The eye is like a sphere that contains water (atrial fluid) and some tissue, which exerts a certain amount of pressure on the walls of the eye. Simply put, glaucoma is caused by an increase in pressure in the eyeball (medically referred to as “intraocular pressure”). The normal eye can produce atrial fluid 24 hours a day, and can also discharge it out of the eye through excretory channels, and when the amount of atrial fluid produced and the amount of atrial fluid discharged are equal, the IOP is normal. Why do some people have elevated intraocular pressure? Generally speaking, it is because the drainage system in the eye is blocked and excess water keeps accumulating in the eye where space is limited, and the IOP becomes high. So why does glaucoma occur when IOP is elevated? For example, the optic nerve is the most intolerant part of the eye. If the eye pressure is too high for a long time, the optic nerve will be damaged, and the range of vision will be narrowed (narrowing of the field of vision), and the vision will be reduced. Glaucoma. Since optic nerve cells cannot be regenerated after death, this loss of vision or narrowing of the field of vision in glaucoma is also irreversible and irretrievable. Medical doctors do not yet know the definite cause of glaucoma. However, what we can be sure of is that glaucoma is not contagious and not life-threatening. With earlier diagnosis, early treatment and adherence to treatment, glaucoma is still treatable and many patients can maintain useful vision for life.