Esotropia is a form of strabismus that describes the inward turning of one or both eyes. It is the most predominant form of strabismus in children, and its characteristic feature is a cross-eyed appearance.
In infants below 20 weeks old, the misalignment tends to resolve on its own, especially when the crossing is intermittent or less severe. If the condition does not resolve and remains untreated, it may result in amblyopia or other visual problems.
In some instances, children may have pseudostrabismus, where they appear to have esotropia, but there is no proof of true crossing because of the eyelid or nasal bridge's shape. A child can have pseudostrabismus and a true ocular alignment. Therefore, parents should take their children for thorough eye examinations once they suspect any eye misalignment.
Also Known As
- Crossed eyes
- Convergent strabismus
Types
The various classifications of esotropia in children are based on the age of onset, frequency, and the relationship to eye focusing. They include:
Infantile vs. acquired
Infantile esotropia appears during the first year of a child's life or, rarely, at birth. It is often correlated with other eye problems such as farsightedness, nystagmus, and upward eye drifting. The condition presents with a chronic esodeviation of the visual axes when a child is 8-16 weeks old, followed by weeks of transient eye misalignment.
On the other hand, acquired esotropia occurs after infancy, typically affecting children between 2-5 years. The angle of deviation in this type is relatively small. Many patients with the condition complain of double vision, which interferes with their everyday life.
Constant vs. intermittent
Constant esotropia is present all through, whereas intermittent esotropia is only discernible when a child is sick, tired, or looking at distant or close objects. Intermittent esotropia requires medical attention to prevent it from evolving to constant esotropia.
Accommodative esotropia
Refers to eye-crossing that results from the eye's accommodative effort to see clearly. It can be classified into refractive, non-refractive, or partially accommodative esotropia. Patients with accommodative esotropia are usually hyperopic; thus, they strain hard to see clearly especially when objects are close-by. It affects children between six months to 7 years, but the average age is 2.5 years.
An illness or trauma mostly triggers the condition, which accounts for more than 50% of all esotropia observed in children. In older children, it may be linked to diplopia, although it disappears with the onset of a suppression scotoma.
Causes & Risk Factors
Causes of esotropia are mostly idiopathic. However, some factors like genetic disorders affecting the eye, pediatric cataracts and glaucoma, and a family history of the condition may put a child at risk of developing the condition.
Signs & Symptoms
The primary indicator for esotropia is the inward turning or crossing of the eyes. Other signs and symptoms may include squinting or rubbing the eyes, double vision, headache, and decreased vision and depth perception.
Diagnosis
A pediatric ophthalmologist or optometrist usually diagnoses esotropia. S/he will review the child's family and medical history then examine the child's eyes to determine visual acuity. The examination may involve dilating the eyes to discern the degree of farsightedness.
The doctor may also recommend further tests such as:
- Diagnostic imaging to perceive whether the eye-crossing is due to a muscle or nerve problem
- Genetic studies to identify chromosomal patterns that could suggest hereditary syndromes
Treatment
Correcting misaligned eyes provides other functional benefits besides improving a child's appearance. With the eyes adequately aligned, binocular vision is enhanced, depth perception improves, and the child becomes less prone to developing amblyopia.
Medical Therapy
The main form of treatment is eyeglasses, which a child needs to wear all through to prevent permanent eye-crossing that would require surgery to correct. After initiating the use of glasses, particularly in children with accommodative esotropia, the eye deviation will heighten when a child is not wearing spectacles.
The child gets used to a much decreased accommodative effort, and so when s/he removes the spectacles, the accommodative effort increases to a greater extent than pre-treatment. The increased esotropia may be a significant concern to parents or caregivers, and therefore, appropriate counselling is essential before treatment.
On a few occasions, such as when a child is not compliant with wearing spectacles or is repeatedly breaking them, the ophthalmologist may prescribe topical miotics instead of glasses. Some children may still cross their eyes even while wearing the prescribed glasses, and so, bifocals may be the necessary treatment.
For amblyopia, the doctor may recommend a suitable eye patch for the child to wear over the stronger eye or atropine drops that would cause the stronger eye to blur, forcing the child to strengthen and utilize the lazy eye. The child should still wear glasses even after the treatment.
Surgery
An ophthalmologist would recommend eye muscle surgery where glasses fail to correct the misalignment completely or when a previously controlled misalignment deteriorates. Surgery would involve weakening the medial rectus muscle in both eyes. For patients with amblyopia, the operation strengthens the lateral rectus in the amblyopic eye only. It is imperative to note that surgery does not intend to stop the use of eyeglasses.
Prognosis & Long-Term Outlook
Early treatment for all esotropia forms could result in better vision, a stable eye alignment for surgery, when necessary, and an improved binocular function. Accommodative esotropia may result in permanent blindness if patients do not receive amblyopia and strabismus treatment before 4-6 years.
On the other hand, patients with infantile esotropia can still develop good vision without treatment. However, the binocular function will be low, leading to poor depth perception and an abnormal appearance. Intermittent esotropia may also develop into constant esotropia if treatment is not offered.
Many patients have the ability to properly align the eyes without wearing spectacles before becoming teens if they regularly wear glasses in the younger years.
Prevention & Follow Up
Preventing esotropia is still not possible, but the complications that arise from it can be stopped when detected early. Close monitoring of children from infancy to preschool to identify possible eye problems is vital, especially if a family member has strabismus. The recommended age for a thorough eye examination is between 3-5 years.
All patients should visit the hospital annually or when esotropia becomes severe for a repeat of some eye examinations. Follow-ups for amblyopia treatment should be at intervals of 1-4 months, depending on the patient's age, while stable patients should visit every six months.
