Late Breaking News
Glaucoma: With Early Diagnosis, the Eye Can Be Protected from Vision Loss
- Categorized in: June 2009 Issue
WASHINGTON—Glaucoma is a group of diseases that can damage the eye’s optic nerve and result in vision loss and blindness. It is a leading cause of vision loss in the U.S. While there is no cure for glaucoma, with early diagnosis, the eye can be protected from vision loss.
“This is a preventable, treatable disease, and the most important thing for the patient is a regular eye exam to identify risk factors at an early stage,” said Col. Jonathan Briggs, USAF, MC, an ophthalmologist who is the director of the glaucoma service at Wilford Hall Medical Center.
The most common type of glaucoma in the US is open-angle glaucoma. In one form of this glaucoma, ﬂuid that should be exiting the eye through a drain-like spongy meshwork passes too slowly through the meshwork. This results in the ﬂuid buildup, causing the pressure inside the eye to rise, and subsequently, to damage tothe optic nerve. When the optic nerve is damaged from this increased pressure, vision loss can occur.
Dr. Briggs, who treats active duty military, their families, and retirees, said that it is a condition that can strike anyone, though age is a major risk factor. “It is much more prevalent in the retirees. Age is one of the major risk factors, but we do have it in our active duty as well, although in a much smaller number. But there is a signiﬁcant number in the active duty population as well,” he said.
Elevated pressure inside the eye, called intraocular pressure (IOP), is a risk factor for open-angle glaucoma. But, not everyone who has elevated eye pressure will develop glaucoma. In addition, there are some patients who do not have higher than “normal” IOP, but develop glaucoma. “Pressure is one risk factor and everyone gets caught up in pressure, but you can have normal pressure and have glaucoma,” Dr. Briggs said.
While anyone can develop open-angle glaucoma, some people are at a higher risk than others. According to the National Institutes of Health, African Americans over age 40 are at increased risk, with studies showing that glaucoma is ﬁve times more likely to occur in African Americans than in Caucasians.
In addition, everyone over age 60, especially Mexican Americans, is at an increased risk. People with a family history of glaucoma are also at increased risk. But those risk factors do not mean that others cannot get a form of the disease. “Babies can actually get it, although that is fairly rare,” Dr. Briggs said. “I see maybe one or two of those patients every year or two. That is not common, but it does happen. I have a handful of patients who are in the adolescent age group that have it.”
If open-angle glaucoma remains untreated, the person may miss objects to the side and out of the corner of their eye. Without treatment, an individual with this condition will slowly lose peripheral vision. Over time, straight-ahead vision may decrease until no vision remains.
A challenge is that open-angle glaucoma has no symptoms in its early stages. An individual with it may not recognize that they have a problem. “There are probably over 70 million people worldwide that have glaucoma, and the statistics you ﬁnd probably represent half of those people who actually have glaucoma, ” Dr. Briggs said. “A big issue is that there are no symptoms. It affects your vision and it affects your visual ﬁeld, and usually it affects your peripheral vision ﬁrst. Your brain kind of ﬁlls in the areas if one eye is worse than the other. I have a number of patients with advanced glaucoma, and if you ask them if they have any symptoms, they would say, ‘no, I really don’t notice any problem.’”
The lack of symptoms is also one reason why a comprehensive dilated eye exam is so critical in determining whether a patient has the disease or is at risk. Dr. Briggs said that he generally recommends that anyone under 45 should have an eye exam every 3 or 4 years, assuming they have completely healthy eyes with no risk factors.
Individuals over the age of 45 should have an eye exam every one to two years. People with speciﬁc risk factors for glaucoma but otherwise normal eyes should have exams every one to two years. People who actually have glaucoma need to have their eyes checked at least every six months, and sometimes more frequently, depending on the level of control and severity of disease, he advises.
Preventing Vision Loss
The goal of treatment for glaucoma is to get someone to the end of life with fully functional vision. “That doesn’t mean that they won’t have any damage necessarily, but that they will have fully functional vision,” Dr. Briggs said.
If a patient comes in with untreated open-angle glaucoma, Dr. Briggs says he sets a target for reducing the pressure in the eye. “If someone comes in with glaucoma with damage that hasn’t yet been treated, I look at how high the pressure was when the damage occurred,” he said. “From previous studies, we know that a 20 to 30% reduction in their pressure will signiﬁcantly reduce their risk of having progression, so we set a target for their pressure and then follow them over time. If they have more damage at the target pressure, target pressure must be reset. There are a lot of different factors going on as we treat these patients, but in the vast majority, we are able to prevent further progression.”
People who have multiple risk factors, including high eye pressure, but no damage to the optic nerve or vision loss, are considered to be “glaucoma suspects.” The physician and patient must decide if treatment should be started. Some patients may want to start treatment, while others may want to wait. “It can be challenging as far as when to start treatment and what level of risk are you willing to accept,” he said. “There are numerous factors to take into account. Some is based on how comfortable the patients are—their pressure may be 30mm Hg and they may have no damage. Their nerve may be completely normal in appearance and their ﬁeld may be completely normal, but they have high pressure. That is a signiﬁcant risk factor, and they need at least very regular follow-ups, but they may be not comfortable with the pressure that high and most people would probably treat that.”
Patients who choose to wait to get treatment must continue to be followed by their physician on a regular basis because if they do not have regular follow-ups they may come back years later and have a signiﬁcant amount of eye damage. “Damage is irreversible. Once you have it, it is gone for good. We can only preserve what is left,” he said.
Treatments can be very effective in preventing further vision loss. “We have several different classes of medicine, and the easiest way to think about it is with medicines we either decrease the production of ﬂuid inside the eye or increase the outﬂow through that drain,” Dr. Briggs said. “So, if you think of the sink analogy where we are pouring less water into the sink, we can turn down the faucet a little bit, or we can open up the drain.”
While some people never need more than one medication throughout their life to control the condition, other people need multiple medications. If those fail, other options are available, like laser therapy or surgery. “When we get to the point where multiple medicines are not adequate, we can either do laser that may augment those medicines or do a surgery where we actually make a little bypass opening in the eye through a couple of different means,” he said. “We can create a trap door with a little hole under it that lets the ﬂuids ﬁlter out of the eye, or we can put a microscopic tube into the eye that is a pathway for the ﬂuid to come out of the eyes.”