Relative Afferent Pupillary Defect

Question 1

Also known as

Answer 1

Marcus-Gunn pupil

Question 2

Features

Answer 2

the affected and normal eye appears to dilate when light is shone on the affected

Question 3

Cause

Answer 3

It is caused by a lesion anterior to the optic chiasm i.e. optic nerve or retina

retina: detachment
optic nerve: optic neuritis e.g. multiple sclerosis

Question 4

Pathway of pupillary light reflex

Afferent vs Efferent

Answer 4

afferent: retina → optic nerve → lateral geniculate body → midbrain
efferent: Edinger-Westphal nucleus (midbrain) → oculomotor nerve