Duane syndrome is a congenital type of strabismus (a disorder in which the eyes don’t look in exactly the same direction at the same time).
Where most forms of strabismus leave side-to-side eye movements intact, in Duane syndrome the “wiring” of the eye muscles gets mixed, and movement of eye(s) becomes limited in certain directions.
Thus, people with Duane syndrome have difficulty rotating one or both eyes outward or inward.
Causes and Types of Duane Syndrome
Duane syndrome is caused by an abnormal development of the nerves that control the eye(s), and it impacts the fetus early in gestation.
The 3 different types of Duane syndrome
There are three types of Duane syndrome — in all three types, the opening of the eye narrows and the eyeball retracts when the eye moves inward.
Type I Duane Syndrome:
- limited or no ability to move the eye outward (the eye widens when the person tries to move it outward)
- little to no difficulty for the eye to move inward
Type II Duane Syndrome:
- limited or no ability to move the eye inward
- little to no difficulty for the eye to move outward
Type III Duane Syndrome:
- limited or no ability to move the eye either inward or outward
Symptoms and Treatment of Duane Syndrome
Symptoms of Duane syndrome include:
- misaligned eyes
- abnormal head posture as people struggle to see better
- reduced vision in the affected eye
Additionally, the affected eye may appear smaller than the other eye, and it may deviate upward or downward from time to time.
Because the affected sixth cranial nerve cannot be repaired or replaced, there is no cure for Duane syndrome. However, for people whose lives are significantly disrupted by the condition, surgery can be very helpful.
The aim of surgery is to:
- Reduce / stop the abnormal head posture many develop attempting to see better
- Reduce the angle of strabismus (misalignment of the eyes)
Duane syndrome can be also sometimes be treated more conservatively with glasses or patching of the unaffected eye.