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Supplemental therapies, exercise may help manage glaucoma
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The traditional method for treating open-angle glaucoma is to use medications to reduce the intraocular pressure (IOP). In addition, for situations in which medications do not adequately control the IOP or slow glaucomatous damage, surgical modalities (argon laser trabeculoplasty and surgical filter) are considered. The contradiction is that while we recognize IOP is one of a host of factors that may cause glaucomatous optic neuropathy, therapy only revolves around its reduction. Still, the concept of treating glaucoma in ways other than by lowering the IOP may soon occur.
The Food and Drug Administration (FDA) has approved a study sponsored by Allergan to investigate memantine, an NMDA [N-methyl-D-aspartate] blocker and neuroprotectant, for managing glaucoma. This oral agent used for treating dementia in Europe has significant risks and side effects. The goals of this study are visual field and optic nerve preservation, not IOP reduction. Unfortunately, it will be several years before the results are available, though it offers credibility that there may be other means to prevent and stabilize glaucomatous damage in addition to IOP reduction.
Patients who have glaucoma often ask if there is anything else they can do to help their condition. Until recently, my answer would be a quick “no,” adding to try not to miss taking any of their eye drops. Now, data suggest that additional modalities and therapeutic regimens may aid in glaucoma management. While medications are the first line of therapy, with surgery used to complement the therapeutic regimen, lifestyle changes (exercise, smoking cessation) as well as therapeutic options (food or vitamin supplements) may supplement the treatment scheme.
Moderate exercise may help
Moderate amounts of exercise, such as walking, have been shown to reduce IOP by approximately 20% if done regularly. This is similar to the addition of a medication and appears to be additive to the medical or surgical regimen. Passo and colleagues in 1991 enrolled in an exercise program nine sedentary individuals who were suspected of developing glaucoma (Passo MS, Goldberg L, Elliot DL. Exercise training reduces intraocular pressure among subjects suspected of having glaucoma. Arch Ophthalmol. 1991;109:1096-1098). By the end of the 3-month conditioning period, the mean IOP had decreased by 20%. When the exercise program was stopped, the IOP returned to the pre-conditioning levels within 3 weeks.
Qureshi and colleagues have also studied exercise and its effect on IOP (Qureshi IA. Exercise training can reduce intraocular pressure in open-angle glaucoma patients. Ann Ophthalmol. 1997;296-301; Qureshi IA. Magnitude of decrease in intraocular pressure depends upon intensity of exercise. Korean J Ophthalmol. 1996;10:109-115; Qureshi IA. The effects of mild, moderate and severe exercise on intraocular pressure in glaucoma. Japan J Physiol. 1995;45: 561-569). They found exercise led to reductions in IOP that lasted for prolonged periods of time. In one study, they compared the effects of mild, moderate and severe exercise on IOP in glaucoma patients. The reduction in IOP was 7.72 mm Hg with walking, 10.86 with jogging and 12.86 with running.
In another study, they placed 50 male glaucoma patients on exercise for 25 weeks and used a control group who did not exercise. At the end of 25 weeks, the mean IOP reduction was 20.5% (6.4 mm Hg) for the exercise group. With this body of work, it appears that simple exercise done regularly will have a positive impact on IOP and should be encouraged. Still, considering that many of our patients are elderly, clearance should be obtained by their family physician before anyone starts on a protracted regimen of exercise.
Smoking affects vascular regulation
Smoking has been known to be a free radical producer that may have a deleterious impact on the level of antioxidants. Smoking also appears to affect vascular regulation and blood flow and has been associated with age-related macular degeneration. Currently, few data directly link smoking and open-angle glaucoma. Leske did find an association with smoking and IOP in the Barbados Eye Study (Wu SY, Leske MC. Association with intraocular pressure in the Barbados Study. Arch Ophthalmol. 1997;115:1572-1576). Carel and colleagues in 1984 found a similar association between elevated IOP and smoking (Carel RS, Korczyn AD, Rock M, Goya I. Association between ocular pressure and certain health parameters. Ophthal mology. 1984;91:311-314).
Recently, there has been a great deal of work viewing glaucoma as a neuro-biologic condition. Smoking may then affect the health of the retina or nerve fiber layer at a number of locations by either reducing blood flow, increasing toxic chemicals within the retina or affecting the trophic factors released and used as part of the feedback loop within the optic nerve. Further work is needed to confirm a link between smoking and glaucoma. Still, for individuals at risk for glaucoma, I now ask in my history if they smoke, and, if so, I try to counsel them on additional reasons for smoking cessation.
Ginkgo biloba improves blood flow
Ginkgo biloba is a Chinese herb available as a prescription medication in some European countries. In the United States, it is available in health food stores and is classified as a food supplement.
Ginkgo appears similar to aspirin, because both are available without prescription and are powerful medications with significant therapeutic effects. Ginkgo’s original claim was to improve blood flow and, in particular, mental activity in the elderly. In one published study, the cognitive ability of individuals with dementia improved with ginkgo as compared to a control group.
Ginkgo appears to increase blood flow in the brain, to be an NMDA blocker and, thus, to be similar to certain neuroprotectants under study and inhibit platelet activating factor. Because of its ability to improve blood flow, ginkgo has been described as having calcium-channel blocking characteristics.
The FDA considers ginkgo “probably safe.” Still, ginkgo is not completely innocuous, because it can reduce the time needed for blood to clot. The herb should not be used by people with clotting disorders or who are on anticoagulant medications. Very large dosages can cause restlessness, diarrhea, nausea and vomiting.
There are two components to ginkgo: the terpene fraction, which is significant for its platelet activating effects, and the flavonoid portions, which appear to be free radical scavengers. The better forms of ginkgo should have both components. Typically, individuals placed on ginkgo begin on elevated dosages that are tapered to a maintenance dosage after 2 to 3 months. While a few studies have looked at ginkgo’s effects in diabetics, few data are available on its use in glaucoma. Still, similar to smoking, as we learn more about why glaucoma develops, it appears that ginkgo may be beneficial, theoretically, in at least certain forms of glaucoma. But the use of ginkgo biloba is controversial and difficult to recommend for all our patients at this time.
Currently, I am judicious in its use as I review the literature for data in its support. I now recommend it only in difficult or dire situations. Still, over time and with more experience and data, it may become a common addition to our glaucoma armamentarium.
Glaucoma therapy is evolving. We are attempting to use as few medications as possible to meet the target goals. Combination products now available allow us to do more with less. In addition, by having our patients exercise, stop smoking and possibly take some dietary supplements, glaucoma therapy may be enhanced.
Suggested Reading
Smith W, Mitchell P, Leeder SR, et al. Plasma fibrinogen levels, other cardiovascular risk factors and age-related maculopathy: the Blue Mountains Eye Study. Arch Ophthalmol. 1998;116:583-587.
Klein R, Klein BE, Moss SE. Relation of smoking to the incidence of age-related maculopathy. The Beaver Dam Eye Study. Am J Epidemiol. 1998; Jan 15:147:103-110.
Le-Bars PL, Katz MM, Berman N, et al. A placebo controlled double-blind, randomized trial of an extract of Ginkgo biloba for dementia. JAMA. 1997;Oct 22-29:278:1327-1332.
For Your Information:
- Murray Fingeret, OD, is chief of the optometry section at the Department of Veteran's Affairs Medical Center in Brooklyn and St. Albans, N.Y., and a clinical associate professor at SUNY College of Optometry. He is also a member of the Primary Care Optometry News Editorial Board. He may be contacted at St. Albans VA Hospital, Linden Blvd. and 179th St., St. Albans, NY 11425; (718) 526-1000; fax: (516) 569-3566; e-mail: murray@liii.com. Dr. Fingeret has no direct financial interest in the products mentioned in this article, nor is he a paid consultant for any companies mentioned.