The initial assessment will involve an orthoptist assessment and a medical consultation. The orthoptist will measure the visual function and eye motility with cover testing and prisms. He will also test the patient’s ability to use the eyes together, called binocular vision, the amount of stereopsis, and whether the patient has a lazy eye. This is followed by a medical consultation.
The consultant will use the results of the orthoptist assessment and provide the patient with a more detailed assessment by taking the necessary eye measurements to diagnose the type of strabismus. Then the consultant will decide whether neurological opinion or further investigations are required before the surgery is considered. After this the consultant explains the type of surgery and its benefits and risks, or whether there is a non-surgical alternative. Depending on the outcome of the assessment and the opinion of the consultant the treatment options can be glasses, prisms or injection of botulinum toxin into one of the tiny eye muscles.
The surgery is done as a day case under general anaesthesia and usually takes an hour if two muscles are being operated on. One or more muscles are delicately moved in relation to the eye and tiny stitches reattach the muscles. In some cases ‘adjustable sutures’ are used which allows a following small refinement under local anaesthetic, usually a couple of hours after the procedure. If there is no need for correction, the suture is hidden and is dissolvable. So it disappears after a few weeks.
After squint surgery, there are antibiotic steroid drops to use for the first 4 weeks. There is a first follow-up visit during that time, to check the healing. At the post-operative orthoptic assessment, we check with measurements the improvement. We usually require three follow-up visits at week 1, 4 and 12.
Surgery carries a success rate of around 80%. Some patients (less than 10%) need further surgery, dependent on what they have already had done.