tonic pupil

a pupil that is dilated as a result of damage to the nerves supplying the ciliary muscle and iris. It reacts poorly to light but contracts normally for near vision, with slow redilation of the pupil on refixation at a distance. The most common characteristic of the tonic pupil is its extreme sensitivity to dilute 0.1% pilocarpine drops, which cause marked constriction of a tonic pupil but has little effect on a normal pupil.