Strabismus surgery

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.

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.

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.

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.