👁️ RAPD (Relative Afferent Pupillary Defect) — Clinical Guide 🔬 What is RAPD? RAPD (Relative Afferent Pupillary Defect), also called Marcus Gunn pupil, is a sign that one optic nerve or retina is not transmitting light signals properly to the brain. 👉 It indicates a problem in the afferent visual pathway (retina → optic nerve → brain). 🧪 How to Test — Swinging Flashlight Test Shine light in one eye → both pupils constrict (normal reflex). Quickly swing light to other eye. Normal: both pupils