My GF currently has it, she has some other long term conditions which make it even worse. It actually affected her eyesight at it's worst last week, pupils constantly moving making it near impossible to focus. Dr has told her 4 - 6 weeks to clear completely, improvement expected within 2 weeks.
Apparently the test which makes it obvious is have the patient follow the movement of a pen in front of the eye whilst observing and jerkiness of pupil motion.
If you have it you have my sympathy!