Glaucoma is the second leading cause of blindness worldwide and is still a mysterium. Despite some risk factors are known, like individually elevated intraocular pressure, myopia, age, genetic factors, as well as vascular risk factors and smoking, the exact mechanism developing a glaucomatous optic neuropathy are still unknown. In the pathogenesis of glaucoma oxidative stress seems to play an important role. The mitochondria have an abnormal DNS and the antioxidative capacity is reduced. In addition, in the anterior segment, e.g. trabecular meshwork as well as in the posterior pole glaucoma patients show an increased oxidative stress. Therefore oxidative stress should be considered in therapeutic approaches to glaucoma patients.