It is a benign condition.
Females (70%) > males (20%)
Unilateral in 80% of cases
A Holmes-Adie pupil is sluggish to accomodate and reacts poorly, if at all, to light.
If a Holmes-Adie pupil is associated with absent leg reflexes it is known as Holmes-Adie Syndrome.
Since that was such a short battle lets just throw in a quick recap of the diferentials for a dilated pupil:
- third nerve palsy
- trauma - sphincter pupillae rupture