Check light reaction: Is anisocoria greater in light or dark?

Good light reaction in both eyes
More anisocoria in dark room

Poor light reaction in one eye
More anisocoria in lit room

Physiologic anisocoria

Horner syndrome

Check for dilation lag
Consider 0.5% or 1% apraclonidine test
Consider 10% cocaine test

Dilation lag of smaller pupil absent
Dilation occurs with 10% cocaine

Dilation lag of smaller pupil is present
Reversal of anisocoria with 0.5% or 1% apraclonidine
Dilation does not occur with 10% cocaine

End

Postganglionic Horner syndrome

Central or preganglionic Horner syndrome

Hydroxyamphetamine (Paredrine) test^*

Dilation occurs with 1% hydroxyamphetamine

Dilation does not occur with 1% hydroxyamphetamine

End

Adie pupil

Traumatic iris damage

Slit lamp examination of iris
Check near constriction
Consider 0.125% pilocarpine test

Torn pupillary border
Sluggish near constriction

Round pupil
Poor near constriction
No constriction with 0.125% pilocarpine

Sector iris palsy
Tonic near constriction
Constriction occurs with 0.125% pilocarpine

Pharmacologic pupil dilation

Third cranial nerve palsy

Pilocarpine 1% test

Constriction occurs with 1% pilocarpine

Constriction does not occur with 1% pilocarpine