What is cataract?
A cataract is simply a clouding of the tissue that makes up the lens of the eye. It is not a ‘skin’ growth over the eye as is often thought. It is a common condition that affects many people over the age of about 60 and it is readily treatable in the vast majority of cases.
What causes cataracts?
The exact cause of cataracts forming in the lens is not known. There is some evidence that environmental and lifestyle factors can have an influence as can previous eye surgery for other conditions such as glaucoma (although the surgery doesn’t cause the cataract, rather it may speed up the development of an existing cataract). Age is usually thought to be the most important factor as most cataracts develop in people as they become older. Many people over the age of 50 have some early signs of cataract in their lens, but this does not usually become noticeable or symptomatic until older age.
There are forms of cataract that are related to the treatment of other conditions such as diabetes and cataracts can be present at birth – congenital cataracts, but in many such cases the final cause is not known.
Sometimes, young people get cataracts (even children) which, in this situation, may be connected to other conditions and are not an ageing phenomenon. Prolonged and unsupervised use of topical or systemic steriods can cause cataract and, of course, can also cause glaucoma.
What are the symptoms of cataract?
As we have already seen, the lens is part of the focussing mechanism of the eye, i.e. it works with the cornea to focus a clear image onto the light sensitive layer at the back of the eye (the retina). In order for the lens to provide a clear image it must itself be clear, but if a cataract exists it becomes progressively more cloudy and this loss of clarity in the lens causes various symptoms.
There are three main symptoms of cataract, blurred vision, excessive glare (for example from sunlight or from oncoming car headlamps) and reduced contrast or colour vision, so blacks may look grey and colours become dull. Because these changes happen slowly, they may not be noticeable until quite a late stage (especially the dullness of colours), simply because we tend to get used to things and adjust our expectations naturally.
It is however, important to remember that all of the above symptoms can also be symptoms of other more serious eye conditions, so if you notice any of the above, it is very worthwhile to see an optometrist or other eye specialist in order to be sure of the cause.
The vast majority of cataracts are first detected during a routine examination for glasses by an optometrist. The patient may have noticed some of the symptoms of cataract, or may simply have felt that their glasses were scratched or no longer of the correct prescription.
The detection itself does not require any tests that are additional to the normal sight test, but the news that a cataract is present or that it may be causing some visual problems can be worrying.
The first thing to know about cataract is that it does not harm the eye until very advanced, so that most cataracts may be left alone safely if symptoms are minimal or if there is great concern about risks of an operation. The treatment for symptomatic cataracts is the surgical removal of the old cloudy lens material and the replacement of the lens with an intraocular lens implant (made of clear plastic, this lens lasts for a lifetime). The modern procedure is relatively quick and very reliable and is the most common operation performed in hospital eye departments across the country.
It is no longer necessary to wait until the vision has become very poor (in the past this used to be referred to as the cataract becoming ‘ripe’) before an operation is recommended and surgery is usually offered as soon as a person’s vision has become troublesome or is affecting daily life. It may also be performed in order to ensure that a person remains within the visual standard required for safe driving, or if it is necessary to monitor conditions at the back of the eye (such as glaucoma or diabetes), as advanced cataracts may reduce the view of the retina or optic nerve.
Before the operation the eye will be checked in order to establish the strength of the lens that will need to be implanted (biometry) and also to ensure that there are no other complicating factors or conditions present (this is known as the pre-operative assessment).
The operation itself usually takes between 20 and 30 minutes and most people have a local anaesthetic so that they are awake throughout the procedure. If you want, the surgeon will let you know what is happening at all times during the operation, but even though you will be awake, you won’t feel any pain (because of the anaesthetic) and you won’t be able to see what the surgeon is doing. It is possible to request a general anaesthetic for the operation, but recovery from a general anaesthetic takes much longer and there are more inherent risks. Stitches are only occasionally necessary to close the operation site.
After the operation you may have a shield and pad put over the eye to prevent any accidental bumps or knocks and you will have drops to put into the eye for up to about a month in order to prevent any infection and to control any inflammation. Most people who have a local anaesthetic can go home on the same day as the operation.
Shortly after the operation (hours to days later) almost everyone notices a rapid improvement in the vision of the eye that has had the operation. Colours appear brighter and things are usually seen much more clearly than before. Glasses are likely to be needed for reading and close work, but the distance vision is usually very good indeed.
After the operation you will need to be careful about lifting heavy items (for a week or so), rubbing or knocking the eye (particularly when you are asleep) getting dust or other foreign bodies in the eye (on a windy day perhaps) and you should avoid swimming for about 2-4 weeks, but once everything is fully healed, then life should return completely to normal.