Duane Syndrome: A Closer Look at the Rare Eye Movement Disorder

Medically reviewed by Tina Patel, Contact Lens Optician at Feel Good Contacts on 11 August 2023

• Understanding Duane syndrome
• Classification and subtypes of Duane syndrome
• Causes and risk factors
• Recognising the symptoms
• Diagnosis
• Treatment options
• Living with Duane syndrome
• Research and future outlook

Understanding Duane syndrome

Duane syndrome (DS) is a congenital eye movement disorder and is present from birth. It can affect one or both eyes. Certain cranial nerve pathways in the brain are affected, subsequently influencing the movement of the eyes. In particular, the functionality of the lateral rectus muscle, responsible for eye movement towards the ear, is compromised by this syndrome.

The rarity of this condition is accentuated by its prevalence rate in the wider population, believed to be anywhere between 1 in 1,000 and 1 in 10,000 individuals. Despite its relatively scarce occurrence, Duane syndrome makes up a considerable number of strabismus cases, a condition characterised by the misalignment of the eyes.

Classification and subtypes of Duane syndrome

Duane syndrome is typically classified into three primary subtypes - type 1, type 2, and type 3. These classifications are based on the specific limitations and abnormalities observed in the eye movements of the affected individuals.

• Type 1: this is the most common form of Duane syndrome, characterised by a limitation or complete inability to move the eye outward toward the ear. However, the inward movement of the eye towards the nose is usually normal.
• Type 2: in this type, the ability to move the eye inward towards the nose is limited, while the outward movement toward the ear is generally normal.
• Type 3: this type is characterised by limited ability to move the eye both inward toward the nose and outward toward the ear.

Causes and risk factors

Duane syndrome is an eye condition where some of the nerves fail to develop normally and therefore fail to work properly. This eye condition can be caused by genetic or environmental influences during the early stages of pregnancy. In Duane syndrome, the nerves that regulate the medial (middle) and lateral (outside) eye muscles are incorrectly connected. Approximately 10% of cases with Duane syndrome have family members who also suffer from the condition. However, the majority of cases arise without any identifiable cause.

Recognising the symptoms

The symptoms of Duane syndrome can vary depending on the specific subtype and severity of the condition. However, some common symptoms include:

• Head posture: individuals with Duane syndrome often adopt an abnormal head posture, typically turning their head to the right or left. This compensatory head turn is an intuitive attempt to improve their vision by aligning the eyes better.
• Eye misalignment: Duane syndrome is a form of strabismus, where the eyes are misaligned and point in different directions. This can occur occasionally or frequently, depending on the severity of the condition.
• Eye closure: in some cases, individuals with Duane syndrome may close one eye to see better. This is particularly common when trying to focus on objects at a distance or in bright light.

Older children and adults may experience double vision, neck pain, headaches, and difficulty seeing things on the side of the affected eye. However, since these symptoms can also be caused by other eye disorders, it's crucial to attend regular eye tests.

Diagnosis

The diagnosis of Duane syndrome typically involves a comprehensive eye examination by an ophthalmologist. The doctor will gather a complete medical and family history, conduct a full medical exam and vision test, measure the degree of eye misalignment, test the range of eye movements, and assess whether an abnormal head turn is being used to improve vision.

In addition to these clinical evaluations, the doctor may recommend referral to a primary care doctor or specialist to check for possible disorders associated with Duane syndrome. This could involve examining the spine, neck, hands, hearing, and palate (the roof of the mouth) to rule out other associated conditions.

Treatment options

The treatment approach for Duane syndrome is typically tailored to the individual's specific symptoms and needs. Some people with Duane syndrome may not experience significant symptoms that interfere with their daily lives. For such individuals, long-term monitoring by an eye doctor may be all that's required.

However, eye muscle surgery may be necessary for those with more severe symptoms, such as serious eye misalignment or the inability to see properly without turning their heads to the side. While surgery cannot correct the underdeveloped cranial nerve causing limited eye movement, it can help reposition the other eye muscles to improve eye alignment and function.

Non-surgical treatment options may also be considered, including spectacles or contact lenses for refractive error, prism glasses to improve the compensatory head position, and the use of botulinum toxin to reduce the amount of deviation and leash phenomenon (upshoot or downshoot of the globe with adduction).

Living with Duane syndrome

Living with Duane syndrome can present certain challenges, but with the right support and management strategies, individuals with this condition can lead a normal and fulfilling life. It's important to regularly monitor the condition, follow the prescribed treatment plan, and maintain open lines of communication with the healthcare team.

In addition, adopting specific coping strategies can be helpful. For instance, learning how to use a compensatory head turn to improve vision, wearing corrective glasses, or using eye patches can all contribute to managing the condition effectively.

Research and medical advancements

The field of research related to Duane syndrome is continually evolving, with ongoing studies and clinical trials seeking to better understand the condition and develop improved treatment strategies. Current research focuses on understanding the genetic factors associated with Duane syndrome, exploring new surgical techniques, and studying the long-term outcomes of existing treatment approaches.

Despite the challenges associated with Duane syndrome, the future looks promising. With advancements in medical research and the continued development of more effective treatment strategies, there is hope for improved management and quality of life for individuals with this condition.

Conclusion

Duane syndrome is a rare eye movement disorder that can significantly impact the lives of those affected. However, with early diagnosis, an appropriate management plan, and ongoing monitoring, individuals with Duane syndrome can lead fulfilling lives. Continued research and advancements in treatment options promise a brighter future for those living with this condition. As awareness and understanding of Duane syndrome increases, so does the potential for improved patient outcomes.