Strabismus

What is strabismus?

Strabismus is a vision problem that consists of misalignment of the eyes; it is a binocular vision dysfunction, which means that while one eye is looking at one object, the other deviates in a different direction.

There are two different types of strabismus: horizontal, convergent (inward) strabismus or divergent (outward) strabismus; and vertical strabismus, one eye looking up and one looking down. However, there are cases of strabismus with various combinations of these.

Treatment

Strabismus has two consequences, one aesthetic and another more important visual one.

The visual defect, amblyopia or lazy eye, is treated with glasses and by covering the dominant eye, i.e. “an eyepatch over the good eye”, to thus force the vision in the affected eye. This treatment does not cure the strabismus and does not reduce the deviation, except in a few cases, so it is not a treatment for the aesthetic problem, but rather for the visual disturbance caused by the strabismus.

The aesthetic consequence is treated by an operation that is usually performed under general anaesthetic in children and which consists of strengthening or weakening the ocular muscles responsible for the poor alignment.

In adults, strabismus surgery can be performed under local anaesthetic.

Strabismus surgery is not complicated: it is a matter of tightening or loosening the muscles that control eye movements. The difficulty lies in the precision of the procedure in order to achieve the most accurate angle possible to correct the deviation. This is measured in prism dioptres.

Botulinum toxin is sometimes used to achieve this. Specialists generally use botulinum toxin in convergent strabismus in patients under the age of 4 who suffer from minor deviations without any associated vertical component. In other cases, surgery is the usual option.