End Stage Glaucoma
May 24, 2000
Norma Devine, Editor
On Wednesday, May 24, 2000, Dr. Rick Wilson, a glaucoma specialist at Wills, and the glaucoma chat group discussed “End Stage Glaucoma.”
Moderator: Greetings newcomers and old timers. Tonight’s topic is “End Stage Glaucoma.” We’ll discuss the topic with Dr. Rick Wilson, a glaucoma specialist, for about 30 minutes. Please wait until the discussion ends before asking Dr. Wilson questions unrelated to the topic.
Dr. Wilson: End stage glaucoma is different from early glaucoma in that the visual field loss is step-wise down, rather than a gradual slope down. If you have a million five-dollar bills and lose five percent of them, you may not notice. But if you have 80,000 and lose five percent, that is very noticeable. A damaged nerve is also “softened up” and can suffer more damage at lower pressures than a healthy nerve. There may be an abrupt drop in visual field followed by a stable period, then another drop off.
Moderator: What defines “end stage?”
Dr. Wilson: End stage usually means vision is reduced to a center island of vision, and a crescent of vision off to the side.
P: Are you talking about tunnel vision?
Dr. Wilson: Tunnel vision is only a central island.
P: What percent of diagnosed patients progress to end stage?
Dr. Wilson: That depends upon the race. Among white Americans, the number is small. Among African-Americans, the number is six times as great. In Nigeria, 10 percent of the population has glaucoma. Of that 10 percent, 34 percent are bilaterally blind and 90 percent are unilaterally blind.
P: I have a problem with the normal vision test at my appointments. For me to see the black letters clearly, I actually look a little to the side, much as you do to see better at night. Does that mean I’m probably end stage?
Dr. Wilson: No, that sounds more like macular degeneration.
P: Once one is in end-stage, does that mean total loss of vision is no
t far off?
Dr. Wilson: No, people can stay at end stage for years, if the intraocular pressures are low enough.
P: What if there is central vision loss to start with?
Dr. Wilson: Central vision loss is usually seen late in glaucoma, although it is more common in low-tension glaucoma.
P: Is there more loss of central vision in low-tension glaucoma because other issues beside IOP are probably at play?
Dr. Wilson: Yes, such as circulation.
P: What can be done to improve circulation? I have NTG and also Raynaud’s Syndrome. I think there is some correlation, but my doctor is not convinced.
Dr. Wilson: It is hard to improve circulation. Vitamin E helps, as does exercise and ASA, under the supervision of an internist.
P: What is ASA?
Dr. Wilson: ASA is aspirin, as in acetylsalicylic acid.
P: My sister, who is a pharmacist, just told me to start taking vitamin E. What dose should I take?
Dr. Wilson: I recommend taking 400 IU per day. Use the alpha variety, and the dextro isomer if you can find it.
P: How often should you see the doctor to protect yourself from glaucoma?
Dr. Wilson: Yearly, if you don’t have glaucoma.
P: Are researchers working to regenerate nerve cells? If so, could this help strengthen the optic nerve?
Dr. Wilson: Yes.
P: Doctor, getting back to the central vision loss — a person with NTG who has central vision loss is not necessarily at end stage. Is that correct?
Dr. Wilson: End stage is a relative term and means different things to different people. So the answer to your question depends upon the extent of the central vision loss.
P: Is the end stage painless?
Dr. Wilson: The end stage is also without symptoms.
Moderator: Do you treat end stage differently?
Dr. Wilson: Yes, more aggressively to get the pressure lower.
P: If I’m having terrible side effects from all glaucoma drops, can a doctor just monitor my pressure without my using the drops so I won’t have this problem?
Dr. Wilson: Not if the pressure is harming you at this level.
P: What measures do you take with end stage glaucoma ?
Dr. Wilson: End stage glaucoma is treated just like early glaucoma, except the target IOP is much lower. Usually medicines are tried first, then lasers, then surgery.
P: Do most people wait until the “end stage” to learn coping techniques such as Braille?
Dr. Wilson: Yes.
P: When someone has tunnel vision, is he or she legally blind?
Dr. Wilson: In the U.S., legally blind is vision of less than 20/200 in the better eye or visual field of less than 10 percent.
P: How can we measure a loss of 10% of visual field?
Dr. Wilson: That’s mostly done by just eye-balling the visual field compared to normal.
P: Would you once again define peripheral and central loss in glaucoma?
Dr. Wilson: Central loss is the central 10 to 15 degrees of vision. Peripheral vision is 20 or more degrees off from fixation. Fixation is the center of your vision.
P: I am newly diagnosed with glaucoma. What is the marijuana connection anyway?
Dr. Wilson: Marijuana lowers IOP for a short time. The effect may be related to relaxation of muscle pressure on the eye.
P: So you’d have to stay stoned all the time for it to do any good?
Dr. Wilson: The effect is fairly short-lived, which is why long-acting drops are the mainstay of treatment.
P: Will shunts eventually be superior to trabeculectomies?
Dr. Wilson: Perhaps they will be when we perfect valves and can figure out a way to get as low an IOP with shunts as we get with trabeculectomies.
P: If your pressure stays the same, will you avoid loss of vision?
Dr. Wilson: The pressure should be low enough to prevent further loss. If it is, then no further vision loss will occur.
P: What are the advantages of shunts over trabeculectomies, assuming intraocular pressures are as low as in trabeculectomies?
Dr. Wilson: The advantages are avoiding thinning of the conjunctiva that allows for leaks, avoiding too low an IOP, and avoiding the chance for infection.
P: I was interested in something mentioned earlier. Is there work being done on regenerating nerve cells, particularly the optic nerve, but any in general that might lead to something helpful for us? Or is that just a pipe dream at the moment?
Dr. Wilson: Lots of people are working on that, but there’s still a way to go. The optic nerve contains 900,000 to 1,200,000 fibers in something about the size of a small matchstick. It’s hard to get those fibers to regenerate in the right places so vision is not all jumbled up. I would guess that should be possible sometime during our lifetimes.
P: What is the significance of the optic nerve size?
Dr. Wilson: It’s just to help you picture how fine the nerve fibers are.
P: Is optic nerve size with end stage always 1.0? Mine is now .9, but I still have pretty decent vision.
Dr. Wilson: How was that measured? I would bet that the discrimination ability of the measurement apparatus is not that good.
P: I suspected that, since different doctors gave me different numbers. The first doctor said .7. The doctor I’m seeing now, a glaucoma specialist, measured .9.
Dr. Wilson: He is probably talking about the cup, or depression in the surface of the optic nerve, not the width of the nerve behind the eyeball.
P: Do you have any patients who don’t take drops and just have the pressure monitored by you? I can’t take the side effects. I don’t have field loss. I was just recently diagnosed.
Dr. Wilson: If you can’t tolerate the eye drops and your pressure is too high and is damaging your nerve, you have to have laser, if you are a good candidate for surgery.
P: I have had two implants and would like to start playing tennis in a couple of weeks. Are there any special risks because of my eye implants?
Dr. Wilson: I would wear protective eyewear. I’ve seen too many people with their eyes smashed by tennis and squash balls.
P: How soon after an implant can I wear contacts again?
Dr. Wilson: Usually about a month, but that is not my area of expertise.
P: My doctor has a poster with the progression of sizes (starting from .1 going to 1) and correlating pictures. When the size gets to 1.0, the poster says “total fixation.” That’s in the context of my 0.9. Is this the cup or the actual width of the optic nerve?
Dr. Wilson: That is the cup, meaning the cup takes up 90% of the area of the total disc.
P: Why is Xalatan taken at night?
Dr. Wilson: Xalatan is taken at night because in the Swedish study, the effect was greater if the drug was taken at night. In the American arm of the study, there was no difference in the effect because of the time of day.
P: Are there any preservative-free drops besides Timoptic?
Dr. Wilson: Yes, preservative-free Pilocarpine is available from ALCON. I heard that preservative-free Alphagan will be available soon, but I haven’t seen it.
P: What is considered normal pressure, and what is way too high?
Dr. Wilson: “Normal” IOPs are normal for normal people. Many glaucoma patients don’t have normal ocular health and may not be able to tolerate the “normal” range of 12 to 22.
P: What is a block?
Dr. Wilson: A block is usually an injection of local anesthetic to “block” feeling to a small area.
P: My doctor said I had a block in my right eye.
Dr. Wilson: That may be a block in the drainage out of the eye.
P: Are IOPs of 24 in the left eye and 26 in the right eye bad enough to need drops?
Dr. Wilson: That depends upon the health of the nerve, the health of the person, the family history, and so on.
Moderator: Will you explain how to close the tear duct?
Dr. Wilson: Okay. With your head tilted back, reach across the nose with the hand not holding the bottle and push down and in where the two lids come together to close the clear duct. Using the other hand, put the drop in the eye, and gently close the eye to avoid squeezing out the drop. Keep the pressure on the tear duct for three minutes. That is the perfect way. Few people are that rigorous. I especially recommend blocking the duct before using beta blockers and Alphagan.
P: If someone has a pressure of 20 is it possible to stop the drops?
Dr. Wilson: If the pressure is 20 on meds, it would likely be 30 off meds.
P: Another point to consider: sometimes other health issues are responsible. I thought I was having a side effect from Alphagan. Actually, the problem was related to undiagnosed Hashimoto’s Thyroiditis. (Nobody told me I was going to fall apart when I reached 40.) Anyway, make sure you consider other stuff in your health history.
Dr. Wilson: Forty was a disaster for me, too.
P: How often do you see a 30% drop in IOP with meds?
Dr. Wilson: I see that all the time. That is what you are aiming for with treatment, at least a 30% drop in IOP.
P: Does Alphagan last any longer than 12 hours or is the effect totally gone after that?
Dr. Wilson: The effectiveness of Alphagan starts to taper off after 8 hours, and has less and less effect after 12 hours.
P: I have Reiter’s syndrome and so do my two daughters, ages two months and four years. What is the probability of developing glaucoma if Reiter’s anomalies are present?
Dr. Wilson: Fifty percent.
P: How often should my children be seen by a pediatric ophthamologist?
Dr. Wilson: Probably every six months. Thanks gang. I’m going to celebrate my birthday by going to bed, so I can get up at 5:15 tomorrow morning to be at the New Jersey office by 7:00 a.m. See you next week.
Moderator: Happy birthday from all of us and thank you.
End of highlights for May 2th chat.