Chat Highlights
Cornea, Dry Eyes and Glaucoma
February 7, 2001

Norma Devine, Editor

On Wednesday, February 7, 2001, Dr. Christopher Rapuano, a cornea specialist at Wills, and the glaucoma chat group discussed "Cornea, Dry Eyes and Glaucoma." 

Moderator:  Welcome, Dr. Rapuano.

Dr. Rapuano:  Thank you.  I am new at this, so forgive me if  I am a little slow.

Moderator:  Dr. Wilson sends his regards and is sorry he could not be here tonight.

P:  Doctor Rapuano, we are going to pick your brain about corneas tonight! 

P:  And about dry eyes.  

Dr. Rapuano:  Sounds good to me.

Moderator:  Dr. Rapuano, before we begin, why don't you tell the group a little about yourself?

Dr. Rapuano:  I am a cornea specialist at Wills Eye Hospital.  As far as surgery, I do primarily corneal transplants and refractive surgery.  I see a lot of patients with dry eyes, not to mention other cornea problems.

Moderator:  Dr. Rapuano, what is the cornea?

Dr. Rapuano:  The cornea is the clear covering of the surface of the eye.  It covers the iris (the brown or blue part) and the pupil (the opening for light to the back of the eye).  The smallest scratch in the center of the cornea can cause a real drop in vision.

P:  What conditions may require corneal transplants?

Dr. Rapuano:   We perform corneal transplants for many conditions, including corneal swelling (Fuchs dystrophy or swelling after eye surgery, typically cataract surgery, but occasionally trabs or tube shunts), corneal scarring (from trauma or infection), corneal irregularity, such as keratoconus, and inherited corneal opacities.

P:  What can a person do who has the cornea problem, "Fuchs", and needs a trabeculectomy for glaucoma in an eye that sees fairly well (about a 9).  After a trabeculectomy in the fellow eye five months ago, the vision in that eye is fuzzy and can't be depended on for reading, driving, etc. 

Dr. Rapuano:   Fuchs' dystrophy is a problem in the cornea that leads to corneal swelling and poor vision.  Trabs can cause the swelling to become worse.  However, the cornea can be replaced, whereas an optic nerve damaged from glaucoma cannot!  My preference is to have the glaucoma surgery first, to get the pressure under control. Once the pressure is under control, a transplant is safer, and has a better rate of success.  

P:   If a person with stem cell deterioration got a cornea transplant, would the cells grow in that too?  I am probably going to have another trab, but it seems so fruitless to have it when my cornea problem will prevent reasonable sight anyway.

Dr. Rapuano:   Corneal transplants do not include stem cells, so the cornea may well cloud up after a transplant.

P:  How old can donors' corneas be that are used for transplants?

Dr. Rapuano:   We accept donor tissue up to 72 years old. We try to use older tissue for older patients and vice versa.

P:  Will there be enough corneas in eye banks for transplants that will be needed by the large baby boomer generation?  

Dr. Rapuano:  I certainly hope there will be enough corneas for the future. 

P:   How many eye banks, approximately, are there in the U.S.?

Dr. Rapuano:   Eye banks in the U.S.?  That is a good question. I would guess 150.

P:   Would corneas from glaucoma patients be acceptable?

Dr. Rapuano:  Yes, glaucoma patients' corneas are accepted. We check the health of the cornea, no matter who it comes from, to make sure it is healthy enough for transplantation.

P:  Would the recipient of a glaucoma patient's tissue get glaucoma? 

Dr. Rapuano:   If a donor has glaucoma, the person who gets that donor's cornea is not more likely to get glaucoma. 

P:  I've had two dellen.  One was caused by a cyst on the bleb, which was resolved by a revision of the trab.  But the other, caused from mitomycin C damage, was only resolved by removing the bleb (shunt surgery.) We have patients with mitomycin C damage to the cornea; can their dellen be resolved with a bleb revision?

Dr. Rapuano:   Mitomycin C damage is somewhat different from a delle.  You can have both.  A delle is from dryness from an adjacent elevation. Sometimes repairing the elevation is the only solution.

P:  Are our glaucoma doctors likely to spot dellen?

Dr. Rapuano:  Glaucoma docs should be able to spot dellen.

P:  How soon after harvesting must a donor cornea be transplanted?

Dr. Rapuano:   We prefer to use corneas within three to seven days after death.

P:  Is there a huge shortage of corneas for transplant?

Dr. Rapuano:  There is no great shortage of corneas in the U.S.  It is quite expensive, around $1600 per cornea, to obtain corneal transplant tissue.  

P:   Are most of the people who undergo corneal transplants happy with their vision? Is the vision sufficiently improved to justify the risks?

Dr. Rapuano:  Most people are happy after corneal transplants.  However, there are a few things patients need to know.   (1) It takes about one year to get good vision. ( 2) There is no guarantee.  ( 3) Certain conditions have much better results than others.  For instance,  Fuchs dystrophy has quite good results, while stem cell problems do not. There is also a small risk of a big problem, such as bleeding or infection, where the vision might be no better or even worse (or even blind in that eye).

P:  Are cornea transplants covered by insurance?

Dr. Rapuano:  Cornea transplants are usually covered by insurance.

Moderator:  I have heard several times that I might have dry eyes.  What is a dry eye?  

Dr. Rapuano:  The surface layer of the cornea is called the epithelium.  It needs to be kept moist to work. There are numerous tear-producing glands in the eye that secrete tears, which keep the surface moist. The lids blink the tears to keep the tear surface smooth.  Dry eyes is a condition that causes problems with this function.

P:  Why do so many of us glaucoma patients who have had surgery complain of  dry eye?

Dr. Rapuano:  Many of the drops used to treat glaucoma, such as timolol, cause a decrease in tear production.  Glaucoma surgery can also damage the conjunctiva, which can affect some of the tear-producing cells, too.  Dry eyes can be due to problems in several different locations. The tear-producing glands can be malfunctioning, so not enough tears are produced. The surface layer (epithelium) can be damaged, too. The oil glands in the lids can also malfunction.

P:   What is the conjunctiva?

Dr. Rapuano:  The conjunctiva is the clear tissue-like substance that covers the white of the eye.

P:  Do weather and allergies have a connection to dry eyes?   

Dr. Rapuano:  Sure, the weather can certainly affect dry eyes. The more humid, the less people are bothered by it, in general.  The same holds true for allergies.  Plus, many anti-allergy meds dry the sinuses and eyes. 

P:  What should the examination of a patient with dry eye include?    

Dr. Rapuano:  The examination of someone with dry eyes should include a complete corneal evaluation, with special dyes, such as fluorescein or rose Bengal, to see how healthy the cornea is.  It often includes a Schirmer's test, where a small piece of white filter paper is placed in the eye for three to five minutes to measure tear production.

P:  Should a dry-eye exam also include inspection under the eyelid, toward the top? I  understand that the Meibomian glands are up there. Can they be seen?

Dr. Rapuano:  A good, complete eye exam should include looking under the upper lids, but the Meibomian glands, which secrete the oils that coat the tears, are at the edge of the eyelids and can be seen without flipping up the eyelids. But, of course, the glands should be examined, as malfunction can make dry eyes much worse.

P:  What are the symptoms of dry eye?  

Dr. Rapuano:  Dry eye symptoms include scratchiness, irritation, mucous discharge (usually worse as the day goes on) and, if the dry eye is severe, even pain.   Sometimes people have excess tearing!  That is because the eye is so scratched there is reflex tearing.

P:  I understand that infection can be a cause of dry eye. If that were the case, how long can the infection last without treatment?  How would it be determined that an infection is the cause of dry eye? 

Dr. Rapuano:   Infections do not generally cause dry eyes, although rarely certain infections can.  Dry eye certainly predisposes to infection. The longer and the worse the dry eye, the greater the likelihood of infection.

P:  How much is the middle tear layer, the aqueous, affected by IOP?  Does a low IOP mean less middle tear layer and does a high IOP mean more?

Dr. Rapuano:  Intraocular pressure has nothing to do directly with the size of the middle tear layer.

P:  When I arise in the morning, a large quantity of  liquid runs down my face. Is this consistent with dry eye?

Dr. Rapuano:  Hmm, I am not sure what that is.

P:  I had a lot of liquid, too, and found I had a blocked duct.  I still have it.  

P:  If only one of  the tear layers was missing, which one would cause the most discomfort?

Dr. Rapuano:  Most of us think of the tear film as having three distinct layers, but in reality, they are intertwined. All three layers are important.

Moderator:  I find that artificial tears, even those that are preservative free, make my eyes drier and I don't use them.  My doctor told me to use artificial tears eight times a day, but  I never actually followed his instructions.

Dr. Rapuano:  Eight times a day is a lot to ask for someone to use tears. You should think about punctal plugs!

Moderator:  Where is the plugging done?  Is a local anesthetic used?   

Dr. Rapuano:  Plugging the tear ducts is done in the office using just topical (drop) anesthesia.  It's a  relatively straightforward procedure.  Placing a silicone plastic plug may take five minutes and is pretty painless.

P:  Is Alocril prescribed for irritated eyes, dry eyes, or both?

Dr. Rapuano:  Alocril is an anti-allergy drop, which is also soothing. It has very few side effects, and since many dry-eye patients also have allergies I have no problem with it.  Some people find thicker tears, such as Celuvisc or GenTeal gel, very helpful.  The problem with these is that they can blur the vision temporarily.  My favorite artificial tear is TheraTears.  Many of my patients think they are better than the others. 

P:  So dry eye does affect the cornea over time, and the artificial tears help to combat that?

Dr. Rapuano:  Yes, tears can help prevent permanent corneal damage.

P:  Everyone blink!

Dr. Rapuano:  Blinking is good.

P:  Cold weather seems to affect my vision.

Dr. Rapuano:  Cold weather is typically very dry, so the eyes dry out quickly, affecting the vision.  Anything that affects the corneal surface can affect vision.

P:  Can dry eyes cause halos and would that be considered extreme dry eye?

Dr. Rapuano:  Halos can be due to cornea problems, such as dry eyes.

P:  Will you describe the various treatments for dry eyes?  I arrived late.

Dr. Rapuano:  Treatment of dry eyes depends on the exact reason for the dryness.  If it is lack of tear production, then adding tears is a good solution.  We start with tears in bottles that have minimal preservatives, and move up to preservative-free artificial tears.  If someone still has severe dry eyes, then we can block the tear drainage ducts, called punctal occlusion.  

P:   Please explain punctal occlusion.

Dr. Rapuano:  Punctal occlusion can be temporary, such as with silicone plugs, or permanent such as with cautery.

P:  How much is the middle tear layer, the aqueous, affected by IOP?  Does a low IOP mean less middle tear layer and does a high IOP mean more?

Dr. Rapuano:  Intraocular pressure has nothing to do directly with the size of the middle tear layer.

P:  What is the best solution for the dryness caused by the shape of the trabeculectomy bleb?

Dr. Rapuano:  Dryness caused by the shape of a trab is often due to the eyelid being elevated over the trab and not spreading the tears over the entire cornea.  That can lead to an area of the cornea that dries out severely and can even become very thin, called a dellen.  A delle is a dry area of the cornea that thins. 

P:  Can something be done about that?

Dr. Rapuano:  The solution for a large trab bleb causing a delle is lubrication, generally with ointment.  If that doesn't help, then the bleb may have to be revised to shrink it.

Moderator:  The hour passed very quickly.  Thank you, Dr. Rapuano.  Please come back.

Dr. Rapuano:  Thank you for inviting me to participate.

On February 14, Dr. Wilson discussed "Glaucoma and Pregnancy" in the Chat room. Click here for highlights of that meeting.

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