Can an afferent pupillary defect disappear?

Here is My Question:
Can a relative afferent pupillary defect and pallor of the optic disc disappear? I have conflicting reports from neurologist and opthamologist. How frequently or easily are these misdiagnosed and does it make a difference is practioner is using direct eye exam or dilated eye exam?

Answer:
An afferent pupillary defect can disappear over time depending on what caused the afferent pupillary defect (the vast majority of the time it is due to optic nerve damage, for example, optic neuritis).
If the cause of an afferent pupillary defect is a mild case of optic neuritis with excellent recovery it is possible for the afferent pupillary defect to disappear.  However most of the time, once an afferent pupillary defect occurs, it is rare for it disappear.  

However optic nerve pallor does not disappear.  Once an optic nerve is damaged and pallor sets in, it is irreversible.

Both an afferent pupillary defect and optic nerve pallor may both be misdiagnosed for a variety of reasons (including but not limited to: the experience of the physician doing the exam, presence or absence of cataracts, etc.).  

An afferent pupillary defect can only be tested prior to dilation (once the eyes are dilated one can no longer test for an afferent pupillary defect).

It is usually easier to detect optic nerve pallor on a dilated eye exam but a competent physician can detect it even on a direct, undilated exam.

Sincerely,

Benjamin Osborne, MD
Associate Professor
Departments of Neurology and Ophthalmology
Georgetown University Hospital