Cataracts: symptoms, causes, surgery and recovery

The NHS describes a cataract as the lens in your eye becoming cloudy, causing blurred vision and loss of sight. It usually affects older adults and can be treated with surgery. Moorfields Eye Hospital explains that a normal lens is clear and helps focus light onto the retina at the back of the eye, and that when a cataract develops the lens becomes cloudy so the retina receives a dull and fuzzy picture.

Moorfields says a cataract usually forms slowly over years, causing gradual blurring that eventually cannot be corrected with glasses, although in some people vision can deteriorate relatively quickly. The most common type is age-related, which it says can occur at any time after the age of 40. Other types include congenital cataracts present at birth, drug-induced cataracts linked to steroids, and cataracts after injury to the eye.

The NHS says symptoms usually develop slowly, that you will often have cataracts in both eyes, and that symptoms may differ between the eyes. Its list is:

• blurred vision

• difficulty seeing at night

• difficulty reading and watching television

• eyes being uncomfortable in, or sensitive to, light and glare

• double vision when looking at one object

• seeing glowing rings (halos) around lights

• colours looking faded, especially blue

• needing to change your glasses prescription more often than usual

The NHS says you may be more likely to get cataracts if you are aged 60 or over, have had an eye injury or eye surgery, have another eye condition such as uveitis or being very short-sighted, have taken steroid medicines for long periods, smoke, have a parent, brother or sister who has had cataracts, are a woman, or have had regular unprotected exposure of your eyes to a lot of sunlight. Some long-term conditions can also raise risk, namely type 2 diabetes, severe dermatitis and high blood pressure.

Moorfields describes the usual process as the lens hardening and becoming cloudy with ageing, and says cataracts are also more common in people with diseases such as diabetes.

The NHS advises seeing an optician if you have symptoms of cataracts. If they think you have cataracts, they refer you to an eye specialist for more tests or treatment. Moorfields describes the usual first step as updating your glasses, and says that when an optician cannot improve your vision further with glasses or contact lenses, they refer you to a cataract clinic to be considered for surgery.

Before surgery, the NHS says a specialist will examine and measure your eye. NICE's cataract guideline asks for the eye to be measured with optical biometry where possible and the curvature of the cornea to be measured, and says people should be told what cataracts are, what surgery involves, the risks and benefits, the likely recovery, and that they may need glasses for some tasks afterwards.

The NHS says cataracts do not usually need treatment straight away. Over time they get worse and you will need surgery if you want to improve your sight. A GP or eye specialist will talk through whether you want surgery, which may depend on how cataracts are affecting daily life and whether one or both eyes are affected. Using stronger glasses and brighter light for reading may help for a while.

NICE advises that the decision to refer should rest on a discussion covering how the cataract affects vision and quality of life, whether one or both eyes are involved, what surgery involves, how quality of life may be affected if you choose not to have it, and whether you want it. NICE also says access to cataract surgery should not be restricted on the basis of visual acuity. The NHS adds that if you decide to have surgery there may be a wait, and that you should ask your eye specialist how long.

The NHS says surgery is done in hospital, usually under local anaesthetic, given as drops, an injection or both. You are awake but should not feel pain, and you are unlikely to see detail of what is happening. Drops widen the pupil, the eye is cleaned and covered with a sterile sheet, and the surgeon makes a tiny hole through the front of the eye. Ultrasound may be used to break up the lens, which is removed with suction, and a clear plastic lens is placed in the lens capsule. The NHS gives the usual operating time as 20 to 45 minutes. Moorfields gives an average of about 20 minutes.

You do not usually need stitches, the NHS says, and you should be able to go home the same day, but you should not drive yourself home. If both eyes have cataracts they are treated on separate days. NICE says to consider bilateral simultaneous surgery only for certain people, for example those at low risk of eye complications or who need general anaesthesia that carries increased risk.

According to the NHS, most people recover quickly. Vision may be blurry for a few hours because of the dilating drops, the eye may hurt for a few days, it may take several days for vision to improve, and you may feel more tired than usual for a few days. You will be given eye drops to help healing and prevent infection, usually for about 4 weeks, and you may need a plastic shield at night. You may still need glasses for reading or distance, with a prescription that can differ from before.

The NHS advises not rubbing the eye, not driving until your vision is back to normal, avoiding heavy lifting and sport, eye make-up, getting water in the eye and swimming, even with goggles, and wearing sunglasses if lights seem brighter than normal.

The NHS says serious complications are rare. Possible complications include vision problems such as cloudiness or dark shadows, and eye problems such as detached retina, infection, bleeding, inflammation or a problem with the position of the new lens. Some need further surgery. Sometimes vision becomes cloudy months or years later, which may be posterior capsule opacification, and the NHS says to go to an optician if your vision becomes cloudy or blurry.

Moorfields gives figures in its patient video: visual outcomes are excellent in over 90 per cent of cases; around one in a thousand people may have a problem that significantly or permanently reduces vision; one in a hundred may need further surgery for a complication at the time; and for around one in ten the lens capsule may become hazy, which it says is treated with a simple laser procedure. These are one hospital's figures and individual risk varies. NICE asks clinicians to discuss each person's own risk, for example the risk of retinal detachment in people with high short-sightedness.

The NHS says you may still be able to drive if your vision is good enough, and that you must tell the DVLA if your eyesight does not meet the minimum standards for driving. An optician can advise if you are unsure. It notes that without treatment cataracts will eventually cause sight loss.