miércoles, 14 de marzo de 2012

WHO | Visual impairment and blindness

WHO | Visual impairment and blindness

Visual impairment and blindness

Fact Sheet N°282
October 2011

Key facts

  • 285 million people are visually impaired worldwide: 39 million are blind and 246 have low vision.
  • About 90% of the world's visually impaired live in developing countries.
  • Globally, uncorrected refractive errors are the main cause of visual impairment; cataracts remain the leading cause of blindness in middle- and low-income countries.
  • The number of people visually impaired from infectious diseases has greatly reduced in the last 20 years.
  • 80% of all visual impairment can be avoided or cured.


There are four levels of visual function, according to the International Classification of Diseases -10 (Update and Revision 2006):
  • normal vision
  • moderate visual impairment
  • severe visual impairment
  • blindness.
Moderate visual impairment combined with severe visual impairment are grouped under the term “low vision”: low vision taken together with blindness represents all visual impairment.

The causes of visual impairment

Globally the major causes of visual impairment are:
  • uncorrected refractive errors (myopia, hyperopia or astigmatism), 43 %
  • cataract, 33%
  • glaucoma, 2%.

Who is at risk?

Approximately 90% of visually impaired people live in developing countries.
People aged 50 and over
About 65 % of all people who are visually impaired are aged 50 and older, while this age group comprises about 20 % of the world's population. With an increasing elderly population in many countries, more people will be at risk of age-related visual impairment.
Children below age 15
An estimated 19 million children are visually impaired. Of these, 12 million children are visually impaired due to refractive errors, a condition that could be easily diagnosed and corrected. 1.4 million are irreversibly blind for the rest of their lives.

Changes over the last twenty years

Overall, visual impairment worldwide has decreased since the early 1990s. This is despite an aging global elderly population. This decrease is principally the result of a reduction in visual impairment from infectious diseases through concerted public health action.

The global response to prevention of blindness

Globally, 80% of all visual impairment can be prevented or cured. Areas of progress over the last 20 years include:
  • governments establishing national programmes to prevent and control visual impairment;
  • eye care services increasingly integrated into primary and secondary health care systems, with a focus on the provision of services that are available, affordable and high quality;
  • campaigns to raise awareness, including school-based education; and
  • stronger international partnerships, with engagement of the private sector and civil society.
Data over the last 20 years shows that there has been significant progress in preventing and curing visual impairment in many countries. Furthermore, there has been a massive reduction in onchocerciasis-related blindness as part of a significant reduction in the disease. This has been achieved through a number of successful international partnerships.
Specific achievements include Ghana and Morocco, both of whom have reported elimination of trachoma (2010 and 2007 respectively). Over the last decade, Brazil has been providing eye care services through the national social security system. Since 2009, China has invested over 100 million dollars in cataract surgeries. Oman has completely integrated eye care service provision in the primary health care framework over the last decade and since 1995 India has made available funds for eye care service provision for the poorest at district level.

WHO response

WHO coordinates the international efforts to reduce visual impairments.
It's role is to:
  • develop policies and strategies to prevent blindness;
  • to give technical assistance to Member States and partners;
  • to monitor and evaluate programmes; and
  • to coordinate international partnerships.
In 2009, the World Health Assembly approved the 2009-13 Action Plan for the Prevention of Avoidable Blindness and Visual Impairment , a roadmap for Member States, WHO Secretariat and international partners.
WHO works to strengthen national and country-level efforts to eliminate avoidable blindness, help national health care providers treat eye diseases, expand access to eye health services, and increase rehabilitation for people with residual visual impairment. Building and strengthening health systems is a particular area of focus.
WHO leads an international alliance of governments, private sector and civil society organizations aiming to eliminate blinding trachoma from the world by the year 2020.
For the last ten years WHO has worked with the International Agency for the Prevention of Blindness in the global initiative "Vision 2020: the Right to Sight".
Since 2004, WHO in partnership with Lions Clubs International has established a global network of 35 childhood blindness centres in 30 countries for the preservation, restoration or rehabilitation of sight in children.
In response to the increasing burden of chronic eye disease WHO is now developing policies and guidelines for diabetic retinopathy, glaucoma, age-related macular degeneration and refractive errors.
Finally, to support comprehensive eye care systems, WHO provides epidemiologic and public health technical support to its Member States.

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