Open-angle glaucoma is more common than narrow- (or closed-) angle glaucoma. In open-angle glaucoma, the drainage canals in the eyes gradually become clogged with tiny, microscopic deposits over months or years. However, narrow angle glaucoma is a medical emergency.
Southland Eye Clinic has plenty of background information, which you can access using these links:
What is Narrow or Closed Angle Glaucoma (NAG)?
Why do attacks happen?
What are the symptoms of NAG?
How dangerous is an acute attack of NAG?
What medicines should patients with Narrow Angle Glaucoma avoid?
Steroids and Narrow Angle Glaucoma.
How is an acute attack of NAG treated?
How can you prevent glaucoma attacks?
Can laser-made openings close?
Merck manuals has a nifty video to explain the complex anatomy.
Normal Fluid Drainage
Fluid is produced in the ciliary body behind the iris (in the posterior chamber), passes into the front of the eye (anterior chamber), and then exits through the drainage canals.
What is Narrow or Closed Angle Glaucoma (NAG)?
This is the second most common form of glaucoma. Patients often have acute attacks of eye pain due to sudden increases in eye pressure. Between attacks the eye pressure is normal.
Why do attacks happen?
A watery fluid is generated inside the normal eye. It circulates through the eye and drains out of the eye in the “angle” between the cornea (the clear window of the eye) and the iris (the coloured part of the eye). Some people are born with narrow, slit-like draining angles. In such people, anything that further narrows the angle prevents adequate drainage and causes the pressure to build up. The patient then experiences an acute attack of Narrow or Closed Angle Glaucoma.
What are the symptoms of NAG?
Between attacks the eye pressure is normal and there are no symptoms. During the attack there are often eye pain, nausea and sometimes vomiting. The eye may be red, vision may be blurry and patients may see halos around the lights.
How dangerous is an acute attack of NAG?
An attack of this type of glaucoma is an emergency. Untreated, it may cause blindness in a day or two.
What medicines should patients with Narrow Angle Glaucoma avoid?
Patients with Narrow Angle Glaucoma should avoid cold remedies which contain Pseudoephedrine, Phenylephrine or Neo-Synephrine; anti-histaminics Chlorpheniramine, Diphenhydramine or Benadryl and overactive bladder remedies such as Detrol. These remedies often carry a warning telling you not to use them if you have glaucoma. If your Narrow Angle Glaucoma has been treated with laser, these medicines become safe for you to use. The above medicines generally do not cause problems to patients who have POAG type glaucoma.
Steroids and Narrow Angle Glaucoma.
Steroids (cortisone, hydrocortisone, prednisolone, etc.) increase eye pressure. They are potential problem for patients with the POAG type glaucoma, not for patients with Narrow Angle type glaucoma.
How is an acute attack of NAG treated?
Narrow Angle Glaucoma is treated with a laser. In this office procedure a small drain hole is created in the iris, the colored part of the eye. The hole is of microscopic size. The operation is painless. In addition to laser treatment, eyedrops are administered to lower the pressure.
How can you prevent glaucoma attacks?
An easy and painless way to prevent attacks is to create a microscopic drain hole with the laser. This preventive treatment can be done at any time. We recommended this approach to people prone to acute attacks (people born with narrow angles). When such people are traveling they may not have access to prompt treatment. If they have an attack, serious damage may occur in a matter of hours, long before they reach a treatment center. Also, people may delay treatment until it is too late because they do not recognize that they are having a glaucoma attack. They often think that they are just having a headache, or a migraine. Because they do not suspect glaucoma they fail to seek treatment and damage to the nerve takes place. Once the nerve fibers are dead, the damage cannot be reversed.
Can laser-made openings close?
Yes, rarely. Then new attacks may occur. If the pain comes back while you are taking medicines known to cause glaucoma attacks, do not take any more and call us immediately. Explain to the receptionist your situation. Tell her that you might be having an acute glaucoma attack. Ask her to have your pressure checked now. If the office is closed, call or page me or go to KEI to be checked (see “Emergencies”).
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