Aging is a risk factor for many problems. We are generally aware that as we get older we are likely to have problems with our heart or be susceptible to one of the many cancers. However, a sense that we all depend on is sight, and diminution or loss of that severely restricts our quality of life. This brings us to this month's potential problem – glaucoma.
What is Glaucoma?
Glaucoma is a variety of physiologic problems that end up causing irreversible damage to the optic nerve. The optic nerve is responsible for transmitting the signals from the eye to the brain for proper interpretation. If the optic nerve suffers damage, vision becomes impaired since the brain no longer receives the signals of sight. Glaucoma is generally a result of elevated pressure in the eye that produces the damage to the nerve.
What Causes Glaucoma?
Normally fluid continuously is formed inside the anterior chamber of the eye and leaves it at the angle where the cornea and iris meet.
The result of either an increase in fluid production or an obstruction (reduction) in elimination of the fluid from the eye increases the pressure in the eye. This pressure then is transmitted to the optic nerve that suffers the permanent damage.
There are two main types of glaucoma, the most common in American (about 90%) is "open - angle" glaucoma. The less common form is "closed - angle." Open - angle develops insidiously over time. On the other hand, one form of closed - angle is acute and if not treated within a day or two can rapidly progress to blindness. Open - angle usually takes years to produce loss of sight.
The reason that glaucoma is called the silent thief of sight, is that it usually has no symptoms until there is loss of vision. This, by definition, means the optic nerve is already damaged. If allowed to progress without treatment, patients with glaucoma will notice a loss of peripheral vision. Vision in the center of focus is clear, but objects and even light in the periphery are blurred and not sharp. The term "tunnel vision" is typically used to describe sight in advanced glaucoma. In closed - angle, there can be pain in the eyes and headaches and possibly nausea. The onset is sudden and there can be loss of peripheral vision that relatively quickly can progress to complete and permanent blindness. (This is unusual in the United States.)
Who is Prone to this Disease?
Anyone over 60 years of age is a possible candidate for glaucoma. That means, of course, that some of the readers of this column could develop glaucoma. African Americans over 40 years of age are particularly susceptible to glaucoma. People with higher than 20 mm of mercury pressure in a tonometry eye examination are at risk for developing glaucoma. Finally, anyone with a family history of glaucoma is at risk for developing glaucoma.
Glaucoma is diagnosed by an ophthalmologist or licensed eye care professional. Loss of visual fields and damage to the optic nerve are the two ways to diagnose glaucoma. There usually is an associated finding of increased intraocular pressure determined with tonometry. All of these diagnostic signs require an examination, using drops to dilate the eye and to anesthetize the eye so that tonometry can be performed. An instrument is used to map the peripheral vision.
There are three main way to treat glaucoma. First is a great variety of medications, either drops or oral medicines. These must be prescribed by an ophthalmologist, and it is absolutely required that patients comply every day with the use of the medicine. A second therapy is laser surgery that can be used alone or with medicines to treat the problem. Finally, if medicine and laser have failed, eye surgery in an ambulatory setting can be performed. The goal of all therapies is to reduce pressure in the eye and to prevent damage to the optic nerve. If treated early and monitored, these therapies are usually effective in preventing blindness.
The Bottom Line
Because by age 80, ten percent of us will have glaucoma, it is essential that at a minimum of every two years after age 60 we see a licensed eye care specialist to make sure that we do not have either high intraocular pressure or early signs and symptoms of glaucoma. If we do have high pressure, more frequent visits will be required. This is just another example of our being active in taking care of our healthy aging.
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