What is (are) Duane syndrome type 1 ?
Duane syndrome type 1 is the most common type of Duane syndrome, an eye movement disorder that is present at birth. People with Duane syndrome have restricted ability to move the affected eye(s) outward toward the ear (abduction) and/or inward toward the nose (adduction). The different types are distinguished by the eye movements that are most restricted. Duane syndrome type 1 is characterized by absent to very restricted abduction and normal to mildly restricted adduction. The eye opening (palpebral fissure) narrows and the eyeball retracts into the orbit with adduction. With abduction, the reverse occurs. One or both eyes may be affected. The majority of cases are sporadic (not inherited), while about 10% are familial. 70% of affected people do not have any other abnormalities at birth (isolated Duane syndrome).