Strabismus surgery is an operation that repositions the muscles controlling eye movement to correct misaligned eyes. It is the most common eye muscle surgery performed on both children and adults, and it’s typically done as an outpatient procedure, meaning you go home the same day. The goal is to realign the eyes so they point in the same direction, which can restore binocular vision, eliminate double vision, and improve appearance.
Why the Surgery Is Performed
Strabismus, commonly called crossed eyes or wall eyes, happens when the six small muscles that control each eye’s movement don’t work together properly. One eye may turn inward, outward, upward, or downward while the other looks straight ahead. This misalignment can cause double vision in adults, and in children it can lead to amblyopia (lazy eye), where the brain starts ignoring input from the turned eye.
Surgery becomes an option when nonsurgical treatments like glasses, prism lenses, or vision therapy haven’t corrected the alignment. The primary aim is restoring proper ocular alignment. Secondary goals include treating amblyopia, maintaining the ability to use both eyes together, and eliminating double vision. For adults with long-standing strabismus, the surgery may be largely cosmetic, improving how the eyes look even if binocular vision can’t be fully restored. For children, early alignment gives the visual system the best chance of developing normal depth perception.
How the Surgery Works
The surgeon operates on the muscles attached to the outside of the eyeball, not on the inside of the eye itself. A small incision is made in the thin tissue covering the white of the eye (the conjunctiva) to access the muscle underneath. Depending on which direction the eye needs to move, one of two main techniques is used.
Recession weakens a muscle by detaching it from the eye and reattaching it to a point farther toward the back of the eye. Because the muscle now pulls from a more distant position, it exerts less force. Resection strengthens a muscle by removing a small section to shorten it, which increases its pulling power. In many cases, both techniques are used during the same operation: one muscle is weakened while the opposing muscle is strengthened to shift the eye into proper alignment.
Before surgery, your eye alignment is carefully measured using a prism and cover test. Prisms of varying strengths are held in front of the eye while the examiner watches how the eye responds, pinpointing the exact degree of misalignment. Some clinics also use a prism adaptation test, where you wear prism glasses for at least an hour so the surgeon can identify the maximum angle of deviation and plan the precise amount of muscle adjustment needed.
Adjustable Sutures
In some cases, particularly for adults, the surgeon uses adjustable sutures instead of tying the muscle permanently in place during the initial procedure. The muscle is secured with a temporary or sliding knot. After you’ve recovered from anesthesia and are alert enough to cooperate, the surgeon checks your eye alignment and fine-tunes it by shortening or lengthening the suture.
This adjustment typically happens one to two hours after surgery, though it can be done anytime within the first 24 hours. Some newer techniques extend this window up to 14 days. Adjustable sutures give the surgeon a second chance to optimize alignment while you’re awake and able to look at a target, which can be especially helpful for complex cases or reoperations.
Anesthesia and What to Expect on Surgery Day
Children almost always receive general anesthesia. Adults have more options: general anesthesia works for all age groups and is standard for bilateral or complicated procedures, but some adults can have the surgery under a regional nerve block (which numbs the area around the eye) or even topical anesthesia with numbing drops for straightforward single-muscle operations. Regional blocks reduce certain reflexes during surgery and provide pain relief afterward, though you’ll feel some pressure and need to stay still.
The procedure itself usually takes between 30 and 90 minutes depending on how many muscles need adjustment. Nausea and vomiting are common side effects of eye muscle surgery, especially in children, so preventive anti-nausea medication is typically given during the procedure. Pain afterward is managed with a combination of standard pain relievers and topical numbing drops, keeping opioid use to a minimum.
Recovery Timeline
Most people experience soreness, redness, and a gritty sensation in the eye for the first few days. Mild swelling of the tissue over the white of the eye (chemosis) occurs to some degree in everyone, though it’s rarely severe. The redness can last several weeks and is most noticeable when you look to the side where the surgery was performed.
You can generally return to light daily activities within a few days. Swimming and submerging your eyes in water should be avoided for several weeks to prevent infection while the conjunctival incision heals. Contact sports are off limits for a similar period. Many adults return to desk work within a week, though some experience intermittent double vision during the early recovery period as the brain adjusts to the new eye position. Children tend to bounce back faster than adults in terms of comfort.
Success Rates and Repeat Surgery
A successful outcome is defined as residual misalignment of 10 prism diopters or less at six weeks after surgery, which translates to an alignment close enough that the eyes appear straight and binocular vision can function. By this standard, roughly 60% or more reduction in the overall deviation is considered a good result. To achieve true stereoscopic depth perception, the residual deviation needs to be even smaller, around 4 prism diopters or less.
In a large study of over 11,000 children who underwent strabismus surgery, 7.7% needed a second operation. The reoperation rate was lower for horizontal muscle surgery (6.7%) and higher for vertical muscle surgery (11%). These numbers reflect the reality that eye alignment can drift over time as the muscles heal and adapt, and some cases are inherently more complex. Adjustable suture surgeries had a slightly higher reoperation rate of 9.6%, likely because they tend to be used in more difficult cases rather than because the technique itself is less effective.
Risks and Complications
Strabismus surgery is considered safe, but like any procedure it carries risks. The most common complications are minor. Small corneal depressions called dellen can form near the surgical site, particularly after resection procedures, but they typically resolve with lubricating drops. Pyogenic granulomas, fleshy red bumps at the incision site, occasionally develop but usually go away on their own.
More serious complications are rare. Scleral perforation, where the needle passes through the thin wall of the eye, has been reported in roughly 5% of cases in one prospective study, though most perforations are recognized and managed immediately without long-term consequences. Serious infection (endophthalmitis or orbital cellulitis) is exceptionally uncommon, with endophthalmitis estimated at roughly 1 in 18,500 cases or fewer. Most strabismus surgeons will see only one or two such infections in an entire career.
Anterior segment ischemia is a rare but potentially sight-threatening complication that occurs when surgery disrupts blood flow to the front of the eye. Risk factors include older age, diabetes, high blood pressure, previous eye muscle surgery, and operating on three or more muscles at once. Surgeons plan staged procedures when multiple muscles need work to reduce this risk.
For patients over age seven, a postoperative diplopia test is performed before surgery. Prisms are placed in front of the deviating eye to simulate the corrected position. If the brain suppresses the image from one eye, the risk of troublesome double vision after surgery is low. If double vision persists during the test, the surgeon may use a diagnostic injection of botulinum toxin to further evaluate before committing to surgery.
Botulinum Toxin as an Alternative
Injecting botulinum toxin (Botox) directly into an overactive eye muscle can temporarily weaken it, allowing the eye to shift toward better alignment without surgery. This approach is used for several specific situations: recovering nerve palsies where alignment may improve on its own, fine-tuning under-corrections or over-corrections after surgery, small deviations, and cases where general anesthesia poses a risk.
The injection is less invasive, but it’s also less reliable for permanent correction. A Cochrane review of four studies comparing the two approaches found that surgery was more likely to achieve successful alignment than botulinum toxin. The reoperation rate after botulinum injection in children was 44.9%, compared to 7.4% for traditional surgery, reflecting the temporary nature of the toxin’s effect. Botulinum toxin remains a valuable diagnostic and therapeutic tool, but for most people with stable, significant misalignment, surgery offers a more durable result.