Strabismus Surgery

Each eye is moved by six muscles that attach to its outer wall, and the brain coordinates them so both eyes look at the same target. In strabismus this balance is lost and one eye turns. Surgery changes where a muscle attaches or how much it pulls. Moving a muscle further back on the eye, called a recession, weakens its pull; shortening or folding a muscle, called a resection or plication, strengthens it. Often a muscle on each side of the eye is adjusted, and sometimes both eyes are operated on even when only one appears to turn, because the aim is a balanced system. The muscles are reached through a small opening in the conjunctiva, the thin clear skin covering the white of the eye, and the eye stays in its socket throughout. Dissolving stitches are used, so there is nothing to remove afterwards.

In children, an inturning eye that appears in the first months of life, an outward drift that becomes more frequent and squints that do not fully straighten with glasses are common reasons for surgery. A squint can lead to amblyopia, often called lazy eye, so treatment usually starts with glasses and patching to build vision in the weaker eye, and surgery follows to align the eyes. Surgery does not replace glasses or treat amblyopia itself. In adults, reasons include a childhood squint that has returned or was never corrected, double vision after a nerve palsy, stroke or head injury, misalignment from thyroid eye disease and squints after retinal or other eye surgery. A squint that appears suddenly in a child or an adult needs prompt medical assessment first, because it can be the sign of a condition elsewhere that must be investigated before any eye muscle surgery is planned.

Children have a general anaesthetic, and most adults do too, although some adult procedures and the later adjustment of stitches use numbing drops or a local injection. The surgeon opens the conjunctiva, hooks the muscle, places stitches through it and reattaches it at a carefully measured position, then closes the surface with fine dissolving stitches. The amount of movement is planned from detailed measurements of the squint taken before surgery. In adults, and occasionally in older children, the surgeon may use adjustable stitches: the muscle is tied with a temporary knot, and a few hours later or the next morning, once you are awake and can look at targets, the alignment is checked and the stitch is tightened or loosened before being fixed. This allows fine-tuning based on how your eyes actually work together. The operation takes about 30 minutes for one muscle and up to 90 minutes for several, and most people go home the same day.

Before surgery, an orthoptist and an eye surgeon measure the squint in different directions of gaze, at near and distance, test vision in each eye and check how the eyes work together. Several visits may be needed in children, because the measurement must be stable before surgery is planned. Adults with double vision have their fields of single vision mapped, and a test with prisms may show what alignment is realistic. Previous eye operations, thyroid disease and any nerve palsy are reviewed, and a palsy is usually given several months to recover on its own before surgery is considered. Bring old glasses prescriptions, orthoptic reports and photographs that show the squint over time. A routine check confirms fitness for anaesthesia, and children need the usual fasting before a general anaesthetic. Discuss expectations openly: surgery improves alignment, but it cannot always give perfect single vision in every direction.

After surgery the eye looks red and feels scratchy, as though something is in it, and may water. Simple painkillers and lubricating, antibiotic and steroid drops for about 2 to 4 weeks help. Most of the redness fades within 2 weeks, although a patch over the reattached muscle can stay pink for several weeks. Children usually return to school and adults to work within about a week, and swimming should be avoided for about 2 weeks. Some people notice double vision in the first days or weeks as the brain adjusts to the new position; this usually fades. For travel, plan to stay about 3 to 7 days, long enough for any stitch adjustment and the first check of alignment and healing. Flying does not affect the eye after strabismus surgery. Back home, an orthoptist or eye specialist reviews the alignment at about 6 weeks, and glasses and patching continue for children as advised.

Strabismus surgery is a common operation with a low rate of serious problems. The main limit is precision: the eyes may end up slightly under or over corrected, and alignment can drift over months or years, so a second operation is needed in some people, particularly after complex squints, previous surgery or thyroid eye disease. New or persistent double vision can occur, especially in adults, and is usually temporary but occasionally needs prisms or further treatment. Less common risks include infection, a cyst or scar on the eye surface, a muscle that slips from its new position and, rarely, a puncture of the eye wall by a stitch or reduced blood supply to the front of the eye when several muscles are operated on. Most people are left with straighter eyes, better comfort and often better use of both eyes together, and adults frequently report more confidence in eye contact.