New drugs are developed rapidly with novel ideas of action mechanisms for the treatment of glaucoma. The most classic drugs under development are to lower the intraocular pressure (IOP). New agents were invented to lower the IOP through ① induction of metalloproteinases (MMPs), ② contraction of trabecular meshwork cells, ③ inhibition of aqueous humor secretion, and ④ activation of CB-1 receptor, The second class of drugs under development is intended to improve the ocular blood flow (OBF), particularly in retina and optic nerve head (ONH). Drugs that improve the OBF irrespective of the IOP changes could be quite useful for the treatment of normal tension or low-tension glaucoma. Neuroprotection is the latest developed mechanisms of glaucoma treatment. Although the history of neuroprotection research is very short, there are many agents under investigation in this class. They include ① blockade of N-methyl-D-aspartate receptor, ② neurotrophic agents, ③ inhibition of inducible nitric oxide synthases (iNOS), ④ inhibition of apoptosis, ⑤ protective autoimmunity, ⑥ stem cell therapy, and so on. Since all drugs for glaucoma treatment are used to stabilize the disease rather than to cure it, it is critical that an ideal drug with high therapeutic index and low cost price should be invented.