| Glaucoma |
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Glaucoma is a disease characterized by chronic progressive damage to the optic nerve. The optic nerve sends visual information from your eye to the brain, thereby allowing you to see. In most cases of glaucoma, damage occurs very slowly over a period of years, but sometimes can occur more rapidly. As damage to the nerve occurs and progresses, vision loss will occur. Most of the time initial damage to the nerve causes side, or peripheral, vision loss. Since we are often less aware of subtle changes to this part of our vision, most individuals have no symptoms when they are first suspected of having glaucoma, often during a comprehensive eye exam. If not detected and treated early, the loss of peripheral vision can progress until it starts to affect the central vision. Vision loss from glaucoma is permanent. Therefore, it is critical to detect glaucoma early before significant damage to the nerve occurs.
Glaucoma is a very common disease which affects about 2% of the population over the age of 65. It also occurs in younger age groups but with much less frequency. It can affect people of any age, sex, and race. Certain groups of people, including those of African descent, those with a family history of glaucoma, and possibly those with nearsightedness, diabetes, or high blood pressure, are at an increased risk. The risk of glaucoma increases significantly in people of African descent over the age of 35, and in people of Caucasian descent over the age of 50 years.
High pressure inside the eye is known to cause glaucoma. There is a constant circulation of a nutrient fluid inside the eye. The normal eye continuously produces and drains fluid internally to maintain the globe shape, and internal pressure of the eye. This fluid also nourishes the lens, cornea and other vital structures inside the eye. In glaucoma, there may be excessive fluid production or a blockage of the fluid drainage, either of which causes the pressure inside the eye to rise. The exact mechanism resulting in this elevated pressure is very complex and poorly understood. Much research is being done to further our understanding in this area. If the pressure is too high, it may start to damage the optic nerve.
Interestingly, although elevated pressures significantly increase an individual’s chance of developing glaucoma, there are some people with elevated pressures who seem to tolerate high pressures without developing optic nerve damage characteristic of glaucoma. Likewise, some people develop glaucoma without evidence of having high eye pressure. Recent studies show that somewhere between 30 – 50% of people with glaucoma may have eye pressures that never exceed normal values. In these cases, it is believed that the damage to the nerve may be caused by poor blood flow circulation to the nerve, or an abnormal concentration of naturally occurring hormones or chemicals in the eye.
Unfortunately, there is no cure for glaucoma, but effective treatments do exist. The goal of therapy is to control the disease so that vision is STABILIZED. Control is a matter of reducing intraocular pressure down to a level tolerated by the nerve and maintaining adequate blood and nutrient flow to the retinal nerves. Most commonly, treatment begins with eye drops to lower the pressure in the eye. There are several types of medicines; some reduce the inflow while others increase the outflow of fluid from the eye. Sometimes pills are used, but because of their long-term side effects, they are rarely used any more, except for short periods of time.
When drops cease to be effective, if the pressure rises as a result of the normal progression of the disease, or if allergies or sensitivities develop to the prescribed medicines, other forms of therapy are used. The most useful tool in this setting is Selective LASER Trabeculoplasty (SLT). In a single setting the outflow channel is treated with laser light resulting in greater outflow of fluid from the eye. The laser procedure is usually performed in office, takes only a few minutes, and is normally painless. If this is not successful, traditional glaucoma surgery may be considered.
Although glaucoma is a disease that stays with the person for life, through good control vision loss can be avoided. Control is manifest in stable pressures, stable visual field and stable appearance of the optic nerve head. Good management consists of the vigilant and frequent monitoring of these three factors. This is why patients with glaucoma should be re-examined every 3 to 4 months for the rest of their lives. Glasses need to be updated in glaucoma patients just as in the normal population. With regular exams and good cooperation the outlook is bright for almost all patients with this disease. |
