An estimated 253 million people live with vision impairment: 36 million are blind and 217 million have moderate to severe vision impairment, according to a report in Web India 123.
Globally, chronic eye diseases are the main cause of vision loss. Uncorrected refractive errors and then un-operated cataract are the top two causes of vision impairment. Un-operated cataract remains the leading cause of blindness in low- and middle-income countries.
Vision function is classified in 4 broad categories, according to the International Classification of Diseases -10: normal vision, moderate vision impairment, severe vision impairment and blindness.