Can Breathing Exercise or Pranayama Affect the Intraocular Pressure in the Short-term?

Supplemental Digital Content is available in the text. Purpose: To demonstrate any transient short-term effect of a particular type of breathing exercise (alternate nostril breathing of Nadi Shuddhi type of pranayama exercise) on the intraocular pressure (IOP) in glaucomatous as well as healthy eyes. Methods: A prospective, nonrandomized, observational, cross-sectional study was conducted in a tertiary eyecare hospital setup recruiting 3 groups of subjects—glaucoma group and a normal group that underwent the breathing exercise as well as a normal group that did not. IOP was recorded at baseline, then at 4 minutes after 10 cycles of the breathing exercise and also after 10 minutes of rest—corresponding to IOPb, IOPc, and IOPr of all the study groups. Only those subjects were recruited who were above 18 and under 80 years and were naive to breathing exercise. Results: A total of 56 normal eyes (28 subjects, Normalb) and 33 glaucomatous eyes (19 subjects) were recruited for the breathing exercise and were compared with the IOP as obtained for 26 eyes of 26 subjects that did not undergo the breathing exercise (Normalnb). IOPb did not differ between both normal groups (13.7±1.4 mm Hg in Normalb vs. 13.9±1.6 mm Hg in Normalnb, P=0.183) but was significantly different between groups (16.7±3.1 mm Hg in the glaucoma group and 13.7±1.4 in Normalb, P<0.001 and Normalnb 13.9±1.6 mm Hg, P<0.001) but analysis of variance was not significant within groups comparing IOPb, IOPc, and IOPr of all the study groups. Conclusion: There is no short-term transient effect of alternate nostril breathing exercise on IOP; a longitudinal study is recommended.

G laucoma is a chronic, irreversible disease in which intraocular pressure (IOP) remains the only modifiable risk factor against the progression of glaucoma-associated optic nerve damage. The socioeconomic burden of glaucoma 1 and its treatment often leads patients to seek alternative therapies, for example, oral supplements 2,3 or meditational. Yoga and specifically pranayama are noteworthy where the latter is concerned. 4 Yoga, an age-old practice in India, predominantly comprises of 3 forms, namely-asana (posture), pranayama (awareness of breathing and its exercise), and meditation (concentration). Pranayama is a type of yogic exercise aimed at controlling the flow of vital energy which is responsible for maintaining the physiology of the body. It can be of several types [viz., Nadi Shuddhi or anulom-vilom alternate nostril breathing (NS), Bhastrika or bellow's breath, Bhramari or humming bee breath, Kalpabhati or breath of fire-among others]. 5 NS type of pranayama is low intensity, prolonged and slow type of breathing. This breathing exercise entails the following (see Video, Supplemental Digital Content 1, http://links.lww.com/IJG/A456demonstrating one full cycle of Nadi Shuddhi type of alternate nostril breathing exercise)-sitting in a straight posture, closure of the right nostril with the thumb of the right hand, with slow and deep inhalation through the left nostril for at least 4 seconds. This is followed by closure of the left nostril with the ring finger of the same hand and simultaneous release of the (right) thumb to allow for slow and prolonged exhalation through the right for at least 8 seconds (inhalation and exhalation in a ratio 1:2). Deep and slow inhalation in a similar fashion is then done through the right nostril with the left one still closed, followed by slow and prolonged exhalation after release of the left nostril and closure of the right one. This constituted one cycle of 24 seconds duration; 10 cycles of this was completed by each study subject (duration 4 min). A variation of this-called Kumbhak-of holding one's breath between the 2 (inhalation and exhalation) for a prolonged period in a ratio of 1:4:2 was excluded from our breathing exercise routine.
Although this breathing exercise is by no means very forceful (as opposed to some of the others, eg, Kalpabhati), but as there is some evidence of both low and high resistance wind musicians experiencing a transient rise in their IOP, 6 we set out to observe if there was any short-term transient change in IOP due to NS pranayama.

METHODS
A prospective, nonrandomized, observational, crosssectional study was conducted in a tertiary eyecare hospital setup. Three groups were recruited-glaucoma group and a normal group that underwent the breathing exercise as well as a normal group that did not. As there was no precedent study available, we conducted a pilot in 5 glaucoma subjects and normals to determine the sample size. To demonstrate an effect size of 2 mm Hg, with a SD of 2 and the alpha set at 5% (and power of 95%), the sample size required per group was determined to be 26.
Inclusion criteria for glaucoma study subjects: eyes of subjects above 18 and under 80 years diagnosed with any etiology of primary glaucoma with typical changes in the optic nerve head and retinal nerve fiber layer ± corresponding visual field changes, on anti-glaucoma medication or had filtering surgery and were either naive to breathing exercise or had not actively performed it in the past 3 months.
Inclusion criteria for normal study subjects (with breathing exercise, Normal b and without breathing exercise, Normal nb )-normal eyes of subjects above 18 and under 80 years that did not have any ocular disease, other than cataract, and were naive to breathing exercise.
Exclusion criteria in all groups-any active ocular surface disease, any active ocular inflammation, any refractive surgery or intraocular surgery (other than trabeculectomy in the glaucoma group and cataract surgery in all the groups), sinusitis, self-reported breathing problems or asthma or on inhalers and heart disease. Lactating or pregnant females were also excluded.
Baseline IOP (IOP b ) was measured with Goldmann applanation onometer (GAT) and the study subjects performed 10 cycles of pranayama following which GAT was recorded again (IOP c ). A final reading of IOP was taken after 10 minutes (IOP r ). The same procedure was performed in normal and glaucomatous study subjects. Data was also obtained for a third group (Normal nb ) who did not undergo the breathing exercise but had IOP recorded at baseline, then at 4 minutes and 10 minutes-corresponding to IOP b , IOP c and IOP r of the study groups. All 3 readings were taken by a single observer with the same tonometer, reducing interobserver variation and errors caused due to the change in instrument.
Ethics approval from the Institutional Ethics Committee of the University was obtained. Informed consent was taken from each participant and data handling was as per the tenets laid down by the declaration of Helsinki.
Data analysis was done using the IBM SPSS statistics 22.0 software.

RESULTS
Fifty-six normal eyes (28 subjects, Normal b ) and 33 glaucomatous eyes (19 subjects) were recruited for the breathing exercise and were compared with the IOP as obtained for 26 eyes of 26 subjects that did not undergo the breathing exercise (Normal nb ).
Mean age of patients with glaucoma was 58.9 ± 4.2 years and those for Normal b was 33.8 ± 13.1 years (P < 0.001). Mean age of Normal nb group was 36.4 ± 11.2 years, P = 0.156 when compared with Normal b and <0.001 when compared with the glaucoma group. The etiology of glaucoma in each eye of the study subjects, in descending order, included-primary angleclosure glaucoma (n = 20), primary open-angle glaucoma (n = 7), combined mechanism glaucoma (primary open-angle glaucoma converting to primary angle-closure glaucoma) (n = 4), and normal tension glaucoma (n = 2). IOP b did not differ between both normal groups (13.7 ± 1.4 mm Hg in Normal b vs. 13.9 ± 1.6 mm Hg in Normal nb , P = 0.183). Glaucoma patients were on 1.7 ± 1.3 antiglaucoma medication and IOP b was significantly different between groups (16.7 ± 3.1 mm Hg and 13.7 ± 1.4 in Normal b , P < 0.001 and Normal nb 13.9 ± 1.6 mm Hg, P < 0.001). Analysis of variance of IOP within groups immediately after 10 cycles (IOP c ) and 10 minutes later (IOP r ) was not significant in the glaucoma group (IOP c 16.9 ± 3.3 mm Hg, IOP r = 16.8 ± 3.0 mm Hg; P = 0.308) as well as in Normal b (IOP c 13.7 ± 1.8, IOP r = 13.5 ± 1.7; P = 0.154) and in Normal nb [IOP c (without breathing exercise), 13.6 ± 1.9 mm Hg, IOP r 13.5 ± 1.8 mm Hg; P = 0.106), respectively (Fig. 1).
The results did not differ even when only 1 eye was selected randomly for analysis in the glaucoma group (19 eyes) and compared with 26 eyes each in Normal b and Normal nb .

DISCUSSION
Our results show that there is no statistically significant change in IOP immediately after 10 cycles of NS pranayama and 10 minutes after relaxation in either of the groups that underwent the breathing exercise, when compared with baseline. Furthermore, there appeared to be no difference in both groups of normals-the one that undertook breathing exercise and the one that did not.
Unlike the observations of Schuman et al 6 who carried out their IOP observations with pneumotonometry in individuals while blowing wind instruments in the supine position, we chose GAT for IOP measurements as the breathing exercise is in an upright seated position. The increase in IOP that Schuman et al 6 reported was due to Valsalva-type maneuver and venous engorgement that was demonstrated in uveal tissues via ultrasound biomicroscopy. NS pranayama is probably far gentler as we could not demonstrate any transient change in IOP, in either the glaucomatous or healthy eyes.
Breathing exercises are a very common practice in India in patients with chronic diseases as this alternative therapy brings about comfort and contentment. Therefore, recruitment of breathing-exercise naive subjects in the glaucoma group was expectedly difficult. It is very evident from literature that longer term practice of pranayama tilts the systemic balance toward parasympathetic tone which has the capability of reducing stress, decreasing heartbeat, and blood pressure as well as increasing blood supply to the vital organs in the body. 7,8 On the other hand, as there is also some evidence that ocular and cerebral blood flow is reduced in glaucoma due to sympathetic mediated vasospasm and ischemia, 9 observations involving IOP and visual fields with longer term practice of breathing exercises may yield differing results. This was beyond the ambit of this cross-sectional study and therefore the study was limited to the breathing itself, without an emphasis on the meditational aspects of Yogic breathing exercise.
Other limitations of the study include the nonrandomized design, the lack of inclusion of a glaucoma-no-breathing-exercise group and recruitment of the Normal (nb) group after the other 2 groups. Furthermore, the cohort sizes were not large enough to undertake other exploratory analyses such as sensitivity to age, baseline untreated IOP, or type of glaucoma.
We conclude that there is no short-term transient effect of Yogic breathing exercise (Nadi Shuddhi or alternate nostril breathing) on IOP. However, study of longer-term practice of breathing exercise and its effect on IOP in a longitudinal study is highly recommended, as this kind of alternate therapy may contribute immensely to a patient's well-being.