious and devastating event in any person’s life. It also has deep socio-economic and public health implications. However, many of the diseases that cause blindness are preventable and treatable. The most common diseases that cause blindness are cataract, trachoma, onchocerciasis, childhood blindness, and refractive errors and low vision. Other equally important causes are glaucoma, trauma, and diabetic retinopathy.
Cataract, which refers to the clouding of the crystalline lens of the eye, is a major cause of blindness with an estimated 20 million people blinded by this condition. Cataract surgery can restore near normal vision but does require resources and expertise.
Trachoma is endemic in 49 countries, mostly in Africa, Southeast Asia, the Eastern Mediterranean, and Western Pacific. There are an estimated 5.6 million blind or visually impaired from trachoma. The disease is common in areas that are socio-economically deprived of basic needs in housing, health, water, and sanitation.
Onchocerciasis, or river blindness, is endemic in 30 countries in Africa and Latin American. Currently, there are an estimated 18 million people who are affected.
Childhood blindness is most often caused by Vitamin A deficiency, measles, conjunctivitis in the newborn, congenital cataracts, and retinopathy of prematurity (ROP). There are an estimated 1.5 million blind children in the world.
Refractive errors and Low vision. The magnitude of refractive errors is not known. The World Health Organization estimates that 35 million people are in need of low vision care. Most cases can be corrected by eye glasses.
by Karanjit S. Kooner, M.D., Ph.D. 
