Infantile Esotropia Vs Alternating Esotropia

Infantile esotropia and alternating esotropia are two types of strabismus, a condition where the eyes are misaligned and do not look in the same direction. Infantile esotropia is a form of inward deviation of one or both eyes that typically begins before the age of six months, while alternating esotropia is also an inward deviation that shifts between the right and left eyes and occurs intermittently. In this blog post, we will discuss a clinical case study of a 1-year-old patient with infantile esotropia versus alternating esotropia.

Case presentation:

A 1-year-old female patient was brought to the pediatric Vision Vibes Orthoptics clinic for evaluation of her eyes. The child’s mother reported that she had not noticed any turning of the child’s eyes turning inward until it was pointed out by a friend. The patient had no significant medical history, and her birth history was unremarkable.

The mother was asked to provide us with old photos to determine the onset of the eye turn. In most photos, the right eye is presented with an inward turn from a very early age. Other photos appeared straight whereas a few showed a left inward eye turn. 

Upon presentation, the child seemed to have an inward eye turn in the right eye. She had full movements of her eye muscles with no “overactions” or “underactions”, No “up/down shoots”, and no narrowing of palpebral fissures.

Her visual acuity was tested using Teller Acuity Charts and she seemed to be able to see even the finest gratings with each eye alone. She also did not object to occlusion. 

The child seemed to respond to the stereo Fly presented, however as she is not yet verbal, no further stereo acuity was obtained.

The child was constantly on the move and as such cover testing, alternate cover test and prism bar measurements were not taken.  

With the above information, we can assume that at this stage there is no amblyopia present as both eyes appear to have equal vision. If on the contrary, the child preferred one eye over the other, objected to occlusion, or showed a difference in visual acuity between the two eyes, then investigating amblyopia is necessary. 

It is important to note, the child demonstrated gross stereo acuity which implies that the eye turn is potentially intermittent. However, during that particular visit, the child had a constant right eye turn. As such, she was diagnosed with right infantile esotropia (pending future investigations).

At this point, we asked the mother to keep observing the direction, which eye, and timing of these eye turns and to return for a visit when the child is 3 years old for a more comprehensive assessment.

In this case study we are considering a right infantile esotropia versus an alternative esotropia for a differential diagnosis. 

Other differential diagnoses such as Duane’s or Brown’s were dismissed as the patient had no significant signs on ocular movements tests.

Typical presentation of infantile esotropia 

•  A Large angle of esotropia that is not affected by distances.
• Early onset (6 months)
• Constant
• Hypermetropic Cycloplegic refraction 
• With or without amblyopia

Management 

• Prescribe eye glasses to correct his hyperopia 
• Patching therapy for amblyopia management. 

The exact cause of infantile esotropia is unknown, but it is thought to be related to abnormal visual processing in the brain or a defect in the control of eye movements. Treatment options for infantile esotropia include glasses to correct refractive errors, patching therapy to treat amblyopia, and surgery to strengthen or weaken the eye muscles. 

Alternative Esotropia:

Alternative esotropia is a type of strabismus that occurs intermittently, meaning that the eye deviation alternates between the two eyes.

• The deviation may be constant in one eye but alternates between the two eyes over time.
• Alternative esotropia is often associated with a small angle of deviation, which may be less than 10 prism diopters.
• The deviation is also more likely to be influenced by distance and near fixation compared to infantile esotropia.

Alternative esotropia can be caused by a variety of factors, including refractive errors, muscle weakness, or neurological disorders. Treatment options for alternative esotropia include glasses, vision therapy, and surgery

The main differences between infantile esotropia and alternative esotropia are summarized below:

1. Onset: Infantile esotropia typically begins before the age of six months, while alternative esotropia can occur at any age.

2. Frequency: Infantile esotropia is constant, meaning that the deviation occurs all the time, while alternative esotropia is intermittent, meaning that the deviation alternates between the two eyes.

3. Angle of deviation: Infantile esotropia is characterized by a large angle of deviation, while alternative esotropia is often associated with a small angle of deviation.

4. Treatment: The treatment of infantile esotropia often involves a combination of glasses, patching therapy, and surgery, while the treatment of alternative esotropia may involve glasses, vision therapy, or surgery.

BONUS Differential Diagnosis 

Alternating Exotropia masked by Infantile Esotropia 

It is possible for someone to have constant Esotropia and then when the patient is tired or overworked an intermittent alternating Exotropia appears. 

In this case, it is likely that the alternating exotropia will be more evident in primary gaze and distance fixation, while esotropia would manifest more in near fixation. 

Management:

The management of infantile esotropia and alternating exotropia depends on the severity of the condition and the age of the patient. 

Management will require an accurate prescription of eyeglasses to effectively manage refractive errors. Next, patching therapy may be necessary to treat and prevent amblyopia. 

Vision therapy for exotropia may be worth a try but may be challenging.

Surgery should be considered depending on the severity of the deviation and lack of improvement with conservative therapy.