Angle-closure Glaucoma
Chat Highlights
March 13, 2002

Norma Devine, Editor

On Wednesday, March 13, 2002, Dr. Rick Wilson, a glaucoma specialist at Wills, and the glaucoma chat group discussed "Angle-closure Glaucoma."

Moderator:  Welcome, all.  Tonight we will be discussing angle-closure glaucoma with Dr. Rick Wilson.  

P:  Dr. Rick, is angle closure always an emergency situation?

Dr. Rick Wilson:  Actually, about two-thirds of patients with angle-closure develop it slowly, with few or no symptoms.

P:  What are the most common symptoms of angle closure? 

Dr. Rick Wilson:  The most common symptoms are blurred vision, which is characterized as similar to looking through a mist, often combined with an ache in the eye, and red vessels on the surface of the eye.

P:  Is there a difference between narrow-angle glaucoma and angle-closure glaucoma?  

Dr. Rick Wilson:  There really is not a narrow-angle glaucoma.  People with narrow angles that have not closed are prone to glaucoma.

P:  Is the use of miotics indicated or contraindicated? 

Dr. Rick Wilson:  Usually a trial with the miotics in the office is required if the miotics are to be prescribed.

P:  If the angles are narrow, what are the indications for performing an iridotomy?

Dr. Rick Wilson:  The angle is judged possibly occludable if:   (1)  the IOP (intraocular pressure) is elevated, (2) the pupils require dilation, (3) the angles are documented as progressively narrowing, (4) PAS (peripheral anterior synechiae*) develop, (5) there is a family history of acute-angle closure, (6) the patient requires medication that may provoke angle closure, (7) the patient’s quality of life is compromised by the threat of acute-angle closure.  

*adhesions binding the iris periphery to the cornea 

P:  How are the angles graded?   

Dr. Rick Wilson:  The angles are graded by the angle of approach to the trabecular meshwork.  Some methods talk about the shape of the iris and the place of the insertion of the iris into the wall of the eye.

P:  How common is angle-closure glaucoma?

Dr. Rick Wilson:  A talk at the last American Glaucoma Society meeting suggested that because of the high prevalence of angle-closure in China compared to America, and the numbers of Chinese, angle-closure glaucoma may be the most common type of glaucoma worldwide.

P:  Is that related to the shape of the East-Asian eye?  

Dr. Rick Wilson:  Yes, the East-Asian eye has an iris shape that puts the peripheral iris close to the trabecular meshwork in many Asians.  In the Chinese, acute-angle closure glaucoma is most common between 55 and 65 years of age and can occur in both the aged and in children.  

P:  How common is angle-closure glaucoma in the U.S.? 

Dr. Rick Wilson:  Angle-closure glaucoma accounts for about 5 to 10% of glaucoma cases in the U.S.  The prevalence over age 40 is 0.1% to 0.17% in whites, 1.4% in the Chinese, and 2.65% in the Inuit (Eskimo).

P:  Do blacks suffer a higher rate of angle-closure glaucoma than whites? 

Dr. Rick Wilson:  Acute-angle closure glaucoma is uncommon in blacks, but chronic angle-closure glaucoma is common.  The prevalence of  primary angle-closure glaucoma may be similar for both races.

P:  Is acute angle-closure glaucoma more common in men or in women?  

Dr. Rick Wilson:  Women of all races develop acute angle-closure three to four times more often than men.  

P:  Why is that?

Dr. Rick Wilson:  Women have shallower anterior chambers than men.

P:  Are miotics indicated or contraindicated to open the angle? 

Dr. Rick Wilson:  Miotics make the pupil smaller, pulling the peripheral iris away from the trabecular meshwork.  But miotics also shallow the front chamber of the eye. The balance of those two effects determines whether pilocarpine will help or hurt the narrow angle.

P:  And will gonioscopy reveal that?

Dr. Rick Wilson:  Yes, it will.  

P:  What is the most common treatment for angle closure?

Dr. Rick Wilson:  To lower the intraocular pressure (IOP), all kinds of drops are used to reduce the amount of fluid the eye makes .  A miotic is added to pull the iris off the drain.  A thick solution may even be given through the blood stream to pull fluid out of the eye. Where possible, a laser is used to make a hole in the iris to allow the pressure behind the iris, which is pushing the iris forward, to be equalized.  That results in the iris near the drain falling backward toward the back of the eye.  

P:  I've heard that having eye pain in low-light conditions (such as in a darkened movie theater) can be a symptom of primary open-angle glaucoma.  Does that mean there is a degree of angle closure related to the pupil being dilated, or is that something different?  

Dr. Rick Wilson:  You are correct in that when the iris dilates, the iris moves closer to the trabecular meshwork.

P:  So that would be angle closure?

Dr. Rick Wilson:  The miosis could shallow the anterior chamber and throw the person into angle closure.

P:  Is it possible to have a closed-angle attack if you have had a trabeculectomy and have hypotony?  

Dr. Rick Wilson:  It's possible, but very unlikely.  

P:  If a patient's IOP consistently goes up when miotics are used, would you suspect a narrow or closed angle?  Would it be dangerous for such a person to do a lot of close focusing in bright light (that is, physiological miosis)?

Dr. Rick Wilson:  The answer to both your questions is, possible though unusual. 

P:  I was originally diagnosed as having mixed-mechanism glaucoma.  I understand that is a combination of  primary-open angle glaucoma and closed-angle glaucoma.  Now I only have POAG.  I've never understood that.  

Dr. Rick Wilson:  In mixed-mechanism glaucoma, the patient has open-angle glaucoma but with the addition of, or an area of, angle closure that adds to the pressure rise.

Moderator:  Thanks again for your help, Dr. Rick.  Have a good trip to California tomorrow.

Illustrations Copyright 2003 Tim Peters and Company, Inc. Peapack NJ 07977 USA. All Rights Reserved. www.timpetersandcompany.com

End of highlights for March 13, 2002.

On March 20, Dr. Wilson discussed "The Stress of Having Glaucoma" in the Chat room. Click here for highlights of that meeting.

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