Understanding Strabismus and Lazy Eye: Causes and Treatments for Children and Adults

Early screening and possible treatment of strabismus and lazy eye are absolutely crucial to optimize visual brain development and to minimize permanent damage, or at least developmental delay. If strabismus develops later in life (older child or adult), it will be more difficult, if not impossible, to develop suppression as an adjustment mechanism. The double vision can therefore be more disturbing. But because the brain has developed visually normally up to a certain age, the rehabilitation of previously acquired and practiced visual skills will also normally proceed more quickly.

In both cases, visual therapy, or secondarily eye muscle surgery, should attempt to restore eye alignment, neurological fusion of both eye images, and depth perception. Strabismus and lazy eye often have an underestimated but far-reaching impact on visual functionality. Restoring binocular vision is important for reading and learning skills, motor skills, mobility, (later) career opportunities and mental well-being. Research over the last two decades has shown that the neurological core of lazy eye and strabismus is much more treatable than previously believed. In the vast majority of cases, the patient’s eyes, eye muscles, and brain are physiologically healthy, but the brain must learn to correctly use and integrate the eyes, eye muscles, and visual information flows (again).

Strabismus in babies

In newborns it is sometimes a pseudostrabismus or a false form of strabismus. In fact, aligning the eyes is a skill learned during the first months of life. During the first six months of life, approximately half of all children have their eyes crossed from time to time. That is normal. Babies also often have a wide nose bridge, which makes it seem as if the eyes turn inward. Nevertheless, as a parent you can keep an eye on the evolution of the eye position. If you are concerned, you can have a refractive examination carried out at the ophthalmologist from six months onwards to identify risk factors. Even if there is a family history of strabismus, that is not a bad idea. However, if the strabismus is present continuously from birth, early examination and appropriate treatment is necessary.

Strabismus in young children

Some children do not develop a strabismus until after 12 months of age or in toddler or preschool age. Possible causes are:

• An eye defect, as a result of which one eye sees less sharply or there is a large difference in sharpness between the two eyes (anisometropia).
• Long-sightedness, as a result of which the eyes have to make more effort to obtain a sharp image, can lead to the inward turning of one eye. This kind of strabismus is called accommodative strabismus.
• A less good control or coordination of the different eye muscles. This can happen if the neurovisual development process goes off track for some reason, possibly after going through a childhood illness or extreme fatigue.
• An accident or neurological abnormalities can lead to a disturbed innervation of one or more eye muscles, resulting in partial ocular muscle paralysis.
• An accident with damage to the eye socket can be the cause of strabismus.

Strabismus in adults

In adults, multiple causes of strabismus are also possible:

• Strabismus that has or has not been treated in childhood can sometimes (again) worsen in adults. This is called decompensation of the strabismus. Decompensation often occurs in the thirties or forties in someone who has never really been thoroughly visually rehabilitated or who had eye muscle surgery as a child. Eye muscle operations often only treat the strabismus cosmetically. However, the brain has not learned to use the eyes correctly and to integrate neurologically. That is why that apparent straight eye position will often calve back over time. Decompensating for strabismus is also often accompanied by disturbing symptoms such as headaches, tired eyes, light sensitivity and possibly double vision.
• A visually impaired eye as a result of an accident or other eye injury can also be the cause of an eye turning away in adulthood.
• Paralytic strabismus or strabismus due to eye muscle paralysis can occur after an accident, but also as a neurological symptom of other disorders (e.g. cerebral haemorrhage, MS, diabetes, oxygen deficiency due to vascular disease, …)
• Restrictive strabismus or strabismus due to mechanical limitations of the eye muscles usually occurs after an accident with damage to the eye socket or in patients with thyroid problems that lead to damage to the eye muscles.