Duane's Retraction Syndrome Type 1 is defined by which limitation?

Duane's Retraction Syndrome Type 1 is defined by which limitation?

• A. Abduction deficit
• B. Adduction deficit
• C. Vertical movement deficit
• D. Convergence deficit

Answer: (A)

Duane retraction syndrome is a congenital horizontal movement disorder caused by miswiring of the lateral rectus. In Type 1, the defining feature is a marked limitation of abduction, so the eye has trouble moving outward. Adduction tends to be relatively preserved, though there can be some limitation, and when the eye attempts to adduct, the globe can retract due to co-contraction of the horizontal muscles. This pattern—clear abduction deficit with relatively preserved adduction—best fits Type 1. The other options don’t match this specific motility pattern: a problem with adduction would point to a different presentation, vertical movement deficit isn’t characteristic of Duane syndromes, and a convergence deficit isn’t the defining feature of Type 1.

Duane retraction syndrome is a congenital horizontal movement disorder caused by miswiring of the lateral rectus. In Type 1, the defining feature is a marked limitation of abduction, so the eye has trouble moving outward. Adduction tends to be relatively preserved, though there can be some limitation, and when the eye attempts to adduct, the globe can retract due to co-contraction of the horizontal muscles. This pattern—clear abduction deficit with relatively preserved adduction—best fits Type 1. The other options don’t match this specific motility pattern: a problem with adduction would point to a different presentation, vertical movement deficit isn’t characteristic of Duane syndromes, and a convergence deficit isn’t the defining feature of Type 1.