Do you want to see specific content for your country or region? Continue This link opens in a new tab

What does the treatment involve?

Strabismus surgery is performed on the extraocular muscles, which are the muscles that control the movement of the eyeball. Contraction of these muscles allows the eye to “rotate” on its 3 axes of space. The extraocular muscles work as an antagonistic pair, meaning that when one contracts, the other relaxes to allow movement.

When is this treatment indicated?

In children, when optical deviation persists, despite attempted ocular correction (glasses or contact lenses) and treatment for lazy eye and depending on the severity, surgical intervention is advised to prevent amblyopia and restore binocular vision where possible.

In adulthood, operating on strabismus causing diplopia (double vision), torticollis, visual fatigue or cosmetic defect and/or that has a psychological impact on the patient’s quality of life is advised.

It is worth emphasising that, when strabismus appears suddenly in an adult, it is imperative to perform a thorough examination of the patient to rule out any underlying pathology (neurological issues, trauma, tumours…) before deciding on surgical intervention.

In the case of mild optical deviation, there are alternative therapeutic treatments available such as botulinum toxin (Botox), eye exercises and prism lenses.

How is it performed?

During surgery, the ophthalmologist makes a small incision in the tissue covering the anterior segment of the eye (conjunctiva and sub-tenon) in order to access the muscles.

Depending on the direction of the deviation, the muscle traction is adjusted to achieve maximum eye alignment. There are different techniques to either strengthen or weaken a muscle, but the most common method of “weakening” the muscle is reattaching it to a point closer to the back of the eye, so that it is “more relaxed” and therefore “pulls” less.

If the objective is to strengthen the muscle, it is common practice to shorten the muscle so that it becomes “tenser” and therefore “pulls” more. The number of muscles that need to be operated on will depend on the type of strabismus and the patient characteristics (age, vision in each eye, surgical history etc.).

Surgery could be required on one or both eyes and in one or more stages. Twenty to thirty percent of cases require more than one intervention throughout the patient’s life.

Surgery will be performed on children under general anaesthesia, owing to their young age. While for adults, using local anaesthesia is an option. In both cases, the surgery is an outpatient procedure, meaning the patient can go home on the same day.


In the postoperative phase patients will experience red eye, watering and mild irritation for 3-4 weeks and will have to apply physiological saline solution as well as an antibiotic and anti-inflammatory eye wash for approximately 20 days.

The application of dressings will not be necessary, nor will the removal of sutures, since absorbable sutures are used which will dissolve in 7-10 days. Although the complexity of each case should be taken into account, in general, the patient will be able to resume normal daily activity after a few days, provided they avoid more strenuous activity, high-impact sports and swimming. In the case of younger children, a period of 15 days off school, is often necessary after surgery.

The objective of strabismus surgery is not limited to correcting ocular alignment and binocular cooperation, but is also to eliminate or reduce diplopia (double vision), correct instances of persistent tilting of the head (torticollis), reduce visual fatigue and improve the cosmetic look and quality of life of the patient.

It is important to bear in mind that a percentage of patients will require more than one surgical intervention.

Possible risks

As with any invasive surgery, strabismus surgery is not risk-free. Although uncommon given the nature of the extraocular surgical approach, these risks must be highlighted.

Intraoperative: risks inherent in anaesthesia, haemorrhage, scleral perforation and difficulty isolating the muscles during reintervention.

Postoperative: infection, cysts and conjunctival scars, allergic reaction to stitching, undercorrection or overcorrection (unsatisfactory eye alignment), diplopia (double vision).

The majority of these complications can be corrected through medical treatment, however, in some instances, surgical reintervention is required.


Professionals who perform this treatment

Frequently asked questions

  • This depends on each particular case, the type of strabismus, the vision in each eye, your eye surgery history and any underlying pathology… Approximately 30-40% of patients who undergo strabismus surgery will require more than one operation. The reason this figure is so high is because, in the majority of cases, the brain of the strabismus patient does not have the capacity for binocular vision (the ability to maintain visual focus with both eyes), which is a contributing factor to correct eye alignment.

  • It is never too late for strabismus surgery. The success rate of an adult is the same as that of a child. Intervention can achieve better symmetry in the eyes and therefore improve the patient’s cosmetic appearance and quality of life. It is important to bear in mind, however, in the case of lazy eye, surgery will not improve vision, since the period for optimum visual development is from birth up to approximately age 8-9. Eyesight that hasn’t fully developed in childhood cannot be restored in adulthood.

  • That will depend on the where the patient works and on the complexity of each particular case (if surgery was on one or both eyes, surgical history, how many muscles were operated on, the patient’s age…) but in general, postoperative discomfort is mild and the sutures used dissolve, so after approximately 15 days, the patient will be able to gradually return to their normal working routine. It will take at least 1 month for the redness and irritation to completely subside.