Botulinum Toxin (Botox) for squint

Botulinum toxin (Botox) injected into a muscle causes complete or partial weakness of that muscle. Its effects are temporary. The treatment has been used for squint (misaligned eyes) since 1979.

The treatment is safe and there is no significant systemic absorption. With any medication, there is a small potential risk of an allergic reaction (anaphylaxis). However, we have never had anyone experience this problem. There is no known risk for the use of botulinum toxin during pregnancy or breastfeeding, although come women choose to delay their treatment until after pregnancy or after weaning their child.

Several drops of anaesthetic are given into the eye to be injected. The anaesthetic thoroughly numbs the surface of the eye. During the procedure a pressure sensation is felt.

Electrodes are then place on your forehead and temple. The needle is attached to an electric amplifier. Throughout the whole procedure, it is important to keep your head still but you will be asked to move your eyes. You will be first be asked to look away from the muscle to be injected, the needle will be inserted into the muscle. To confirm the correct position of the needle, you will then be asked to look towards the direction of the muscle. Once correct position is confirmed using the electric amplifier, a small amount of the medication will be injected into the muscle. The needle will be held in place for a few seconds before being removed.

The whole procedure takes less than a few minutes and only causes mild discomfort.

To treat children the procedure is performed under a very short general anaesthetic.

Immediately after the injection you will be asked not to rub the eye for at least half an hour. You may request an eye pad to be placed over the eye. You may feel an ache in the eye and a painkiller such as Panadol maybe taken.

You will start to see an effect 2-3 days after the injection.

The effect can vary but usually lasts 3-4 months. You will initially notice a reversal of your squint, followed by a gradual straightening of the eyes as the muscle weakness or paralysis wears off.

Nearly all side effects are temporary and wear off over a few weeks.

You may get double vision as the eyes are closer together and/or the squint is reversed. You may consider patching the eye temporarily to ease the double vision.

If you experience temporary double vision it is important NOT to drive.

Sometimes, adjacent muscles are inadvertently affected (especially if you have had previous surgery). This can cause a droopy eyelid (in 15%) or a vertical shift of the eye. These effects almost always wear off.

Redness or bruising of the eye may occur uncommonly and will get better.

There is the very rare possibility of the needle perforating the eye to cause severe loss of vision (<1/10,000).

You usually will be asked to return to clinic 2 weeks after the injection. If the first injection did not produce an adequate effect, we may offer a repeat injection at that visit.