Visual impairment and blindness

Key facts

• About 314 million people are visually impaired worldwide, 45 million of them are blind.
• Most people with visual impairment are older, and females are more at risk at every age, in every part of the world.
• About 87% of the world's visually impaired live in developing countries.
• The number of people blinded by infectious diseases has been greatly reduced, but age-related impairment is increasing.
• Cataract remains the leading cause of blindness globally, except in the most developed countries.
• Correction of refractive errors could give normal vision to more than 12 million children (ages five to 15).
• About 85% of all visual impairment is avoidable globally.

There are four levels of visual function:

• normal vision
• moderate visual impairment
• severe visual impairment
• blindness.

Global trends

Global trends since the early 90s show reduced rates of visual impairment worldwide, and a shift in the causes. Visual impairment and blindness caused by infectious diseases have been greatly reduced (an indication of the success of international public health action), but there is a visible increase in the number of people who are blind or visually impaired from conditions related to longer life expectancies.

Globally about 314 million people are visually impaired, 45 million of them are blind.

Presbyopia, the inability to read or perform near work that occurs with ageing, causes visual impairment if it is not corrected. The scope of the problem is not known, but preliminary studies indicate that the problem could be vast, especially in developing countries.

Who is at risk?

By age: About 82% of all people who are visually impaired are age 50 and older (although they represent only 19% of the world's population).

Increasing numbers of people are at risk of age-related visual impairment as the global population grows and demographics shift to a higher proportion of older people, even in developing countries.

Child blindness remains a significant problem globally. An estimated 1.4 million blind children below age 15 will live in blindness for many years. In addition, more than 12 million children ages five to 15 are visually impaired because of uncorrected refractive errors (near-sightedness, far-sightedness or astigmatism): conditions that could be easily diagnosed and corrected with glasses, contact lenses or refractive surgery.

By gender: Studies consistently indicate that females have a significantly higher risk of being visually impaired than males, in every region of the world, and at all ages.

Geographically: Visual impairment is not distributed uniformly throughout the world. Approximately 87% of visually impaired people live in developing countries.

Source: WHO/Prevention of Blindness

Causes of blindness

Globally, the leading causes of blindness, in order of frequency, are:

• cataract (a clouding of the lens of the eye that impedes the passage of light),
• uncorrected refractive errors (near-sightedness, far-sightedness or astigmatism),
• glaucoma (a group of diseases that result in damage of the optic nerve),
• age-related macular degeneration (which involves the loss of a person's central field of vision).

Other major causes include corneal opacities (eye diseases that scar the cornea), diabetic retinopathy (associated with diabetes), blinding trachoma, and eye conditions in children such as cataract, retinopathy of prematurity (an eye disorder of premature infants), and vitamin A deficiency.

Prevention

Globally, about 85% of all visual impairment and 75% of blindness could be prevented or cured worldwide.

Since the 90s, areas of significant prevention progress on a global scale include:

• further development of eye health care services, which has led to increased availability and affordability;
• increased commitment to prevention and cure from national leaders, medical professionals and private and corporate partners;
• higher awareness and use of eye health care services by patients and the general population; and
• implementation of effective eye health strategies to eliminate infectious causes of vision loss.

Brazil, China, Ethiopia, the Gambia, India, Mauritania, Mexico, Morocco, Nepal, Oman, Pakistan, and the United Republic of Tanzania, among others, have reported notable progress.

Global partnerships of Member States, nongovernmental organizations and community groups (such as Vision 2020 the Right to Sight and Global Elimination of Blinding Trachoma by 2020) have played key roles in eliminating avoidable visual impairment.

WHO response

WHO works with Member States and public and private partners to prevent blindness and restore sight in every part of the world. WHO provides technical assistance, monitoring and coordination among partners to strengthen country-level efforts to eliminate avoidable blindness, treat eye diseases, expand access to eye health services, and increase rehabilitation for people with residual visual impairment (including tools and skills for daily life).

For more information contact:

WHO Media centre
Telephone: +41 22 791 2222
E-mail: mediainquiries@who.int