Glaucoma comprises a group of progressive, neurodegenerative disorders characterized by retinal ganglion cell death and nerve fiber layer atrophy. Several randomized controlled trials have consistently demonstrated the efficacy of intraocular pressure lowering to slow or halt the measurable progression of the disease. Medical therapy, in places where it is easily accessible, is often the primary method to lower intraocular pressure. We review the medical options currently available and possible future options currently in development. The 5 contemporary classes of topical agents in use include prostaglandin analogs, beta blockers, carbonic anhydrase inhibitors, alpha agonists, and cholinergics. In addition, several fixed combination agents are commercially available. Agents from each of these classes have unique mechanisms of action, adverse effects, and other characteristics that impact how they are used in clinical practice. Despite the plethora of medical options available, there are limitations to topical ophthalmic therapy such as the high rate of noncompliance and local and systemic adverse effects. Alternate and sustained drug delivery models, such as injectable agents and punctal plug delivery systems, may in the future alleviate some such concerns and lead to increased efficacy of treatment while minimizing adverse effects.