Most types of glaucoma do not present their symptoms until the advanced stage. Thus early detection is critical for the best outcome of treatment in glaucoma and is possible by routine ocular examinations or routine health check-up. Once glaucoma is suspected, diagnostic work-up should be performed including evaluation of the optic nerve head and retinal nerve fiber layer and visual field examinations. Treatment of glaucoma is focused to lower the intraocular pressure(IOP) that serves as the most important risk factor of glaucoma. Setting a target pressure before initiation of IOPlowering therapy is important. Medication should be selected in consideration of the efficacy, mode of action, and side effects of agents along with patient compliance. In addition to IOP-lowering therapy, possible systemic vascular problems should be evaluated and managed. The treatment outcome should be followed by measurement of IOP, evaluation of optic nerve head and RNFL, and visual field examinations.