Lifestyle Factors and Glaucoma: Lots of Common Sense, Not So Much Evidence

SAN DIEGO -- Limited data support a role for lifestyle factors in the prevention or management of glaucoma, according to a review presented here.

Intuitively, diet, mental health, and good posture should contribute to good eye health, but the evidence does not support the intuition. Despite the dearth of positive studies, a better-safe-than-sorry approach remains good advice for patients, said Simon Law, MD, of the University of California Los Angeles, during the American Society of Cataract and Refractive Surgery meeting.

"I have probably raised more questions than answers," said Law. "I have not provided any suggestions on nutrition, mental health, or [body] positioning on glaucoma because I don't believe we have enough evidence. I have just two or three recommendations for patients. I tell them to have a balanced diet and behavior. I tell them to try to get more exercise and have a regular sleep habit."

"When patients ask questions, use that as an opportunity to bond with the patient," he added. "When a patient says, 'Hey, doctor, I have one more question,' that's often the most important question. Try not to be dismissive. Consider it as an opportunity to connect. Listen and understand their concerns."

Ophthalmologists also should use patient discussions to emphasize the proven benefits of conventional therapy for glaucoma, he added. Whatever patients are currently doing or contemplating, that should not interfere with or serve as a substitute for proven conventional glaucoma therapy. At the same time, patients should not have to give up their beliefs or hopes to accept the clinician's projection of reality.

The Case for Diet, Nutrition

The adage "we are what we eat" suggests nutrition should be important to health and disease, said Law. However, research on nutrition and glaucoma have been based primarily on pathophysiologic theories related to glaucoma and are not well established.

Most studies to date have been cross-sectional and relied mostly on food questionnaires and surveys. Interaction between different nutrients, between nutrients and diet, and food processing have not been studied, he continued. Most studies failed to control for variables, and studies have approached glaucoma as a single disease entity, ignoring potential differences among subtypes.

"Of course, the absence of evidence does not mean evidence of absence," said Law.

One recent study evaluated contrast sensitivity 2 hours after consuming dark chocolate or milk chocolate and showed sensitivity was slightly better after the former. A subsequent study failed to replicate the findings.

Multiple studies have examined effects of flavonoids and eye health, producing little supportive evidence. A long-term population-based study showed no association between flavonoid intake and the risk of open-angle glaucoma. Data from the Nurses' Health Study showed a small protective effect of certain flavonoids found in tea against primary open-angle glaucoma but not flavonoids in general.

Mitochondrial abnormalities might be an early driver of neuronal dysfunction in glaucoma, said Law. Laboratory studies of nicotinamide and pyruvate suggested a protective effect for mitochondrial function, providing a rationale to study the two combined in patients with glaucoma. Preliminary data showed statistically significant short-term improvement in visual function versus placebo, but Law cautioned that the findings are too early to draw conclusions.

Studies of vitamin intake and glaucoma have yielded conflicting results. A meta-analysis showed an association between vitamins A and C and a lower risk of glaucoma, but blood levels of the vitamins did not correlate with glaucoma risk. Vitamin D has associations with multiple diseases but no consistent link to intraocular pressure or glaucoma, said Law.

Similarly, studies of dietary patterns have shown no consistent associations with age-related macular degeneration, cataract or diabetic retinopathy, but data for glaucoma are lacking.

"My recommendation [regarding nutrients and glaucoma] is very conservative," said Law. "I tell patients to maintain a balanced diet, include a wide variety of foods, and maintain moderate consumption."

Mental Stress

Most people consider vision their most important sense. Glaucoma, as a condition that can lead to blindness, is stressful for many patients, said Law. Glaucoma has a significant association with depression, with key risk factors that include advanced disease, older age, female sex, and faster progression of vision loss.

Beyond the potential for vision loss, concomitant factors can add to the stress of the disease itself: financial burden, comorbidities, stressful life events, and family- and work-related stress. Law used to tell patients that stress does not contribute to elevated intraocular pressure (IOP). His opinion changed after a prospective study from Europe showed a small increase in IOP and a trend toward worse visual performance in people after a mental stress test.

A study evaluating anxiety and depression in patients with visual dysfunction showed that visual dysfunction had multiple adverse effects on patients' quality of life. Patients complained of frustration about their inability to complete tasks and their loss of independence that accompanied the vision problems. They lacked self-confidence and felt socially isolated and lonely.

"If glaucoma is associated with mood disorder, and mental well-being can affect treatment effectiveness and outcome, we should pay more attention to picking up the disorder," said Law. "Screening tools for depression and anxiety are available online."

"Obviously, mental health is a huge topic and cannot be covered in a few minutes, but I want to emphasize one point -- be caring," he added. "Care for our patients' mental well-being. We should also care for ourselves. We need to be mentally healthy before our patients can find hope in us."

Body Position

With the growing popularity of yoga, more patients with glaucoma ask about the effect on IOP. Some yoga poses may involve body inversion, which can severely elevate IOP, said Law. IOP returns to baseline as soon as the patient returns to a sitting position. Prolonged inversion should be avoided by patients with advanced optic nerve damage.

Several studies have shown that sleeping position can affect IOP. In one study, 75% of patients expressed a preference for sleeping on their sides (lateral decubitus position). Three-fourths of patients with that preference had worse glaucoma in the eye that corresponded with the sleeping position.

"I find that sleep disorder, sleep apnea, insomnia, sleep deprivation are common," said Law. "I am more concerned about these problems than the sleeping posture. Glaucoma also is associated with sleep disorder."

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