Pranayama, IOP and the Parasympathetic Nervous System

When I started this IOP data collection project, I expected stress management tools like meditation and pranayama (yoga breathing exercises) to lower my IOP. Immediately after starting the project, I was surprised to find that my IOP was much higher after meditation when we measured it. Those initial meditation sessions consisted of several elements, including pranayama. Today I tested a 10 minute session of pranayama alone, without any meditation. This is part of what will be an ongoing effort to understand more about what caused my IOP to go so high after those initial meditation sessions.

There are many styles of pranayama. The style I used today was simple left-right alternate nostril breathing with a normal, relaxed breathing pattern. This style does not used any forced breathing or breath retention. It does not involve any strain. 

As you will see in the data below, the pranayama certainly did not lower my IOP has I hoped it would. My IOP increased from 14.0 & 21.0 to 16.7 & 23.0 (left and right respectively). The more troublesome fact is that one-half hour later, the IOP in my right eye increased further to 29.3. We do not know if that further increase was related to the pranayama or not.

UPDATE: see this post in the IOP Research blog about pranayama and IOP. The researchers found that closing the left nostril and breathing exclusively through the right nostril lowered IOP. They felt this was connected with increased left brain hemisphere activation (which induced sympathetic nervous system activation). Their breathing technique, however, had the opposite effect on three subjects with neovascular glaucoma (i.e., it raised IOP significantly). In my case, I am not sure if my pranayama results indicate that there are other complications in my right eye. None of the doctors on my medical team have opinions about the IOP increase after my pranayama exercise today, so I am left with many questions. I will offer a few comments of my own. I feel my IOP responds somewhat differently from the results described in this study for the majority of subjects. However, I do feel this study supports my own experience that the balance between the sympathetic and parasympathetic nervous systems has an influence on IOP. I also need to note that I do not have glaucoma simplex (primary open angle glaucoma), which is what this study focused on. I have pigmentary glaucoma.

My right eye IOP returned back to the baseline value about 1.5 hour later, after a series of activities that usually lower my IOP. Those activities are designated in the comments in the table below. Exercise and doing activities outside such as playing Frisbee with my dog have a very good track record in lowering my IOP. As you review more of the data here on my blog, that trend should be obvious.

Time	Left	Right	Comments
8:49	20.7	18.7
9:19	14.0	21.0	Working at computer.
9:42	16.7	23.0	After 10 min of pranayama.
10:12	15.3	29.3	Working at computer.
10:22	16.7	25.0	After 5 min of Bates sunning.
10:40	15.3	21.7	After 15-20m of low intensity cycling exercise.
10:56	16.0	24.0	Working at computer.
12:50	13.7	23.3	Working at computer.
12:52		22.7	Repeated measurements for right eye only.
12:54		22.0	Repeated measurements for right eye only.
13:12	13.3	20.0	After playing 10m frisbee with my dog.
17:48	13.0	21.0	After cooking and eating.
19:10	14.3	24.4	Working at computer. Feeling stressed.
20:14	12.3	19.7	After a relaxing shower.
23:06	15.7	22.7	After watching comedy movie on TV ("RV").
0:02	13.3	19.0	Relaxing.
0:04	11.0	18.3	Repeated.
0:08			Xalatan in each eye
0:48	14.0	21.3	After laying down for 40m.

I'll continue today's discussion with a more general look at the data. Today's overall averages are:

Left 14.7; Right 22.1 (differential 7.4)

We collected a total of 104 IOP measurements underlying the above averages. 

I see that my IOP went from 24.4 to 19.7 in my right eye as I shifted from working at the computer to taking a relaxing shower. Today's data alone doesn't make a convincing case for a connection between stress (parasympathetic vs. sympathetic nervous system balance) and IOP, but that connection starts to look more real after examining thousands of my IOP measurements, as I have been doing. This is obviously an unexpected result given that ophthalmologists and glaucoma researchers generally feel stress does not increase IOP. Since we are only looking at my IOP data, we can't say anything about the whole population of people with glaucoma, but I suspect that down the road statistical analysis of my data will show that there is a strong connection between stress and my IOP in my right eye. (The relationship is weaker for my left eye; my left eye is also not as strongly affected by glaucoma.)

Looking over the entire data set, I see hundreds of examples of my IOP increasing 3-4 mm Hg or more in connection with activities that could be called "stressful." One fairly consistent example of such an activity is a confrontational interpersonal communication, especially in a business setting. Informally, these activities seem to be associated with increased sympathetic nervous system activation. There are also hundreds of examples of my IOP decreasing 3-4 mm Hg (or more) after activities such as playing Frisbee with my dog. Informal measures such as hand temperature indicate that these activities may be associated with increased parasympathetic nervous system activation.

If you accept my observations about stress and IOP as I describe them above, today's data shows something that, at first, looks like a paradox. Today, my family and I watched the comedy movie "RV" with Robin Williams. I expected that watching a relaxing comedy might be correlated with a lower IOP. As you can see in the data above, my IOP was higher after watching RV. We have tested my IOP after many types of movies and TV shows. My IPO is almost always higher after exciting, tense or stressful shows. And sometimes my IOP is lower after relaxing shows. However, my IOP is sometimes higher after a relaxing or funny show, as was the case today. I suspect that over time this situation will become more clear. At the moment, I can only speculate. I'll throw out a few guess. It is possible that my posture or my breathing are confounding factors. It is also possible that certain types of tragic comedy are stressful for me. It might be possible, in the future, to gain further insight via things like cortisol testing (blood or saliva) or galvanic skin response measurements. My medical advisory team is helping me evaluate those options and others. I look forward to sharing my future insights on this subject with you.