Cataracts are cloudy patches or areas in the lens inside your eye. They can develop in one or both eyes. One eye can often be more affected than the other.
The lens is normally clear. It allows light to pass through to the back of your eye, helping you to see sharp images. If parts of the lens become cloudy (opaque), light cannot pass through the cloudy patches. Over time, these patches usually become bigger, and more of them develop. As less light is able to pass through the lens, your vision may become blurry or cloudy. The cloudier the lens becomes, the more your sight will be affected.
Cataracts are the main cause of impaired vision in the world, especially in developing countries. They affect men and women equally.
In one RSA research study, around 30% of people aged 65 and over had cataracts in one or both eyes that impaired their vision.
Cataracts are most commonly found in older people. These are called age-related cataracts.
Rarely, babies can have cataracts when they are born.
The causes of age-related cataracts are not known. Research suggests that some factors may increase the risk that cataracts will develop.
As people grow older, there can be changes to the protein that makes up the lens in the eye. Some experts think that this may be linked to how fluids and nutrients reach the eye. These changes in the lens protein can lead to cloudy areas developing.
It is not known how or why getting older causes these changes to happen.
Research suggests that some factors may increase the risk of age-related cataracts developing. For example:
In younger people, cataracts may have other less common causes. For example:
If you have problems with your vision, you should see your optician (optometrist) or your GP. They may look at your eyes with an instrument called an ophthalmoscope. By shining a bright light into your eye, the ophthalmoscope enables your optician to see inside it.
If you have cataracts, your optician will be able to see them in your eye. They will also be able to see how much of your lens is affected. In some cases, you may be referred to a specialist eye doctor (ophthalmologist or ophthalmic surgeon) for a diagnosis.
Sometimes cataracts are diagnosed during a regular eye test, even if you have had no symptoms.
Symptoms usually develop over many years, most commonly in older people. Gradually, more of the lens in your eye becomes cloudy. If your cataracts are mild, you may not notice any symptoms to start with.
If you have cataracts in both eyes, one eye may be more affected than the other.
Blurred, cloudy or misty vision is the most common symptom of age-related cataracts. You may have small spots or dots in your vision – patches where your sight is not as clear.
Your sight may be affected by the light. For example, you may find it more difficult to see:
Other ways that cataracts may affect your sight can include:
If you wear glasses, you may find that they have become less effective. Less commonly, you may see a halo (a circle of light) around bright lights such as car headlights or street lights.
The symptoms of cataracts can be similar to the symptoms of other eye conditions. It is therefore important to see your optician (optometrist) or GP for a check-up.
A rare symptom of cataracts is double vision (seeing two images of an object instead of one).
Treatment may not be needed if:
In the early stages of a cataract, your vision may be improved with stronger glasses or using a brighter light, for example, to read. However, the improvement may not last long. When cataracts are more severe, the only way to treat them is through surgery.
Your optician (optometrist) or GP will probably recommend treatment if your loss of vision affects your usual daily activities. For example:
Cataracts are treated by having an operation to remove the cloudy lens in your eye. In most cases, the natural lens is replaced with an artificial clear plastic lens. This is called an intraocular implant or intraocular lens (IOL).
Most cataract operations in the RSA are done as keyhole surgery under local anaesthetic. You will not need to stay in hospital overnight – you will probably be admitted as a day patient (day case).
The most common operation is usually called phacoemulsification. Sometimes it may be called phaco extracapsular extraction.
Cataracts cannot be treated with laser surgery.
Your optician or GP will refer you to a specialist eye doctor (ophthalmologist or ophthalmic surgeon) who will assess your eyes and your general health. This is called a pre-operative assessment.
During the assessment, measurements of your eye will be taken, to prepare for the artificial lens that will replace your natural lens.
An appointment will probably be made for your operation to take place in a separate visit.
Just before the operation, drops to widen (dilate) your pupil will be applied to your eye. You will also be given a local anaesthetic. This may be applied to your eye as drops, although sometimes injections in the tissue around the eye may be used instead.
Once the anaesthetic takes effect, you will not be able to feel anything. While the operation is taking place, all you will be able to see is a bright light. You will not be able to see what is happening.
Different types of replacement lens are available. For example:
Your doctor will discuss with you what type of lens will suit you.
Multifocal and accommodating lenses are not normally available through the medical aid. Ask your ophthalmologist what lenses are available in your area.
For information about accommodating lenses, see the 'cautions' section.
The doctor makes a very small cut in the surface (cornea) of your eye at the front. The doctor inserts a tiny probe through this cut. The probe breaks up the cloudy lens into tiny pieces using ultrasound. Then the tiny pieces are sucked out of the eye.
Once this is done, the doctor inserts an artificial clear plastic lens through the cut. The lens sits in a little 'pocket' (the lens capsule) to keep it in place. The lens is folded when it is inserted. Once in position, it is allowed to unfold.
The operation usually takes 15-30 minutes, although sometimes it can take slightly longer. You may be given a pad to wear over your eye, to protect it after the operation.
Two other operations may be performed to remove age-related cataracts, although these are much less common. In manual extracapsular extraction, the doctor makes a slightly larger cut in the eye, and the lens is removed in one piece, rather than being broken up first by ultrasound.
In intracapsular extraction, the lens capsule is removed, as well as the lens. A replacement plastic lens is then sewn into the eye. In some cases, special (aphakic) glasses or contact lenses may need to be worn instead. This type of operation is rare in the RSA.
For most people, vision improves noticeably straightaway, although it may take a little while to settle down completely. The cut in the eye's surface is so small that it usually heals by itself, although sometimes a small stitch may be needed.
Your doctor will probably advise you to take it easy, for example, by avoiding sports and any vigorous activities. When the operation is done, your plastic lens will be set up for a certain level of vision. After your operation, you will probably need to wear glasses, for example, to see objects that are:
If you wore glasses before, your prescription will probably change. It takes several weeks after the operation for your vision to settle down before your optician can give you a new prescription.