Pupil dilating medications are usually ciliary muscle paralyzing agents, which can be divided into two types depending on the duration of action: the first type, short-acting ciliary muscle paralyzing agents, usually tropicamide eye drops, which usually last for about 6-8 hours. The second, long-acting ciliary muscle paralyzing agent, such as atropine sulfate ophthalmic gel or atropine drops, usually lasts about three weeks. The difference in the action of these two types of medications determines the use for different purposes. Short-acting ciliary muscle numbing agents are generally used for optometry in children from six years of age and up to twelve years of age, or for moving the pupil after internal eye surgery, such as in the treatment of uveitis. Long-acting ciliary muscle paralytics, on the other hand, are generally used for dilated eye examinations in children up to six years of age.