Strabismus (Squint, or Turned Eye)

Normally, both eyes work together to look at the same object. The brain then fuses the two pictures into a single three-dimensional image, giving us depth perception. Strabismus is a condition in which the eyes are misaligned and point in different directions. Whilst one eye may look straight ahead, the other eye may turn inwards (esotropia), outwards (exotropia), upwards (hypertropia), or downwards (hypotropia). Strabismus is present in about 2% of children and occurs equally between the sexes. Some people use the term "lazy eye" to refer to a turned eye, but this is not an accurate description.

Why is strabismus a problem?

When the eyes are misaligned, two different pictures are sent to the brain. In an adult this causes double vision. In a young child the brain learns to ignore the image of the misaligned eye and sees only the image from the good eye. The child then loses depth perception. Babies who have a strabismus after the age of six months should be seen by a paediatric ophthalmologist as there is a risk of developing amblyopia (decreased vision in one or both eyes).

What causes Strabismus?

Strabismus can be caused by a refractive error, unequal pulling of the muscles controlling eye movement or paralysis of these muscles. Children with a family history of strabismus are at increased risk of having strabismus themselves. A paediatric ophthalmologist can determine the nature of the strabismus and can treat the cause appropriately.

How is strabismus recognised?

An obvious sign of strabismus is an eye that is not straight or does not appear to be looking in the same direction as the other eye. Sometimes children will squint one eye in bright sunlight or tilt their head to use their eyes together. Children who have had strabismus since birth or soon afterwards do not often complain of double vision. However, any child who does complain of double vision should be seen by a doctor promptly. All children should have their vision checked by a paediatric ophthalmologist at an early age, especially if there is a family history of strabismus or amblyopia.

Infants and young children often look cross-eyed. This is because they tend to have wide, flat noses with folds of skin in the inner corners of their eyes that can make the eyes appear uneven. This appearance of strabismus goes away as the child grows. However, a child will not outgrow a real strabismus. An ophthalmologist can tell the difference between true and false strabismus.

Treatment for strabismus

Treatment for strabismus works to preserve vision, straighten the eyes, and restore binocular vision. These treatments are only to be prescribed by a paediatric ophthalmologist who, after examining the child, can recommend appropriate treatment and monitor progress.

• Glasses
  When the strabismus is caused by a refractive error wearing glasses to normalise vision may completely straighten the eyes, or at least make an improvement to eye position.
• Occlusion/patching
  If the child has a strabismus with amblyopia he or she can be forced to use (and thus strengthen) the weaker eye by covering the good eye with a patch. Patching should be started as early as possible and continued for as long as your doctor recommends. After about the age of 8 it is generally too late to use patching treatment as vision is fully developed. Patching does not cosmetically straighten the eyes.
• Surgery
  An operation on the muscles that control eye movement is often necessary to make the eye appear straight. Before considering an operation the child is treated with glasses (if necessary) and patching to give the best possible vision. The child will need further visits to the ophthalmologist after the operation to check progress and continue treatment.