A neurological disorder characterized by a pupil that reacts poorly to light but better to accommodation. The affected pupil is initially dilated and responds sluggishly to light. Pupillary constriction is more noticeable with near focus and remains tonically constricted with slow re-dilation. Adie’s pupil is usually unilateral, with an average onset age of 32 years, and may be associated with absent deep tendon reflexes in Holmes-Adie syndrome.