Primary Angle Closure Glaucoma
Chat Highlights
December 1, 2010

On Wednesday, December 1, 2010, Dr. Michael Pro, a glaucoma specialist at Wills, and the glaucoma chat group discussed "Primary Angle Closure Glaucoma".

Moderator: Tonight's topic is “Primary Angle Closure.” What is primary angle closure?

Dr. Pro: Primary Angle Closure or Primary angle closure glaucoma is the same as chronic angle closure glaucoma. You see all these terms used for the same disease. Essentially this means glaucoma that is caused by closure of the drainage structure of the eye. The drain of the eye is located in the angle formed by the inside of the cornea and the iris. This part of the eye is examined by the eye doctor with a special mirrored prism during the slit lamp exam. In most individuals the drain is visible, but in some the drain is blocked because the iris and the cornea are too close together, the angle is narrow.

If this condition is not recognized soon enough scar tissue develops in the angle and drain and the IOP goes up leading to glaucoma.

P: Is it possible for a person to have open angle glaucoma and also primary angle closure glaucoma?

Dr. Pro: The two are generally separate. But it is possible for someone to be found to have a narrow angle. Then, a laser iridotomy is done to help open up the angle and prevent acute or chronic angle closure glaucoma. Although the angle looks open after the laser the patient goes on to develop glaucoma. This probably represents a form of open angle glaucoma, but you can see how patients do not always present in a straightforward manner.

P: What are angles grades, and how and why are they graded? Should we all know our grade of angles?

Dr. Pro: There are several grading schemes. The most common are the Schaffer system and the Spaeth system. In the Schaffer system the angle at which the iris attaches to the inside of the eye at the angle is evaluated. Grades are given from I to IV. A grade one means the angle is very narrow (about 10 degrees) and the patient is at risk for an angle closure attack. A IV means the angle is wide open. The Spaeth system is more complex, but it offers more information by analyzing not just the angle degree, but also the iris contour and area where the iris inserts into the eye.

What you should know is whether your angle is narrow and whether your doctor feels you need a laser iridotomy to help prevent acute or chronic angle closure.

P: Can part of the angle be more closed than another part? Such as nasally it might be closed, but inferiorly it might start to be more open.

Dr. Pro: Yes. Typically the superior angle is more closed.

P: What are the symptoms of an acute primary angle closure attack?

Dr. Pro: Eye pain, halos around light, and blurry vision. You may also feel nauseated and have a headache. In all, an attack of angle closure is an awful experience and it is a true ocular emergency as the IOP can be very high.

P: How is an attack stopped or does it just end on its own?

Dr. Pro: It is stopped with a combination of glaucoma drops, maybe glaucoma pills, and patients usually need a laser procedure (iridotomy) to help open the angle.

P: Does just one attack cause blindness or are multiple attacks required?

Dr. Pro: Multiple attacks are very rare. Usually something is done after the first attack, like a laser or even cataract and/or glaucoma surgery. I have seen patients who have had sub acute angle closure, in which they have had sort-of mini attacks that were recognized later on, but that is less common. A single attack can lead to blindness if not addressed in time. The high IOP can lead to glaucoma nerve damage, but there is also a risk of a vascular injury to the retina or nerve.

P: Does scar tissue develop with iridotomy? Is it a problem? Also what causes scar tissue to form in the angle and drain?

Dr. Pro: The iridotomy may close up. I normally see this shortly after the laser is first done or in persons who have iritis (intraocular inflammation). Scar tissue develops in the angle due to rubbing of the iris against the drain of the eye (trabecular meshwork).

P: What is iridoplasty?

Dr. Pro: Iridoplasty is a laser technique that is most commonly done for a particular subset of angle closure called plateau iris. In this laser technique contraction burns are placed on the iris which flatten the iris down and help open up the iris.

P: Can angle closure be treated by an optometrist?

Dr. Pro: At this time, in the United States, optometrists are not allowed to perform laser procedures. I believe this is the case in all 50 States, but they have been lobbying to perform more surgical procedures including laser procedures. Optometrists can treat persons in angle closure with drops or even pills in many states.

P: How often are prophylactic iridotomies done? And does the grading scheme indicate when this should be considered?

Dr. Pro: They are frequently done. I discussed the grading systems above which we use to guide our treatment decisions.

P: What is a normal recuperation after a laser peripheral iridotomy?

Dr. Pro: There is very little recuperation. There are no restrictions on almost all activities. The one exception is if there is blood in the eye after the laser. In these cases, an individual may be advised to rest. Significant blood in the eye after a laser iridotomy is very rare.

P: What is the recuperation after iridoplasty?

Dr. Pro: The same as with an iridotomy. In general one should be warned that the vision could be blurry for the rest of the day and the eye might be a bit sore. One can typically go back to work the next day with no restrictions. Follow-up is usually one or two weeks after the laser.

P: With all that can happen in rubbing eyes, is sleeping with a shield a good idea? For example, I often awake with the pillow hard against my face or on one eye.

Dr. Pro: I have all my patients sleep with a shield after glaucoma surgery (a trabeculectomy). This is to avoid breaking a suture and harming the surgery. I do not advise patients to wear a shield after the eye has healed from surgery. Most people find the shield to be uncomfortable. You might consider sleeping on your back.

P: What is the white line glare that can occur after an irdotomy? Is it temporary or permanent? Why does it occur?

Dr. Pro: It is caused by light getting through the peripheral iridotomy (PI) and hitting the retina. It may occur in about five% of patients, but it usually goes away. Probably the brain learns to ignore the unwanted image. In very rare cases the image does not go away and patients are so bothered that some intervention is performed to ameliorate the situation.

P: I know I should avoid decongestants and antihistamines (I have closed angle). Are there other medicines I should avoid? I get bad sinus headaches, and I'm trying a new nasal spray made with capsicum (hot pepper) which really works, but I want to be sure it's not going to raise my IOP.

Dr. Pro: I have not seen reports of capsicum causing problems. Many classes of medicines can affect angle closure. In general it is any medicine that has the side effect of dilating the pupil. These include the medicines you listed above plus anti-seizure medications and many anti-depressants.

P: With a bleb, does a previous iridotomy continue to function or is it likely to close?

Dr. Pro: The iridotomy is unaffected by the presence of the bleb. With a trabeculectomy a much larger hole in the iris is typically made, we call this an iridectomy. It is done to prevent the iris from plugging the little hole in the cornea/sclera where the aqueous fluid drains into the bleb.

P: What is a pupillary block? What is the difference between primary angle closure with pupillary block and without?

Dr. Pro: Pupillary block refers to the contour of the iris. If the iris is bowed forward it indicates that there is a pressure gradient from the back part of the eye (where the aqueous is made) to the front part of the eye (where the aqueous is drained).
Pupillary block is relieved by making the PI. One can see the iris go to a flatter contour indicating that the pressure gradient is reduced and the iris is no longer up against the trabecular meshwork. Angle closure without pupillary block is due to other causes, like a very mature cataract or plateau iris configuration.

P: When would vitrectomy be an option for angle closure, as well as lensectomy/implant? Not very often?

Dr. Pro: Vitrectomy is not performed for typical angle closure. It is done for a very rare condition called malignant glaucoma where everything—lens, iris—are up against the cornea. Cataract surgery and lens implants can be very helpful in angle closure and there is a trend to earlier cataract surgery in persons with narrow angles or angle closure glaucoma. Removal of the lens frees up space in the front of the eye and opens up the drain.

P: What is PI? Is pupillary block common? Are there grades of blockage?

Dr. Pro: PI is peripheral iridotomy. Pupillary block is the most common form of angle closure. Grades of blockage are generally assessed with the gonioscopy exam using the grading systems that I had described.

P: I'd appreciate it if you would describe plateau iris more. Can this develop in a patient already diagnosed with glaucoma?

Dr. Pro: We are going to have an entire chat dedicated to this topic in January. In brief it is a condition where the iris insertion is more anterior and the peripheral iris is bunched up into the angle.

P: Thank you for the explanation. Does the thickness or thinness of corneas affect angles?

Dr. Pro: No.

Moderator: Have a good holiday season folks! See you in 2011!!

Dr. Pro: Happy holidays everyone. Thanks for the great and smart questions!

On January 5, Dr. Pro discussed "Glaucoma Suspect for Life" in the Chat room. Click here for highlights of that meeting.

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