A persistently small pupil (miosis)
A notable difference in pupil size between the two eyes (anisocoria)
Little or delayed opening (dilation) of the affected pupil in dim light
Drooping of the upper eyelid (ptosis)
Slight elevation of the lower lid, sometimes called upside-down ptosis
Little or no sweating (anhidrosis) either on the entire side of the face or an isolated patch of skin on the affected side