Modulation of intraocular pressure by unilateral and forced unilateral nostril breathing in young healthy human subjects

The Clinical Efficacy of Different Relaxation Exercises on Intraocular Pressure Reduction: A Meta-Analysis

Objective: The aim of this study was to synthesize the available evidence on the clinical efficacy of different relaxation exercises on intraocular pressure (IOP) reduction. Methods: A systemic search of PubMed, Embase, Cochrane CENTRAL, and Web of Science was undertaken from the earliest record to 10 April 2024. Peer-reviewed studies that reported on healthy individuals and glaucoma patients engaging in relaxation exercises for at least three weeks were included. The primary outcome was changes in IOP levels from baseline, before the commencement of relaxation exercises, to post-exercise. Our statistical analysis employed a random-effects model, with effect sizes reported using Hedges' g. Results: Twelve studies were included, totaling 764 eyes (mean participant age ranging from 21.07 to 69.50 years). Relaxation exercises significantly reduced IOP, with Hedges' g being -1.276 (95% CI: -1.674 to -0.879) and I2 = 84.4%. Separate subgroup analyses showed that breathing exercises (Hedges' g = -0.860, p < 0.0001), mindfulness-based stress reduction (MBSR) (Hedges' g = -1.79, p < 0.0001), and ocular exercises (Hedges' g = -0.974, p < 0.0001) were associated with reduced IOP levels. The reduction in IOP following the relaxation exercises was found to be associated with baseline IOP either greater than (Hedges' g = -1.473, p < 0.0001) or less than 21 mmHg (Hedges' g = -1.22, p < 0.0001). Furthermore, this effect persisted with follow-up durations of less than (Hedges' g = -1.161, p < 0.0001) and more than one month (Hedges' g = -1.324, p < 0.0001). Conclusions: The current meta-analysis indicates that relaxation exercises can significantly reduce IOP levels. Relaxation exercises are a potential class of novel treatments for glaucoma patients that deserve further evaluation.

The Effect of Specific Techniques of Nasal Breathing [Pranayama] on Intra-Ocular Pressure in Normal Individuals, a Randomized Trial

PURPOSE

Glaucoma is an optic neuropathy where intraocular pressure is the only modifiable risk factor. Yoga is thought to adversely affect intra-ocular pressure (IOP) but we do not know if yogic breathing exercises can influence IOP. With this study, we aimed to determine the effect of specific nasal breathing techniques on intra-ocular pressure in normal individuals.

PATIENTS AND METHODS

One hundred and sixty-four normal subjects were randomly assigned to one of four specific breathing groups - right nostril breathing (RNB), left nostril breathing (LNB), alternate nostril breathing (ANB), normal breathing (NB). The IOP was measured in both eyes at baseline and following the breathing exercise; and the change was analyzed.

RESULTS

Eighty-five women and 79 men participated and there was no significant difference in baseline age or IOP between the groups. In RNB, IOP reduced significantly in both right and left eyes, from 14.3 ± 3.0mmHg to 13.9 ± 2.6mmHg, (p=0.022) and from 14.7 ± 3.2mmHg to 14.2 ± 3mmHg (p=0.016) respectively. In LNB, there was no significant IOP change in the right eye, whereas in the left eye, there was a significant reduction from 14.2 ± 2.7mmHg to 13.3 ± 2.5mmHg (p< 0.0001). There was no significant IOP change in ANB and NB.

CONCLUSION

Specific breathing techniques like right and left nostril breathing, alternate nostril breathing are safe and do not raise IOP in normal subjects. Additionally, right and left nostril breathing techniques have a beneficial effect of lowering IOP.

A Pilot Study on the Effect of Alternate Nostril Breathing and Foot Reflexology on Intraocular Pressure in Ocular Hypertension

The purpose of this study is to investigate the effects of alternate nostril breathing (ANB) and foot reflexology (FR) on lower intraocular pressure (IOP) in patients with ocular hypertension (OHTN). This prospective pilot study recruited 11 patients from 2014 to 2016 from Temple opthamology outpatient clinic. Patients had OHTN with ages of 48-78 years. Patients were excluded if they currently performed ANB or FR, were unable to perform the task, had previous eye surgery or laser, were receiving other complementary and alternative medicine for OHTN, or were unable to complete drug washout period. After a 30-day drug washout, patients were randomly assigned to complete either ANB or FR for 5 min. After instruction, patients completed either ANB or FR, and completed the alternate task 2 weeks later. IOP was measured before the task, immediately after the task, and then every 30 min for 2 h. Decrease in IOP compared with baseline IOP was significant for ANB and FR at all time points. Baseline IOP was 25.86 ± 3.19 mmHg for ANB and 25.41 ± 3.54 mmHg for FR (N = 22 eyes). There was only one significant difference between IOP for the right and left eyes for FR at 120 min. Otherwise, there was no difference between eyes for both ANB and FR. There was a significant decrease in IOP at 30 min post task with IOP decrease of 1.98 ± 1.70 mmHg for ANB and 3.59 ± 1.89 mmHg for FR (both p < 0.0001) and at 60 min post task with IOP decrease of 2.39 ± 2.05 mmHg for ANB and 3.86 ± 1.89 mmHg for FR (both p < 0.0001). The decrease in IOP at 90 and 120 min post task was less but remained significant (p < 0.0001). Both FR and ANB had a small but significant IOP lowering effect. These alternative therapies could serve as possible adjunctive treatments for lowering IOP.

Measuring and Characterizing the Human Nasal Cycle

Nasal airflow is greater in one nostril than in the other because of transient asymmetric nasal passage obstruction by erectile tissue. The extent of obstruction alternates across nostrils with periodicity referred to as the nasal cycle. The nasal cycle is related to autonomic arousal and is indicative of asymmetry in brain function. Moreover, alterations in nasal cycle periodicity have been linked to various diseases. There is therefore need for a tool allowing continuous accurate measurement and recording of airflow in each nostril separately. Here we provide detailed instructions for constructing such a tool at minimal cost and effort. We demonstrate application of the tool in 33 right-handed healthy subjects, and derive several statistical measures for nasal cycle characterization. Using these measures applied to 24-hour recordings we observed that: 1: subjects spent slightly longer in left over right nostril dominance (left = 2.63 ± 0.89 hours, right = 2.17 ± 0.89 hours, t(32) = 2.07, p < 0.05), 2: cycle duration was shorter in wake than in sleep (wake = 2.02 ± 1.7 hours, sleep = 4.5 ± 1.7 hours, (t(30) = 5.73, p < 0.0001). 3: slower breathing was associated with a more powerful cycle (the extent of difference across nostrils) (r = 0.4, p < 0.0001), and 4: the cycle was influenced by body posture such that lying on one side was associated with greater flow in the contralateral nostril (p < 0.002). Finally, we provide evidence for an airflow cycle in each nostril alone. These results provide characterization of an easily obtained measure that may have diagnostic implications for neurological disease and cognitive state.

Differential effects of uninostril and alternate nostril pranayamas on cardiovascular parameters and reaction time

BACKGROUND

Recent studies have reported the differential physiological and psychological effects of yogic uninostril breathing (UNB) and alternate nostril breathing (ANB) techniques. This study aims to determine differential effects of these techniques on reaction time (RT), heart rate (HR), and blood pressure (BP).

MATERIALS AND METHODS

Twenty yoga-trained subjects came to the lab on six different days and RT, HR, and BP were recorded randomly before and after nine rounds of right UNB (surya nadi [SN]), left UNB (chandra nadi [CN]), right initiated ANB (surya bhedana [SB]), left initiated ANB (chandra bhedana [CB]), nadi shuddhi (NS), and normal breathing (NB).

RESULTS

Overall comparison of ∆ % changes showed statistically significant differences between groups for all parameters. There was an overall reduction in HR- and BP-based parameters following CB, CN, and NS with concurrent increases following SB and SN. The differential effects of right nostril initiated (SB and SN) and left nostril initiated (CB, CN, and NS) UNB and ANB techniques were clearly evidenced. Changes following NB were insignificant in all respects. The overall comparison of ∆ % changes for RT showed statistically significant differences between groups that were significantly lowered following both SB and SN.

DISCUSSION AND CONCLUSION

Our study provides evidence of sympathomimetic effects of right nostril initiated pranayamas with sympatholytic/parasympathomimetic effect following left nostril initiated pranayamas. We suggest that the main effect of UNB and ANB techniques is determined by the nostril used for inspiration rather than that used for expiration. We conclude that right and left yogic UNB and ANB techniques have differential physiological effects that are in tune with the traditional swara yoga concept that air flow through right nostril (SN and pingala swara) is activatory in nature, whereas the flow through left nostril (CN and ida swara) is relaxatory.

Spectral Estimation of Nasal Cyclic Rhythm by Nasal Airflow Temperature Measurement

.The nasal cycle is referred to a cyclic fluctuation in congestion of the nasal mucosa that results in rhythmic and bilateral reciprocal alteration of nasal airway patency. The purpose of this study is to deal with statistical and power spectral analysis of nasal cycle by measuring the temperature difference between the airflow of both left and right nostrils. Five adult voluntary healthy subjects are enrolled for the study. Nasal temperature probe combined with amplifier are used for recording nasal airflow temperature on both nostrils. The highest nasal airflow temperature values are detected at the end of expiration and the lowest values are detected at the end of inspiration. Nasal cycle found in all the subjects and lasted to the minimum of 30 minutes to maximum of 6 hours. The difference in temperature of both nostrils is statistically significant (p<0.05) and spectral estimation is made using autoregressive modeling. The method is used to quantify nasal obstruction in pathological condition and also to correlate the related physiological phenomenon.

Selective unilateral autonomic activation: implications for psychiatry

Research advances have led to three methods for selectively activating one half of the autonomic nervous system in humans. The first method is an ancient yogic technique called unilateral forced nostril breathing (UFNB) that employs forced breathing through only one nostril while closing off the other. The second method works by stimulation of an autonomic reflex point on the fifth intercostal space near the axilla. The most recent method employs unilateral vagus nerve stimulation (VNS) via the mid-inferior cervical branch and requires surgical implantation of a wire and pacemaker. UFNB is non-invasive and seems to selectively activate the ipsilateral branch of the sympathetic nervous system with a possible compensation effect leading to contralateral VNS. UFNB and VNS have been employed to treat psychiatric disorders. While UFNB has been studied for its potential effects on the endogenous ultradian rhythms of the autonomic and central nervous system, and their tightly coupled correlates, VNS has yet to be studied in this regard. This article reviews these three methods and discusses their similarities, putative mechanisms, their studied effects on the endogenous autonomic nervous system and central nervous system rhythms, and their implications for the treatment of psychiatric disorders.

Effect of unilateral forced nostril breathing on tonic accommodation and intraocular pressure

BACKGROUND

Unilateral forced nostril breathing (UFNB) has specific measurable effects on the autonomic nervous system. Ocular accommodation, which is controlled by the autonomic nervous system, would be expected to be under the influence of UFNB when it is applied. The purpose of this study was to investigate the effect of UFNB on the resting state of the accommodation system, i. e. tonic accommodation (TA), along with measures of intraocular pressure (IOP), blood pressure and heart rate.

METHODS

TA levels were measured using the Shin-Nippon autorefractor before and after 20 minutes of UFNB. IOP, blood pressure and heart rate, which are known to be affected by UFNB, were also measured with a non-contact tonometer and an automated blood pressure monitor respectively.

RESULTS

Right and left UFNB produced slight, but not significant changes in TA. However, there was a tendency for left UFNB to produce a greater decrease in TA in subjects with higher base-line TA levels. Right UFNB produced a statistically significant decrease in IOP while the effect of left UFNB on IOP was not significant.

CONCLUSION

UFNB produced changes in IOP consistent with previous reports. As studied in this trial, UFNB did not have any significant effect on TA. Further studies using a larger sample size are required to investigate the effect of UFNB on the autonomic inputs to the ciliary muscle of the eye and the subsequent measures of tonic accommodation.