Causes of blindness

2.2 billion people globally have partial or no sight. Here are the five most common causes of blindness worldwide.

A woman in Burkina Faso covers one eye and looks out the other during a vision check. A bandage hangs from her cheek and she is smiling. She holds up two fingers to confirm what she can see. A white-gloved hand holding up two fingers is in the foreground.

1. Cataract 

The world’s most common cause of blindness, cataract affects 65 million people. Age, injury or genetics can cause the typical cloudy lens. It can take just 15 minutes to perform a sight-restoring cataract operation.

2. Glaucoma 

The third leading cause of blindness, glaucoma can be treated with medication. An operation can help reduce its effects, but it’s not curable.

3. River blindness 

Onchocerciasis, or River Blindness, is a parasitic disease caused by onchocerca volvulus. It is characterised by itchy skin and severe swelling in the eye which results in impaired vision, including permanent blindness. River blindness is on the retreat worldwide thanks to the widespread distribution of the drug Mectizan.

4. Trachoma 

About 2 million people have impaired vision or are blind because of trachoma – the most widespread infectious cause of blindness. Repeated infections with the bacterium Chlamydia trachomatis cause the inside of the eyelid to scar, making the eyelashes turn inward. These, in turn, scratch the cornea, leading to irreversible blindness. In its earlier stages, trachoma is treated with antibiotics and can be prevented by keeping the face clean. In the final stage of the illness, known as Trachomatous Trichiasis, surgery on the eyelid is the only way to avoid loss of sight.

5. Uncorrected refractive error (URE) 

Around 124 million people have uncorrected refractive error, which causes blurred vision. Yet many people just need a pair of glasses to see clearly again. In Uganda, Light for the World together with the Brien Holden Vision Institute has launched a national programme giving poor people access to high quality, tailor-made spectacles.

Three-year-old Greta was born with cataracts, but thanks to a national programme in Uganda supported by Light for the World, she got the surgery and glasses she needed. Around 1 million children worldwide are blind and about 19 million visually impaired due to uncorrected refractive error, vitamin A deficiency, cataract or injury. © Light for the World 

Our goal

At least 75 percent of blindness is avoidable. Over the last 30 years, we’ve been working to reduce avoidable blindness. In most cases, prevention or treatment would be easy if enough resources were in place – like medication and making routine operations accessible – but many people still don’t have access to these. 

We’re trying to plug this gap. In 2019, our partners performed 68,000 eye surgeries and distributed 12.6 million doses of medication against diseases like blinding trachoma. We will continue to promote eye health, doing our utmost to reach the unreached – people who are marginalised and have no access to affordable eye care.