Some people believe, “With glaucoma you should drink less water, even if you are thirsty, you should limit your water intake.” Some people also think: “Drinking water will not increase the IOP.” In fact, both of these perceptions are inappropriate. Whether a glaucoma patient should drink more or less water is actually related to the type of glaucoma the patient has, and we will introduce them one by one below. What we need to understand is that the atrial fluid related to intraocular pressure does not come directly from the water in the blood, it is generated by the eye through the selective active secretion of special tissue structures, and is responsible for the nutrient metabolism of many tissues in the eye. Glaucoma is a type of disease that causes increased intraocular pressure and damage to the optic nerve due to obstruction of atrial flow in the eye. When a patient drinks a lot of water at one time, the blood volume in the body increases, causing a sudden decrease in blood osmolarity and a relative increase in intraocular atrial aqueous osmolarity, which leads to a corresponding increase in atrial aqueous production. Therefore, if a patient with glaucoma who has not undergone surgery, especially the closed-angle type, consumes a large amount of water in a short period of time, the increase in atrial aqueous production will cause a significant increase in intraocular pressure, resulting in an acute attack. However, on the other hand, thirst is a physiological signal of the body, indicating a lack of water in the body, which should be replenished in time, otherwise it may cause metabolic disorders of water and electrolytes in the body with undesirable consequences, especially in the elderly and patients with certain diseases such as hyperviscosity. Severe dehydration can contribute to thrombosis and induce cerebrovascular accidents or myocardial infarction. Therefore, patients with glaucoma should live normally without restricting their water intake. However, for patients with glaucoma without surgery, especially those with closed-angle glaucoma, they should avoid consuming large amounts of water in a short period of time. For patients with open-angle glaucoma, since its pathogenesis is different from that of closed-angle glaucoma, the mechanism of glaucomatous optic nerve damage may be related to poor blood circulation (high blood viscosity, etc.), therefore, proper water intake is beneficial, together with moderate aerobic exercise, which can promote the body’s metabolism and may also improve the condition. Do I need to control the amount of water I drink for glaucoma patients who have undergone surgery? As we know, the principle of glaucoma surgery is to unblock the atrial aqueous outflow channel, which is artificially created through surgery, so there is a possibility that the atrial aqueous outflow may be too smooth. For such patients, we not only do not restrict the amount of water they drink, but sometimes they need to drink more to increase atrial aqueous production and maintain the ideal anterior chamber and intraocular pressure. For patients who have undergone glaucoma surgery and whose IOP is well controlled, they can drink water as normal, but avoid stimulating drinks such as strong tea, coffee, cocoa, etc., because these drinks tend to have an excitatory effect on the nervous system, affecting the stability of the vegetative nervous system and making IOP rise.