Pseudoexfoliative Glaucoma
Chat Highlights
August 5, 2009

On Wednesday, August 5, 2009, Dr. Michael Pro, a glaucoma specialist at Wills, and the glaucoma chat group discussed "Pseudoexfoliative Glaucoma".

Moderator: Good one Dr Pro! Hope you are well rested from vacation! Our topic this evening is Pseudoexfoliative Glaucoma. What is pseudoexfoliation glaucoma?

Dr. Pro: Pseudoexfoliative glaucoma (PXFG or XFG) is one of a group of secondary open angle glaucomas.

These are types of glaucoma which have in common an open appearing angle when the angle is examined on gonioscopy. The most common type of open angle glaucoma is primary open angle glaucoma, or POAG. We don't really know why people develop POAG, although there are some risk factors like increasing age, high IOP, thin corneas.

With the secondary open angle glaucomas we think we understand the cause, which often entails some mechanism for dysfunction of the aqueous outflow.

XFG is the most common of these conditions. Basement membrane disorder characterized by deposition of amyloid-like material on anterior segment structures.

It is most common in Scandinavian populations. Rates vary widely in other countries and ethnic groups.

P: Is there a relationship between pseudoexfoliation glaucoma and other diseases?

Dr. Pro: I have a few studies to discuss.

Systemic Disease: 55 patients with aneurysms of the abdominal aorta and 41 controls with carotid-artery occlusion. Twenty-four of 55 patients with aortic aneurysm showed signs of manifest (17 of 55 patients) or early-stage (seven of 55) pseudoexfoliation syndrome.
This means that it is a systemic disease which may affect organs far away from the eye.
So in the study that I quoted from a high proportion of patients with large vessel disease were found to have the condition (not necessarily glaucoma, but the findings in the eye).

Let me explain what it looks like in the eye. Basically it is a condition that causes the build-up of fluffy looking white material on the iris and lens capsule. The material is very small and it can be quite subtle. It is seen on careful examination in the office with the slit lamp.

It can lead to problems beyond glaucoma in the eye, although glaucoma is the main problem. We think the higher IOP is due to some kind of obstruction of the aqueous outflow (think of a clogged drain); the high IOP leads to glaucomatous nerve damage.

Meanwhile it doesn't always cause glaucoma, but it can cause difficulty with cataract surgery making the support system for the natural lens weaker, so that cataract surgery can be more difficult.

P: Is it hard to diagnose?

Dr. Pro: Not really, but if you aren't looking for it you won't see it in early cases. Sometimes the white material really builds up on the pupil and it is quite obvious.

P: If the material derived from basement membranes is in excess in the eye, is it also in excess in other areas of the body?

Dr. Pro: We think it is amyloid material from the basement membrane of cells, thus it is also found in other places. The study that I mentioned above theorizes that it can cause vascular disease.

P: Is there is blood test that can be performed to measure the amount of the fibrillar, proteinaceous substance in the body which could mean an excess in the eye?

Dr. Pro: Not that I know of. Good idea though.

P: Although it is written that pseudoexfoliation glaucoma occurs in the sixth to eighth decades of life, what is the youngest age of patient your practice has seen?

Dr. Pro: Great question. I really don't recall seeing it in someone younger than 60.

P: How high of an eye pressure is usually seen with pseudoexfoliation glaucoma?

Dr. Pro: We teach that the IOP on presentation (when the patient walks into the office) is higher than with POAG and is much more labile. I would generally agree, although you can wee very high pressures with POAG, too. I find that the XFG patients are less predictable. They may run higher IOP after uncomplicated cataract surgery; they have pressure that varies wildly between visits.

P: What happens to the continued flaking after a trab? Does it leave the eye or pile up?

Dr. Pro: No. Presumably the process continues. We really don't see material building up in the drain, or the trab. Rather we presume that the condition somehow clogs up the drain. In fact what you really see in the trabecular meshwork (drain) is dark pigment. The condition also leads to excessive pigment release in the anterior segment from the iris, and we really don't understand why.

P: How does the body clear the eye of the debris material?

Dr. Pro: Eventually the material is absorbed by phagocytes which are like the vacuum cleaners of the body.

P: Can the debris itself cause vision loss because of the quantity in the eye?

Dr. Pro: No, it is really on a very small level and is not detectable to the patient.

P: Can an optician diagnosis PSXF?

Dr. Pro: Maybe if he or she were quite adept at using a slit lamp.

P: If a patient has another form of glaucoma, are they more likely to develop pseudoexfoliation glaucoma or are the two types of glaucoma independent?

Dr. Pro: That is one of those grey zone questions. Generally if we see the amyloid material at the pupil and the patient has glaucoma, then we say that they have XFG. It can be seen with angle closure glaucoma, but this combination is rare.

P: Why aren’t repetitive Selective Laser Trabeculoplasties effective to keep the intraocular pressure within normal limits so that medication or surgery would not be needed?

Dr. Pro: That gets to treatment. In general treatment of XFG is similar to POAG. We start with drops or laser (SLT). Eventually we proceed to a trab or a tube if the glaucoma is really uncontrolled.

But some studies have found that SLT is more effective in XFG patients. This may be because they have more pigment in the angle (drain) and it is the pigment which absorbs the laser energy. Just like in POAG SLT works in some patients and not in others. I find that if the laser doesn't work for an initial attempt, a second treatment may work. If an SLT doesn't work after two attempts, then it is unlikely to ever work and another therapy should be tried.

P: What is the other therapy? Drops?

Dr. Pro: Drops, and ultimately surgery if nothing is working and the glaucoma is getting worse.

Moderator: That's all for tonight Dr. Pro. Thank you!

Dr. Pro: You're welcome. Good night.

On August 19, Dr. Pro discussed "Visiting a Glaucoma Specialist" in the Chat room. Click here for highlights of that meeting.

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