Trying to arrest a ‘silent thief’

Many Americans with glaucoma remain undiagnosed

WHO’S AT RISK

As one of the leading causes of blindness around the world, glaucoma affects as many as 2.5 million Americans — thankfully, with early diagnosis and proper treatment, most glaucoma patients can preserve much of their vision. “Glaucoma is a condition characterized by damage to the optic nerve, which is the cable that takes information from the eye to the brain,” says Tsai, “This damage is related to eye pressure that is too high for the eye to tolerate.”

The vision loss caused by glaucoma follows a signature pattern. “First, we see a decrease in the side vision that the patient has,” says Tsai. “That vision loss can worsen and eventually cause loss of central vision. One of the problems is that many patients don’t notice any symptoms until they experience significant vision loss.”

There doesn’t seem to be a single underlying cause to glaucoma. “We actually think that glaucoma is not just one disease, but a group of diseases that damage the optic nerve,” says Tsai. “We suspect that there is a genetic predisposition, but it’s complicated — many genes have been discovered to have some association with glaucoma.”

The risk factors for glaucoma are quite broad. “You’re considered at high risk if you’re African-American or you have a family history of the disease,” says Tsai. “The risk also goes up tremendously with age.”

SIGNS AND SYMPTOMS

Glaucoma is often called “the silent thief” of sight because it sneaks up on people. “The scary thing is that so often, there are no symptoms — you may not have eye pain, and you may not notice the loss of side vision initially,” says Tsai. “That’s why the NIH recommends comprehensive eye exams to catch glaucoma even before the patient notices symptoms.” Half of all Americans with glaucoma are not aware of it.

Many patients will experience elevated eye pressure. “About two-thirds of patients are found to have elevated eye pressure, but the other third don’t,” says Tsai.

TRADITIONAL TREATMENT

The trick to combating glaucoma is catching it before it causes much vision loss. “Early detection is the key because we have therapies that can slow down the disease or stop it, but we can’t undo the damage once vision is lost,” says Tsai.

The universal screening guidelines recommend comprehensive eye exams, with a time frame that depends on the patient’s risk factors. “The National Eye Institute at NIH recommends that African-Americans and people with a family history start getting comprehensive eye exams at age 40, while other groups should start at 50 to 60.” People with a family history of glaucoma are four to six times more likely to develop the disease than the general population.

Glaucoma screening includes several different steps. “The doctor should take a comprehensive history, check your vision, look at the eye with a microscope, assess the visual field, and do a comprehensive eye dilation exam,” says Tsai. “By putting drops in the eye to enlarge the pupils, the doctor can actually look at the optic nerve.”

The treatment options for glaucoma include medications — usually eye drops — laser therapy, and surgery. “We usually start treatment when the eye pressure is too high, or when we see signs of damage that we are confident is glaucoma,” says Tsai. “There are three indications when treatment is called for: either the doctor believes that the eye pressure is too high for the patient, special computerized machines or disc photographs detect increased damage to the optic nerve, or the visual field test shows worsening loss of side or central vision.”

Eye drops help check the progression of glaucoma by affecting the amount of fluid in the eye. “The drops either turn down the amount of fluid being produced by the eye or open up the channels that let fluid out,” says Tsai. “There’s also a laser therapy that helps open up the drainage channels. And when medications and laser aren’t enough, we can do an incisional cutting surgery to decrease eye pressure.”

Unfortunately, glaucoma surgery can’t roll back vision loss that has already occurred. “Cataract surgery can restore vision, but glaucoma surgery just lowers the pressure to prevent the disease from getting worse,” says Tsai. “The surgery allows patients to keep what they have, but it doesn’t recover lost vision. That’s why early detection is so crucial.”

RESEARCH BREAKTHROUGHS

The next step in treating glaucoma is being able to undo the damage. “Our lab and others are working on innovative ideas for recovering vision loss from glaucoma,” says Tsai. “There are also new drops for glaucoma that should be coming out soon and new surgeries that are increasingly being offered these days.”

QUESTIONS FOR YOUR DOCTOR

No one should hold back from asking, “Does my optic nerve look suspicious for glaucoma?” “Sometimes the doctor will just check the eye pressure and not look at the optic nerve carefully enough,” says Tsai. “Determining that the optic nerve looks normal is the only way to rule out glaucoma.” And everyone should ask, “How often should I have my eyes checked?” The answer will depend on the severity of your risk or of your disease. “Getting a regular eye exam and getting screened for glaucoma are two of the best things you can do to preserve your sight,” says Tsai. “If you’re diagnosed early before you’ve lost much side vision or central vision, there are many therapies that we can use to preserve your sight.”