Barnet Dulaney Perkins Eye Center Official Blog

There are several types of glaucoma.
1. “Wide” or “ Open” Angle Glaucoma
2. “Narrow” or “Closed” Angle Glaucoma
3. “Combined” or “Mixed” Mechanism Glaucoma

Patients should know which type or types of glaucoma they have or are at risk for.

WIDE OR OPEN ANGLE GLAUCOMA
This represents roughly 70% of the glaucomas. In this glaucoma, the eye’s drainage channels are blocked by debris and the aqueous fluid cannot leave the eye as quickly as it is produced. Thus, the eye pressure becomes elevated. The analogous situation would be if you had a sink with a faucet and a drain. In this type of glaucoma, the small spaces in the drain become “clogged.” The clogging of the drainage channels prevents the fluid from leaving the eye as fast as is necessary. Thus, the eye produces the fluid faster than it can be removed. This leads to an elevation in the eye pressure. Elevation of eye pressure leads to damage to the optic nerve. This type of glaucoma often occurs slowly and without symptoms.

Often patients can have this disease for years without any awareness of their eye pressure being elevated. The only way to determine the eye pressure is to see the eye care professional.

Treatment for Open Angle Glaucoma usually involves the use of eye-drop medications to lower the eye pressure. If these medications fail to lower the pressure adequately, the eye doctor can suggest additional treatment strategies to try to lower the eye pressure to a normal level.

NARROW OR CLOSED ANGLE GLAUCOMA
Unlike Open Angle Glaucomas which does not have symptoms until very late in the disease, Narrow Angle Glaucoma can present with a sudden onset of pain, redness, reduced vision, and possibly nausea and vomiting. Narrow Angle Glaucoma is a Medical Emergency. This type of glaucoma warrants prompt treatment to prevent complete sight loss and even blindness. If we use the sink analogy to explain this type of glaucoma, it would be as though a rubber stopper was abruptly placed over the drain at the bottom of the sink. Thus, the faucet would continue to run but no fluid could enter the drain. All the fluid entering the sink or in this case the eye, would be trapped because the drain is completely obstructed. In that case, the treatment involves making an opening in the rubber stopper. This opening which we call a “laser iridotomy” allows fluid to pass through the obstruction and enter the normal drainage canals

MIXED MECHANISM GLAUCOMA
Many patients with narrow or closed angle glaucoma also have a component of open angle glaucoma as well. Thus we describe these patients as having “combined or mixed” mechanism glaucoma. These patients require both laser iridotomy as well as the use of eydrops on a chronic or long-term basis.

HOW DO I KNOW WHAT I HAVE?
Your eye care professional can determine for you what type or types of glaucoma you have or may be at risk for. Once this is determined, the doctor can help you gain a better understanding of how to protect and treat your glaucoma risk.

The goal in preventing and treating the risk of glaucoma, or the presence of glaucoma, is to lower the pressure in the eye which we refer to as the intraocular pressure (IOP).

Glaucoma is defined as damage to the optic nerve. Glaucoma is not defined as elevated eye pressure. In most patients, the cause of the nerve damage (glaucoma) is the fact that their eye pressure becomes higher than is safe for their eye. In general, we believe that the normal eye pressure ranges from 12mm Hg to 20mm Hg. Most patients who are not at risk for glaucoma and who do not have glaucoma usually have pressures in this range (12-20mm Hg). Most patients (75%) who are at risk for glaucoma have eye pressures above this range (usually above 20mm Hg) on a routine basis. In these patients, we generally recommend that the patient lower their eye pressure using medications in the form of eye drops. There is a minority of patients (25%) who are at risk for glaucoma but who do not reveal elevated eye pressures. These patients are said to be at risk for “Normal Tension Glaucoma or Low Tension Glaucoma, both are names for the same condition. In these 25% of glaucoma sufferers, the eye pressure does not become elevated yet they appear to be at risk for glaucomatous damage.

The treatment for both types of glaucoma patients (those with high eye pressures and those with normal eye pressures) is the same. The goal of treatment is to lower the eye pressures to the low end of normal. Thus, although eye pressure is the greatest risk factor for glaucoma, there are clearly other events which contribute to the risk of glaucoma.

When you see your eye care professional, they can help you determine if you have or are at risk for one of these types of glaucoma.

Glaucoma is the leading cause of permanent blindness worldwide. It is known as “The Silent Thief of Sight” because it often progresses slowly without the patient becoming aware of their sight loss until late in the disease.

The best way to determine if you have glaucoma, or if you are at risk for glaucoma, is to visit your eye care professional. Your eye doctor will be able to assess your risk for glaucoma by performing a thorough medical history as well as an exam of your eye health. This exam is painless and does not result in any long-term compromise to your vision. Your eye doctor will measure your eye pressure otherwise known as your intraocular pressure (IOP). This is done by instilling some eyedrops which serve to numb the surface of the eye. Once these drops are instilled, the doctor can then accurately check your eye pressure. In addition, to measure the eye pressure, your eye doctor will test several other aspects of your eye health including the assessment of your vision, and your visual field. To complement these measurements, your eye doctor will also take photographs and high resolution “scans” of the optic nerve. Together, your eye pressure, your visual function, and your eye and optic nerve scans will serve to help the doctor determine if you are at risk for glaucoma or if you have early signs of glaucoma.

Early detection is critical because once sight is lost to glaucoma it cannot be brought back. Over half of the patients with glaucoma in the United States do not know that they have the disease. Thus, in order to determine your risk, make an appointment with your eye care professional today and maintain your annual eye exams.