Glaucoma is a disease where the eye pressure is typically too high, leading to damage to the optic nerve. The optic nerve supplies all of the vision for the eye, and any damage that occurs is typically irreversible. The pressure level at which damage occurs is variable from person to person. There are many different types of glaucoma. The differences between types of glaucoma usually relate to the cause of increased pressure in the eye. Primary open angle glaucoma is the most common type of glaucoma in Western countries, and this basically means that there is no particular reason that can be seen to explain elevation in eye pressure. Most ophthalmologists consider glaucoma that develops with eye pressures in the statistically normal range “normal tension” or “low tension” glaucoma, but this could be considered a subtype of “primary open angle glaucoma”.
For most people, glaucoma is a slowly progressive process that takes years to cause serious damage to the vision. There is no “cure” for glaucoma, but the majority of people with glaucoma can be controlled with medications. Laser may be helpful in some cases as a relatively easy and low-risk office procedure. A significant minority of patients will require surgery. These patients are at risk for losing vision, but many of them will maintain their vision as well with successful treatment.
There are certain risk factors for losing vision from glaucoma. Being diagnosed early in the course of the disease can be helpful. Glaucoma is often a silent disease, with no symptoms until late in the course of the disease. Fifty percent of people with glaucoma even in developed countries may be undiagnosed. Patients who already have more advanced disease may tend to be more difficult to control. With less reserve left in the optic nerve, there is less of a chance of maintaining the vision long-term. Patients who don’t follow their doctor’s recommendations for treatment and follow up put themselves at risk for losing vision. Patients who do research about their condition on their own seem to understand their disease better and comply better with treatment.
Certain types of glaucoma are more likely to lead to blindness. Glaucomas related to blood vessel problems (diabetes, a stroke in the retina) can be quite severe. Glaucoma related to inflammation in the eye, or glaucoma occurring after certain operations can be tougher to control. Angle closure glaucoma tends to be more severe and harder to control, and surgery carries a higher risk of complications. Glaucoma associated with higher pressure and greater pressure fluctuation tends to be more aggressive. Pseudoexfoliation glaucoma is characterized by dandruff-like flecks in the eye, and is an aggressive type of glaucoma, often with high pressures and wide pressure fluctuation. “Low tension” or “normal tension” glaucoma, on the other hand, may be slowly progressive, and in some cases may not even get worse over time.
The only well-proven treatment for glaucoma currently involves lowering the eye pressure. Studies show that about a one-third decrease in the eye pressure, and pressure in the low or mid teens with treatment, can stop progression in the majority of cases. However, pressure fluctuates, both at and between office visits. Different people may get worse at different pressures. Lowering eye pressure to an ideal level may not always be risk free. Pressure control and optic nerve damage may worsen over time. It is important that glaucoma patients follow up with careful regular monitoring of the eye pressure and the structure and function of the optic nerve to see if further treatment is necessary, and to minimize any damage from uncontrolled glaucoma. With modern diagnostic techniques, medications, laser and surgery, the risk of going blind from glaucoma has decreased significantly.