APD
Afferent Pupillary Defect
Plain-language definition
A defect in the visual signal pathway from eye to brain, detected by the swinging flashlight test. Often called a Marcus Gunn pupil.
Where this term comes up
“An APD (Marcus Gunn pupil) is one of the most important signs of optic nerve damage”
Test · Pupil Examination
- Category
- Clinical term
- Also written as
- No alternate forms listed.
Clinical terms are words clinicians use to describe symptoms, signs, risk factors, or patterns seen during evaluation.
Related glossary terms
- RAPD
Relative Afferent Pupillary Defect
- sympathetic
Sympathetic Nervous System
- afferent
Carrying Signals to the Brain
- aneurysm
Vessel Bulge
- anhidrosis
Absent Sweating
- anisocoria
Pupils of Unequal Size
A note on medical context
A glossary definition can explain a word, but it cannot tell you whether a symptom or test result is serious. If this term came from an article, use the full article and your clinician's guidance for context.