Medical treatment is a mainstay for the management of glaucoma (Realini 2011; Marquis and Whitson 2005; Hoyng and van Beek 2000). Intraocular pressure (IOP) lowering has been long recognized as and still represents the primary and most widely employed treatment to prevent glaucomatous vision loss (Musch et al. 2011; Leske et al. 2003; The Advanced Glaucoma Intervention Study (AGIS) 2000). Soon after the recognition that "tension" or IOP was related to glaucoma, pharmacological agents were introduced in the mid-1800s, first with the calabar bean (Realini 2011; Proudfoot 2006). Since then, an explosion of pharmacological agents targeting numerous intracellular and molecular signaling pathways has resulted in a plethora of drugs to lower IOP and treat glaucoma. Aqueous humor dynamics provides the basis for understanding each of these medical therapies.