Around 285 million people are estimated to be visually impaired worldwide: 39 million are blind and 246 million have low vision. About 90% of the world's visually impaired live in low-income settings. (WHO, 2014)
South East Asia is the region with the highest rate of preventable blindness, which constitutes 28% of the visually impaired globally.
Cataracts (47.9%) remains the leading cause of visual impairment in all areas of the world, except for in developed countries. Other causes of vision loss or impairment are yrachoma (3.6%), onchocerciasis (0.8%), diabetic retinopathy (4.8%) and childhood blindness (3.9%).
These are all avoidable visual impairments.
"About 65% of all people who are visually impaired are aged 50 and older. With an increasing elderly population in many countries, more people will be at risk of visual impairment due to chronic eye diseases and ageing processes."
top Causes of visual impairment
A cataract is a clouding of the lens of the eye. This can be caused by aging but may also occur because of trauma or radiation exposure, be present from birth or occur following eye surgery for other problems.
Trachoma is an infection that causes a roughening of the inner surface of the eyelids that leads to pain. Untreated, repeated trachoma infections can result in a form of permanent blindness where the eyelids are internally scarred and then turn inward.
Onchocerciasis, also known as river blindness, is an infection that could lead to blindness. It is spread by the bites of a black fly.
Diabetic retinopathy is a diabetes complication that affects the eyes. It is caused by damage to the blood vessels of the light-sensitive tissue at the back of the eye
Childhood blindness can be caused in poor countries by corneal scarring caused by vitamin A deficiency, measles ophthalmia neonatorum (a form of conjunctivitis) as well as harmful traditional practices.
Global strategies and programmes have been developed for the elimination of preventable blindness caused by cataracts, onchocerciasis, and trachoma. For example, the World Health Organization (WHO) has a global initiative to eliminate avoidable blindness, "VISION 2020: The Right to Sight".
- Cataract operations take about 20 minutes and cost about GBP 30 for an adult and GBP 50 for a child, (for an anaesthetist and an overnight stay for children's operations), according to Sightsavers.
- Onchocersiasia (or river blindness) costs an unbelievable just GBP 0.07 per person to treat each year, by taking a tablet once a year for 10-15 years until the risk is eliminated.
- A tablet to prevent trachoma costs GBP 0.35 and surgery to treat advanced trachoma (trichiasis) costs about GBP 8.
Elimination of trachoma is possible through implementation of the SAFE strategy to address the underlying causes of the disease, according to the Schistosomiasis Control Initiative. This comprehensive approach employs:
- Antibiotics (via Pfizer's donation of Zithromax)
- Facial cleanliness
- Environmental improvement (clean water and sanitation management)
River blindness (onchocerciasis), Cataract operations & Trachoma antibiotics
Also provides eye glasses for refractive errors and treats glaucoma, a group of eye conditions.
- Cataract, trachoma, diabetic retinopathy & childhood blindness
- (WHO, 2014)
- Mayo Clinic: Diabetic retinopathy