The downward dog position in yoga increases pressure on the eyes, presenting risks for glaucoma patients, according to the latest study.
January is Glaucoma Awareness Month, and the health care community is focusing on the eye condition that 2.7 million people in the US over the age of 40 grapple with every day.
Glaucoma affects eyesight, usually due to a build-up of pressure in the eye, which can damage the optic nerve.
Although yoga has been lauded for its health benefits - including improving symptoms of arthritis and benefitting men with prostate cancer - the researchers of this latest study investigated the potential risks the practice can present for glaucoma patients.
They publish their results in the journal PLOS One.
The team, led by Dr. Robert Ritch, from the New York Eye and Ear Infirmary of Mount Sinai (NYEE) in New York, NY, notes that glaucoma is the leading cause of irreversible blindness in the US.
They focus on elevated intraocular pressure (IOP), which is the most common risk factor for glaucomatous damage and the only modifiable factor that has been proven to prevent or slow glaucoma progression.
All four yoga poses increased eye pressure
The researchers say that previous studies have only tested the headstand position in yoga, which showed a two-fold rise in IOP.
- In the US, 2.7 million people over 40 have glaucoma
- This number is predicted to rise to 4.2 million by 2030
- Glaucoma costs the US economy $2.86 billion every year.
As such, for their latest research, the team asked healthy participants without eye-related disease and glaucoma patients to complete a series of inverted yoga positions, which included downward dog, standing forward bend, plow and legs up on the wall.
At baseline seated, the researchers captured the IOP in each group, and then again while performing the pose, 2 minutes while holding the pose, just after the pose in a seated position and then again 10 minutes later in the seated position.
Results showed that both groups of study participants had a rise in IOP in all four yoga poses, but the greatest pressure increase was found during downward dog.
"While we encourage our patients to live active and healthy lifestyles, including physical exercise, 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," says Dr. Ritch.
The measurements that the team recorded after the participants returned to a seated position - and then again after waiting 10 minutes - revealed that the pressure mostly remained slightly elevated from baseline.
Further studies are warranted
Study author Jessica Jasien, from NYEE, notes that although their results do not reveal a major difference in IOP between the normal participants and the glaucoma patients, the team believes that further studies with larger populations and longer durations of inversions should be carried out.
"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 small sample size of participants is a limitation of the study; the researchers say this limitation could explain the lack of statistically significant differences between the glaucoma and non-glaucoma groups.
Regarding this limitation, they add that the "absence of proof is not necessarily a proof of absence if the study sample is small."
Other limitations include a lack of blood pressure measurements - which means they did not have any information that could point to associated changes in cerebrospinal fluid pressure due to yoga position - and short pose duration, which does not allow the team to draw conclusions on the change in IOP if yoga positions are maintained for 30 minutes - like they sometimes are in a formal yoga setting.
The team calls for future studies to assess whether certain yoga poses increase the risk of glaucoma progression.
Yoga has become a popular practice in the Western world; by 1998, an estimated 15 million American adults had practiced yoga at least once.
Medical News Today previously investigated the health benefits of exercise, including yoga and pilates.