Blindness and visual impairment are important public health problems. Globally, at least 2.2 billion people have a near or distance vision impairment. In at least 1 billion – or almost half – of these cases, vision impairment could have been prevented or has yet to be addressed. The leading causes of vision impairment and blindness are uncorrected refractive errors and cataracts.
There is substantial variation in the causes between and within countries according to the availability of eye care services, their affordability, and the eye care literacy of the population.