Strabismus (crossed eyes) is a common eye condition among children. It is when the eyes are not lined up properly and they point in different directions (misaligned). One eye may look straight ahead while the other eye turns in, out, up, or down. The misalignment can shift from one eye to the other.
There are six muscles that attach to each eye and control its movement. One muscle moves the eye to the right, and one muscle moves the eye to the left. The other four muscles move the eye up, down, and at an angle. In order to focus on a single image, all six eye muscles in each eye must work together.
With normal vision, both eyes aim at the same spot. Our brain combines the two images from our eyes into a single, three-dimensional (3-D) image. This is how we can tell how near or far something is from us (called depth perception).
When one eye is out of alignment, each eye sends a different signal to the brain. In a young child, the brain learns to ignore the image of the misaligned eye. Instead, it sees only the image from the straight or better-seeing eye. As a result, depth perception may be affected.
Causes of Strabismus
There are many reasons a child's eyes may point in different directions. One of the most common reasons is if the child is near-sighted or far-sighted. If a child's vision is blurry because of near-sightedness or far-sightedness, their eyes may have to strain to see clearly. This straining can cause a child's eyes to cross or drift apart. But when these kids wear glasses to improve their blurry vision, their eye alignment can improve too.
Other causes of strabismus include:
- Premature birth
- Neurological (brain-related) disorders
- Down syndrome
In many children, strabismus can happen without an obvious cause.
Symptoms of Strabismus
You may notice that your child’s eyes look in different directions at the same time. You may also notice that your child closes one eye or tilts their head when looking at an object. This may be your child’s way of getting both eyes to work together—a sign of strabismus.
Your child’s general practitioner, school nurse, or teacher may notice these signs, too.
Treatment of Strabismus
Treatment of strabismus can be accomplished non-surgically or with a surgical procedure.
Eyeglasses
Sometimes strabismus can be treated with eyeglasses. If a child's vision is blurry due to near-sightedness or far-sightedness, they may have to strain to see clearly. This straining can make the eyes cross or drift apart. Glasses can correct the strabismus in these children.
Patching or Eye Drops
Sometimes an ophthalmologist may recommend patching or eye drops to strengthen a child's weaker eye. This can make it easier for the child to hold their eyes straight.
Surgical Correction of Strabismus
Surgery is often done to correct the alignment of a child’s eyes. Ophthalmologists are specially trained to do this surgery safely and effectively on children's eyes.
While the child is fully asleep under general anaesthesia, the ophthalmologist makes a small cut in the tissue covering the eye to find the eye muscles inside the eye socket. The surgeon can weaken a muscle to make it pull less, or the surgeon can tighten a muscle to make it pull harder. This may need to be done in one or both eyes. And some children may need a second surgery to align their eyes.
After surgery, most children can get back to their daily routine in about 2 to 3 days. As with any surgery, there are risks with strabismus surgery. While rare, they can be serious. Your ophthalmologist will discuss these risks and benefits of surgery.
Strabismus surgery is usually a safe and effective way to treat eye misalignment. However, it does not replace eyeglasses, patching or blurring if the ophthalmologist recommends them too.