Glaucoma can be divided into two categories according to its etiology: primary glaucoma and secondary glaucoma. Patients with primary glaucoma generally have anatomical factors, such as small eye size, short eye axis, hyperopia, and shallow anterior chamber. Glaucoma may be triggered by mood swings, staying too long in dimly lit areas, and prolonged head-down reading. Severe cases can lead to acute grand mal seizures, which can result in permanent blindness if not treated in time. Secondary occurrence of glaucoma is mostly due to trauma, inflammation, hemorrhage, tumor, etc., which damages the structure of the atrial angle and causes the atrial fluid drainage to be obstructed and leads to an increase in intraocular pressure. In conclusion, glaucoma is caused by the inability of the water generated in the eye to drain properly.