What is glaucoma?
Glaucoma is a disease characterized by damage to the optic nerve (the tissue that takes information from the eye to the brain) that leads to progressive irreversible loss of vision.
It is the second leading cause of blindness in the world. It is estimated that 3 million Americans have glaucoma, only half of the people being aware of it. It is estimated that the total number of suspected cases of glaucoma is over 60 million people worldwide.
What causes glaucoma?
Damage to the optic nerve is caused by a pressure that is too high for your eye. “Normal pressure” in the eye is between 10 and 21 millimeters of mercury. However, 25% of glaucoma develops in individuals with normal pressures, while some people may have elevated pressures and never develop the disease. Therefore a comprehensive ocular exam is needed to detect and diagnose glaucoma.
What are the differing types of glaucoma?
There are two major types of glaucoma-
- Open angle glaucoma is the most common type, where the fluid produced in the eye has open access to the drainage structure. The drainage structure becomes resistant, resulting in increased fluid buildup within the eye. Since the eye is a closed structure, this leads to increased pressure and subsequently, optic nerve damage and progressive loss of vision.
- Angle-closure is the second major type of glaucoma. Here, the iris (the colored portion of your eye) covers and blocks the fluid from reaching the drainage system. This may occur gradually with slow increase of pressure and gradual loss of vision, or it may block the drainage structure abruptly, causing the pressure to rise rapidly. If this happens suddenly, you may develop headache, eye pain, nausea and vomiting, see rainbow or haloes around lights, and get blurred vision.
What are risk factors for developing glaucoma?
Everyone is at risk for developing glaucoma. Most people are older, but 1 in 10,000 babies are born with the disease.
- Age: You are six times more likely to get glaucoma if you are over 60 years old.
- Family history of glaucoma: This increases your risk approximately 6 fold.
- African-American heredity: You are 6 to 8 times more likely to develop glaucoma than a Caucasian and 6 to 8 times more likely to be blinded by the disease.
- Hispanics ancestry, particularly, over 60 years of age.
- Asian descent is at increased risk for angle-closure glaucoma.
- Steroid users such as prednisone and other therapeutic uses
- Prior eye trauma: This can occur immediately or years after the trauma. Baseball and boxing injuries are the most common.
- Health conditions, such as diabetes, hypertension, and migraine headaches.
- High myopia (nearsightedness)
How is glaucoma detected?
A complete exam from an eye physician includes measuring the intraocular pressure, dilating your pupils to evaluate your optic nerves, and placing a special lens on your eye temporarily to determine if the drainage structure is open or closed. There is a special test to evaluate your peripheral vision (peripheral vision is lost before encroaching on your central vision) called a visual field. Another frequently ordered test is an OCT which provides a measurement of the healthy optic nerve tissue. Stereo disc photos are obtained in order to document the appearance of the optic nerve for future comparisons. Finally, the thickness of the cornea is measured as glaucoma is more prevalent with thinner corneas.
How is glaucoma treated?
The goal of treatment is to stabilize your vision. Glaucoma can be controlled, but is usually a lifelong disease. Since most glaucomas (particularly, open-angle glaucoma) are chronic, they must be monitored for life. Treatment options include eye drops-this is the most common form of treatment.
Laser treatment may be used for both open-angle and closed-angle glaucoma. It is a painless, quick procedure performed in the office. This procedure may be used either if medication fails or as a first line of treatment.
Conventional surgery: this is chosen when medical/laser therapy fail to adequately control the pressure. It is performed as an out-patient procedure. These procedures lower the pressure by providing a new pathway for the fluid to drain out of the eye.