Chat Highlights
Genetics and Glaucoma
July 26, 2000

Norma Devine, Editor

On Wednesday, July 26, 2000, Dr. Rick Wilson and Dr. Jeffrey Henderer, glaucoma specialists at Wills, and the glaucoma chat group discussed "Genetics and Glaucoma."  Dr. Henderer substituted for Dr. Rick Wilson until he was able to join us. 

Moderator:  Welcome Dr. Jeff.  Thanks for coming at such late notice.  The topic tonight is Genetics and Glaucoma.

Dr. Henderer:  I like the topic, but I am not quite an expert in it.  I'll help all I can.  I am researching the topic for a book chapter I am going to write.

Moderator:  Are some types of glaucoma more likely than others to be passed down in families?  

Dr. Henderer:  As far as I know, several forms of glaucoma are inherited.  I am not sure if one is more likely than another.  I would say that open-angle glaucoma is probably the result of multiple genes, so that might be the most likely one.  It appears that infantile glaucoma is related to a problem on Chromosome 1, and pigmentary glaucoma, and probably pseudoexfoliation, are single (or just a few) genes.  

Moderator:  Do you tell your patients that their families should be tested for glaucoma?  

Dr. Henderer:  I tell people that they should not be tested for glaucoma now, but that in a few years it may be the best test we have.

P:  My open-angle glaucoma was diagnosed eight years ago.  A week ago my wife learned she has pigmentary glaucoma.  What are the chances that my two children will develop one of those types?  

Dr. Henderer:  Since you and your wife have different forms of glaucoma, the chances are not any higher (I don't think) than if only one of you had the disease.

P:  What would those chances be?  

Dr. Henderer:  I don't honestly know.  I think it depends a great deal on the gene defect.  For recessive genes, you need two bad copies, one from each parent.  For dominant genes, you need only one bad copy. The chances are greater if you have one of the dominant forms. I think that most of the glaucoma genes identified so far are recessive.

P:  What inherited characteristics might predispose one to open-angle glaucoma?

Dr. Henderer:  Myopia (near-sighted), being older, African-American, migraine headaches and diabetes may predispose one to primary open-angle glaucoma.  Remember that open-angle glaucoma is a term that can encompass pigmentary glaucoma and other types.  Primary open-angle glaucoma is the most common form and that is what my comment pertains to.

Moderator:  Do you think that one day gene therapy might help us?

Dr. Henderer:  Yes, gene therapy is definitely in the cards. I saw a presentation not too long ago using a virus to insert a new gene into the drain of a  monkey eye to help with glaucoma.  This may be really promising.  I have not seen anything very recently though. This is an extremely difficult problem to tackle, and you may be aware of recent human gene therapy trials that have gone wrong. The whole field is sort of on hold.

Moderator:   Yes, the gene therapy at  the University of Pennsylvania.

Dr. Henderer:  Penn is one example, but the University of Oklahoma was recently in trouble, too. These gene therapy trials are largely based on cancer.  No one has tried any eye diseases in humans that I know of.  The state of the field in glaucoma is really in the discovery stage.  Various people are trying to find families with glaucoma and then to find the gene in that family. We are a long way from finding all the genes and even longer from any therapy.

P:  I may have pigment dispersion syndrome.  A tennis ball hit my left eye, but the right eye has optic nerve damage, too.  I don't think genes played a role in my glaucoma.  What percentage of glaucoma patients do you think have inherited the genes for glaucoma? 

Dr. Henderer:  Clearly, your glaucoma is related to trauma. That is not genetic. The same holds true for  inflammatory or neovascular glaucoma and many others. But most common glaucomas are probably genetic.

P:  Could trauma in one eye cause glaucoma in both?

Dr. Henderer:  No, glaucoma should only be in the eye with trauma.

P:  Is trauma more likely to precipitate glaucoma if there is a family history of glaucoma?

Dr. Henderer:  Great question.  To be honest, I don't know.    

P:  Is a specific type of glaucoma inherited or just a general group?

Dr. Henderer:  If you are part of a family with glaucoma, we at Wills are trying to collect blood samples. Please contact us.

Moderator:  My family all have closed or narrow-angle glaucoma.

Dr. Henderer:  Closed angle is the best! We have no families with closed-angle glaucoma, and we're very interested in identifying the gene in closed angle!  Please contact us!

Note:  Dr. Rick Wilson enters chat. 

Dr. Wilson:  Hooray, I finally made it.  Thanks so much for your help, Jeff.

Dr. Henderer:   You're welcome Rick.  Maybe I'll stick around for a bit.

Dr. Wilson:   That's fine with me.

Moderator:  Dr. Rick, we're still discussing Genetics and Glaucoma.  What can you tell us about the topic?

Dr. Wilson:  I had a dissertation ready on my other computer when the network went down, and I lost it.

P:  Drs. Henderer and Wilson, how can we ship you blood from Florida?

Dr. Henderer:  We will have to get back to you on that one. I don't know how to ship blood to Pennsylvania.  Maybe Rick knows.

Dr. Wilson:  The Service does it,  but I don't know the particulars.

Dr. Henderer:   Rick, perhaps the Insite Study (Dr. Jones) might have more information.

P:  How do we find out the particulars?

Dr. Wilson:   The last I looked, we are only taking people with at least three close family members with glaucoma.  Visit www.willsglaucomaresearch.org.

Dr. Henderer:  We are especially interested in angle closure glaucoma and genetics, so if you have a family history of angle closure, this would be very helpful (especially if your are Chinese).

P:  When I developed glaucoma,  I started seeing some very small darks things floating in my right eye, specially when in bright light.  My doctor said they are a precipitation of vitreous.  Is that correct?

Dr. Henderer:  Yes, that is correct.  The term is actually "floaters" and they are small precipitates in the vitreous.  They are often normal (especially in young, near-sighted people), but can be a sign of a vitreous detachment in an older person, or even herald a retinal detachment.  Glad you saw your doctor!

P:  Could you please tell me what a vitreous detachment is?

Dr. Henderer:  Yes, sorry.  When the vitreous liquefies with age, it's called a vitreous detachment.  When it separates from the retinal surface, it pulls some tissue with it.  That causes the floater and can lead to a retinal detachment.

P:  Isn't 33 early for that?  Or is the glaucoma related to it? 

Dr. Henderer:  You are young, for sure. It is not really a part of glaucoma, but if you are near-sighted it may be related.

P:  What are the probable gene loci for pigmentary dispersion?

Dr. Wilson:  I don't know it off-hand.  There may well be more than one loci.

P:  But I have pigmentary glaucoma.

Dr. Wilson:   The greatest obstacle to progress seems to be that there are many kinds of glaucoma, and multiple genes may come together to allow expression of that gene, making unraveling the mystery difficult.

P:  Are repressor genes part of the picture?

Dr. Wilson:  I don't know.  Certainly some genes promote expression and others repress expression. The balance determines the extent the gene is expressed.

Moderator:  What is a repressor gene?

Dr. Henderer:  A repressor gene prevents another gene from being expressed.  The most famous example is the p53 gene, which I believe is a suppressor gene that, if lost, can allow other genes to be expressed, leading to cancer.  I don't know of such a situation in glaucoma.

Dr. Wilson:  Jeff left putting his kids to bed to bail me out when my network went down. We all owe him thanks for saving this chat session.

Dr. Henderer:  Rick, my pleasure.  Thank you all and I will sign out now.  Hope to talk to you all in the near future!

P:  Dr. Rick, I was hit with a tennis ball in the left eye only, and I'm being treated for the left eye only. However, my doctor said that I also have optic nerve damage in the right eye.  My  IOP's started at 28/32 and are now 23/21.  The doctor still has not ruled out pigment dispersion syndrome. Can one eye have a different kind of glaucoma than the fellow eye?  I am confused.

Dr. Wilson:  You could have an underlying kind of glaucoma that was exacerbated by the trauma, causing that eye to have more severe or earlier problems.  The underlying kind of glaucoma could be in both eyes, and trauma exacerbated the IOP in the injured eye.

Moderator:  If there are no more questions about genetics and glaucoma, we will open up the chat for general glaucoma questions.

P:  Is there much risk with a laser iridotomy?

Dr. Wilson:  Usually, no.  The cornea can be damaged if the energy is too great or too close to the cornea.  Bleeding is unusual, but possible.

P:  Can allergies raise IOP enough to cause faint halos around lights?

Dr. Wilson:  I would not think so, unless the cornea was affected to the point that it caused the halos.

Moderator:   How can someone with no insurance get help?

Dr. Wilson:  All the drug companies have compassionate assistance programs for those who need financial help paying for medications.  For surgery, you might want to try the service of a teaching hospital.

Moderator:  How does a patient with no insurance find a doctor for general care or a second opinion?

Dr. Wilson:  The American Academy of Ophthalmology's Project Glaucoma 2000 will put patients without doctors in contact with doctors who will see them. 

P:  I called them and they referred me to local help -- like United Way, Lions Club, Salvation Army.  

P:  Maybe you should refer to the Project 2000.  Perhaps the person you were speaking with didn't know about it.

Moderator:   Yes, that might work.  I know someone here got help from them. 

P:  I will keep calling.  I did talk to someone about Project 2000, but I will call back and ask again.  Thanks, all,  for helping me out on my first chat. 

P:  Speaking of people needing medications,  is there anything people like me can do with all the unopened, sealed bottles of drops that our insurance companies send us and then we are taken off the drops?  I have nine bottles of Alphagan, some Cosopt, and others.

Dr. Wilson:  Yes, you can send the bottles to the International Eye Foundation in Washington D.C. or the Christian Eye Ministries.  I'm not sure of the address, but will find out if you e-mail me.

P:  Has anyone heard of a "new" medication based on prostaglandin?  What are the known side effects?

Dr. Wilson:  Rescula is the new drug.  It is a Xalatan-like drug.  It's  not as effective as Xalatan, but has fewer side effects.

P:  Do you take people off drops if  the drops don't lower the pressure and the person is only a glaucoma suspect?

Dr. Wilson:  I only use drops if they are effective and only treat patients if the suspicion warrants it.  If drops are not effective and there is definite glaucoma, then a laser is a possibility.

Dr. Wilson:  I've got to get to bed.  Sorry I was late.  I'll get  the network together for next week.  Good night.

Moderator:  Thanks, Dr. Rick.  Good night.

End of highlights for July 27th chat.

On September 6th Dr. Rick Wilson discussed "Glaucoma and Insurance" in the Chat room. Click here for highlights of that meeting.

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