Embodiments disclosed herein provide devices, systems, and methods for reducing intraocular pressure. For example, the disclosed devices, systems, and methods are useful for reducing intraocular pressure resulting from conditions, such as acute glaucoma, on a short-term basis until a definitive surgical procedure is performed. More particularly, valved trocar cannula systems for reducing intraocular pressure resulting from conditions, such as acute glaucoma, pending surgical intervention in an operating room are disclosed. In practice, a trocar assembly is used to place a valved cannula assembly in a patient's eye, such as in the anterior chamber or pars plana, to reduce high intraocular pressure. The valved cannula is then left in the patient's eye for a period of time to continuously allow aqueous humor or liquid vitreous humor to flow therethrough, until the patient may be surgically treated in an operating room.