Congenital esotropia is a common type of strabismus, a condition where the eyes do not align properly. This misalignment typically manifests as one or both eyes turning inward, towards the nose. Present at or shortly after birth, or developing within the first six months of life, it can significantly impact both eye alignment and the normal development of vision.
Understanding Congenital Esotropia
Congenital esotropia, also known as infantile esotropia, involves a consistent and often large inward turning of one or both eyes. This condition differs from other forms of esotropia, such as accommodative esotropia, because it does not resolve with glasses alone and often requires other interventions.
The inward deviation in congenital esotropia is typically large, often 30 prism diopters or more. Unlike transient eye misalignments common in infants up to three months of age, a constant esotropia of 40 prism diopters or more after 10 weeks is unlikely to spontaneously improve. This persistent misalignment interferes with binocular vision, impacting depth perception.
Identifying the Signs and Underlying Factors
Parents or caregivers might observe a noticeable inward turning of one or both eyes, particularly when the child is tired or trying to focus. Some infants might alternate which eye turns inward, while others consistently show deviation in one eye.
While the exact cause of congenital esotropia is not fully understood, several theories exist. One perspective suggests it stems from a problem with the brain’s ability to coordinate eye movements. Another theory points to a primary mechanical issue with the eye muscles, leading to misalignment. Genetic predisposition is also considered a factor, as the condition can run in families, though specific genes have not been identified.
Diagnosis and Treatment Options
Diagnosing congenital esotropia requires a comprehensive eye examination by a pediatric ophthalmologist. This includes evaluating eye alignment, assessing vision in each eye, and checking overall eye health. The ophthalmologist also determines if glasses are needed to correct refractive errors, such as farsightedness, nearsightedness, or astigmatism. Ruling out other potential causes, like neurological problems or other eye conditions, is also part of the diagnostic process.
The primary goals of treatment for congenital esotropia are to achieve proper eye alignment and support healthy vision development. Non-surgical approaches have a limited role; glasses may be prescribed if a significant refractive error is present, but they typically do not correct the inward turn. Patching, which involves covering the stronger eye, is used to treat amblyopia.
Surgical intervention is the most common and effective treatment for congenital esotropia. This procedure involves adjusting the eye muscles to realign the eyes. Surgery is typically performed early in life, often when the child is under two years of age, to maximize the potential for developing better binocular vision and depth perception. The standard surgical approach often involves weakening the medial rectus muscles, which pull the eyes inward. In some cases, botulinum toxin injections may be used as an alternative or in conjunction with surgery.
Addressing Related Concerns and Prognosis
Congenital esotropia is frequently associated with other eye conditions, such as amblyopia, commonly known as lazy eye. Dissociated vertical deviation (DVD), where one eye drifts upward, outward, or rotates when not fixating, is another common associated finding, occurring in 50-90% of cases. Over-elevation in adduction, or inferior oblique overaction, is also frequently observed in around 70% of patients.
Ongoing follow-up care is important after treatment to monitor eye alignment and vision development. While early diagnosis and appropriate treatment can lead to good cosmetic alignment, some degree of visual impairment or the need for further intervention may persist. For instance, between 15-30% of children may require a second surgery to maintain alignment. Despite potential ongoing needs, early surgical correction has been shown to improve the chances of better alignment and depth perception outcomes.