By George L. Spaeth

Once a person has glaucoma, his or her eyes are predisposed to more damage. Anything causing the eyes not to get the nutrients they need will increase the damage. Thus, marked malnutrition, such as the thiamin deficiency common in some parts of the world, damages tissues such as the optic nerve. Other forms of malnutrition (protein deficiency, other vitamin deficiencies, etc.) can also be damaging.

Obesity

At the other extreme, obesity also can predispose to damage and is in fact a major reason why some people with glaucoma get worse. Obese people may get worse because some people who are heavily overweight may have a biological mechanism that causes them to handle food improperly, and that abnormal biological mechanism may apply to tissues in the eye as well as to those elsewhere in the body.

Obese people also have difficulty breathing, and thus the optic nerve may not get enough oxygen to be fully nourished. Also, obese people tend to have high blood pressure, which predisposes to abnormality of the small blood vessels that nourish the optic nerve.

It may also be that psychological mechanisms are involved, so that the person who is seriously overweight may fail to do those things that are necessary to preserve his or her health in other ways.

Diet

Between the extremes of severe malnutrition and obesity, relatively little is known about the relationship between diet and the development of glaucoma. But it seems safe to conclude that it is prudent to have a diet which is neither deficient in any of the essential requirements nor excessive enough to cause obesity. Some authors have suggested that foods such as carrots and peppers may be beneficial. Others have touted the value of vitamin C, bilberry extract, and gingko.

Many years ago, I looked for a possible beneficial effect of vitamin C and the B vitamins on the course of glaucoma but could find none. It may have been that the doses weren't appropriate or that the study didn't proceed long enough, but no beneficial effect was apparent. Now that more is known about the various types of glaucomas it is important to study in detail whether some of these agents may in fact be beneficial or perhaps even harmful in individual patients with glaucoma. Foundation researchers are already planning such studies.

Exercise

Many years ago a study performed at Washington University in St. Louis demonstrated that people with the type of glaucoma in which the optic nerve becomes damaged even though intraocular pressure is low are more likely to have progressive damage if they are sedentary than if they exercise. Researchers have discovered that vigorous, repeated exercise over a prolonged period of time can lower intraocular pressure around 4 mm Hg. For a person whose intraocular pressure is around 25 mm Hg, and in whom a pressure of 25 mm Hg is high enough to produce damage, a 4-mm Hg lowering of intraocular pressure may be enough to prevent further damage.

One wonders why so little attention has been paid to this report. So much has been written about the importance of "exercise" that it's become quite a fad. In fact it is not totally clear that exercise is quite as beneficial as some authors would lead us to believe. It may be that the reason why people who exercise appear to be healthier and live longer is because they are healthier to start with, and for that reason they exercise. Exercise also is important for the eye because it helps prevent weight gain and keep blood pressure normal. Prolonged high blood pressure can damage the small blood vessels that nourish the optic nerve, decreasing the ability of the nerve to resist the damaging effects of intraocular pressure.

On the other hand, insufficient blood flow in the large vessels that lead from the heart up into the head, the carotid arteries, can cause a generalized decrease in blood flow to the eye, depriving the optic nerve the nutrients it needs to be healthy.

These various and quite different abnormalities of blood flow and regulation of blood flow and how they affect the healthy or sick eye are becoming better understood and are clearly of importance in the development of glaucoma. A person's lifestyle significantly affects the person's cardiovascular system. Thus, not only may there be a direct effect on intraocular pressure or exercise and diet, but there may be indirect effects that relate to maintaining a healthy cardiovascular system. For example, were an individual to participate in a high-altitude road race and not be properly acclimatized, it is reasonable to assume that blood would be shunted away from the eyes to the heart and the muscles, and the person might well have an insufficiency of blood flowing to the eye during the period of the race, resulting in damage to the eye.

Also for example, when blood pressure falls rapidly, as, for example, from severe bleeding during childbirth or as a result of injury, blood flow to the eye may decrease suddenly, causing serious, irreversible damage to the optic nerve. Other situations that may result in an instability of blood pressure include changing position, or taking drugs that affect blood pressure.

Managing Our Lives

Another aspect of lifestyle relates to whether or not a person's glaucoma will get worse is the person's ability to manage his or her own life in the broadest terms. Does the individual know how to listen to his or her own body? Is the person a denier, who does not pay attention to the fact that he or she is losing some visual field? Does the person know how to communicate with his or her physician well, having the ability to articulate clearly the problems and concerns that he or she has? Does the patient know how to use the doctor well, making sure that questions are answered fully and that all concerns are appropriately addressed? Is the person sufficiently disciplined to keep appointments and use medications on schedule? Does the person learn what he or she needs to know to have the best chance of maintaining health?

General Health

Over 50 years ago, Duke-Elder described glaucoma as "a sick eye in a sick body." Though an oversimplification, there is much truth in his comment. Although some types of glaucoma appear to have nothing to do with generalized illness, with regard to many types of glaucoma, the person's general health definitely plays a role in whether or not the glaucoma gets worse. A person's general health is a result of a complex interaction between the person's basic genetic structure and the world to which that genetic structure is exposed: the foods, the toxins, and all those other aspects of the way we live that affect the way our genes are expressed.

Dangers of Generalization

One of the serious errors with regard to glaucoma has been oversimplifying the condition. It is a serious mistake to consider one mechanism of glaucoma damage applicable to everybody. So also is it a serious error to generalize regarding specific aspects of lifestyle or therapy. For example, while exercise may be beneficial for many individuals, exercise so strenuous that it results in a decrease in blood flow to the optic nerve can make the patient's glaucoma worse. Some drugs may well make one person's glaucoma better and another person's glaucoma worse.

It is each person's responsibility to define for himself or herself what lifestyle is most conducive to his or her unique complement of genes being most fully expressed and least likely to be damaged.

Patients frequently ask whether they should stop drinking coffee or stop drinking large amounts of water. The proper answer is almost certainly that there is no single answer, with the exception of avoiding obvious excesses. Those things that predispose to the health of the body probably predispose to the health of the eye as well.

For some that may mean the total avoidance of some things such as coffee, wine, or cheddar cheese. But for most, it means developing a life in which one learns to listen to one's own body and spirit, and to cherish those things that are nourishing and to eschew those that will not lead to a sense of well-being. Surely among the most important factors that affect our health are the way we think, feel, love, and live.