Congenital and Developmental Glaucoma
Chat Highlights
November 9, 2005

On Wednesday, November 9, 2005, Dr. Rick Wilson, a glaucoma specialist at Wills, and the glaucoma chat group discussed "Congenital and Developmental Glaucoma."

Moderator:  Greetings, Dr. Wilson.  Tonight's topic is "Congenital and Developmental Glaucoma."  First of all, what are the differences between the two?

Dr. Rick Wilson:  Developmental glaucoma means that the part of the eye through which the fluid (aqueous humor) leaves the eye may not have developed normally, resulting in resistance to the outflow of fluid and increased pressure.  If that causes glaucoma at birth, it is called congenital glaucoma.  Developmental glaucomas do not necessarily become apparent at birth, but can manifest later in childhood.

P:  What is the difference between congenital glaucoma and juvenile glaucoma?

Dr. Rick Wilson:  Congenital glaucoma is discovered at or near birth; infantile, usually in the first three years of life; and juvenile, from three years to the high teens or low twenties.

P:  On the basis of those definitions, if the glaucoma is of the juvenile type, is it more likely to be developmental?

Dr. Rick Wilson:  The older children are when they develop glaucoma, the less obvious is the cause for the glaucoma. Juvenile glaucomas are defined as primary, that is, not secondary to another cause, such as trauma or inflammation.  They are assumed to be due to a developmental defect in the outflow apparatus.

P:  How is congenital glaucoma different from ordinary glaucoma?

Dr. Rick Wilson:  The cause of the common, garden-variety, primary open-angle glaucoma (POAG) is not known.  The cause of congenital glaucoma is an inadequate development of the eye's outflow system.

P:  Is the long-term outcome for congenital glaucoma better or worse than that for the glaucomas developing in mid-life?

Dr. Rick Wilson:  Unfortunately, much worse. Because the child does not recognize the symptoms and often is not able to complain, damage is often further along when the diagnosis is made.  If the child is under seven years of age, amblyopia, or lazy eye, often complicates the visual outcome.  In infants, signs and symptoms may not be evident until there are breaks in the lining of the cornea.  That, itself, reduces vision by causing opacities in the cornea, glare, and astigmatism.

P:  Has there been any recent long-term research about congenital glaucoma and the implications for adults?

Dr. Rick Wilson:  Most of the current research concerns genetic causes for glaucoma, and significant progress is being made.  Certainly, we are obtaining much more data about results from our present surgeries than we used to have.

P:  Is the outlook for a child born with glaucoma in 2005 better than that of a child born with glaucoma in 1955?

Dr. Rick Wilson:  Absolutely.  Not only are our surgeries more refined, but the potential for genetic and stem cell therapy is mind- boggling.

P:  Are there more pediatric ophthalmologists now than there were five years ago?  My son, born 19 years ago, was not identified as having glaucoma until things became totally out of hand.

Dr. Rick Wilson:  Yes.  I think the number of pediatric ophthalmologists has grown.  I am told still more are needed to keep up with the increasing population.

P:  What are the symptoms of glaucoma in infants or young children?

Dr. Rick Wilson:  The classical symptoms are tearing and light sensitivity, accompanied by enlarged corneas that may be hazy to white.

P:  Is it possible to have genetic testing to determine whether glaucoma will occur in future offspring?

Dr. Rick Wilson:  Yes, it is possible to pick up some, but by no means all, of the genetic markers that would allow such a prediction.

P:  I was told by Nichols Institute Diagnostics® that there is an American primary congenital glaucoma mutation.  What do you think of that?

[Editor's note: the URL for the Nichols Institute® is http://www.questdiagnostics.com/brand/business/b_bus_nid.html ]

Dr. Rick Wilson:  Since many of our forbearers have been here for nearly 400 years, it would seem likely that some mutations that are unique to Americans have sprung up.

P:  What are the options to relieve haze in congenital glaucoma cases?

Dr. Rick Wilson:  The IOP must be lowered. Medications are usually not too effective, and follow-up is too difficult to be sure the IOP is adequately controlled.  Getting drops into small children's eyes can sometimes be a challenge.  Crying, if the parent must hold the child down to administer the eyedrop, may wash out a variable amount of the medication.  Therefore, surgery is the usual first option for congenital glaucoma.

P:  If one Ahmed tube does not remove the haze completely (IOP of 20 mm Hg), is putting in a second tube a good option to lower the pressure enough to remove the haze completely and lower the pressure to about 6 or 7 mm Hg?

Dr. Rick Wilson:  Ahmed shunts are often favored by pediatric ophthalmologists, because they are easy to put in, and their valves avoid the need to tie off the tube, and the troubles that glaucoma specialists are used to.  The problem is that they have a small plate, so the IOP result with them is higher that it is with Baerveldts or double-plate Moltenos.  The Ahmed shunt is also bulkier, so putting two into a small child's orbit may cause some restriction of motion.  Although they are not my favorite, they have a fairly good track record.

A shunt will never lower the IOP in an otherwise healthy eye to 6 or 7 mm Hg, because the build-up of scar tissue around the plate limits the absorption of the aqueous to levels above that.  Also, the increased IOP in the young, elastic eye leads to an increase in size and serious near-sightedness.  I have been much better at obtaining good vision when both eyes were involved, rather than one.  The problems of near-sightedness in one eye and not the other, and lazy eye, are not as common.

P:  Could glaucoma possibly be caused by trauma in the womb, rather than by genetics?

Dr. Rick Wilson:  Yes, there can be trauma before birth and also at birth.  Direct injury to the eye by forceps during delivery can cause intraocular bleeding and glaucoma.

P:  After being stable for so many years after having trabeculectomies as a young adult, why can things suddenly change for the worse?

Dr. Rick Wilson:  In adults, it has been said that, on average, trabs last seven years.  I hope that figure is significantly on the rise.  However, children heal much faster than adults, and it is harder to get a trab to last for the long term in children.

P:  My glaucoma specialist said that by treating my 22-year-old son's glaucoma, he (the specialist) will learn more about my glaucoma.  Can there be a relationship, or are these two totally different situations?

Dr. Rick Wilson:  It depends on when you developed glaucoma.  If it was close to your son's age, there may be enough similarities to learn something about your case.  If not, I don't see the relationship, except in the genes.

P:  My son is 19-years old, was born with glaucoma, and is albino.  He had a terrible time learning to drive.  His doctor at Wills said that he should be able to drive.  Why do you think learning to drive was so difficult for my son?

Dr. Rick Wilson:  If your son is a complete albino without any pigment at all in his eyes or hair, then the back of his eye did not develop normally, and he probably has rapid to and fro movements of his eye, called nystagmus.  In such a case, it is unlikely that he would have enough vision to be driving legally.  It is probable that he has an intermediate type of albinism, still with some decreased vision, that may be affecting his depth perception.

P:  What is cupping?  How is it measured and what does it indicate?  Does it indicate something different in congenital than in adult- onset glaucoma?

Dr. Rick Wilson:  Cupping is the depression in the center of the nerve.  Most people have a small, normal-sized depression, or cup.  With increasing glaucoma damage, more of the nerve is injured and shrinks away, leaving a larger and larger cup in the center of the nerve.

The cup in congenital glaucoma looks slightly different from the cup in adults, and is much more sensitive to pressure.  High pressure dilates the canal in the sclera through which the nerve exits to the brain.  Since the hole is larger, but the amount of nerve tissue is the same, or only slowly being lost, the cup can increase markedly.  When the IOP drops, the cup can become smaller, and the canal returns to normal size, squeezing the nerve back into shape.

Moderator:  Thank you, Dr. Wilson.

On November 16, Dr. Henderer discussed "AAO Meeting Update" in the Chat room. Click here for highlights of that meeting.

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