Glaucoma is caused by a large group of eye diseases that raise the pressure inside the eye. The elevated pressure is caused by an obstruction to the flow of water out of the atrium in the eye. In the long run, the excessive pressure will cause damage to the optic nerve. Only through early detection, diagnosis and treatment can your vision be preserved. The eye is like a pool of water, with the faucet and drain always open. Atrial water is constantly circulating through the anterior chamber. The atrial fluid is secreted by the ciliary body, which is located behind the iris. It flows between the iris and the lens, nourishes the cornea and lens, and exits through the trabecular meshwork. The trabecular meshwork is a very small, sponge-like tissue that is about 1/5 of an inch wide and acts like a drainage outlet for the eye. The trabecular meshwork is located at the point where the cornea meets the iris. When the drainage opening is blocked, the atrial fluid that is constantly being produced cannot leave the eye quickly enough, resulting in a regression in atrial fluid retention. However, because the eye is a closed container, the water in the “pool” cannot escape, so the retained fluid causes an increase in intraocular pressure (IOP). We call this glaucoma. To understand how the elevated pressure affects the eye, we can think of the eye as a balloon. When too much gas is pumped into the balloon, the rising pressure bursts the balloon. But the eye is still relatively strong and does not burst as easily. Instead, the pressure acts on the weakest point, which is the sclera where the optic nerve leaves the eye. The normal value for intraocular pressure is 10-21 mmHg. The optic nerve is the part of the eye that transmits visual information to the brain. It is made up of millions of retinal ganglion cells, each about several inches long, and it is extremely long and thin, about one-two-thousandth of an inch in diameter. When the pressure inside the eye rises, the nerve cells are compressed, causing them to become damaged and eventually die. The death of these cells will result in permanent vision loss. Early diagnosis and treatment can prevent this from happening.