Expert reviewer, Professor Simon Taylor, Consultant Ophthalmic Surgeon
Next review due May 2022

A cataract is when the lens of your eye becomes cloudy, making it less transparent. This can make your vision blurred or misty over time, often building up slowly over several years.

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About cataracts

Your lens is near the front of your eye just behind your iris (the coloured part of your eye). It’s normally clear and helps you to see things in focus. Your lens directs light rays on to the back of your eyeball (retina) to form an image, which is then sent to your brain.

If you have a cataract, your lens becomes cloudy, which causes your vision to become blurred. Cataracts usually form over a long period of time, causing your eyesight to gradually get worse. Cataracts can affect 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 cataract surgery may depend on how much your cataracts affect your daily life. Some cataracts may not affect your vision at first. However, you may decide to have surgery if your cataracts are stopping you from reading or driving safely at night.

You're more likely to have cataracts as you get older. In the UK, age-related cataracts affect around half of people over 65. Cataracts can sometimes affect children too.

Cataract symptoms

If you have a cataract, you may not notice any symptoms at first. Cataracts don’t usually cause any pain. Your symptoms will depend on how severe the cataract is and if you have a cataract in one or both of your eyes.

Cataract symptoms include:

  • cloudy or blurred vision – this may make it difficult for you to read, watch television or recognise faces
  • trouble coping with bright light, including light from the sun
  • problems with glare, especially when driving at night
  • difficulty seeing colours – blues especially 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, such as diabetes or glaucoma. So if you notice any problems with your vision, make an appointment with your optometrist. An optometrist is a registered healthcare professional who examines eyes, tests sight and dispenses glasses and contact lenses.

Diagnosis of cataracts

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

You may be diagnosed with a cataract during a routine eye test. This is because the changes in your lens can develop slowly over many years– so you may not have noticed any symptoms.

Self-help for cataracts

You may find that stronger glasses or contact lenses help your symptoms. Your optometrist will change your prescription to help you see more easily. You may find it easier to read if you don’t sit too close to a light source, such as a lamp. But because cataracts are likely to get worse over time, these are only short-term solutions. You’ll be recommended to have regular eye examinations to check your cataracts and make sure your vision isn’t getting worse.

Cataract treatment

Removing your cataract with surgery is the only way to restore your vision back to normal. Your ophthalmologist will discuss with you whether cataract surgery is right for you. This will depend on many things, such as how much your cataract is affecting your daily activities.

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.

The most common procedure for removing cataracts is 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 procedure once your surgeon knows that the first one worked well.

Sometimes though, your surgeon will recommend having surgery on both eyes at the same time. This may 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 if you need to have a general anaesthetic rather than a local one, and you’re likely to react badly to it, having one operation will be safer than having two.

What causes cataracts?

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

  • diabetes
  • an injury to your eye
  • severe inflammation of your eye (uveitis)
  • exposure to ultraviolet (UV) light in sunlight – wearing a wide-brimmed hat and UV-blocking sunglasses may help to protect your eyes
  • taking medicines called corticosteroids in high doses or for a long time
  • smoking
  • drinking too much alcohol
  • a family history of cataracts

Complications of cataracts

Cataracts may stop you doing some of the activities you enjoy, such as reading, driving or watching TV. If your cataract isn’t treated, you may eventually lose your vision completely. Cataracts that are affecting your vision can make you 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 what’s called angle-closure glaucoma. This may happen if a cataract makes your lens swell up (get bigger). If you have angle-closure glaucoma, the pressure in your eye increases very quickly. This can cause intense 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, you should get medical help straight away to make sure your sight isn’t permanently damaged.

Frequently asked questions

  • 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 gets cloudy or blurry after cataract surgery, it’s important to get your eyes checked by an optometrist. You may have an underlying eye condition, such as glaucoma or age-related macular degeneration.

    Sometimes though, cataract surgery can cause a condition called posterior capsule opacification. This can 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 because it’s used to hold the new artificial lens in place.

    Around one in 10 people find posterior capsule opacification affects their vision after cataract surgery. The blurring of your vision can take months or even years. If you’re affected, you’ll be offered a minor laser procedure to restore your vision. This can usually be done in an outpatient clinic and only takes a few minutes.

  • Whether or not you can drive will depend on how bad your cataract is and if your sight is still within the legal limits for driving. If your cataract isn’t affecting your vision, it’s often safe for you to drive. In this case, you may not need to tell the Driving and Vehicle Licensing Agency (DVLA).

    By law, your vision must meet certain criteria so that you can hold a driving licence. Your optometrist or ophthalmologist will be able to test whether your vision meets the DVLA standards. It’s fine if you need to wear glasses or contact lenses to meet the criteria.

    The DVLA standards state that you must be able to read a vehicle's registration plate in good light from 20m away. If the registration plate dates from before September 2001, you must be able to read it from 20.5m away. You shouldn't drive if you can't read a registration plate at these distances and you should inform the DVLA. You must also have a score of at least 6/12 on a Snellen test. This is a test for visual acuity (how much detail you can see).

    If you can read a number plate according to the DVLA standards but suffer from glare, this may also mean you shouldn’t be driving.

    If you're worried about whether or not your vision meets the DVLA standards, book a sight test with your optometrist or contact the DVLA.

  • Cataracts affect people in different ways so it’s difficult to predict how they’ll affect your vision. But your vision will probably keep getting worse if you don't have your cataract taken away and lens replaced. This may happen slowly, sometimes over a number of years. If you have an underlying medical condition such as diabetes, your vision may be affected more quickly.

    You may not realise at first that you have a cataract if the changes happen very slowly. Most cataracts are diagnosed during a routine eye check. But over time, you may notice your vision is cloudier and colours seem faded. You’re less likely to notice these symptoms if just one of your eyes is affected. If both of your eyes are affected, you may also find it more difficult to judge distances properly.

    Cataract surgery may help to restore your vision. But if you also have another undiagnosed eye condition, such as glaucoma, you may need some other treatment as well.

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Related information

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  • Reviewed by Natalie Heaton, Specialist Health Editor, Bupa Health Content Team, May 2019
    Expert reviewer, Professor Simon Taylor, Consultant Ophthalmic Surgeon
    Next review due May 2022