Strabismus
Strabismus is the medical word for a misalignment of the eyes. One eye may turn inwards, outwards, or more rarely upwards or downwards, while the other eye looks straight. The eye turn can alternate between the eyes. The eye turn can be noticeable all the time or it can be intermittent, where sometimes the eyes are straight and sometimes the eyes cross or drift.
What are the common types of strabismus in children?
Babies can be born with a mild tendency for the eyes to cross or drift. If this comes and goes and resolves within the first weeks of life, it is likely just part of normal development.
There are three commonly seen childhood causes of strabismus:
- Infantile esotropia is a type of strabismus that usually starts in the first 6 months of life. Babies develop a large inward crossing of the eyes (esotropia) that is sometimes associated with a need for glasses. Infantile esotropia is important to recognise early, as treatment with glasses and surgery is more successful at a younger age.
- Accommodative esotropia is a type of strabismus that usually starts in toddlers, where an inward crossing of the eyes develops (esotropia). The esotropia is sometimes constant and sometimes intermittent, where it comes and goes. It can become more pronounced in some children with focusing on near objects. Children with accommodative esotropia are often farsighted and need to wear glasses full time to help control the eye turn. In many instances, the glasses completely correct strabismus. If there is a residual tendency for the eyes to cross while wearing the glasses, then the child may require strabismus surgery.
- Intermittent exotropia is a type of strabismus that usually starts in children over the age of four. One or both eyes will have a tendency to drift outwards. It commonly is intermittent, meaning the child is are able to keep the eyes straight much of the time. It is usually more noticeable when children focus on far away objects, and when they are day dreaming, tired, or sick. Children with intermittent exotropia may have near sightedness (myopia) and sometimes astigmatism, that can be corrected in glasses and may help control the eye turn.
If children with intermittent exotropia start to lose control of the eye turn, where the eye drifts close to 50% of the time or more, then they likely would benefit from strabismus surgery.
There are many other causes for strabismus and rarely strabismus can have a neurological cause that requires more investigations. Strabismus can also be associated with other medical conditions. A comprehensive eye examination with an eye doctor can determine the type of strabismus.
What are the risk factors for strabismus?
- Strong need for glasses (refractive error)
- Prematurity
- Genetic factors (family history of strabismus)
- Maternal smoking during pregnancy
- Associated medical conditions
What are the treatments for strabismus?
The treatment for strabismus depends on the type of eye turn and the overall eye health. The first step is to evaluate whether the vision in each eye is equal and normal, whether glasses are required, and whether the eye anatomy and eye health is normal.
Children with strabismus are at risk of developing amblyopia (lazy eye) and sometimes they may have to wear an eye patch for a few hours every day to help strengthen the weaker eye. If required, treatment for a lazy eye will be discussed at your optometrist or ophthalmologist visit.
Eye surgery for strabismus may be required to straighten the eyes. If done at a young age, then strabismus surgery can sometimes help in the development of binocular vision or stereoacuity.
What should I do if I think my child has a strabismus?
If you think your child is developing an eye turn, then you should have them promptly assessed by their optometrist. At this visit the optometrist will assess their vision, eye health, and need for glasses.
Many types of strabismus are associated with a need for glasses, and the sooner the child gets glasses the better. Rarely strabismus is associated with a developmental problem in eye health, like a cataract. Retinoblastoma, an eye cancer in childhood, is an extremely rare cause of strabismus. Cataract and retinoblastoma, though extremely rare, require urgent assessment and treatment by an ophthalmologist.
It is a good idea for all children to have a comprehensive eye exam with their optometrist between 6 and 12 months of age.
