World Sight Day 2017

Key facts

  • An estimated 253 million people live with vision impairment: 36 million are blind and 217 million have moderate to severe vision impairment.
  • 81% of people who are blind or have moderate or severe vision impairment are aged 50 years and above.
  • 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 income countries.
  • The prevalence of infectious eye diseases, such as trachoma and onchocerciasis, have reduced significantly over the last 25 years.
  • Over 80% of all vision impairment can be prevented or cured.

The causes of visual impairment

According to recent estimates, the major global causes of moderate to severe vision impairment are:

  • uncorrected refractive errors, 53%
  • un-operated cataract, 25%
  • age-related macular degeneration 4%
  • glaucoma, 2%
  • diabetic retinopathy 1%.

The major causes of blindness are:

  • un-operated cataract 35 %
  • uncorrected refractive error 21 %
  • glaucoma 8 %.


Who is at risk?

People aged 50 and over

81% of all people who are blind or have moderate to severe vision impairment are aged 50 years and above. With an increasing population of older people, more people will be at risk of vision impairment due to chronic eye diseases.

Children below age 15

An estimated 19 million children are vision impaired. Of these, 12 million children have a vision impairment due to refractive error. Around 1.4 million have irreversible blindness, requiring access to vision rehabilitation services to optimize functioning and reduce disability (2).

Changes over the last twenty years

Overall, the prevalence of vision impairment worldwide has decreased since early estimates in the 1990s. This decrease is associated with:

  • overall socioeconomic development;
  • concerted public health action;
  • increased availability of eye care services;
  • awareness of the general population about solutions to the problems related to vision impairment (surgery, refraction devices, etc.).

However it is estimated that the number of people with vision impairment could triple due to population growth and ageing. For example, by 2050 there could be 115 million people who are blind, up from 38.5 million in 2020.

The global response to prevent blindness

Globally, more than 80% of all vision impairment can be prevented or cured. Areas of progress over the last 25 years include:

  • governments established national programmes and regulations to prevent and control vision impairment;
  • eye care services increasingly available and progressively integrated into primary and secondary health care systems, with a focus on the provision of services that are high quality, available and affordable;
  • campaigns to educate about vision function importance and raise awareness, including school-based education; and
  • stronger government leadership on international partnerships, with increasing engagement of the private sector.

Data over the last 25 years shows that there has been significant progress in preventing and curing vision impairment in many countries. The substantial reduction in onchocerciasis- and trachoma-related blindness is part of a significant reduction in the disease distribution and has substantially reduced the burden resulting from these infectious diseases. This has been achieved through a number of successful international public-private partnerships.

Need Help?

The Clinical and Patient Care Teams from Cathedral Eye Clinic are always on hand to have a chat about potential treatment options and the provision of eye health advice. Feel free to contact the Clinic on 02890 322020 or email for an initial, complimentary assessment (for freedom from glasses suitability assessments).

We would like to thank the World Health Organization for providing the information and statistics in this article. For more information and references, please visit

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