Consent before strabismus (squint) surgery

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What is this information about?

This information is about the possible risks and complications that might happen during strabismus surgery, or after the surgery. It explains what they are, and how likely they are to happen. 

Why have I been given this information?

You have been given this information because you are going to have strabismus surgery. As with any operation, there are risks as well as benefits, so it important to read through this information and ask questions if you are not sure about anything. 

Consenting for your Operation

This leaflet gives you information you should know before agreeing to have surgery to correct strabismus (squint). We encourage you to read this and ask any questions before signing the consent form on the day of your surgery.  

What are the benefits of this surgery?

• To improve how the strabismus looks, with glasses if worn.  
• If you have double vision, to reduce how often it happens, and how severe it is. 
• To improve the control that you have over the strabismus.  
• To help the eyes to work together as a pair. 

Not all of these problems apply to you. You will be able to discuss this with your surgeon.  

What are the risks of this surgery?

As with every operation, strabismus surgery has risks.

• All serious complications are rare.  
• The main risk is the possibility that the surgery may over-correct or under-correct your strabismus. This may mean you need further surgery. This may be soon after the original surgery, or many years afterwards. 90% of people have a good outcome after one operation. 
• The operation may give you double vision. This may occur as the brain adjusts to the new position of the eyes. This often settles over days to weeks. If it is permanent other treatment may be necessary. 
• Blurred vision, itchiness and redness is normal immediately after surgery and settles. 

What are the possible complications during the operation?

These are all very rare: 

• One of the eye muscles may slip and be difficult to find during surgery.  
• One of the sharp instruments used during the surgery may pierce the wall of the eye. This is called ‘globe perforation’. The risk of this is 0.1% or 1 per 1000* people. If this happens, you may need antibiotics or laser treatment. Depending on where the perforation is, your eyesight could be affected. 
• An incorrect muscle may be operated on.  
• It may not be possible to perform as much surgery as is needed because you have already had the maximum amount of surgery you can have in a previous operation.  

What are the complications after the operation?

• Over- or under-correction of the squint.  
• Double vision which does not settle within a few weeks.  
• Inflammation or infection of the eyeball. This is called scleritis, and would need extra medicine to treat. 
• Damage to the sight of the eye. This can happen because of a detached retina or infection in the eye. This is called Endophthalmitis, and the risk of this is 0.05% or 1 patient per 2000*. 
• A cyst forming at the site of dissolvable sutures (stitches).  
• ‘Slipped muscle’. This means that the eye is in a good position after surgery, but then suddenly worsens again in the days following surgery. (0.09% or 1 patient per 1100*). More surgery may be needed but sometimes it is not possible to correct this. 
• Anterior Segment Ischaemia (reduced blood flow to the front of the eye). This is a risk if you have had lots of other operations for strabismus or an increasing number of muscles being operated on in one eye. 
• Overall serious risks occur in 0.3% or 3 patients per 1000* 

(*according to the British Ophthalmic surveillance unit) 

Alternatives to surgery

Alternatives are available to some patients such as prisms in glasses, regular botulinum toxin injections or use of a special patch or contact lens to block the vision in one eye.

These can be discussed with your orthoptist or ophthalmologist (specialist eye doctors).

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