Yoga is generally considered a perfect exercise for overall health; however, head-down positions may be harmful to glaucoma patients. A small study at a yoga studio found that positions that put the head downward increased intraocular pressure. The positions studied were Adho Mukha Svanasana, Uttanasana, Halasana and Viparita Kirani.
Intraocular pressure is associated with glaucoma, a serious and degenerative eye disease. During a standard eye exam, this pressure is often used as a screening.This is a complex disease. Not all patients have increased intraocular pressure.
Pressure in the eyeball was increased for all study participants who held all 4 poses for 2 minutes each (8 minutes total), regardless of whether they had glaucoma. Two minutes after stopping the exercises and resting, the pressure when back to normal.
In the same way the pregnant women should avoid certain yoga poses, glaucoma patients should be wary of head-down poses. Studies in the future may look at how cerebralspinal fluid pressure affects the progression of the disease.
Study: “Intraocular Pressure Rise in Subjects with and without Glaucoma during Four Common Yoga Positions” by Jasien JV et. al. PLOS December 23, 2015 DOI: 10.1371/journal.pone.0144505