Expert reviewer, Professor Simon Taylor, Consultant Ophthalmic Surgeon
Content review by Victoria Goldman, November 2021
Next review due November 2024

A cataract is when the lens of your eye gets cloudy so it’s less see-through. This can make your vision blurred or misty over time. Cataracts often build up slowly over several years.

About cataracts

Your lens is near the front of your eye just behind your iris (the coloured part of your eye). It’s normally see-through and helps you to see things clearly. Your lens directs light rays onto the back of your eyeball (retina) to form a picture, which is then sent to your brain.

If you have a cataract, proteins in the lens of your eye change over time. This causes your lens to become cloudy, which makes your vision blurry. Cataracts usually form over a long period of time. This makes your eyesight get worse very slowly. You're more likely to develop cataracts as you get older. You can get a cataract in just one or both of your eyes.

The only way to treat a cataract is to replace your cloudy lens with an artificial one. But your decision to have cataracts surgery may depend on how much your cataracts affect your daily life. Some cataracts may not change your vision at first. But you may decide to have surgery if your cataracts are stopping you from reading or driving safely at night.

Causes of cataracts

Cataracts are caused by changes in your eye that make your lens cloudy. These changes usually happen naturally as you get older. But other things may make you more likely to get cataracts. These include:

  • diabetes
  • an injury to your eye
  • bad inflammation (swelling and redness) of your eye (uveitis)
  • exposure to ultraviolet (UV) light in sunlight over a long time
  • taking medicines called corticosteroids in high doses or for a long time
  • smoking
  • drinking too much alcohol
  • a family history of cataracts

Types of cataracts

There are different types of cataracts that can affect adults. These form in different parts of the lens in your eye.

The three main types of cataracts are:

  • Nuclear cataracts. These form in the middle of your lens. They’re more common as people get older.
  • Cortical cataracts. The cloudiness starts off on the outside of your lens. It then slowly moves towards the centre. These don’t always cause symptoms unless you’ve had them for a long time.
  • Posterior subcapsular cataracts. These form at the back of your lens. They’re more common in younger people.


Some babies are born with cataracts (called congenital cataracts).

Cataract symptoms

If you have a cataract, you may not notice any symptoms at first. Cataracts aren’t usually painful. Your symptoms will depend on:

  • the size of your cataract
  • where it is in your lens (the type of cataract you have)
  • whether you have a cataract in one or both of your eyes


Cataracts symptoms include:

  • cloudy or blurred vision – for example, finding it harder to read, watch television or recognise faces
  • trouble coping with bright light, including light from the sun
  • problems with glare, especially when you’re driving at night
  • difficulty seeing colours – shades of blue, in particular, may seem washed out or faded
  • seeing ‘halos’ around lights


If you have cataracts, you may notice that the prescription for your glasses or contact lenses changes more often than usual.

Some of these symptoms could be caused by problems other than cataracts – for example, diabetes or glaucoma. So if you notice any changes to your eyesight, make an appointment with your local opticians. An optometrist can check the health of your eyes, test your sight and prescribe glasses and contact lenses if you need them.

Diagnosis of cataracts

If you think you have symptoms of cataracts, get your eyes tested by an optometrist. They’ll look into your eyes using a special instrument called an ophthalmoscope.

If you have a cataract, your optometrist will be able to see that the lens of your eye is cloudy. Your lens may look brown or white when they shine a bright light into your eye. Your optometrist will then refer you to an ophthalmologist for treatment. An ophthalmologist is a doctor who specialises in eye health.

Your optician may notice you have a cataract during a routine eye test. This is because the changes in your lens can happen slowly over many years – so you may not have noticed any symptoms.

Self-help for cataracts

If your cataracts aren’t very bad, you may be able to try some things to help you see more clearly. You may find that:

  • stronger glasses or contact lenses help (your optometrist will change your prescription if your vision is getting worse)
  • it’s easier to read if you don’t sit too close to a light source such as a lamp


Because cataracts are likely to get worse over time, these options will only work for a short while. You’ll need to have regular eye examinations to check your cataracts and make sure your vision isn’t getting worse. If your eyesight keeps getting worse, your optometrist may recommend that you have cataracts surgery.

Cataract treatment

Removing your cataract with surgery is the only way to get your vision back to normal. Your ophthalmologist will talk to you about whether or not cataracts surgery is right for you. This will depend on lots of things, such as how much your cataract is affecting your daily activities.

Cataracts affect everyone differently. If you don’t read much, you may not be bothered if your cataracts are making it harder for you to read. In that case, you may decide to wait longer for surgery. But if you drive a lot, especially at night, or need to see things in detail, you may decide to have a cataracts operation sooner.

Most cataracts are removed during an operation called phacoemulsification. This usually takes around 15 to 20 minutes and is carried out under local anaesthesia. In the procedure, your surgeon will use a special probe to destroy your cloudy lens with ultrasound. Your lens is then taken out and replaced with a lens made from a clear, artificial material such as plastic.

Your surgeon will usually only operate on one eye at a time. If you have cataracts in both eyes, your eye with the worst vision will usually be treated first. You’ll have the second operation once your surgeon knows that the first one worked well.

Sometimes, your surgeon may recommend having surgery on both eyes at the same time. This could be because you’re unlikely to have any serious eye complications after surgery so it’s safe for you to have just one operation. Or it may be safer for you to have one operation rather than two. This might be because you need to have a general anaesthetic rather than a local one, and you’re likely to react badly to it. Speak to your surgeon to find out if this is an option for you.

Most people don’t have any sight problems after surgery. But you may need to wear reading glasses afterwards. If your vision doesn’t get better after surgery, this may be because you have another eye condition, such as glaucoma or age-related macular degeneration. Sometimes, your ophthalmologist can’t diagnose these other eye conditions until your cataract has been taken away.

Sometimes, cataracts surgery can cause a condition called posterior capsule opacification. This may make your vision cloudy, but it’s not the same as a cataract. It's caused by a thickening of your natural lens casing – the part of your eye that holds your lens in place. This lens casing isn’t usually taken away during surgery. If you have this condition, you’ll be offered a minor laser procedure to fix your vision. This can usually be done in an outpatient clinic and only takes a few minutes.

Complications of cataracts

Cataracts may stop you doing some activities you enjoy, such as reading, driving or watching TV. If your cataract isn’t treated, you may eventually not be able to see properly at all. If your cataracts are affecting your vision, you may be more likely to have an accident or a fall. But cataracts are normally diagnosed and treated well before they affect your vision really badly.

Cataracts can make it harder for your ophthalmologist to diagnose other long-term eye conditions, such as glaucoma. If you have diabetes, you’ll need to have some special eye tests regularly to check your eyes are healthy. But if you have a cataract as well as diabetes, these special eye tests may not work so well. This is why you may be advised to have the cataract taken away.

Sometimes cataracts can cause a condition called angle-closure glaucoma. This may happen if a cataract makes your lens swell (get bigger). If you have angle-closure glaucoma, the pressure in your eye increases very quickly. This can cause sudden, strong pain in your eye, blurred vision and a red eye. You may also have a headache and feel sick. If you have any of these symptoms, get medical help straight away to make sure your sight isn’t permanently damaged.

Prevention of cataracts

You can’t prevent cataracts. But you may be able to reduce your chances of getting one by:

  • staying safe in the sun and wearing UV-blocking sunglasses to protect your eyes from sunlight
  • stopping smoking or cutting down if you can’t stop completely
  • drinking less or no alcohol
  • if you have diabetes, making sure your blood sugar levels are well controlled


Doctors don’t recommend any particular foods or food supplements to prevent cataracts.

To stop your cataracts getting very bad:

  • have regular check-ups with your optometrist or ophthalmologist
  • consider having cataracts surgery if they recommend it

Your cataract can’t come back after surgery. This is because your natural lens has been taken away and replaced with an artificial lens. If your vision is still cloudy after cataracts surgery, you may have developed a condition called posterior capsule opacification. For more information, see our section: Cataracts treatment above.

Some people can still drive with cataracts. This will depend on how bad your cataract is and if your sight is still within the legal limits for driving. If your cataracts affect your driving, you will need to contact the Driver and Vehicle Licensing Agency (DVLA). Check with your optometrist before you drive.

Cataracts affect people in different ways so it’s hard to predict how quickly they’ll affect your vision. Your eyesight will usually get worse very slowly, sometimes over a number of years. If you have an underlying medical condition such as diabetes, your vision may be affected more quickly.

Most cataracts are caused by changes to the lens of your eye that happen naturally as you get older. But they can also be caused by other things – for example, diabetes, smoking, an injury to your eye or being in strong sunlight over long periods of time. For more information, see our Causes of cataracts section above.

You’ll be recommended to have your cataracts taken out if they’re affecting your daily life. Bad cataracts can stop you seeing properly and may make you more likely to fall or have an accident. For more information, see our section: Cataracts treatment above.

At first, you may not notice any cataracts symptoms. Or you may struggle to see properly when you try to read, watch television or even recognise faces. You may find it harder to drive at night because there’s too much glare. For more information, see our section: Cataracts symptoms above.

There are different types of cataracts in adults. The type of cataract you have will depend on where in your lens it develops. The three types are nuclear cataracts, cortical cataracts and posterior subcapsular cataracts. For more information, see our section: Types of cataracts above.

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