For convergence-retraction syndrome, is the convergence/retraction component the fast phase or slow phase?

• A. Slow phase
• B. Null point
• C. Fast phase
• D. Neutral point

Answer: (C)

When the patient attempts to look upward, the unusual movement that catches attention is a rapid, jerky convergence with globe retraction. That brisk inward/adduction burst is the fast phase of a convergence-retraction nystagmus. The upward gaze attempt is not sustained smoothly because the dorsal midbrain pathways that normally drive upgaze are disrupted, so the eyes momentarily snap into convergence and retract quickly, followed by a slower, less coordinated phase that doesn’t complete a true upward movement. So the convergence/retraction component is the fast phase.