Chat Highlights
Advanced Glaucoma
October 20, 2004

Norma Devine, Editor

On Wednesday, October 20, 2004, Dr. Elliot Werner, a glaucoma specialist at Wills, and the glaucoma chat group discussed "Advanced Glaucoma."

Moderator:  Welcome, Dr. Werner.  Our topic tonight is advanced glaucoma.  How do you define advanced glaucoma?

Dr. Elliot Werner:  I would define advanced glaucoma as having enough loss of vision to produce significant symptoms and functional impairment.

P:  What are the symptoms of advanced glaucoma?

Dr. Elliot Werner:  The symptoms often vary. The patient may notice difficulty with a variety of visual tasks, such as driving, reading, seeing in low-light situations, tiring easily from visual tasks.

P:  Can someone with advanced glaucoma still drive?

Dr. Elliot Werner:  In Pennsylvania you must have 20/40 vision in the better eye and more than 30 degrees of visual field in all directions to drive.  

P:  Is glare caused by bright lights a symptom?

Dr. Elliot Werner:  Many glaucoma patients in my experience complain more about low light situations, but some do complain about glare with bright light environments as well.  Believe me, when you have lost 80 to 90 percent of your optic nerve, you don't see well and you always have problems.

P:  Why do people with advanced glaucoma have decreased contrast sensitivity?

Dr. Elliot Werner:  People with glaucoma have impairment of all their visual functions, because the optic nerve carries all visual functions from the retina to the brain.  If your optic nerve is damaged, all visual functions will be affected, including color, acuity, contrast sensitivity, etc.

P:  What color perceptions are most affected by advanced glaucoma?

Dr. Elliot Werner:  Studies have generally shown that glaucoma seems to affect yellow-blue perception more than red-green, but again as the optic nerve is lost, all vision is affected.

P:  Is there a particular color of tinted glasses that improves contrast sensitivity for patients with advanced glaucoma?

Dr. Elliot Werner:  Sometimes amber (light yellow) glasses seem to help a lot with glare and contrast.

P:  Do the visual field tests of patients with advanced glaucoma show a typical pattern of visual loss?

Dr. Elliot Werner:  The usual pattern is loss of visual field both superiorly and inferiorly.  The visual field loss often encroaches on fixation near the center of the visual field.

P:  Are certain shapes, sizes, and locations of defects in the visual fields predictive of poorer prognosis?

Dr. Elliot Werner:  Defects that split fixation, that is, come right to the center of fixation, have a poorer prognosis.  Otherwise, the type of visual field defect doesn't make much difference in the outcome.

P:  Is it usual to develop symmetrically shaped and similarly located visual field defects, or do you see mostly asymmetrical defects?

Dr. Elliot Werner:  Both.  Most open-angle glaucoma patients have fairly symmetric defects in their visual fields, but asymmetry with one eye worse than the other is also not unusual.

P:  Do the results of the visual field tests of a patient with advanced glaucoma sometimes vary significantly?

Dr. Elliot Werner:  The visual field test results always vary to some degree from test to test in all patients.  Other visual function tests also show some fluctuation.  Many patients with advanced glaucoma also complain that they have good days and bad days with their vision, so there does seem to be some variation in how well patients with advanced glaucoma see.

P:  How much of the optic nerve is cupped in advanced glaucoma?

Dr. Elliot Werner:  In advanced glaucoma, the cup-to-disc ratio is at least 0.8 or 0.9, meaning that at least 80 to 90 percent of the nerve substance has been lost.

P:  Why is the optic nerve of an advanced glaucoma patient more susceptible to damage at lower eye pressures?

Dr. Elliot Werner:  I'm not sure anyone knows exactly why.  It may have to do with the loss of reserve.  For example, if you have 500,000 nerve fibers, about half the normal number, and you lose 50,000, you're only losing 10 percent of your nerve.  If you have only 100,000 nerve fibers and you lose 25,000, you're losing 25 percent of the nerve so you notice it more.

P:  Why do some people in developed countries progress to advanced glaucoma? 

Dr. Elliot Werner:  Many patients present with advanced glaucoma, either because they have ignored significant symptoms or because they haven't seen a doctor in a long time.  Some patients progress to the advanced stage despite being under care, but that is unusual in patients diagnosed early.

P:  When would you surgically intervene in the case of advanced glaucoma?

Dr. Elliot Werner:  That decision depends upon if the patient shows definite signs of progression, if the IOP (intraocular pressure) seems too high for that patient based on the pre-treatment pressure. It also depends upon the target pressure the doctor has defined, and the extent of nerve damage.

P:  What is the difference between advanced glaucoma and end-stage glaucoma?

Dr. Elliot Werner:  A patient with end-stage glaucoma would be legally blind.  A patient with advanced glaucoma might not be legally blind.

P:  What percentage of advanced glaucoma patients progress to end-stage glaucoma?

Dr. Elliot Werner:  That's hard to say.  A recent paper showed that in a population survey about 0.3 percent (about 3 per 1000) of people reported significant visual impairment from glaucoma.

P:  Regarding that statistic you just cited, is that 0.3 percent of glaucoma patients, or 0.3 percent of the general population?

Dr. Elliot Werner:  That was 0.3 percent of the population surveyed.

P:  Does a patient with end-stage glaucoma always go blind?

Dr. Elliot Werner:  If a patient has end-stage glaucoma and still has some vision, and if the IOP can be controlled at a low enough level, they may never go blind.  The timing depends upon the level of IOP.

P:  Why do some patients who do not have advanced glaucoma have surgery?

Dr. Elliot Werner:  Some patients with early to moderate glaucoma who continue to show progressive deterioration despite medical and/or laser treatment end up having surgery to try to prevent their glaucoma from becoming advanced.

P:  I have advanced glaucoma and need a cornea transplant.  Do patients like me have a good success rate with corneal transplants?

Dr. Elliot Werner:  If the IOP is controlled, the success rate with corneal transplants is about as good as in patients without glaucoma.

Moderator:  What is endocyclophotocoagulation (ECP)?

Dr. Elliot Werner:  ECP is a procedure that uses laser to destroy some of the ciliary body to reduce the amount of aqueous in the eye and therefore lower the IOP. 

P:  I have substantial field loss close to fixation in one eye. The other eye is fine right now.  If I had the same kind of loss close to fixation in my good eye, would you call that advanced glaucoma?  What are my chances for acquiring the same type of defect in both eyes? 

Dr. Elliot Werner:  If the defects in the good eye were as extensive as in the other eye, I would say yes.  Remember, however, there is no cut off-point.  It's like saying someone is tall.  Is 5'11'' tall, or do you have to be over 6'2'' to be tall?

P:  When I ask my glaucoma specialist about my glaucomatous eye he answers, "you have glaucomatous damage."  After almost three years as his patient, I still don't know how severe the damage is or what my optic nerve looks like.  Is there another way I could phrase the question, to find out how much damage I actually have?

Dr. Elliot Werner:  Ask him to show you your visual field and describe how much of the field has been lost.  Ask for your cup-to-disc ratio.

P:  I have both glaucoma and cataracts.  Should I have the trabeculectomy and cataract surgery done separately or combined?  I have astigmatism in both eyes.

Dr. Elliot Werner:  Unless it is absolutely necessary, my preference is not to combine trabeculectomy and cataract surgery because of the greater risk of complications and the prolonged recovery time.

P:  Should I have the glaucoma surgery first in the eye with advanced glaucoma?

Dr. Elliot Werner:  Normally, we operate on the worst eye first unless there is some reason not to.

P:  I hear ophthalmologists say glaucoma treatment is "buying time."  How much time do current treatments, in the aggregate, actually buy?

Dr. Elliot Werner:  No glaucoma treatment is 100 percent effective.  Some patients get worse no matter what, but most patients can be maintained with good treatment and follow-up.

End of highlights for October 20, 2004.

On November 3, Dr. Wilson discussed "Unconventional Glaucoma Treatments" in the Chat room. Click here for highlights of that meeting.

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