Glaucoma is the leading cause of irreversible blindness in the United States. As a chronic issue, it can also dramatically affect the quality of life for patients, causing moderate to severe loss of vision and requiring daily care. And hidden dangers can arise from simple daily activities. A new study published by researchers at the New York Eye and Ear Infirmary of Mount Sinai (NYEE) warns that glaucoma patients may experience increased eye pressure as the result of performing several different head-down positions while practicing yoga.
Glaucoma occurs when pressure builds up inside the eye. Essentially, the visual organ is a hollow ball filled with a clear jelly-like substance called vitreous humor. Under normal circumstances, this fluid circulates and then drains away. If this draining process slows or stops, pressure inside builds, pressing on and so damaging the optic nerve. This elevated intraocular pressure (IOP) is the only glaucoma risk factor for which treatment has a proven effect on preventing or slowing the progression of the disease.
Though treatable, keeping IOP at a safe level can be a delicate business. "While we encourage our patients to live active and healthy lifestyles, including physical exercise," says the study's senior author, Dr. Robert Ritch of NYEE, "certain types of activities, including pushups and lifting heavy weights, should be avoided by glaucoma patients due to the risk of increasing IOP and possibly damaging the optic nerve."
Previously, research had only investigated the effects of the headstand position, which itself has been shown to double IOP. For the new study, researchers wanted examine a number of different positions. To do this they compared the results of a group of healthy participants with no eye disease as well as one of glaucoma patients, asking each to perform a series of inverted yoga positions — these included downward facing dog, standing forward bend, plow and upside-down seal.
The individual pressure for each participant was measured at five specific points: after establishing a baseline measurement by recording the IOP while the subject was seated before attempting the pose, the pressure level was recorded immediately after beginning the pose, two minutes into holding the pose, immediately after each pose when back in the seated position and finally again after 10 minutes of resting back in the seated position.
For both normal participants and for those with glaucoma, a rise in IOP for all four yoga positions was recorded — the greatest increase of pressure occurring during the downward facing dog pose. Even in the measurements taken after the participants returned to a seated position and again after 10 minutes, the pressure in most cases remained slightly higher than the baseline figures that had been recorded at rest.
"While our study results don't show a dramatic difference in IOP between the normal participants and those with glaucoma, we believe that additional research, with a larger study population and longer durations of practicing the inverted positions is warranted," said first author Jessica Jasien, research associate at NYEE. "As we know that any elevated IOP is the most important known risk factor for development and progression of nerve damage to the eye, the rise in IOP after assuming the yoga poses is of concern for glaucoma patients and their treating physicians. In addition, glaucoma patients should share with their yoga instructors their disease to allow for modifications during the practice of yoga."
The authors of the study stress the importance of awareness for glaucoma patients with regard to all the risks and benefits relating to physical exercise and general vision health. Knowledge of these factors, they say, along with those including diet, lifestyle choices and other related conditions like diabetes can help glaucoma patients stay in control of their condition. "This new study will help clinicians advise their patients on the potential risk associated with various yoga positions and other exercises that involve inverted poses," says Ritch.
The study was published in the journal PLOS ONE. For more facts about the condition as well as tips regarding glaucoma prevention and treatment, visit the NYEE website or check out this video by the Glaucoma Research Foundation, which offers an insight into the causes of the disease and some of the available treatment options.