Definition and Overview

Squint or strabismus surgery is performed on extraocular muscles to correct eye misalignment. In the United States, it is one of the most commonly performed surgical procedures on the eyes.

A squint or strabismus, which affects one in 20 children, is a common eye condition in which the eyes are pointing in different directions, instead of moving and focusing together in the same direction. Squints typically develop before the patient reaches five years old, but there are also cases when the condition develops later in life.

Symptoms of a squint can easily be observed. One of the patient's eyes might turn outwards, inwards, downwards, or upwards, while the other eye looks forward. However, it is important to note that not all squints are constant—there might be instances when the eyes look normal. Minor squints are not obvious and might be misdiagnosed as another condition.

Aside from its effect on an individual’s appearance, a squint can also cause blurred or double vision. If left untreated, the patient can eventually develop amblyopia or lazy eye. Also, the vision in one eye will not develop properly, and as a result, the individual will rely more on the good eye and the brain will ignore signals coming from the eye with the squint.

It is best to have a child’s vision checked regularly. Newborn babies will occasionally cross their eyes when they are tired, but this is not normal for babies older than three months.

Some individuals are born with congenital squints, but there are also some other cases when the individual acquires the condition later in life. Acquired squints often develop when the affected eye is trying to overcome refractive errors, including myopia (short-sightedness), hyperopia (long-sightedness), and astigmatism (where the cornea is unevenly curved, resulting in blurred vision).

Childhood illnesses like measles, genetic conditions such as cerebral palsy and Down’s syndrome, hydrocephalus, and other conditions affecting the eye muscles or the retina can also result to a squint.

Squint surgery is not the first type of treatment recommended to patients. Individuals diagnosed with the condition are often given prescription glasses, which should be constantly worn to correct refractive errors. Eye exercises can also be provided to help the eyes work together. Recently, doctors have been prescribing a less invasive treatment that involves botulinum (or Botox) injections to the patient’s eye muscles. This substance weakens the muscles, allowing for proper alignment of the eyes for approximately three months.

Who Should Undergo and Expected Results

If other treatments described above do not work, patients can undergo a corrective squint surgery. It is best to have this surgical procedure performed upon the diagnosis of strabismus—especially in young children—to prevent further complications from developing.

Squint surgery can improve the alignment of the eyes and thus improves the patient's appearance. It can also prevent the development of eyesight complications in the future and enable the eyes to work together properly.

How is the Procedure Performed?

Prior to the procedure, standard diagnostic tests such as slit lamp and motility exams are performed. Specialised testings such as forced ductions, force generation, and saccadic velocities can distinguish excessive scarring, lost or slipped muscles, and fat adherence. Pupillary reactions are also assessed and a dilated exam performed to determine the presence of other retinal or vitreal problems that may require additional treatment. Based on the diagnosis, the condition can be managed with optical treatments, (such as a change in refraction), medical treatment (which may involve the use of corticosteroids and anti-inflammatory medications) and surgical treatment (which may involve the release of scar tissue, excisional biopsies, and treatment of retinovitreal disorders).

If squint surgery is deemed to be the most appropriate treatment, the patient is scheduled for the surgery, which is often performed in a hospital, though there are some specialised eye clinics that are fully equipped to offer this kind of surgical procedure. Squint surgery is performed under general anaesthetic and often as an outpatient procedure, which means that the patient can go home the same day.

Once the patient is properly anaesthetised, the affected eye will be held open with a lid speculum. Using a small, precise scalpel, the doctor will detach a part of the muscle connected to the eye moving it backwards to weaken the pulling effect that causes the squint. The muscle can also be shortened and tightened to increase the pulling effect, depending on the need.

The surgeon then proceeds by suturing the eye muscles back in place. Dissolvable stitches are used for this procedure, which means that the patient does not have to return within seven days for their removal.

Recovery from corrective squint surgery can take up to several weeks. The doctor will prescribe pain medication to help with the soreness of the eyes. After the procedure, patients can immediately return to daily activities such as reading once they feel that they are able to perform the task. It is important to get the patient’s eyes working normally as soon as possible.

Possible Risks and Complications

Squint surgery has various risks and complications although most of them rarely occur. These include:

  • Double vision, which usually goes away a week after the procedure
  • Eye infection
  • Excessive bleeding
  • Perforation of the eye and nearby structures
  • Change in refraction, which is managed through optical therapy
  • Allergic reaction to the anaesthetic, suture material, or post-operative medications
  • Conjunctival scarring
  • Anterior segment ischemia, which occurs when the procedure resulted in impaired blood flow to the anterior segment
  • Ptosis on the vertical rectus muscles

Post-operative complications are typically managed with medical therapy. Topical and systemic antibiotics are used to treat post-operative infection and antibiotic eye drops for allergies. Patients are closely monitored following the procedure to ensure that complications do not arise.


  • Engel JM (September 2012). "Adjustable sutures: an update". Current Opinion in Ophthalmology 23 (5): 373–6.

  • Kushner, Burton J. (2014). "The Benefits, Risks, and Efficacy of Strabismus Surgery in Adults". Optometry and Vision Science 91 (5): e102–e109.

  • Wright, Kenneth W.; Thompson, Lisa S.; Strube, Yi Ning; Coats, David K. (August 2014). "Novel strabismus surgical techniques—not the standard stuff". Journal of American Association for Pediatric Ophthalmology and Strabismus (JAAPOS) 18 (4): e47

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