Kabuki syndrome

Definition

Strabismus is an eye alignment anomaly. Normally, both eyes gaze in the same direction. This is not the case in a child with strabismus. One or both eyes may deviate in any direction (inward, outward, or, more rarely, upward or downward). 

The condition can be constant or intermittent (e.g., appearing only when the child is tired), affecting the same eye consistently or alternating between eyes (alternating strabismus), producing the same degree of deviation regardless of gaze position (comitant strabismus), or varying based on gaze position (incomitant strabismus or ophthalmoplegia). Strabismus before three months of age is generally considered normal and tends to resolve spontaneously. 

In Kabuki syndrome, strabismus is one of the most frequent ocular symptoms. It usually appears during the first months of life and tends to stabilize or even improve with age. The hypothesis as to why strabismus manifests itself in patients with Kabuki syndrome assumes that it is due to general muscle weakness, i.e. the muscle is too weak to move into the correct position.

Symptoms

In the general population, when strabismus is intermittent, the patient may experience double vision (diplopia). When strabismus is constant and treatment has not yet begun, the child may lose the ability for depth perception. Since the brain suppresses the images sent from the diverging eye, this eye could become functionally blind (amblyopia). 

In children with KS, strabismus is usually inward (esotropia), may alternate between eyes (alternating), and does not vary in degree based on gaze position (comitant). However, in some children, it may be outward (exotropia). In our experience, when children are younger, it tends to be constant (although it may switch eyes), while it becomes intermittent as they grow older (more so when they are tired). Because strabismus alternates between eyes, it is likely that children experience double vision; in our experience, this usually does not lead to blindness (although one case of amblyopia has been reported). 

Treatment

Strabismus can be corrected when treated early with glasses, eye patches, or specific medications (such as botulinum toxin injections). If these measures fail, surgery may be performed. If there has already been a loss of function (such as loss of depth perception or amblyopia), surgery will not restore these functions; in such cases, the surgery would have only an aesthetic effect. 

Given the tendency for improvement with age, it is recommended to initially use non-definitive measures (glasses, botulinum toxin), while not ruling out surgical intervention in specific cases.