Overview
A cataract is a cloudy area in the lens of the eye. The lens is the clear part that focuses light so that we see sharply. When it turns cloudy, vision becomes blurred, a little like looking through a misted window.
Most cataracts develop slowly with age. They often affect both eyes, though not always to the same degree. Cataract is one of the leading causes of vision loss worldwide, and sight can usually be restored with surgery.
Symptoms
Early cataracts may cause no symptoms. As the lens becomes cloudier, symptoms can include:
- Cloudy, blurred or misty vision
- Difficulty seeing at night or in dim light
- Glare from sunlight, lamps or oncoming headlights
- Halos around lights
- Colours looking faded
- Double vision
- Frequent changes in spectacle power
Cataracts are usually painless and do not make the eye red.
When to see a doctor
See an eye doctor if vision is becoming blurred or cloudy, if glare is making driving difficult, or if spectacle power keeps changing. Regular eye checks are also advisable for older adults and people with diabetes.
Causes
The lens is made mostly of water and proteins. With age, the proteins break down and clump together, forming cloudy patches that slowly grow larger and denser.
Cataracts can also follow an eye injury or eye surgery. A few babies are born with cataracts or develop them in childhood.
Risk factors
- Older age
- Diabetes
- Smoking
- Heavy alcohol use
- Long exposure to strong sunlight without eye protection
- Long-term use of steroid medicines
- A previous eye injury or eye surgery
- A family history of cataracts
Complications
An untreated cataract gradually worsens and can eventually cause severe vision loss or blindness. Poor vision also makes reading, driving and daily tasks difficult, and raises the risk of falls.
Cataract surgery is very common and serious problems are uncommon, but like any operation it carries some risks, such as infection, bleeding or detachment of the retina. Some people develop cloudiness behind the new lens months or years later (a secondary cataract), which is treated with a laser procedure.
Prevention
Age-related cataracts cannot be fully prevented, but these steps help protect the eyes and may delay cataracts:
- Wearing sunglasses and a hat or cap in strong sunlight
- Not smoking
- Keeping diabetes well controlled
- Eating plenty of fruit and green leafy vegetables
- Wearing protective eyewear during risky work or sport
- Having regular eye examinations
Diagnosis
An eye doctor diagnoses a cataract with a simple, painless eye examination. This usually includes:
- A vision test using a letter chart
- Eye drops to widen (dilate) the pupil
- Examination of the lens and the back of the eye with a special microscope
The drops can blur vision for a few hours afterwards.
Treatment
In the early stages, new spectacles, brighter lighting and anti-glare sunglasses may be enough. Surgery is the only treatment that removes a cataract. It is usually advised when poor vision starts to interfere with daily activities such as reading, working or driving.
During the operation, the cloudy lens is broken up and removed through a very small cut, and a clear artificial lens () is put in its place. It is usually done under local anaesthetic, so the person is awake but should feel no pain, and most people go home the same day. If both eyes need surgery, they are usually operated on separately.
Eye drops are used for some weeks afterwards while the eye heals. Most people see better after surgery, though many still need spectacles for some tasks, such as reading.
Myths and facts
Things people often say about this. Open each one to see what is true.
Myth“A cataract has to ripen or become fully mature before it can be operated.”What is true?
Fact
There is no stage of ripeness to wait for. Surgery is usually suggested when poor vision starts to get in the way of everyday things such as reading, working or driving, and waiting does not usually harm the eye or make the operation harder later.
Myth“Eye drops, tablets or eye exercises can dissolve a cataract.”What is true?
Fact
Surgery is the only way to get rid of a cataract. Early on, stronger spectacles, brighter light for reading and anti-glare sunglasses can help for a while, but they do not clear the cloudiness.
Myth“A cataract is a film or skin growing over the eye, and it can be scraped off.”What is true?
Fact
A cataract is a cloudy area inside the lens of the eye, the clear part that focuses light. Nothing is growing over the surface of the eye. The operation removes the cloudy lens and puts a clear artificial one in its place.
Myth“Cataracts come from reading too much, sewing or watching too much television.”What is true?
Fact
Most cataracts come from normal changes in the lens with age, as the proteins in it break down and clump together. Diabetes, smoking, heavy alcohol use, steroid medicines, eye injury and long exposure to strong sunlight add to the risk. Using the eyes for close work is not among the known causes.
Myth“The cataract will grow back after the operation.”What is true?
Fact
The cloudy natural lens is removed and replaced, so the cataract itself cannot return. Some people find vision clouding again weeks, months or even years later, because the thin membrane behind the new lens has become cloudy. An eye doctor can clear that with a short laser treatment.
Questions to ask your doctor
Tick the ones you want answered and take them with you.
Common questions
Can cataracts be cured with eye drops or medicines?
No. At present, no eye drop, medicine or diet has been shown to clear a cataract. Surgery to replace the cloudy lens is the only effective treatment.
Do I have to wait for the cataract to mature before surgery?
No. With modern surgery there is no need to wait until a cataract is fully mature. Surgery is usually considered when vision problems start to affect daily life, and the timing is decided together with the eye surgeon.
Can a cataract come back after surgery?
A cataract cannot grow back, because the natural lens has been removed. In some people, the thin membrane behind the new lens becomes cloudy later on, causing blurred vision again. This is called a secondary cataract and is treated with a short laser procedure.
