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.