What is Esotropia (Deviation of the Eye Toward the Nose)?
Esotropia is a condition where the eyes are not aligned correctly, and one eye turns in towards the nose. The name “esotropia” comes from ancient Greek, with “Eso” meaning “within” and “Tropia” meaning “a turn.” This eye condition can be present from birth, or it may develop over time. It can happen on and off or be a constant issue, and might potentially shift from happening intermittently to occurring all the time. Plus, the degree of misalignment can either be constant or might vary depending on the direction of gaze, leading to classifications of esotropia as concomitant or incomitant. Squinting can occur in one eye or switch between both eyes.
Concomitant esotropia is a subgroup of the condition that comprises variations like Infantile (congenital) esotropia, accommodative esotropia, acquired non-accommodative esotropia, sensory esotropia, and consecutive esotropia. On the other hand, incomitant esotropia is classified by the root cause, split into paralytic or non-paralytic types. This summary is mainly focused on describing the category of concomitant esotropia and its specific types in a more understandable way.
What Causes Esotropia (Deviation of the Eye Toward the Nose)?
Esotropia is a condition where the eyes turn inward. What causes esotropia depends on the type. Here’s a simple explanation for each type:
Infantile Esotropia:
Infantile esotropia shows up in babies. There are two main factors that can cause it:
– Innervational Imbalances: This means there’s a disruption in the balance between eye movements that turn our gaze towards or away from each other, causing the eye to deviate.
– Accommodation: This is the ability of the eye to adjust its focus. Genetics may play a part in infant esotropia, and in some cases, the ability to focus might become a factor at around 2 to 3 years of age.
Refractive Accommodative Esotropia:
This type is mainly caused by uncorrected farsightedness. Other contributing factors include an inability to keep the eyes properly aligned, a high ratio of the focusing response to the eye turning response, and the patient’s personality.
Non-Refractive Accommodative Esotropia:
This type is linked to a high AC/A ratio, which is a comparison of the eye’s focusing response to its turning response. However, the patient’s ability to focus up close is expected to be normal for their age.
Partially Accommodative Esotropia:
These cases occur when there’s uncorrected farsightedness, with a normal AC/A ratio.
Sensory Esotropia:
Sensory esotropia happens when there’s poor vision in one eye early in a child’s life. The eye with poor vision often turns inward, while the eye with good vision becomes the “dominant” eye.
Consecutive Esotropia:
This type usually happens when eye surgery to correct an outward-turning eye is overcompensated, leading to an inward-turning eye.
Risk Factors and Frequency for Esotropia (Deviation of the Eye Toward the Nose)
Various studies have reported on the prevalence of certain eye conditions. One study showed that 0.77% of people have esotropia, a condition where one or both eyes turn inward. Another study of school children found that 3.11% had strabismus, which is a misalignment of the eyes. Within that group, the majority had exotropia, where the eyes turn outward, with a ratio of 9.75 to 1 when compared with esotropia. It was also observed that the prevalence of these conditions didn’t significantly differ based on age (between 6-8 years) or gender.
The prevalence of strabismus and its types also varies among different races. For example, a study conducted in Baltimore found that 3.3% of white children and 2.1% of African American children had noticeable eye deviations. In both groups, esotropia and exotropia were almost evenly distributed.
- In Minnesota, a study of patients diagnosed with Esotropia showed that:
- 36% had fully accommodative esotropia
- 17% had non-accommodative esotropia
- 10% had partially accommodative esotropia
- 8% were born with the condition (congenital)
- 6.5% had paralytic esotropia, caused by damage to the nerve that controls eye movement
- The rest had esotropia due to unknown causes.
Signs and Symptoms of Esotropia (Deviation of the Eye Toward the Nose)
If you have esotropia – the condition where your eyes turn inward – your doctor will need to take a detailed medical history and perform a careful examination. They’ll focus on some key details such as your age, how long you’ve had the problem, the type of esotropia like constant or intermittent, whether it affects one or both eyes. They should also look for any unusual head postures, complaints of double vision or headaches, feeling uncomfortable in the eyes, or a tendency to close one eye in bright sunlight. Potential triggers like recent viral illness, head injury, or excessive near-vision work, as well as a family history of ‘squinting’, and any perinatal (around the time of birth) history should be recorded. Previous treatments – glasses, patching, or surgery – are also important to know.
Your doctor will evaluate your general health, bodily constitution, and nutritional status. They should also examine things like head posture, eye and facial characteristics, inter-eye distances, and any unusual facial shapes or characteristics of the eyelids. A full eye examination includes a comprehensive look at both the front and back parts of the eye. When they examine the front part of the eye, they’ll look for any abnormalities in the eyelid positioning, abnormal eyelid movements when chewing, cloudiness in the cornea or lens, and pupillary reactions which could indicate problems with the optic nerve and retina.
When it comes to the back part of the eye, your doctor will perform a dilated eye examination to rule out problems like scarring in the macula, underdevelopment of the optic nerve, and retina problems. They’ll also check your visual sharpness using age-appropriate methods, measure the angle of deviation with the Hirschberg tests, and conduct a prism bar cover test for near and distance vision, amongst others.
Additionally, the doctor should check your Accommodation Convergence/Accommodation ratio (AC/A), and examine the limit of your fusional divergence (your eyes’ ability to stay aligned when looking at near and distant objects), binocular vision, depth perception, eye movements, and your eye’s refractive error using atropine cycloplegia assessments. These tests will help identify the specific type of esotropia you have and inform the next steps in your treatment. The doctor should also check for any other related clinical features such as overaction of the inferior oblique muscle, dissociated vertical deviation, and latent nystagmus.
Testing for Esotropia (Deviation of the Eye Toward the Nose)
When looking at a patient with esotropia, which is a condition where one or both eyes turns inward, there typically isn’t a need for specific lab tests. Instead, doctors usually rely on a detailed account of the patient’s past health and a thorough physical exam to identify potential causes and decide the best way to treat it. Sometimes, if the doctor suspects any nervous system-related conditions or if esotropia comes on suddenly, they might recommend imaging tests.
To give you a better understanding, here’s some information about the most common types of esotropia seen in children:
Infantile Esotropia: This type of esotropia appears within the first six months of a child’s life. Children with this type typically have a noticeable inward turn of the eye, which is more than 30 degrees. It can also be observed when the child is looking at an object close up or far away. It can sometimes be mistaken for a condition called bilateral sixth nerve palsy, which affects the nerves that control eye movements, but can be ruled out through specific eye tests. Children’s vision is usually unaffected as they compensate for the inward turn by using their other eye, and there are no significant underlying issues with the actual shape of their eyes.
Refractive Accommodative Esotropia: This type of esotropia usually starts around ages 2-3. The inward turn of the eye is usually intermittent and often first noticed by parents when the child is focusing on objects close to them. This condition can get progressively worse, evolving from an inside eyeshift only for near vision to a constant inward turn of the eye. Doctors check the way the eyes respond to changes in light and perform an eye refraction test (which checks how well the eyes focus light) with specific eye drops. This test generally reveals that the child is far-sighted.
Non-Refractive Accommodative Esotropia: This type of esotropia is related to how the eyes adjust to focusing on objects at different distances, without any significant retinal issues. It can often progress from an inside eyeshift when looking at nearby objects to an inward shift for both near and distant objects. It typically begins around age 2-3, and the inside shift is mostly seen when trying to focus on close-up things.
Partially Accommodative Esotropia: In these cases, a large inward turn of the eye, high farsightedness (difficulty seeing objects up close), and normal reaction to changes in light are observed. The inward eye turn may be more noticeable when looking at objects close up and improves partially with glasses alone.
Sensory Esotropia: This type is often characterized by poor vision in one eye, which leads to the unused eye turning inward. This is often accompanied by ‘lazy eye’ (when vision doesn’t develop properly), and the brain favors the other eye.
Treatment Options for Esotropia (Deviation of the Eye Toward the Nose)
Non-surgical and surgical treatments are available to manage poor eye alignment, or ‘esotropia’. Both types of treatments aim to assist patients in using both eyes together (binocularity), prevent a weak or ‘lazy eye’ (amblyopia), and promote the ability to align the eyes when focusing on objects at different distances (peripheral fusion).
Non-surgical treatments involve corrective eyeware and exercises:
* Correcting the eye’s ability to focus (refractive error) – Prescriptions lenses are usually advised for patients after examination. Full prescriptions for hypermetropia (long sightedness) more than +1.5D are recommended, and the patient’s eye alignment should be reassessed after six weeks. Bifocals may be necessary for children with issues aligning their eyes at different distances. The sooner corrective lenses treatment starts after the onset of esotropia (inward misalignment of the eyes), the lower the chance of a lingering condition – partially accommodative esotropia.
* Miotics (a type of eye drop) might also be suggested as an alternative for patients who have difficulty with glasses. If the patient develops preferential vision in one eye (amblyopia), therapies such as patching the preferred eye can be recommended. Exercises to overcome suppression of one eye and to improve eyes working together (negative fusional convergence) can also be beneficial.
* Some studies have also found botulinum toxin injections helpful in treating inward eye alignment in infants and newly diagnosed cases.
Surgical treatments are typically personalised according to the type of esotropia, severity, other clinical findings, patient compliance to non-surgical treatment and such. Here are some common surgical approaches:
* Infantile/Congenital Esotropia – The best time for surgery is usually between 6 months and 2 years. This decision is often made considering the child’s cooperation and understanding of the condition by the parents and the examiner. Surgery may involve weakening the inward pull of the eyes (bimedial recessions) and reducing the strength of eye muscles causing misalignment.
* Refractive Accommodative Esotropia – This type should always avoid surgical intervention. If there’s a vertical deviation associated or A/V pattern, it might require surgical correction.
* Non-Refractive Accommodative Esotropia – Most cases are managed non-surgically with bifocals and eye exercises. However, surgical intervention may be considered if non-surgical methods don’t correct the issue. Procedures might include weakening the inward pull of eyes (medial rectus recession) or restricting this movement (Faden procedure).
* Partially Accommodative Esotropia – Surgery is required for residual deviation that isn’t corrected by glasses. Results have shown improved stereo vision when surgery is done for nonaccommodative conditions in a timely manner.
* Sensory Esotropia – Surgery is usually for cosmetic reasons. Correction of aphakia (absent eye lens) or traumatic cataracts in children is done alongside occlusion therapy, with typically a follow-up of correction once the best possible vision is attained. Surgical intervention is usually done on the less functioning eye.
* Cyclic Esotropia – Surgical correction or the use of botulinum toxin might be needed. The choice of method would be based on the degree of eye deviation on the ‘esotropic’ day, i.e., the day of inward misalignment.
What else can Esotropia (Deviation of the Eye Toward the Nose) be?
It’s important to differentiate between esotropia, which is a condition where one or both eyes turn inwards, and other similar conditions. These include:
- Pseudoesotropia: This can be distinguished from true esotropia by signs like visible skin folds on the inner corner of the eyes, a short distance between the pupils, a wide nasal bridge, or an unusual position of the visual axis.
- Ciancia syndrome: Features of this syndrome include eyes that both appear to be turned in towards the nose, along with uncontrolled eye movements, an inability to move the eyes side to side, and a tight eye muscle.
- Congenital fibrosis syndrome: Also known as strabismus fixus, this condition is typically present from birth and can run in families. It’s characterized by severe inward deviation of one or both eyes and a strong limitation in side-to-side eye movements.
- Congenital sixth nerve palsy: These cases result in limited outward movement of one or both eyes.
- Nystagmus blockage syndrome: This condition involves esotropia in a child with uncontrolled eye movements. The esotropia is believed to be a response to excessive inward movement or convergence to reduce the uncontrolled eye movements.
- Cyclic Esotropia: Characterized by alternating periods of normal and misaligned eyes. The cycles can vary – 24 hours of misalignment followed by 24 hours of normal alignment, or 48 or 72 hours cycles each. This disorder can occur at any age but is mostly seen between the ages of 2 to 6 years.
- Microtropia: In this condition, the misalignment angle is very small (1 to 5 degrees) and can be accompanied by mild vision loss, defective 3D vision, and an area of reduced vision on the retina.
The right diagnosis is crucial because the conditions need different treatments.
What to expect with Esotropia (Deviation of the Eye Toward the Nose)
Overall, the future looks positive for individuals with esotropia, a condition that causes the eyes to turn inwards. A well-structured plan, regular check-ups, and following the treatment protocol carefully are the key factors that determine the outcome. While most esotropia cases are manageable without surgery, a type called congenital esotropia often requires surgical intervention. Opinions vary on whether such surgery should be performed early or later.
It is now generally agreed that aligning the eyes before the age of 2 years can lead to better vision and some maintenance of the eyes working together, often saving a part of vision known as peripheral fusion. Studies have shown that aligning the eyes early on can result in better stability in the long term, improved depth perception (stereopsis), and better development of the eye-brain connection. However, it’s worth noting that about half of the people who undergo surgery for congenital esotropia might need additional surgery later.
Possible Complications When Diagnosed with Esotropia (Deviation of the Eye Toward the Nose)
Managing a child’s cross-eyed condition, also known as esotropia, can come with several drawbacks. These can relate to a loss of dual vision, an increased risk of lazy eye, difficulties with following the treatment plan, and the need for long-term monitoring. In addition, children may face insecurities about their appearance, which may lead to social withdrawal and poor school performance.
Surgical intervention for esotropia has its own possible complications. These include remaining cross-eyed after the surgery, developing a divergent eye turn (exotropia), infection, small non-cancerous growths due to suture material, issues with front part of the eye due to insufficient blood supply, mishaps with the eye muscle such as slippage or loss, or an automatic decrease in heart rate due to eye or eyelid manipulation. Additionally, there are risks associated with general anesthesia that should be considered before making a decision about surgery.
Potential Issues:
- Loss of simultaneous use of both eyes
- Risk of developing lazy eye
- Difficulty adhering to the treatment plan
- Requirement for long-term monitoring
- Appearance-based insecurities leading to antisocial behavior
- Underperformance in school
- Residual cross-eyed condition after surgery
- Development of divergent eye turn post-surgery
- Chances of infection or non-cancerous growth due to sutures
- Eye issues due to poor blood supply
- Loss or slippage of eye muscle
- Change in heart rate due to eye or eyelid manipulation
- Risks related to general anesthesia
Recovery from Esotropia (Deviation of the Eye Toward the Nose)
After eye surgery, it’s important for parents, eye doctors, optometrists, and counselors to collaborate closely to ensure proper care. Nurses and counselors play a key role in explaining to parents how to use postoperative eye drops and maintain eye hygiene. They’ll instruct on how to clean eyelashes and lid margins to prevent infections.
The parents’ involvement during the period immediately after the surgery and during follow-up visits is crucial for the treatment to work as planned. Patients need to have regular check-ups over a long period of time. This is important to correct any vision problems and continue therapy for lazy eye, or amblyopia as it’s called in medical terms. This also includes a special type of eye exercise known as orthoptics, at least once every six months.
Every six months, they should also have a check for squint, or misaligned eyes, to see if there are any changes such as under or overcorrection. This careful monitoring allows the healthcare team to adjust treatment as necessary, ensuring the best possible outcome.
Preventing Esotropia (Deviation of the Eye Toward the Nose)
It’s critical to explain to parents the characteristics of the child’s condition and why taking action promptly is so important. The end results of congenital esotropia (a condition where the eye turns inward from birth) heavily rely on how closely the parents follow the treatment plan. This usually involves patching the child’s eye to prevent partial or complete loss of vision (known as amblyopia) until surgery can be arranged.
Understanding the common signs, potential risk factors, and possible treatment options is essential for parents, and can lead to better results. Having open conversations with medical professionals and asking any questions can also be beneficial.
