Glaucoma and lifestyle

While the main emphasis in current glaucoma research is focused on finding more efficacious and safer treatments for the disease, lifestyle-related risk factors should not be overlooked in helping to combat glaucoma onset and progression, according to a presentation at the 2011 World Glaucoma Congress. James C Tsai MD, chairman and Robert R Young, professor of ophthalmology and visual science at Yale University School of Medicine in New Haven, Connecticut, US, said that while a lot more research was needed to understand this complex disease, there is growing evidence that certain lifestyle modifications might be beneficial for glaucoma. “Aerobic exercise does seem to be helpful in reducing intraocular pressure. I also tell my patients to limit their cigarette smoking since this action will improve their general health as well as perhaps enhance their ocular perfusion pressure. A diet rich in antioxidants and low in fat content may also be beneficial. In addition, there is some evidence that limiting caffeine intake, avoiding head-down positions and drinking red wine may help in preventing or slowing down glaucoma,†he said.

Dr Tsai said that he has personally noticed a growing demand from his patients to learn more about the possible role and effects of lifestyle factors in glaucoma.

“There is increasing interest in exploring complementary and alternative treatments, and patients are viewing these non-traditional therapies as possible supplements to their conventional medical and/or surgical therapy. More importantly, patients want greater control over their disease and they are constantly asking what they can do to alter their lifestyle habits for a positive/beneficial effect on their disease,†he said.

Moreover, shedding light on the link between lifestyle and glaucoma may have important implications for public health strategies and possibly provide insights into the causes of the disease, said Dr Tsai.

Reviewing the scientific literature on lifestyle and glaucoma, Dr Tsai stated that some studies had pointed out the negative effects of yoga and head-down activities on IOP levels. Similarly, wearing tight neckties and playing high resistance wind instruments have been implicated in raising IOP, as have caffeine consumption and stress. By contrast, several studies have noted that aerobic exercise has been shown to reduce IOP. Alcohol consumption, while not having a proven effect on the risk of open angle glaucoma, has been shown to lower IOP levels, said Dr Tsai.

He noted that in discussing the potential benefits of exercise for glaucoma, most of the studies in the literature have been carried out in patients without glaucoma.

“In non-smoking and healthy volunteers, exercise increases heart rate, systolic blood pressure and ocular perfusion pressure but it also decreases IOP and diastolic blood pressure. In physically active college-aged students, dynamic resistance exercises lowers IOP as well. There have also been papers looking at healthy subjects where there was a link shown between beta 2 receptor polymorphism and IOP lowering with dynamic exercise. And just this year, there was a paper published in a population of myopic and emmetropic young adults that showed that dynamic exercise does in fact reduce IOP,†he said.

Cigarette smoking has also been targeted for its potentially deleterious impact on ocular health, said Dr Tsai.

“We know that cigarette smoking seems to have broad deleterious effects across the entire health spectrum. There are over 4,000 bioactive substances in cigarettes so it is difficult to isolate out the effects of every one of these bioactive substances. But we know that there appears to be both acute and chronic IOP elevation with smoking,†he said.

Dr Tsai added that there have been some reports linking smoking with increased blood flow to the brain. “There is a possible reduction in the levels of apoptosis; however, smoking has been linked to macular degeneration and cataracts. It is important to stress that when adjusted for IOP level, there does not appear to be an increased risk of glaucoma linked with cigarette smoking at this time,†he said.

The relationship between diet and glaucoma is quite complex, said Dr Tsai, although at least one published paper has suggested that the ratio of omega-3 fats to omega-6 polyunsaturated fats might be important. This study reported that a diet favouring omega-6 fats, which include corn, sunflower and safflower oils, relative to omega-3 fats in flaxseed, canola and soy oils was associated with a reduced risk of primary open angle glaucoma.

There is also some evidence to support the idea of dietary approaches influencing vascular regulation and blood flow to the eye, said Dr Tsai.

“Antioxidants such as those found in ginkgo biloba, and polyphenolic flavenoids found in tea, coffee and red wine may reduce the extent of mitochondrial oxidative stress. In terms of supplements, ginkgo biloba in particular has been studied as a potential neuroprotective agent with possible blood flow effects. One study showed a short-term visual field improvement in patients with normal tension glaucoma taking ginkgo. For other antioxidants, there does not appear to be any effect on the risk of open angle glaucoma,†he said.

Dr Tsai also stressed the role of the cardiovascular system, which is heavily lifestyle influenced, in glaucoma development and progression.

“We know that there may be potential vascular risk factors in glaucoma and one of the proposed ideas is that influencing ocular circulation may be beneficial for the disease process. In certain patients there appears to be abnormal auto-regulatory responses to changes in ocular perfusion pressure in play,†he said.

Studies such as the Barbados Eye Study have reported that lower systolic blood pressure and lower ocular systolic, diastolic and mean perfusion pressures were all associated with an increased risk of developing glaucoma, said Dr Tsai. Another landmark study, the Early Manifest Glaucoma Trial, showed that lower ocular systolic perfusion pressure and cardiovascular history in patients with higher baseline IOPs, as well as lower systolic blood pressure in patients with lower baseline IOPs, were associated with increased progression of glaucoma.