- Dilation of the pupils induced by eyedrops. The opposite of miosis.
* * *- alternating m. m. alternately affecting each eye.- amaurotic m. a moderate widening of both pupils resulting from impaired visual input from one or both eyes.- paralytic m. pupillary dilation due to paralysis of the sphincter muscle of the pupil induced by anticholinergic drugs given topically or systemically, or resulting from lesions of the oculomotor nucleus or nerve, contusion of the eyeball, or glaucoma.- spastic m. pupillary dilation due to contraction of the dilator muscle of the pupil induced by adrenergic drugs or by stimulation of the sympathetic pathway.
* * *my·dri·a·sis mə-'drī-ə-səs n, pl -a·ses -.sēz excessive or prolonged dilation of the pupil of the eye
* * *n.widening of the pupil, which occurs normally in dim light. The commonest cause of prolonged mydriasis is drug therapy (see mydriatic) or injury to the eye. See also cycloplegia. Compare miosis.
* * *my·dri·a·sis (mĭ-driґə-sis) [Gr.] 1. physiologic dilatation of the pupil. 2. abnormal dilatation of the pupil. 3. dilatation of the pupil caused by a drug.
Medical dictionary. 2011.