Causes of blindness

When you think about it, the very act of actually seeing the world around us is an astonishing thing.  It relies on the interaction between the brain and the eyeball, two extraordinarily complex organs, so it's hardly surprising that there are so many ways in which we can suffer sight loss. 

Here are some of the major causes of blindness, and the ways in which Sightsavers is tackling them.


Cataract is the world’s leading cause of blindness, with around 18 million people blind as a result. 

River blindness

Around 37 million people are currently infected with river blindness, and roughly 300,000 of them are already irreversibly blind. Approximately 140 million people in Africa are at risk of infection.


Trachoma is a potentially blinding eye infection, which has been eradicated in most developed countries. It is the world's leading cause of preventable blindness.

Neglected tropical diseases

There are 13 of these parasitic or bacterial infections in total, which affect a sixth of the world’s population. A further two billion people are at risk.

Childhood blindness

It has been estimated that there are 1.4 million blind children in the world, 1 million of which live in Asia and 300,000 in Africa.

Diabetic retinopathy

Diabetic retinopathy affects 1.8 million people globally. It is caused by damage to the small blood vessels in the retina at the back of the eye as a result of diabetes.

Refractive error

Refractive error is when the shape of the eye prevents it from focusing light correctly, resulting in a blurred image. 


Glaucoma is common in both developed and developing countries, and it is estimated that 4.5 million have become blind from it. 

Low vision

Low vision is when, even after interventions like glasses, people have difficulty distinguishing objects and/or distances.

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