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Yvonne Ou, MD, gives patients advice about physical activity, body positions to avoid, leafy green vegetables, caffeine, and blood pressure treatment–as suggestions to help patients control their glaucoma progression.
Patients may ameliorate their glaucoma with exercise, diet, and other lifestyle choices.
After poring over the literature, Yvonne Ou, MD, assistant professor of ophthalmology, University of California, San Francisco, gives her patients advice about physical activity, positions to avoid, leafy green vegetables, caffeine, and blood pressure treatment.
“We know that aerobic exercise lowers intraocular pressure (IOP),” Dr. Ou said. “This has been well studied.”
The prescription may prove challenging, since studies have shown that patients with greater visual field loss perform less physical activity. One study showed the number of steps per day decreased as the visual field mean deviation worsened.
In mice, exercise appears to protect against optic nerve damage. In one experiment, researchers subjected mice to an IOP elevation of 50 mm HG for 30 minutes and put them in a tank of water, forcing them to swim for 60 minutes a day, 5 days a week.
Electroretinograms showed that exercise reversed damage caused by the IOP surge in older mice. Exercise produced its benefits not only if it was administered before the injury, but if it was administered afterward. In a related experiment, levels of brain-derived neurotrophic factor, which enhances neuron growth, were maintained in mice that exercised.
Given this evidence, Dr. Ou tells patients to “get moving, especially if you aren’t already. This can be as simple as the easier habits, such as just getting out for a walk. Even if patients are mobility-impaired, the more they can get up from a sitting position the better.”
Dr. Ou advises patients to avoid certain yoga poses. “We all know that headstands and shoulder stands are bad for your patient,” said Dr. Ou. “They raise IOP.”
The evidence on less strenuous poses, such as downward-facing dog, is less clear, she said. In one recent study on 4 common yoga poses, IOP increased but returned to baseline within a couple of minutes after the participants returned to sitting.
Counseling a yoga instructor with early glaucoma, Dr. Ou measured the patient’s IOP as she performed the poses in Dr. Ou’s office. IOP increased transiently, and Dr. Ou told the patient to avoid shoulder stands and headstands, to modify other poses, and to look for ways to demonstrate inversions without performing them.
“We just don’t have good data to guide patients about optic nerve damage and ganglion loss,” Dr. Ou said. “Unfortunately, you can’t make mice do yoga. This question may remain a little unanswered.”
Sleeping position also may affect IOP. Some studies have shown that lateral decubitus increases IOP in the dependent eye–the eye closest to the pillow, but the case is not settled, said Dr. Ou.
“There have been studies that looked at whether the dependent eye or the nondependent eye had worse structural changes and there’s some debate in the field,” she said.
Another study showed that elevating the head of the head of the bed resulted in a 2 mm Hg lower IOP, but if the neck was flexed IOP was 2 mm Hg higher. “The hypothesis is that this neck flexion creates a situation where you’re compressing neck veins and leads to increased episcleral venous pressure,” Dr. Ou added.
The bottom line? “You could consider advising sleeping with the head of the bed elevated,” said Dr. Ou. “This is still difficult and not super practical. There is controversy about recommendations and a lot of patients spend most of their sleep in the lateral decubitus position.”
Eating leafy greens may benefit people with glaucoma, Dr. Ou found. These plants are a source of dietary nitrate. One study showed that the effect was greatest in glaucoma patients with early paracentral visual field loss at diagnosis associated with vascular dysregulation.
How much is enough? In another study, patients who ate one serving a week or more of collard greens or kale had lower glaucoma risk compared to those who had less than a serving a month.
Most of the research is on glaucoma risk rather than glaucoma progression. “I do tell patients to eat green leafy vegetables because there can’t be too much downside to that,” said Dr. Ou.
As for coffee, there is evidence both pros and cons for glaucoma. In one prospective, randomized controlled trial, 106 subjects ingested about 8 ounces of either caffeinated or decaffeinated coffee. The caffeinated coffee appeared to increase IOP about 1 mm Hg, but increase ocular perfusion pressure by about 1.25 mm Hg to 1.5 mm Hg.
“Those two counteracting forces likely mean that drinking a cup of coffee is not going to make a huge difference,” said Dr. Ou. At least one animal study suggests that caffeine could protect against ganglion cell loss. “I generally tell patients a cup is not a problem.”
In the landmark SPRINT trial, people with hypertension whose systolic blood pressure was lowered to 120 mm Hg or lower had a one-third reduced risk of cardiovascular disease and almost a one-quarter reduced risk of death compared to people whose systolic pressure was lowered to 140 mm Hg.
“So huge benefits,” said Dr. Ou. While the rates of serious adverse events were not statistically different between the 2 groups, there was a higher rate of hypotension and syncope in the intensively treated group.
“Of course, this is an issue for our glaucoma patients because we know that ocular perfusion pressure is likely playing an important role, though that is not entirely well defined at this point,” said Dr. Ou.
A follow-up study showed that the cardiovascular and mortality benefits held for patients 75 years old or older, said Dr. Ou. But in this group, the mean diastolic pressure in the intensive group was 62 mm Hg, which was 5 mm Hg lower than the standard group, raising questions about ocular perfusion. The Early Manifest Glaucoma trial showed that a systolic pressure lower than 125 mm Hg was a predictor of long-term progression in glaucoma.
Armed with this information, Dr. Ou asks patients what cardiovascular risk factors they have. If they do not have many or if glaucoma is progressing despite IOP control, she insures that they are not being overtreated for hypertension.
On the other hand, if patients have low baseline blood pressure, she may talk to them about easy things they can do to boost their ocular perfusion pressure.