Secondary Glaucoma
Chat Highlights
August 24, 2005

On Wednesday, August 24, 2005, Dr. Rick Wilson, a glaucoma specialist at Wills, and the glaucoma chat group discussed "Secondary Glaucoma."

Moderator:  Good evening, Dr. Wilson.  The topic tonight is secondary glaucoma.

P:  I thought glaucoma was glaucoma.

Moderator:  Primary open-angle glaucoma (POAG) has no obvious cause.  Secondary glaucoma has a cause, something discernable that is causing the IOP (intraocular pressure) to be abnormally high.  Some types of secondary glaucoma include pigmentary (angle open); (pseudo)-exfoliative (angle open); early and late traumatic (angle open or closed); steroid induced (angle open); lens induced (angle open or closed); neovascular (angle closed); inflammatory (angle open or closed); and congenital.  Does anyone here have secondary glaucoma? If so, what kind do you have?

P:  I have pseudo-exfoliative (PSXF) and primary open-angle glaucoma (POAG), after years of normal-tension glaucoma (NTG).  SteveB, who can't be here tonight, has traumatic glaucoma in his right eye only, due to injury to that eye years ago.

P:  I was diagnosed with ICE (iridocorneal endothelial syndrome).  My intraocular pressure was 22 mm Hg on Betimol. Adding Alphagan and Lumigan increased the pressure to the high 20's and 30's.  Would you say this secondary glaucoma is progressing if adding more medication hasn't helped and pressure continues to rise?

Dr. Rick Wilson:  Yes. Also, Lumigan increases outflow of the aqueous, and would not be expected to work if you have an ICE membrane covering the angle.

Moderator:  A friend of mine has secondary glaucoma from inflammation in the eye.  Another friend had elevated eye pressure caused by steroids, but the pressure came back down after the steroids were stopped.

P:  I have inflammatory, steroid-induced, open-angle glaucoma.

Dr. Rick Wilson:  It would be interesting to see if you really have a steroid-induced glaucoma.  It is often misdiagnosed.

P:  I had inflammation (iritis and/l/or uveitis) off and on for 18 years and used steroids for the same period.  Then I developed a rise in pressure high enough to need treatment.  I was on every drop for three years to try to lower the IOPs before they peaked at 46 to 48 mm Hg. I had trabeculectomies three years ago.  My Dad has open-angle glaucoma, not secondary glaucoma.  How would I know whether or not my glaucoma was or wasn't induced by steroids?

Dr. Rick Wilson:  If you were a steroid responder, which is genetically determined, and you were on steroids for six or more weeks at a time, you would be expected to have a rise in IOP.  Only about 5% of patients with inflammatory glaucoma are subject to a steroid-induced IOP rise, compared to almost all those with POAG.  The eye makes prostaglandins in response to inflammation.  When a patient with eye inflammation uses steroids, that causes the IOP to rise.

P:  Would you please elaborate on that?

Dr. Rick Wilson:  When you give steroids to someone with inflammation, the steroids stop the production of prostaglandins, which causes the IOP to rise.  Inflammation decreases the production of aqueous, and steroids make the ciliary body healthier, which also increases the IOP.  Therefore, giving steroids to someone with inflammation causes the IOP to go up almost uniformly, because it makes the eye healthier, a totally different mechanism from what is happening in steroid-induced glaucoma, where the steroids probably cause an increase in the blockage of the outflow track of the eye.

P:  Why is steroid-induced glaucoma often misdiagnosed?

Dr. Rick Wilson:  Because doctors misinterpret the expected rise in IOP.  Prostaglandins like Xalatan, Lumigan, and Travatan are naturally occurring compounds in the eye that are greatly increased by inflammation.

P:  Are people with glaucoma more likely to be steroid responders than people who do not have glaucoma?

Dr. Rick Wilson:  Yes, we generally think that about 95% of primary open-angle glaucoma patients will be steroid responders (i.e., have an IOP rise) versus about 5% of the population after 6 weeks of dexamethasone usage 4 times a day.  As much as 50% of the population taking steroids for 6 months would be steroid responders.

P:  I have secondary glaucoma.  I had juvenile rheumatoid arthritis as a child, along with uveitis and glaucoma.  I am also aphakic. I recently had to stop taking pilocarpine when I had a posterior vitreous detachment.  My IOP has increased.  I had a cyclodiode laser treatment at the end of July, which helped a little, but my IOP is still elevated.  My options are to have another laser or to have a tube shunt.  I met a woman through the Bionic Eye message board with a similar history who had a goniotomy and her IOP has been fine for over a year.  Please comment.

Dr. Rick Wilson:  Goniotomy has done nicely in juvenile patients with inflammatory glaucoma.  You are aphakic (your lens has been removed) and I assume are older, so I am not sure how a goniotomy would work for you.  It might depend upon what the angle looks like on gonioscopy.

P:  I am 46 years old.  The woman I mentioned was in her 30's.  Does the age matter or is it more the eye itself that matters?

Dr. Rick Wilson:  Probably the eye itself. I did trabeculotomies 26 years ago for chronic inflammatory glaucoma, but they were only marginally successful.  Trabeculectomies are the next step after goniotomies, and would be expected to work even better than a goniotomy.  On the other hand, a goniotomy is a safe, easy procedure for treating children's glaucoma.  The risk is less than for a shunt or laser.

P:  What is a goniotomy?

Dr. Rick Wilson:  During a goniotomy, the surgeon uses a fine, sharp, knife blade and inserts it across the eye from where the white meets the cornea on one side to the drain on the inside of the opposite wall of the eye.  The knife is then used to incise the inner layers of the trabecular meshwork and any membrane or blockage overlying it.

P:  What about doing a goniotomy after a cyclodiode treatment?  If I were a candidate for it, could that also cause too low a pressure?

Dr. Rick Wilson:  No, because you are just opening up the natural outflow channels.

P:  My eye doctor in the UK, now retired, strongly advised me not to put a tube in my eye and to have more laser surgery.  Everything I read tells me that cyclodiode is a "last resort" procedure.  I have 20/20 vision in that eye. Any thoughts?

Dr. Rick Wilson:  In England, the diode laser is considered by many to be safer than a shunt.  Usually, if a patient has already had a cyclophotocoagulation, I do not recommend putting in a shunt, because the shunts are almost one-size-fits-all.  If the patient isn't making a normal amount of fluid, the patient's IOP may be too low.

P:  Why is goniotomy not usually performed on adults?

Dr. Rick Wilson:  It is usually used for congenital glaucoma, where there is a membrane pulling the iris anteriorly and covering the trabecular meshwork.  Incising that membrane often cures the glaucoma.  In adults, there is no malformation of the trabecular meshwork, so the goniotomy is not as effective.

P:  Are there any tests to measure the amount of aqueous an eye produces?

Dr. Rick Wilson:  Yes, but we can only measure what comes into the front of the eye, not what is absorbed before the aqueous gets into the front of the eye where we can detect it.

P:  Is there such a thing as a secondary glaucoma suspect?

Dr. Rick Wilson:  We usually speak of secondary glaucoma if there is a visible change to the optic nerve or visual field, or if the chance of that happening without intervention is very high.  A person with high IOP, but no noticeable damage, would be termed a "suspect."

P:  What percentage of the general public, as well as your patients, have juvenile glaucoma?  What is being done to get the word out to parents, eye doctors, and pediatricians that this type of glaucoma could be a problem for children?

Dr. Rick Wilson:  In one study in Spain, congenital glaucoma accounted for only 2.85 patients of 100,000.  With medico-legal matters being as they are, the pediatricians are now usually well aware of the signs and symptoms of congenital glaucoma.

Moderator:  It seems that many glaucomas are secondary.

Dr. Rick Wilson:  Still, primary open-angle glaucoma makes up most of the glaucoma cases.

P:  In medicine generally, not just in glaucoma, isn't "primary" somewhat of a provisional concept?  In other words, won't much of -- or at least some of the portion of what's now called POAG -- someday be found to be secondary to causes that simply haven't yet been elucidated, such as vascular, etc.?

Dr. Rick Wilson:  Absolutely. That is one of the exciting things about dealing with diseases that is usually incompletely understood.

On August 31, Dr. Wilson discussed "The Benefits of Exercise" in the Chat room. Click here for highlights of that meeting.

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