Glaucoma is an eye disease where a person may lose vision very slowly. The vision loss takes place so slowly that it is difficult to notice. What vision is lost is generally permanent. It happens more often as a person gets older. The good news about glaucoma is that once identified, it can be treated, and vision loss can be stopped or minimized. The vast majority of people diagnosed with glaucoma do very well and maintain good vision throughout their lives. Problem cases are those that don’t come to attention at the earlier stages.
There are two common misunderstandings about glaucoma. One misunderstanding is the idea that glaucoma exists only when someone has a higher than normal eye pressure. The other misunderstanding is that a normal eye pressure means there is no glaucoma. Both of these ideas are wrong. There are, in fact, people who have a “normal” pressure and yet have glaucoma. And there are people who have a higher than normal pressure who do not have glaucoma.
So what is glaucoma? Glaucoma can be thought of as a disease of a part of the eye called the optic nerve. The optic nerve is the large nerve that exits the back of the eye and sends visual information to the brain. It is like a cable that transmits information. It may be affected by pressure, but each individual, depending on individual differences may be more or less susceptible to damage from eye pressure. That is why one person may have glaucoma with a given pressure and another person with exactly the same pressure may not.
How is glaucoma identified? That is a very good question. An optic nerve with glaucoma has material missing from its structure. With special lenses and equipment, it is possible to see into the back of the eye and look at the optic nerve where it “plugs in.” An ophthalmologist can see what the optic nerve structure looks like. Looking at the appearance of the nerve can tell an ophthalmologist whether an individual may have glaucoma. There are also instruments that produce special images of the optic nerve. These help detect glaucoma in an optic nerve in the early stages.