Monday, February 22, 2010

Yoga under Pressure


Yoga is arguably the most popular fitness fad of the decade. It claims entire specialty stores devoted to clothing, accessories, gear, and mats. You can do zen yoga, aerobic yoga, steamy yoga, strrrretchy yoga, pre-natal yoga, and even Wii Yoga. Any yoga may be tailored to fit your lifestyle (and some tailor their lifestyle to squeeze in some yoga). So, can anything that feels so good be so bad. . . for your intra-ocular (eye) pressure?

Sirsana yoga is a type that involves headstands. One study of Sirsana yoga practitioners in India showed a two-fold increase in intra-ocular pressure during head-stands. Without getting too graphic, imagine a two-fold increase in any function of your body! Multiple studies have demonstrated progression of glaucoma in followers of this extreme form of yoga; and many other studies are now underway on the question of yoga and eye pressure.

Consider some of your favorite yoga (or other recreational) positions: downward facing dog, downward forward bend, child pose, the wheel, or even more exotic ones like the camel or the fish. Amidst this zoo of poses, your head is placed below heart-level. Blood gravitates to the head, pressure in the cerebrospinal fluid surrounding the brain increases, and intra-ocular pressure rises in turn. The same fluid that surrounds your brain, encases your optic nerves as well, so it follows that when cerebral pressure rises, the pressure on your eyeballs increases.

Glaucoma is the most common disease of the optic nerve. According to the Glaucoma Research Foundation, it is the leading cause of blindness in African Americans and the second most common cause of blindness world-wide. While the exact mechanism of glaucoma is not well understood, we do know that it is linked to eye pressure. Intra-ocular pressure that is too high for any particular optic nerve will cause glaucoma damage, in most cases irreversibly.

I am not looking to direct the national tide of yoga aficionados back to the elliptical, but as with everything else, use good sense and moderation. If you know you have glaucoma or a family history of glaucoma, reconsider positions that involve prolonged suspension of the head below heart level. For glaucoma folks, yoga may be an extreme sport -- stick to sky diving! Do not forget to pay your friendly neighborhood eye doc a visit for an intra-ocular pressure check and a peer at your optic nerves.

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