Glaucoma, if left untreated or improperly treated leading to worsening, can result in blindness, which is referred to as absolute glaucoma. In such cases, it becomes impossible to recover vision; in other words, it is irreversible. Therefore, it is crucial to proactively treat glaucoma after its onset by reducing eye pressure to protect vision, adjusting one's mindset, resting adequately, and avoiding close-range activities. The treatment is generally quite successful nowadays. Glaucoma can be classified into acute angle-closure glaucoma and open-angle glaucoma, both of which are types of primary glaucoma. Additionally, it can be categorized into primary glaucoma, secondary glaucoma, congenital glaucoma, and mixed glaucoma. With active treatment, the outcomes for glaucoma are generally good.