Efecto Pigmalión

Current glaucoma treatment involves lowering the IOP, but trying to pre- serve the optic nerve by other means, such as improving blood flow (circu- lation) to the optic nerve and to the area around it, may be the next great advance. Some studies have compared the

blood viscosity in patients with glaucoma to that of people without glaucoma. Viscosity can be thought of as the “thickness” of the blood. Blood with high viscosity travels more

slowly through small blood vessels than does blood of lower viscosity. Thus, circulation might be impaired when blood viscosity is high. These studies

t h e e y e c a r e s o u r c e b o o k

164

Lowering blood viscosity may promote better circula-

have found that patients with glaucoma, including the low-tension variety, have blood with significantly higher viscosity than people with normal eyes or people with elevated IOP but no sign of optic nerve damage.7,8_{This suggests}

why some people with elevated IOP may develop optic nerve damage while others do not.

The most common reasons why some people have a high blood viscosity are a very high red blood cell count or very high levels of proteins in the blood. However, another factor that can play a role is the flexibility of red blood cells, which we call erythrocyte deformability.

When the blood cells are able to “flex” more easily, they are able to flow more easily through tiny blood vessels. Taking dietary supplements of omega- 3 polyunsaturated fatty acids (a type of building block of fat) causes a signifi- cant lowering of blood viscosity, apparently by increasing the erythrocyte deformability. Flaxseed oil and fish oils are especially rich in these fatty acids. Therefore, consuming these oils may lower blood viscosity and improve cir- culation to the optic nerve and elsewhere.

Eskimos, whose diets are very rich in these omega-3 fatty acids, have an extremely low incidence of open angle glaucoma, and this fact has led some people to speculate that the omega-3 fatty acids are protective in this respect. However, many other tribes of Native

Americans, whose diets are much lower in omega-3 fatty acids than those of Eskimos, also have an extremely low incidence of open angle glaucoma. Therefore, it is likely that the low incidence in Eskimos has a genetic basis.

The use of omega-3 fatty acid supplements in patients with glaucoma has never been evaluated in any formal study. Nevertheless, the possibility of pro- tecting the optic nerve in glaucoma patients in this manner is intriguing. Omega-3 fatty acid supplementation for other conditions, such as heart dis- ease and rheumatoid arthritis, has been studied to some degree, but the long- term effects of such supplementation, both good and bad, remain to be determined.

Scientists are now beginning to produce pure preparations of long-chain omega-3 fatty acids, for example, from bacteria or algae, so this type of sup- plementation may become a reality, allowing people to avoid unwanted fatty acids and other substances present in the fish oils, the most common source

g l a u c o m a

165

Omega-3 fatty acids, ginkgo biloba, and a healthy lifestyle

(diet and exercise) all lower blood viscosity.

of omega-3 fatty acids. Since questions remain about the long-term safety of fish oil and other omega-3 fatty acid supplements, however, I do not recom- mend their use at present.

Another substance that has been shown in many studies to lower blood viscosity is an herbal extract of the plant ginkgo biloba. This extract, which contains many components, has already been under consideration as a possi- ble aid to glaucoma treatment because of the

potent antioxidants in it. (Antioxidants may help protect the optic nerve, although this is unproven.) This extract also contains bilo-

balide, a substance that may help protect nerve tissue from damage. But the extract’s main value may be its ability to increase circulation to areas that need it. A recent study showed that taking ginkgo biloba causes a significant increase in blood flow through the ophthalmic artery (the artery that supplies blood to the eye).9_{Ginkgo biloba is one of the most frequently prescribed}

medications in Germany and France, where it has been found effective in improving mental functioning in the elderly, reducing dizziness and tinnitis (ringing in the ears), and lessening the symptoms of claudication (inability to walk more than a short distance because of poor leg circulation).

Ginkgo biloba’s lowering of blood viscosity may be the means by which it increases blood flow to the eye and other organs. Ginkgo biloba is remarkably free of side effects, but the effects of long-term use have not been fully evalu- ated. Because it has a mild effect on platelets, the tiny fragments in the blood that prevent bleeding, it should not be used in people who have bleeding ten- dencies or in people who take the drug warfarin (Coumadin), which affects blood clotting. Actually, this effect on blood platelets could in itself help improve circulation. Although sold by prescription in Europe, ginkgo biloba (Ginkgold and others) is available as an over-the-counter supplement in the United States. Ginkgo biloba appears to have great promise in the treatment of glaucoma, especially the low-tension variety, in which the amount of blood flow to the optic nerve may be critical.

Finally, there is evidence that both exercise and a high-fiber, low-fat diet can lower blood viscosity. In particular, vegetarians, who abstain from beef, fowl, and fish, have been found to have significantly lower blood viscosities than meat eaters, including people who consume animal flesh less than once a week. Exercise and the rice diet, a form of high-fiber, low-fat vegetarian diet,

t h e e y e c a r e s o u r c e b o o k

166

Ginkgo biloba increases blood flow to the eye.

have already been discussed as ways of lowering IOP, but their effects on blood viscosity represent another mechanism by which they may protect the optic nerve in people with glaucoma. Whether a low-fat vegetarian diet can help keep your pressures down or retard the progression of your glaucoma remains to be seen, but such a diet is certainly associated with benefits from a general health standpoint.

Glaucoma Surgery