Eye conditions

What are cataracts?

A cataract is clouding of the lens inside your eye. Your vision becomes blurred because the cataract is like frosted glass, getting in the way of your sight. It isn’t a layer of skin growing over your eye, despite what you may have heard.

As you get older, the lenses in your eyes become thicker and less clear. Ageing and some medical conditions can cause proteins and fibres in the lens to break down and clump together, which clouds the lens. As the cataract develops, the clouding gets worse: it scatters and blocks light passing through the lens, so a sharp image can’t reach your retina. You can develop a cataract in one eye or both.

If your optometrist has told you that you have a cataract, don’t be alarmed. Many people over 60 have some cataract, and the vast majority can be treated successfully.

Close-up of an eye with a cataract

Know the signs

Symptoms, causes and risk factors

Symptoms

  • Blurred, cloudy or dim vision: your sight may look misty, or your glasses may seem dirty or scratched
  • Glare: lights such as car headlights and sunlight may dazzle you
  • Trouble seeing at night
  • Haloes around lights
  • Needing brighter light for reading and other activities
  • Faded or yellowed colours
  • Frequent changes to your glasses or contact lens prescription
  • Double vision in one eye

Causes

The main cause of cataracts is age. As you get older, the proteins in the lens of your eye naturally change and make it cloudy. Cataracts can also be caused by:

  • Diabetes
  • An injury to your eye
  • Severe inflammation in your eye
  • Corticosteroid medicines taken in high doses or for a long time
  • Being born with them (congenital cataracts)

Risk factors

Some things make cataracts more likely:

  • Long-term exposure to UV light in sunlight
  • Smoking
  • Drinking too much alcohol
  • Being female
  • Severe dermatitis
  • High blood pressure
  • A family history of cataracts

Where they form

Types of cataracts

Cataracts can form in different parts of the lens.

Nuclear cataracts affect the centre of the lens. At first, distant objects may look blurry while close-up ones look clear, and your reading vision may even improve for a short time. Over time the lens turns more yellow or brown, your vision gets worse and it can become harder to tell colours apart.

Cortical cataracts affect the edges of the lens. They start as white, wedge-shaped streaks on the outer edge and slowly spread towards the centre.

Posterior subcapsular cataracts start as a small spot near the back of the lens, right in the path of light. They often affect reading vision, cause glare or haloes around lights at night, and tend to grow faster than other types.

Congenital cataracts are present from birth or develop in childhood (see cataracts in children).

Secondary cataracts are linked to another medical condition rather than age alone. Diabetes can damage the blood vessels in the eye, autoimmune conditions such as rheumatoid arthritis and lupus can cause inflammation that damages the lens, and some medicines, including corticosteroids and some chemotherapy drugs, can increase the risk. Treating the underlying condition usually comes first, though surgery may still be needed.

Protect your eyes

Reducing your risk

You can’t prevent cataracts entirely, but some steps can help protect your vision and slow them down:

  • Wear sunglasses or a wide-brimmed hat outdoors to limit your long-term exposure to UV light.
  • Eat a diet rich in antioxidants, such as dark leafy greens, orange vegetables and oily fish. Read more about nutrition and the eye.
  • Avoid smoking and drinking too much alcohol.
  • Have regular eye examinations so any changes are picked up early.

Diets and medicines haven’t been shown to slow or stop a cataract once it has started to form, so surgery is the only effective treatment when a cataract affects your daily life.

Optometrist examining a patient's eyes with a slit lamp

Get it checked

Diagnosing cataracts

If you think you have symptoms of cataracts, book an eye examination. Your optometrist will look into your eyes with an instrument called an ophthalmoscope. If you have a cataract, they’ll see that the lens is cloudy, and it may look yellow-brown, grey or white when they shine a light into your eye.

They may also use a slit lamp, which lights up the front of your eye with a thin line of light so your optometrist can look at each part in close-up. Book an appointment if:

  • Your sight has become blurred or misty, or your glasses always seem dirty
  • Lights dazzle you, especially when driving at night
  • You need more light to read, or colours look faded

Cataracts and driving

  • You must meet the DVLA's eyesight standard to drive
  • You may need your cataract removed to keep your licence
  • Ask your optometrist if you're not sure whether your vision meets the standard

Treatment

Cataract surgery

When glasses can no longer sharpen your vision, the only effective treatment for cataracts is an operation to remove the clouded lens. Cataract surgery is one of the most successful operations there is, and it’s carried out in hospital by an eye specialist.

When should I have the operation?

In the past, eye specialists often waited until a cataract was “ripe” and your vision was very poor before removing it. Now, the operation is usually done as soon as your eyesight gets in the way of daily life: reading, working or doing the things you enjoy.

Before the operation, you and your eye will be carefully checked and measured to plan the details. This may mean a separate visit beforehand.

How safe is it? Cataract surgery is one of the most successful operations. Fewer than 2% of patients have serious, unexpected complications. One of the most common, a thickening of the lens casing (the part that holds the lens in place), is easily corrected with laser treatment. If you have any concerns after your operation, call the eye clinic.

After the operation

Most people notice an instant improvement in their sight, although full healing can take several months. Most people go home the same day (don’t drive yourself home) and can carry on with normal daily activities, but:

  • Avoid rubbing your eye, and wear an eye shield if you’re a restless sleeper.
  • Avoid heavy lifting, strenuous exercise and swimming.
  • Take care when it’s windy in case something blows into your eye.

You’ll be given eye drops to help your eye heal and prevent infection, and it helps to have someone at home if you find drops difficult. The eye clinic will tell you how long to use them and when you can go back to work, drive and fly.

What happens during cataract surgery?

1

Local anaesthetic

Almost everyone has a local anaesthetic, given as eye drops, an injection or both. You'll be awake but won't feel anything in your eye.

2

A small incision

The eye specialist works with a microscope through a tiny cut in your eye. Your eye isn't taken out of its socket, and the operation isn't painful.

3

A new lens

The cloudy lens is removed and replaced with a clear artificial lens, called an intraocular lens, which stays in your eye permanently. Stitches usually aren't needed.

4

Around 15 to 20 minutes

It can take longer. You may see movement and light but no detail, and someone can hold your hand if you'd like. Your eye is then covered to protect it.

Childhood cataracts

Cataracts in children

Cataracts mostly affect older adults, but some babies are born with them and some children develop them while they’re young. They’re rare: in the UK, around 3 to 4 in every 10,000 babies are born with cataracts.

Types and signs

Congenital cataracts are present when a baby is born or shortly afterwards.

Developmental, infantile or juvenile cataracts are diagnosed in older babies or children.

As well as poor vision, cataracts in children can cause “wobbling eyes” and a squint, where the eyes point in different directions. If cataracts are affecting a child’s vision, they may have surgery to remove the affected lens. Book a children’s eye test if you have any concerns.

Possible causes

Often the exact cause can’t be found. Possible causes include:

  • A genetic fault inherited from the child's parents that makes the lens develop abnormally
  • Some genetic conditions, such as Down's syndrome
  • Some infections caught by the mother during pregnancy, including rubella and chickenpox
  • An injury to the eye after birth

FAQs

Frequently asked questions about cataracts

A cataract is clouding of the lens inside your eye. It makes your vision blurred, like looking through frosted glass. It isn’t a layer of skin growing over the eye. Many people over 60 have some cataract, and the vast majority can be treated successfully.

Most cataracts develop as you get older, as the proteins in the lens change. They can also be caused by diabetes, an eye injury, inflammation in the eye or long-term use of corticosteroid medicines. Smoking, too much alcohol, long-term UV exposure and a family history of cataracts make them more likely.

Not entirely, but wearing sunglasses outdoors, eating a diet rich in antioxidants, not smoking, cutting down on alcohol and having regular eye examinations can help protect your eyes. Diets and medicines haven’t been shown to stop a cataract once it has started.

The operation is usually done as soon as your eyesight starts getting in the way of daily life, such as reading, working or doing the things you enjoy. You no longer need to wait until the cataract is “ripe” and your vision is very poor.

The cloudy lens is removed and replaced with a clear artificial lens (an intraocular lens implant). It’s done in hospital under local anaesthetic through a small incision, usually without stitches, and typically takes around 15 to 20 minutes.

Most people notice an instant improvement in their sight, although complete healing can take several months. You’ll use eye drops for a few weeks, and most people go home the same day and carry on with normal activities, avoiding rubbing the eye and strenuous exercise at first.

You must meet the DVLA’s eyesight standard to drive, and you may need your cataract removed to keep your licence. Your optometrist can check your vision and advise you. After surgery, don’t drive yourself home, and ask the eye clinic when you can drive again.

Yes, but it’s rare. Around 3 to 4 in every 10,000 babies in the UK are born with cataracts, and some children develop them later. They can be inherited, linked to some infections during pregnancy, or caused by an eye injury. See cataracts in children.

Medically reviewed by Amar-Kaash Gandecha, BSc(Hons) MCOptom DipTp(IP), Prof Cert Glauc, Director and Optometrist. Last reviewed 14 August 2026.

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