Cataracts

Reviewed by Dr Caroline MacEwen, consultant ophthamologist

What are cataracts?

The word 'cataract' is used to describe any opacity or reduction in clarity of the lens of the eye. This can mean anything from mild cloudiness of the lens to complete opacification.

Most people over the age of 50 have some haziness over the lens and the situation only becomes relevant if the lens opacity is interfering with vision.

Cataract is the most common cause of blindness in the world today. It is, however, treatable with highly effective surgery and cataract removal is the most common operation carried out in the UK today.

How do cataracts develop?

The most common reason for cataracts to develop is increasing age. As people grow older, the lens of the eye becomes less clear until, ultimately, a cataract that causes reduction in vision is present. (Lens opacities actually occur to some degree in around 75 per cent of people aged over the age of 65, but most of these do not need any kind of treatment.)

Cataracts are slightly more common in people with diabetes, in people who take corticosteroid tablets (particularly for long periods of time), in those who have suffered a significant injury to the eye, in those with a family history of cataract or previous inflammation within the eye.

Very rarely, children are born with congenital cataracts. All babies are examined within the first few days of life to ensure that they do not have a cataract. This is usually done by the paediatrician who examines babies before they leave hospital.

What are the symptoms of cataracts?

There are various different types of cataract.

A nuclear cataract causes gradual reduction in vision. It may lead to changes in the spectacle correction for the eye such that new glasses are needed frequently, even up to every few weeks.

A cortical cataract may give rise to poor vision associated with seeing haloes around lights or seeing things double with one eye.

Posterior subcapsular lens opacities tend to cause reduction in vision - especially for reading, susceptibility to bright lights and glare.

These types of cataract are not exclusive and may all occur in the same eye causing all the above symptoms.

If cataract is present in only one eye, then there may be no symptoms at all as the patient can see well with the other unaffected eye.

What can be done to avoid cataracts?

Cataracts are, generally, part of the ageing process but anyone who suffers from diabetes or takes steroid tablets should be aware that they may be at increased risk of developing early cataract.

It has been suggested that too much sunlight may make people more susceptible to cataracts so good quality sunglasses should be worn in bright sunlight.

How does the doctor make a diagnosis?

The most important aspect of cataract is how much it is affecting your vision.

A full examination of the eyes will take place involving checking the level of vision and ensuring that the best spectacle correction is being worn.

The pupil of the eye will be dilated and the lens examined under magnification.

The rest of the eye will also be examined to ensure that there is no other reason for the vision to be reduced or affected.

Anyone who feels that their vision is deteriorating or that they are suffering from any of the symptoms above, should visit their optometrist (optician) who will be able to ensure that they are wearing the best possible glasses. They will be able to advise whether the cataract may be ready for referral to an ophthalmologist (eye surgeon).

How are cataracts treated?

There are no drops or tablets that will treat cataracts. The only method of improving vision is to have the cataract removed surgically.

When will my cataract be ready for surgery?

In the past, doctors used to wait for a cataract to 'ripen', but this is no longer the case.

Anyone who has a cataract that is giving rise to problems should be considered for cataract surgery. Everyone has different demands on their eyesight and the decision has to be made on an individual basis.

If you wish to continue driving, and your vision is not up to the standard required to drive, then surgery is sometimes needed in order to retain a driving licence.

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