If you are able to read these sentences with ease and clearly, you are lucky to have good eye vision. Having good eye sight despite needing glasses or other optical instruments means you are among those who are fortunate to still be able to see the beauty of the world. If you ask a doctor, you will be surprised to know that there are many conditions that may affect the eye function. One of them is Duane syndrome. The question is, is Duane syndrome a lazy eye?
First thing first, what is Duane syndrome? Duane syndrome is an eye movement disorder characterised by horizontal eye movement limitation. This disorder is present at birth, making it a congenital disorder. Duane syndrome is a type of strabismus (misalignment of the eye). Only one eye is affected in around 80% of those with Duane syndrome with the likelihood of the left side being affected. Although, both eyes can be affected in some cases with one eye being more affected than the other. Most people with Duane syndrome get this condition spontaneously, meaning there is no family history of having this condition. 30% of people with Duane syndrome already have other congenital problems.
Duane syndrome is caused from the miswiring of the nerves to the eye muscles. Reasons being why there is limitation to the horizontal eye movement in Duane syndrome is the nerve responsible for this does not develop normally. This specific nerve is known as the 6th cranial nerve. It is not well understood why this nerve is unable to develop normally but the outcome is the nerve can be weak or tight. At times, the muscle responsible for the eye movement did not develop normally. Apart from the 6th cranial nerve problem, there may be miswiring of the 3rd cranial nerve that functions to control the medial rectus muscle. Knowing the cause and effect of Duane syndrome can help you understand the symptoms.
Symptoms of Duane syndrome depend on the types. Generally, there are 3 types. 78% of those with Duane syndrome show type 1 symptoms which are limited ability of the affected eye to move outward toward the ear but able to move the eye toward the nose. Type 2 shows symptoms of limited ability of the affected eye to move toward the nose but able to move outward toward the ears. Meanwhile, type 3 shows the eyes having limitation to move inward toward the nose and outward toward the ears. Apart from symptoms depending on the type, the patient may also show head tilting to one side in an attempt to keep the eye straight. Duane syndrome may make a person have a smaller eye compared to the other side.
Back to our main question, “is Duane syndrome a lazy eye”?. To answer this, we have to know a bit more about the lazy eye itself. Lazy eye or known as amblyopia, is a condition where one eye has blurry vision but another is normal. It is caused by the loss or lack of development or clear vision resulting from the breakdown of the connection of the brain and eye. Thus, the answer to this question is no, Duane syndrome is not a lazy eye but around 10% of those with Duane syndrome do have amblyopia or lazy eyes.
Duane syndrome typically does not cause a person to have other eye problems. They can see well despite their eyes having this movement issue. Follow-up eye exams are recommended to ensure good long-term vision is secured. At times, Duane syndrome may be associated with other eye problems such as amblyopia, cataract, crocodile tears and nystagmus (repetitive uncontrolled eye movement). Vision is usually not affected unless patients have a squint or already require glasses.
It is uncommon for patients to seek treatment as the majority of people with Duane syndrome can make up for the lack of the eye movement with slight change to the way of holding their head. Most patients do not require surgery to fix Duane syndrome symptoms. However, surgery may be needed to prevent amblyopia or to improve patient’s comfort when looking straight and improve other eye problems associated. Multiple eye surgeries may be needed in some cases and take weeks or months before improvement can be seen. Some people may only need treatment such as spectacles or contact glasses to improve their vision. Some may need prism glasses to compensate for the head position and improve their vision. Injection of botox may be recommended in certain cases.
In essence, Duane syndrome is a congenital eye disorder characterised by the eye unable to move horizontally toward the nose or ear, or even both. It is typically caused by the underdevelopment of the nerve responsible for the eye movement. Duane syndrome does not directly translate to lazy eyes despite small cases will have amblyopia. Treatment is not usually needed in most cases but when it is needed, most can be corrected with non-surgical management.
