Mydriatic eyedrops enlarge (dilate) the pupils of the eyes and may allow the person to see around a cataract. Mydriatic drops are rarely prescribed for cataracts and are only used for a short period of time. Decisions about the use of mydriatic eyedrops need to be made after discussion with an ophthalmologist about the potential benefits.

Mydriatic eyedrops may be used in infants and children under age 3 to enlarge the pupil, allowing more light to pass around a cataract that covers only part of the lens. Because more light reaches the retina, the child's sight may be saved. After age 3, the growth rate of the eyeball usually slows considerably. Cataract surgery and replacement of the lens with the appropriate size intraocular lens (IOL) can be done with greater success at that time.

Mydriatic medicines are not used in people who have some types of glaucoma.