When Is Surgery Needed

When is cataract surgery needed?

This section provides more information about the timing of cataract surgery. It expands on the brief explanation given on the previous page.

To Recap:

The timing of a cataract operation should be tailored to the individual patients vision requirements.

The timing of cataract surgery will depend on such factors as:

• Whether the patient needs to see to drive.
• The visual requirements of the patient's occupation.
• The visual requirements of the patients hobbies and past times.
• Whether the patient can see well enough to safely care for themselves.
• Whether or not the patient is bothered by the cataract.

In other words to what degree the cataract is interfering with the individuals life and enjoyment of it.

It is not necessary to wait until the cataract is 'ripe' before surgery can be performed. This is an outdated concept that no longer applies. It used to mean that the cataract was not removed until it was mature or fully developed. In other words that the cataract was left until the affected eye was pretty well completely blind. In a past era when surgical techniques were rather crude and the risks of surgery relatively high this might have been an appropriate approach. This is certainly no longer the case.

As a general rule it is no more technically difficult to remove a mild cataract than a more advanced one. There are exceptions to this but hopefully the eye specialist will be able to inform the patient if there are medical factors that influence the optimal timing of surgery.

In the end the decision to opt for surgery or not rests with the patient. It should be their decision although it is often helpful and reassuring to discuss the issues with family and friends. No one should be arm twisted into having cataract surgery. It is though perhaps worth recalling that for most patients cataract develops slowly and there is a creeping compromise to vision. If this occurs simultaneously in both eyes there is only a faded memory of what vision used to be like. The patient may not therefore fully appreciate what they are missing. It is often with amazement and surprise that they realise, after the cataract has been removed, how bright and colourful the world really still is. So if your vision isn't what it used to be because of cataract and there is no particularly good reason not to have it fixed why go on missing out?

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Special Factors

There may be additional factors that need to be taken into account when considering whether or not to remove a cataract.

Other eye disease.

Sometimes cataract is not the only problem within the eye. This may mean that even if the cataract is successfully removed the vision will still not be restored to normal. This may affect the decision on the timing of cataract surgery. It can also be difficult to predict how much visual improvement will be achieved in removing the cataract when other eye disease is present.

In the elderly the most common eye condition that occurs with cataract is Age Related Macular Degeneration. This is a "wearing out" degeneration of the centre of the retina. This causes impairment to central vision. When this condition is present it is usually not worthwhile removing mild cataract as little if any improvement in vision will be gained. However if the cataract is marked it may well be worthwhile removing it. Although the operation may not perfectly restore central vision and the ability to read small print or see faces it may significantly improve peripheral vision.

Cataract surgery may need to be deferred if some other eye disease requires treatment first. One example of this is diabetic retinopathy. In this condition, which affects patients with diabetes, tiny blood vessels within the retina may leak or abnormal blood vessels may grow on the retina and bleed. If these changes are vision threatening then laser treatment to the retina is required. It may be better to perform this laser treatment before the cataract is removed as is some circumstances the disturbance to the eye involved in cataract surgery may make the retina problem worse. On the other hand if the cataract is so dense that it prevents the laser from effectively reaching the retina then the cataract must be removed as soon as possible in order to allow the laser treatment to be performed.

There are some conditions where removing even mild cataract will allow the best use of what vision remains. Retinitis Pigmentosa is one example of this.

Only eye.

If the patient has cataract in their only useful eye then the possibility of surgery must be thought through very carefully. Although the risk of worse vision or loss of vision following surgery is low should a complication occur in a patient with only one eye it could be devastating. It may therefore be wise to leave the cataract longer than would be the case if the patient had two "good" eyes. In other words the threshold for surgery should be higher in one eyed patients.

When a cataract might be harmful

Again as a general rule it is not harmful to the eye to leave a cataract. It just obscures vision and prevents the patient from seeing as well as they might. There are though a few exceptions to this.

If a significant cataract occurs in the eye of a child under the age of 7 years it will interfere with visual development. During these early years of life clear and focused vision stimulates the formation of the nerve connection within the visual part of the brain. If a cataract prevents a clear image from reaching the retina these connections will not be made as fully and extensively as they should. The result will be a lazy eye (called amblyopia). This is an eye that does not see as well as it should because the brain is not able to use the visual information coming to it from the eye. At around the age of 7 to 8 the nerve connections between eye and brain "set" and visual development comes to an end. After this age the missing connections cannot be created and the defective vision cannot be improved upon. (see chapter 6, Children: a special case.).

A cataract may obscure the doctor's view of the back of the eye and prevent the monitoring of some other eye disease. Removal of the cataract may therefore be recommended to overcome this problem.

A cataract may interfere with the fluid circulation within the eye. This can occur if the cataract is allowed to become very mature or large. In a hyper mature cataract the proteins of the lens start to breakdown and leak out into the fluid that surrounds it. This material may then clog up the drainage channels of the eye causing a rise in the pressure within the eye. This is a rare form of glaucoma. If a cataract becomes physically large within a relatively small eye its bulk may also interfere with the fluid circulation within the eye. This can lead to a sudden and very high rise in the pressure within the eye. The eye will then become red and painful. This is called acute angle closure glaucoma. These phenomena are nowadays rare within the UK. If an eye is thought to be at risk of these scenarios then cataract surgery would be necessary even if the eye was blind from some other condition and sight could not be restored. This would be done to prevent the eye from becoming chronically painful and troublesome.

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