On occasion of World Sight Day (11th October), the World Health Organization (WHO) updated its fact sheet on blindness and visual impairment.
The International Classification of Diseases 11 (2018) classifies vision impairment into two groups, distance and near presenting vision impairment.
Distance vision impairment:
- Mild – presenting visual acuity worse than 6/12
- Moderate – presenting visual acuity worse than 6/18
- Severe – presenting visual acuity worse than 6/60
- Blindness – presenting visual acuity worse than 3/60
Near vision impairment:
- Presenting near visual acuity worse than N6 or N8 at 40cm with existing correction.
Globally, it is estimated that approximately 1.3 billion people live with some form of vision impairment.
The majority of people with vision impairment are over the age of 50 years.
With regards to distance vision, 188.5 million people have mild vision impairment, 217 million have moderate to severe vision impairment, and 36 million people are blind.
With regards to near vision, 826 million people live with a near vision impairment.
Globally, the top two causes of vision impairment are uncorrected refractive errors and cataracts. Other leading causes are:
- age-related macular degeneration
- diabetic retinopathy
- corneal opacity
The proportion of vision impairment attributable to cataract is higher in low- and middle-income countries than high-income countries. In high income countries, diseases such as diabetic retinopathy, glaucoma and age-related macular degeneration are more common.
Among children, the causes of vision impairment varies considerably across countries. For example, in low-income countries congenital cataract is a leading cause, whereas in high income countries it is more likely to be retinopathy of prematurity.
Approximately 80% of all vision impairment globally is considered avoidable.
There are effective interventions available to prevent and treat eye diseases. For example, uncorrected refractive error can be corrected with glasses while cataract surgery can restore vision. Vision rehabilitation is also effective in improving functioning for people with an irreversible vision impairment.
Link to the updated fact sheet:
Link to Universal Eye Health: A global action plan 2014-2019 (multiple languages):
Link to International Classification of Diseases 11:
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