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Cataracts: causes, symptoms and treatment

Cataracts are the world’s leading cause of blindness. Find out about the causes and common symptoms of cataracts, and learn how they can be treated.

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Before he had cataract surgery, Sardar (centre) from Pakistan was struggling to look after his family. Read Sardar’s story

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What are cataracts?

The clear lens at the front of the eye is made from special proteins. Cataracts form when these proteins break down and create cloudy patches on the lens. Over time the patches can grow bigger, causing blurry vision.

The main types of cataracts are:

  • Age-related cataracts: older adults are more susceptible to developing them
  • Congenital cataracts: children can be born with cataracts in one or both eyes, which can lead to permanent blindness if left untreated
  • Trauma-related cataracts: an injury to the eye as a result of an impact or a sharp penetration can cause them to form

Cataracts can form on different parts of the lens. Cataracts that develop in the centre of the eye, called ‘nuclear cataracts’, are most common.

A close-up of a patient's eye.

How do cataracts affect vision?

What does the world look like when you have cataracts? Our simulator will give you an idea.

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100 million people worldwide have cataracts

A white and yellow icon representing an eye with cataracts. The pupil and iris are covered with dashed yellow lines.

17 million people are blind because of cataracts

83 million people have a visual impairment caused by cataracts

Source: Lancet

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What causes cataracts?

A cataract develops when protein in the eye’s lens builds up to form a layer. This natural process happens gradually as we age. It can lead to blurred vision and eventual blindness. Cataracts can also form as a result of trauma to the eye.

Risk factors that can increase your chances of developing cataracts include:

  • Age: people over 50 years old are most at risk
  • Genetics: having family members with the condition
  • Lifestyle: smoking, drinking alcohol and spending time in the sun without wearing sunglasses
  • Health conditions: diabetes and other health issues
  • Medication: certain medicines, such as steroids and statins, can increase the likelihood of cataracts
Caliha stands outside, with a tree behind her.
Losing my sight limited my daily activities. I relied on my granddaughter for fetching water.
Read Caliha’s story
Shahadeb at his local village, one half of image blurred to demonstrate vision loss.

What are common symptoms?

Shahadeb at his local village, one half of image blurred to demonstrate vision loss.

A person may not notice any changes in their vision when a cataract first develops. But as it becomes denser, they’re likely to experience some visible signs.

Common signs of cataracts include:

  • Frequent changes in eye prescription
  • Changes to the colour of the pupil – it may look white
  • Blurred, dim or misty vision
  • Difficulty seeing in low light or at night
  • Sensitivity to light: lights look too bright or glaring
  • Colours look faded, muted or more yellow
  • Seeing a ‘halo’ around bright lights
  • Everything looks more ‘washed out’
If someone has cataracts, things can start to look dim, blurred or distorted, as if they’re looking through dirty glass. Their vision may seem cloudy, and it can also be hard to make out details or colours.

How are cataracts diagnosed?

If someone has cataract symptoms, it’s important they visit a doctor for a diagnosis so they can be treated. They may also be diagnosed by an optometrist during a routine eye test, which should take place every two years.

During an eye exam, an eye specialist may test a person’s vision by asking them to read letters or symbols from a chart and by performing a close check of their eyes to see if the lens has become cloudy.

The benefits of diagnosing and treating cataracts include:

  • Improved or restored eyesight
  • Reduced glare or halos in your vision
  • Improved quality of life
An eye surgeon operates on a patient. Another member of clinical staff assists them.

Cataract surgery

An operation to treat cataracts can take as little as 20 minutes, and a person’s vision can start to return a few hours after surgery.

About cataract surgery

How are cataracts treated?

A boy holds up a mirror to check his reflection. He is smiling broadly and wearing a pair of glasses with a red frame.

Spectacles or contact lenses

Prescription glasses or contact lenses can help improve a person’s eyesight during the early stages of cataracts. However, it’s still important to seek further treatment, such as surgery, to prevent permanent sight loss.

Five medical professionals stand around an operating theatre during a cataract operation. They are all wearing medical masks and medical scrubs.

Cataract surgery

A cataract operation is the only way to restore vision. The operation is straightforward and effective. It involves removing the cloudy lens from the lens capsule and replacing it with an artificial one.

A woman smiles as she puts her arm around a young boy.
I feel great. I am able to do all the chores I used to do previously.
Margaret, with her son Chisomo, after her cataract operation
A woman smiles as she puts her arm around a young boy.

How you can help

We’re making it easier for people in Africa and Asia to be examined and treated for cataracts.

In collaboration with our partners, we help develop quality eye care services so people can get their eyes tested and receive treatment if they needed it.

We also help fund training and skills development for eye surgeons, nurses and community workers to improve the quality of cataract surgery and ensure more operations can be carried out. We’ve already helped to carry out 9.7 million cataract operations since we began in 1950.

With your support, we can reach even more people who are at risk of losing their sight to cataracts and other eye conditions. Will you help us make this a reality?

Angeshita smiling.

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Page last reviewed: February 2026
Next review due: February 2029
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