Esotropia: Definition, Causes, Symptoms, Diagnosis, and Treatment

What Does Esotropia Look Like?

Esotropia may look like the inward-turning of the eyes and may initially occur intermittently. When esotropia occurs, a distinctive sign can be one or both eyes crossing, pointed towards the nose and struggling to move together.

How Common is Esotropia?

Esotropia may be common, according to the Lions Eye Institute strabismus is one of the most common eye conditions that occurs in children. However, there is still insufficient data on the estimate of people specifically with esotropia.

How Does Esotropia Differ From Other Types of Strabismus?

Esotropia differs from other types of strabismus as each form causes the eyes to turn in different directions. While esotropia can prompt the eyes to turn inward, exotropia causes outward turning, hypotropia causes downward turning and hypertropia can cause upward turning. It may be common to mistake comparing esotropia and strabismus, however, like the other forms mentioned, esotropia is one of the four types of strabismus.

1. Intermittent Esotropia

Intermittent esotropia is characterised as a form of strabismus that causes misalignment of the eyes in fluctuation. According to the Optometrists Network, intermittent esotropia can be managed, however, may be triggered by stress or extended periods of performing activities that rely on near-vision. Treatment for intermittent esotropia can include prescription glasses, vision therapy, and surgery depending on the severity of the condition. According to the American Optometric Association, intermittent esotropia may present symptoms such as double vision as the brain is interpreting two images, depth perception issues and impeded vision in one eye. Untreated intermittent esotropia could potentially lead to constant esotropia, therefore, it is important to see an optometrist if you are experiencing such changes.

2. Constant Esotropia

Constant esotropia occurs when the misalignment of the eyes is always present. Intermittent esotropia differs from constant esotropia as the misalignment of the eyes or eye may be brought on by stressful situations or prolonged concentration, whereas the latter presents its implications all the time. Constant esotropia could develop if intermittent esotropia is left untreated in some cases, however, other cases can still remain intermittent according to Science Direct. This type of esotropia is considered more serious and can affect how some individuals may position their heads in order to maintain normal alignment of the eyes according to the National Library of Medicine.

3. Congenital or Infantile Esotropia

Congenital or infantile esotropia is the form of strabismus that occurs either at birth or around six months and is the most common type of esotropia. Patients with congenital or infantile esotropia typically have normal visual acuity. However, amblyopia could develop in the potential case of one eye turning more than the other during congenital esotropia. The factors that may contribute to the occurrence of congenital esotropia can include premature birth, family history of strabismus, seizure disorders, developmental delay and cerebral palsy according to the American Association for Pediatric Ophthalmology. Eye muscle surgery is the main form of treatment for this case of strabismus and should be performed before the patient turns 2. This has been found to produce better results for vision, however, there may be a likely chance of the patient exhibiting a deficiency in depth-perception when older.

4. Nonaccommodative Esotropia

Nonaccommodative esotropia is defined as a type of strabismus that does not improve with the use of prescription glasses. While it may be too difficult to determine the main cause for the development of nonaccommodative esotropia, there may be certain risk factors associated with this condition. These risks can include the occurrence of esotropia before the age of 2 and oblique dysfunction according to the American Academy of Ophthalmology. Strabismus surgery may be recommended to aid misalignment as prescription glasses are not able to resolve this form of strabismus.

5. Accommodative Esotropia

Accommodative esotropia occurs when the eye or both eyes turn towards the nose when trying to concentrate and can be treated with prescription glasses. This form of esotropia is found more in children with farsightedness, and those with poor near-vision. Accommodative esotropia may typically develop in children from the ages of 18 to 36 months and may be more likely for those with a family history of strabismus. It is important to note, that farsightedness does not always result in developing esotropia, however, children may be more susceptible to crossing their eyes when trying to focus to see objects up close clearly. Accommodative esotropia can be treated with prescription glasses.

6. Pseudoesotropia

Pseudoesotropia is a condition in which the eyes are not crossed but appear to be misaligned. Due to a flat or broad nose bridge or a pronounced fold of the upper eyelid, the eyes or eye may appear misaligned. An optometrist will be capable of fully assessing whether the patient does have esotropia by examining how one eye moves while the other eye is covered.

1. Thyroid-Related Eye Disorders

Thyroid-related eye disorders may be a factor in the development of esotropia as it can affect the muscles in the orbit of the eye. Thyroid-related eye disorder, also referred to as thyroid eye disease, causes inflammation in the eye and its surrounding tissues as a result of an autoimmune reaction. As a result of swelling of the extraocular muscles, eye movement may be limited and lead to misalignment according to the American Academy of Ophthalmology. According to a 2020 paper published in the Journal of Current Ophthalmology, esotropia may develop in 15% of all patients with thyroid eye disease.

2. Brain Disorders

Brain disorders such as cerebral palsy, hydrocephalus and brain tumours may be present when strabismus occurs. According to the American Orthoptic Journal, it is common to find patients with cerebral palsy to also have esotropia. Cerebral palsy is a group of disorders that can affect how the body moves and the ability to control balance and posture. Hydrocephalus is a neurological disorder that causes an unusual buildup of fluid in the brain. This may induce esotropia as the nerves that are responsible for eye position and movement can be damaged, prompting misalignment of the eyes.

3. Poor Vision

Poor vision may lead to esotropia due to prolonged eye focus on objects in order to have clear vision. Poor vision such as farsightedness may trigger esotropia as the eye muscles may have to exert more effort in order to maintain clear vision of objects up close, leading to the inward turn of one or both eyes. Farsightedness is characterised as a refractive error that results in having poor near vision.

4. Glaucoma

Glaucoma may also be present when some esotropia cases occur or glaucoma surgery may lead to the development of esotropia. In paediatric cases, patients who also have glaucoma in addition to esotropia may be easier to treat compared to adults who also have these conditions. According to a 2017 paper on Strabismus Associated with Glaucoma and Glaucoma Surgery, in these cases of strabismus, esotropia is the most common form to occur. It is typically sensory and a consequence of amblyopia, sensory esotropia can occur due to poor vision in one eye. Glaucoma is defined as an eye disease that can lead to vision loss due to optic nerve damage.

5. Premature Birth

Premature birth may pose a higher risk of developing eye diseases that can lead to visual impairing and non-visual impairing conditions including esotropia. Premature birth is when a baby is born before the completion of 37 weeks of pregnancy. In a 2015 study of 966 infants, 141 of them had strabismus at the age of 2 and 80% of those cases had esotropia. Premature birth may increase the risk of esotropia due to poor growth of eye nerves or eye muscles. Children with either esotropia or exotropia were found to be at an increased risk of having impaired fixation ability, visual field deficit, cerebral palsy, impaired ability to walk, low mental development index and a low physical development index when compared to their peers without strabismus.

6. Conditions Like Diabetes or Hyperthyroidism

Conditions like diabetes or hyperthyroidism may lead to esotropia due to their implications in the eye. Diabetes and hyperthyroidism may be considered as endocrine or hormone problems according to the Diabetes Journals. Endocrine problems may manifest symptoms in the eye and tissues in the orbital area according to a 2021 paper on Ocular Manifestations of Endocrine Disorders. Diabetes particularly may factor in the development of esotropia as it can be common for patients to experience a lack of circulation, leading to paralytic strabismus according to Riverside Health System. Esotropia can also be a consequence of nerve damage caused by diabetes according to the Cleveland Clinic.

7. Vascular Issues, Including Strokes

Vascular issues including strokes may cause esotropia among other optic issues in adults. According to Stanford Medicine, adults may be susceptible to esotropia as a result of eye or blood vessel damage. Vascular issues are defined as a condition that can affect the circulation of blood to parts of the body excluding the brain and heart. In a study of 519 patients who experienced the onset of a stroke, 19% of them were found to have strabismus after a full orthoptic assessment according to the Nature Journal. A stroke is a medical emergency that occurs when the brain's blood supply is impeded and can cause further medical complications including eye problems.

8. Childhood Cataracts

Childhood cataracts may be a strong factor in the occurrence of esotropia especially after surgery for cataracts. Childhood cataracts occur when the lens of the eye becomes cloudy and occurs at a young age. According to the National Library of Medicine, childhood cataracts have an increased association with strabismus and more so post surgery. An evaluation of paediatric patients' medical reports from 2000 to 2011 found that children who acquired strabismus underwent cataract surgery when they were younger compared to children who did not have strabismus.

9. Amblyopia

Amblyopia may occur along with esotropia as poor vision in one eye may cause the weaker eye to turn inward. Esotropia may occur as a result of amblyopia due to the poor development of proper eye alignment during childhood. Esotropia and amblyopia are commonly associated with each other, however, esotropia differs as it is an issue with eye alignment and amblyopia is characterised as a vision problem in one eye.

10. Hyperopia

Hyperopia may potentially lead to esotropia due to excessive eye focusing required to maintain clear vision. Hyperopia is also known as farsightedness, which may lead to esotropia if left untreated. Accommodative esotropia in particular can increasingly occur in farsighted patients during childhood according to the Web MD. Hyperopia occurs when you can only see objects in the far distance but have difficulty seeing objects up-close.

1. Squinting

Squinting is a potential symptom of esotropia that can occur due to misaligned eyes and may develop in order for the individual to see better. Squinting is the act of partially closing one's eyes in order to see more clearly.

2. Blurry Vision

Blurry vision may arise in adult esotropia cases as the eyes may be required to exert more eye-focusing effort to be able to see better. Blurry vision can be described as images that are not sharp or clear.

3. Diplopia

Diplopia can develop as esotropia can cause the eyes to see two images due to the misalignment of the eyes. Diplopia may likely occur during esotropia as both eyes require innervation of every eye muscle in order to maintain proper alignment according to the American Academy of Ophthalmology. Diplopia is characterised as seeing two images of the same object and has two classifications known as monocular and binocular diplopia.

4. Unsynchronised Eyes

Unsynchronised eyes can refer to the eyes' inability to see and move together when looking at objects. It is a common and distinctive symptom of esotropia and may need to be further examined by an eye care professional.

5. Depth-Perception Issues

Depth-perception issues may be brought on as a consequence of esotropia since the eyes are turned inward and are not coordinated. Depth perception is defined as the ability to see in three dimensions; length, width and depth and the capability to discern the distance of an object.

What is the Difference Between Esotropia and Exotropia?

The difference between esotropia and exotropia is the direction the eyes turn. Esotropia causes the inward turning of the eyes, while exotropia is the outward deviation of the eyes. Both esotropia and exotropia share similar causes, including eye muscle weakness, genetics, conditions like a stroke and poor vision. Additionally, both can be treated with the same methods of prescription glasses and eye surgery.