RAPD
Also written as: RAPD — Relative Afferent Pupillary Defect
Asymmetric pupillary response to light indicating unilateral or asymmetric optic nerve dysfunction.
Full Definition
Relative Afferent Pupillary Defect (RAPD) is a critical clinical sign indicating unilateral or asymmetric damage to the afferent visual pathway, typically the optic nerve or retina. When tested with the swinging flashlight test, the affected pupil paradoxically dilates when light is shifted from the normal eye to the affected eye, despite direct illumination. This occurs because the damaged afferent pathway transmits a weaker signal to the pupillary control centers in the midbrain. RAPD is also known as a Marcus Gunn pupil and is one of the most reliable objective signs of optic nerve disease. The presence and degree of RAPD correlates with the extent of visual pathway damage and is crucial for diagnosing conditions such as optic neuritis, optic neuropathy, and severe retinal disease.
Usage
Usage note: Always capitalize RAPD; specify grade when documenting (trace, 1+, 2+, 3+, 4+).
In Context
- "A 2+ RAPD in the right eye confirmed significant optic nerve dysfunction." — Clinical examination
- "The absence of RAPD helped rule out optic neuritis as the cause of visual loss." — Diagnostic workup