Duane syndrome, also known as Duane retraction syndrome (DRS), is a congenital and non-progressive eye movement disorder. It falls under a group of eye conditions known as congenital cranial dysinnervation disorders (CCDD).
In Duane syndrome, patients may have one or both eyes unable or only partially able to move outward towards the ear (abduction) or inward towards the nose (adduction), or both. The cause of Duane syndrome lies in a congenital faulty development of one of the nerves leading to the eye muscles.
Upper row: Normal eye movements Lower row: When looking to the left, the left eye cannot move freely outward (toward the ear). This sometimes causes the left eye to be turned inward even when looking straight ahead (center).
In Duane syndrome, the sixth cranial nerve, which controls the lateral eye muscle (the muscle that pulls the eye outward toward the ear), does not develop normally. Why this particular nerve does not develop well is not fully understood. As a result, sometimes the muscle itself does not develop normally and is then either weak or tight.
People with Duane syndrome may experience double vision, which may be more pronounced in certain directions of gaze. To avoid perceiving these double images, individuals often adopt a tilted head position, which can be burdensome for the neck in the long term.
Strabismus surgery cannot correct the issue of the underdeveloped nerve or restore normal function to the nerve or muscle. However, the surgery often reduces the bothersome double vision and consequently diminishes the long-term burden of head tilt. Many people with Duane syndrome require multiple eye surgeries.