Mydriasis

Dilatation of the pupil,caused by the use of atropine or other mydriatics, or paralysis of the motor oculi nerve.

Source: Ophthalmic Dictionary including pronunciation, derivation and definition of the words used in Optometry and Ophthalmology by James J. Lewis, Oph. D. Professor of Optometry in the Northern Illinois College of Ophthalmology and Otology, Chicago.