Alternating rapid contraction and dilatation of the pupil of the eye.
Abnormal rhythmical variations in the size of the pupils, independent of the intensity of the light falling on the eyes. It is occasionally seen in various diseases of the nervous system.
Hippus is a tremor of the iris which produces alternating contraction and dilatation of the pupil.
The rhythmic, spasmodic dilation and contraction of the pupil in response to light. It is usually normal and is often more evident in younger people.