the Differences Between Types of Exotropia in Eye Care

The distinction of exotropia?

Hello Dr.
Chuang, I recently went to an optical shop to get new glasses and unexpectedly discovered that I have a problem with exotropia.
The owner mentioned that the previous optical shops I visited did not measure my eyes properly.
I would like to ask you, when I look straight ahead with both eyes and cover one eye, then uncover it and cover the other eye, the eye that was covered appears to be slightly exotropic, and the same happens with the other eye.
I do not feel particularly photophobic, but when I get lost in thought, I have heard others say that my eyes appear somewhat exotropic.
What type of exotropia does this indicate? Additionally, I have researched a lot online but am still unsure about my specific type.
Could you please briefly explain the main differences between constant, intermittent, and divergence excess exotropia? It seems to be a kind of cycle? Lastly, thank you for taking the time to respond, and I wish you all the best!

Ye Xiansheng, 20~29 year old female. Ask Date: 2014/09/02

Dr. Zhuang Yamin reply Ophthalmology

Dear Mr.
Yeh,
Based on your description, it appears that your condition is classified as "intermittent exotropia," also known as "hidden exotropia." In simple terms, this occurs when there is a difference in the strength of the medial and lateral rectus muscles that control eye movement, leading to a tendency for the eyes to drift outward.
However, because the degree of misalignment is not severe, the brain compensates by activating the medial muscles to pull the eyes inward during normal vision, making the eye alignment appear normal and preventing double vision.
Misalignment typically only becomes apparent when one eye is covered, disrupting binocular vision, or when the eyes are fatigued.
This type of strabismus is often congenital and may become more pronounced with age and muscle strength decline.
However, as long as the angle of deviation is not significant, it usually does not affect daily life or work, so there is no need for excessive concern.
It is advisable to take regular breaks during prolonged near work, as the medial muscles are required to exert effort throughout the day.
Wishing you good health,
Department of Ophthalmology, Changhua Hospital
Caring for you~

Reply Date: 2014/09/02

More Info

Exotropia is a type of strabismus (misalignment of the eyes) where one or both eyes turn outward. Understanding the different types of exotropia is crucial for effective eye care and management. The three main categories of exotropia are: concomitant (or common) exotropia, intermittent exotropia, and constant (or non-concomitant) exotropia. Each type has distinct characteristics and implications for treatment.

1. Concomitant Exotropia: This is the most common form of exotropia. In this type, the degree of eye misalignment remains relatively constant, regardless of the direction of gaze. For example, if you cover one eye and then the other, the misalignment will be similar in both positions. This type is often associated with a stable visual acuity and can be present at all distances. Treatment options may include corrective lenses, vision therapy, or surgery, depending on the severity and impact on daily life.

2. Intermittent Exotropia: In this type, the outward turning of the eye occurs occasionally, often triggered by fatigue, stress, or prolonged periods of near work. The misalignment may not be present all the time, which can make it more challenging to diagnose. Patients may notice that their eyes appear to drift outward during specific activities or when they are tired. Intermittent exotropia can sometimes be managed with vision therapy or prisms in glasses, but surgery may be considered if the condition worsens or becomes more frequent.

3. Constant Exotropia: This form of exotropia is characterized by a persistent outward turning of one or both eyes. Unlike intermittent exotropia, the misalignment is always present, which can lead to significant visual impairment and issues with depth perception. Patients with constant exotropia may experience double vision or have difficulty focusing on objects. Treatment often involves surgical intervention to realign the eyes, along with potential post-operative vision therapy to improve coordination and depth perception.

In your case, since you mentioned that when you cover one eye and then the other, the previously covered eye appears to have some outward deviation, it suggests that you might be experiencing intermittent exotropia. This condition can be exacerbated by factors such as fatigue or distraction, which aligns with your observation of the misalignment occurring when you are "lost in thought."
It’s essential to have a thorough eye examination by an eye care professional who can assess the degree of misalignment, the presence of any associated symptoms (like double vision or difficulty focusing), and your overall visual function. They can provide a tailored treatment plan based on the specific type of exotropia you have.

In addition to the types of exotropia, it’s also important to consider the potential impact on your daily life. If you find that the misalignment affects your ability to perform tasks, such as reading or driving, or if you experience discomfort or visual fatigue, it may warrant more immediate intervention.

In summary, understanding the differences between the types of exotropia is vital for effective management. If you suspect you have intermittent exotropia, it’s advisable to consult with an eye care specialist who can provide a comprehensive evaluation and discuss potential treatment options tailored to your needs. Regular follow-ups and monitoring are also essential to ensure that any changes in your condition are addressed promptly.

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