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CAQs: General Questions

What are acceptable eye pressures and at what ages?

An acceptable pressure is whatever pressure is necessary to keep the glaucoma damage from progressing for any particular eye. A normal pressure is a statistical concept derived from large studies in the 1950's, which found the mean intraocular pressure in the population to be 15 to 16 millimeters of mercury (mmHg). The upper 2.5% of pressures were statistically regarded as abnormal and this is how the number 22 mmHg came to represent an elevated IOP. However, many people with pressures in the low 20's can go through life with no problem while others progress to damage at statistically normal pressures. If you have glaucoma, the acceptable pressure is that pressure at which no further progression of the visual loss occurs. Often, the greater the amount of damage, the lower the IOP necessary to control the disease.

How does the public learn about new and/or experimental drugs and how does one volunteer to be included in the experimental studies?

It's not very easy, even though one would think it should be. First, most new drug trials don't use patients with severe glaucoma, but patients with elevated IOP and no or early glaucoma damage because they are testing drug x against one of the drugs already marketed. Additivity studies come later. There is another kind of study called a compassionate case study, in which a new drug is allowed to be given to patients who are uncontrolled on available medications and are facing surgery. We have one new drug study going on now at GANY (Rescula, a prostaglandin analog) and will have two additional studies beginning toward the end of 1998 (memantine, a neuroprotective agent, and OHTL, or ocular hypotensive lipid, which increases aqueous outflow from the eye). More information about these can be found in the CLINICAL TRIALS section. Most of these studies are carried out at 15 to 20 centers. The problem lies in finding out which centers have which studies and in living in an area where such a study is going on.

If eye drops are causing certain side effects can they be changed to a similar medication with less side effects?

All medications can have side effects. Not all medications cause side effects in all people. Medications can cause side effects in some people, but not others. Different medications have different side effects and also have different side effects in different people. If you have side effects with one medication, it makes sense to try a different medication. The only way to be sure if a medication is causing side effects is to stop the medication and see if the side effects go away, then start the medication and see if the side effects come back, and then repeat this once again. Sometimes it is the preservatives in the medications rather than the medications themselves that cause the side effects. In such cases, it is sometimes possible to get preservative-free medication.

Can trauma result from a car crash?

It is certainly possible for glaucoma to result from a car accident if there has been damage to the eye.

Is wearing reading glasses for visual field test necessary?

We routinely do so to standardize the test.

Besides taking your medication and keeping yourself as health as possible, is there anything significant a person with glaucoma could be doing? Emotionally this medical condition is very draining. Not really knowing what the future may hold can be hard to deal with. Can you offer any hope of future medications, treatments, and maybe even a cure in the not-so-distant future?

Until recently, my answer would have been that taking your anti-glaucoma medication rigorously is really the only way to slow down or prevent worsening of the visual damage. However, some very interesting facts have been coming to light and I believe our knowledge of these other factors is going to increase markedly in the next few years. Back in 1981,a study by Dr. Ivan Goldberg, now of Sydney, Australia, and his colleagues showed that patients with normal tension glaucoma who were sedentary had more rapid progression of their disease than patients who exercised. Aerobic conditioning appears t increase blood flow to the eye (as do calcium channel blockers) Researchers in Portland, Oregon, have shown that aerobic conditioning can lower your baseline intraocular pressure, and a further, transient lowering occurs on an acute basis with exercise. A study in Japan has shown that obesity is a very important factor in the progression of glaucomatous damage, parallel to what we already know in association with diabetes and hypertension. Smoking may worsen some patients with glaucoma.

There is increasing evidence, although as yet no proof, that high dose antioxidants may also be of some benefit in at least some patients with glaucoma. How significant all of these factors are and how much their impact is compared to medication remains to be established. New medications and treatments are under development all the time. Glaucoma is not one single disease but really an end stage. It is a particular pattern of optic nerve damage and visual field damage caused by a number of different diseases, which affect the eye. Most of these diseases, but not all of them, are associated with elevated intraocular pressure, which is the most important risk factor, but still only a risk factor for glaucomatous damage. Intraocular pressure is not the disease itself. Some of these diseases are hereditary and some are acquired. We have a great deal to learn about the causes of most of these diseases, but the more we learn, the more specifically they can be treated and the sooner a cure can be developed. Certainly today, the outlook is far, far better for patients with glaucoma than it was even a few years ago. R.R.

I was just classified as a suspect for glaucoma. Took the visual field test and I understand that you are to look at the center which is a green and red object. However, was I only to focus on that green and red object without moving my head. I saw with the corner of my eye light objects and, of course, took my eye off the center and looked at it and pushed the button. I have to take the test again and would like to know if I am using the correct method.

There are a number of different machines for testing the visual field. You are supposed to focus on the target and not move your head so that the computer can determine whether or not you can see the lights appearing in your peripheral vision. When you are taking the test, it is easy for you eye to wander, but the technician administering the test should be with you to watch while you take the test and prevent you from looking around and encourage you in the proper way of taking the test. The technician should also give you complete instructions about how to take the test before you begin. R.R.


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© Robert Ritch, M.D., and Jeffrey M. Liebmann, M.D.

Permission to copy all or part of this work and post to other Web sites is granted, provided that the copies are not made or distributed for resale, and provided that the AUTHOR, COPYRIGHT and NO WARRANTY sections are retained verbatim and displayed as is.

Disclaimer: The authors provide no warranty. The information is provided to assist understanding of glaucoma. It does not replace an eye examination, and is not meant as a guideline for treatment of any individual person suffering from glaucoma. Your feedback is welcome.

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