If you have a private operation planned, it may involve an anaesthetic procedure, in this instance an eye nerve block. You may wish to know what this involves.
 
The information here is a guide to common medical practice. Each hospital and doctor will have slightly different ways of doing things, so you should follow their guidance where it is different from the information given here. Because all patients, conditions and treatments vary it cannot cover everything. Use this information when making your treatment choices with your doctors. You should mention any worries you have. Remember that you can ask for more information at any time.

What is the problem?

You have a condition that requires an operation on your eye. It may be better to perform this operation with you awake.

What is an eye nerve block?

An eye nerve block is a way of numbing the eyeball with local anaesthetic for an operation. This allows surgery to be performed without causing pain. The local anaesthetic is first applied using eye drops onto the surface of the eye. You then have injections of local anaesthetic around but not into the eyeball. The local anaesthetic fills the eye socket and runs onto the nerves that supply the eye. Nothing is injected into the nerves. In addition to making the eye numb it often causes temporary paralysis of the eye muscles. This stops the eyeball moving and helps the surgeon carry out the operation.

Local anaesthetic eye blocks are used instead of a general anaesthetic for many eye operations. The block can be used with a general anaesthetic. This reduces the amount of general anaesthetic needed. It also reduces the amount of painkillers needed after the operation. The majority of cataract operations, for example, will be performed under local anaesthetic eye block with the patient awake.

The aims

The aim is that you feel no pain during the operation. The local anaesthetic block will provide pain relief during the operation and for several hours afterwards. Your anaesthetist will talk to you before doing the block and explain whether you will be awake, asleep (general anaesthetic) or sedated during the operation. 

The benefits

There are a number of benefits. You may have serious medical conditions, such as heart or lung disease. In this case a general anaesthetic may have slightly more risk than normal. Doing the local anaesthetic block, instead of using a general anaesthetic, will cause less stress to your medical condition. It will be safer for you.

It is common to perform a local anaesthetic nerve block with a general anaesthetic. This gives excellent pain relief both during and after surgery. This means that the anaesthetist does not need to give as much general anaesthetic or strong painkillers. This means a faster recovery and less sickness after the operation.

Are there any alternatives?

There is really only one alternative to an eye block. That is a general anaesthetic (GA), where you are put to sleep for the operation.

If you do not want to stay awake for the operation you can have a general anaesthetic and a local anaesthetic eye block. This would still give you the pain relief benefits after the operation. You would need to discuss this with your anaesthetist. There may be a reason that you may not be able to have a GA.

You can have a general anaesthetic without the eye block. In this case other strong painkillers, such as morphine can be given to keep you comfortable when you wake up.

Who should have it done?

Patients needing surgery on the eye can have this type of block for their operation.

Who should not have it done?

Each patient has the final decision to proceed or not. If you are unhappy about the procedure for any reason, you should not continue. There are specific medical situations when a local anaesthetic eye block should not be done and they are as follows:

• Medication that prevents your blood from clotting, such as Warfarin; this would lead to more bleeding than normal. Bleeding around the eye is a serious problem and must be avoided.

• An illness that prevents your blood from clotting, such as haemophilia; this would lead to more bleeding around the eye.

• Infection of the skin over the site where the needle needs to be put in; this could lead to further infection in the deeper tissues and possibly blood poisoning. This could also cause infection around the eyes.

• The shape and size of your eyeball can determine whether or not a standard eye block is safe to perform. The eye surgeon will know this before the operation and the method of anaesthetic changed accordingly.

• Unusual or difficult anatomy; this would make it difficult to put the needle in the correct place.

It is important that you can lie flat and still during the operation. You will not be allowed to talk or move your head. A nurse will hold your hand and if you do need to communicate you can signal this by squeezing their hand. A patient who has difficulty lying still can have a sedative drug given into the drip in their hand.

Author: Dr Sean White FRCA. Consultant in pain and anaesthesia

© Dumas Ltd 2006