History of Glaucoma
Who Gets Glaucoma?
Who is at Risk?
What is Glaucoma?
What Causes Glaucoma?
What Are the Symptoms of Glaucoma?
How Will My Doctor Determine If I Have Glaucoma?
Will Glaucoma Cause Blindness?
How Does Glaucoma Develop?
How is Glaucoma Treated?
Different Types of Glaucoma
Glaucoma was recognized as early as 400 BC. In the 1800′s, glaucoma was recognized as a distinct disorder, although it frequently coexisted with cataracts.
At least 3 million Americans suffer from glaucoma. It is the leading cause of blindness in African Americans and the second leading cause overall in the United States. Glaucoma typically occurs after 40 years of age, although there are several types of glaucoma that present at an earlier age and can even occur in infants. Because of the increasing age of the population the number of patients diagnosed with glaucoma is expected to rise by 50% by the year 2020.
Risk factors or associations for development and progression of glaucoma include advancing age, family history, African American or Hispanic race, elevated intraocular pressure, being nearsighted, previous ocular injury or eye inflammation, long-term use of steroid medications and decreased central corneal thickness.
In glaucoma, the optic nerve – the nerve that is critical for vision – deteriorates in a characteristic fashion, which leads to progressive loss of the field of vision.
Glaucoma is a multifactorial disease. Current theories include mechanical compression from increased pressure within the eye, decreased blood flow to the eye and genetics. While the majority of glaucoma cases in North America and Europe are associated with an elevation of intraocular pressure (IOP), approximately 40% of cases are associated with normal pressures. In either situation, the intraocular pressure is involved in the deterioration of optic nerve function, though this can be accelerated when the IOP is significantly elevated. In almost all cases of glaucoma, this elevation of eye pressure arises from blockage of fluid outflow.
Glaucoma can be classified into two different categories: open and narrow (closed) angle. The difference between the two is complex but, simply put, has to do with where the blockage of eye fluid originates. In open angle glaucoma, which accounts for nearly 90% of cases in the U.S., the eye drain looks anatomically normal but at a microscopic level is not functioning properly. Narrow angle glaucoma, which accounts for about 10% of cases, involves blockage of the entrance to the drain. This usually occurs in people who are farsighted and have cataracts. The determination of the type of glaucoma is made by your physician using an examination technique called gonioscopy.
Glaucoma usually presents without any symptoms, thus it is often referred to as the “sneak thief of sight.” At first you may lose your side, or peripheral vision. Because this happens gradually over time, it is often unnoticeable to you. Late in the disease, after much of the optic nerve has been destroyed, you may lose your central vision, which then becomes noticeable. There are a few types of glaucoma that may have symptoms; such as glaucoma in newborns that may present with eyes that appear large and have a white hue to the front surface of the eye or sudden attack glaucoma where the eye becomes very painful and red. These, however, are a minority of cases in the United States. The majority of glaucoma is asymptomatic.
How Will My Doctor Determine if I Have Glaucoma?
In addition to a careful optic nerve examination and eye pressure measurement, there is a test called a visual field which can be done to determine how much of your vision has been lost. Newer diagnostic tests allow for a direct measurement of the optic nerve tissue, which in some instances may allow for earlier detection of disease.
Many people are devastated when they are told that they have glaucoma. It does not necessarily mean you will go blind. It is extremely important to note that once glaucoma is diagnosed, there are a number of interventions that may be sought to prevent further vision loss or slow down the vision loss to a rate that will not affect your daily life. One of the most important factors in determining your ultimate outcome is how early the diagnosis is made. Vision that has already been lost from glaucoma may not be restored currently. However, further vision loss may be prevented with treatment. Most varieties of glaucoma are chronic, virtually lifelong disorders that can be controlled but not cured.
In order to understand how glaucoma works, you need to think like a plumber.
If you visualize your kitchen sink, there is a faucet and a drain. In the eye, the faucet is always on, producing fluid that helps to maintain the normal shape of the eye as well as carry oxygen and nutrition to the anterior segment of the eye (this is not the tearing system, rather it is a separate plumbing system inside the eye). Moreover, in our analogy, the drain is always open. The balance between the amount of fluid produced by the eye and the amount that can be drained by the drainage system determines the pressure.
Regardless of the mechanism of glaucoma, the primary goal is to lower intraocular pressure. This is the only proven treatment to slow or halt the progression of the disease. This is achieved with eye drops, laser and surgery. Because most eye drops are highly effective and safe, the majority of glaucoma instances can be controlled with medical therapy only. Innovations in laser surgery also allow for safe, effective treatment in a number of patients and in some situations may be a first-line treatment option. For more severe cases, or those not responding to medical therapy, surgery is an effective option.
For cases of narrow angle glaucoma, the preferred treatment is called a laser iridotomy. This involves making a small hole in the colored part of the eye (iris), which in most cases opens up the blocked drainage canal. It is not uncommon to have both types of glaucoma which may be treated with a combination of treatment modalities (i.e. drops and laser).
Glaucoma Research Foundation
The Glaucoma Foundation
National Eye Institute