Glaucoma is a progressive group of eye conditions whereby the optic nerve that connects the back of the eye to the brain loses its fibers at an abnormally high rate, resulting in permanent damage and irreversible vision loss. The optic nerve transmits visual information from the retina to the occipital lobe of the brain.
“We’re born with about a million fibers in that nerve, and as we get older, we naturally lose about one percent per year,” explains ophthalmologist Dr. Kerry Assil. “People with glaucoma lose them even faster.”
Although there are several types of glaucoma, the most common is open-angle, which accounts for roughly 90 percent of all cases. This form of glaucoma occurs when the drainage canals in the angle formed by the cornea and iris become clogged. The blockage causes a gradual buildup of aqueous humor, the transparent fluid occupying the anterior chamber of the eye. When too much fluid accumulates inside the eye, subsequent pressure on the optic nerve causes the fibers to degenerate. Open-angle glaucoma develops slowly and sometimes without noticeable vision loss for many years. “Glaucoma has been referred to as ‘the silent thief of sight,’" Dr. Assil says. "It’s all about early detection of the fiber loss."
According to the World Health Organization, glaucoma is the second leading cause of blindness in the world, affecting approximately 60 million people worldwide. It’s estimated that more than 2 million Americans have glaucoma, but only half of them have been diagnosed.
Risk factors include genetics, being over the age of 60, high blood pressure, heart disease, diabetes and hypothyroidism. Other eye conditions, such as nearsightedness, farsightedness, or previous eye trauma might also trigger glaucoma.
African Americans are more susceptible to developing glaucoma than any other race, particularly if there is a family history of the disease. Statistics show that African Americans are 15 times more likely to suffer visual impairment from glaucoma than Caucasians. Glaucoma also tends to affect African Americans at a younger age, so doctors recommend routine eye exams earlier and more frequently than other ethnic groups.
According to the Mayo Clinic, common symptoms of primary open-angle glaucoma include:
• Gradual deterioration of peripheral vision in one or both eyes
• Tunnel vision, in advanced stages
Symptoms of acute angle-closure glaucoma include:
• Severe pain in one or both eyes
• Nausea and/or vomiting accompanying severe pain
• Blurred vision
• Sudden visiual disturbances, especially in low-light settings
• Eye redness
The American Academy of Ophthalmology recommends comprehensive eye exams beginning at age 40 and every three to five years after; however, if a patient has elevated risk factors, screenings are scheduled every one to two years.