A Study Showing Influence of Autonomic Nervous Activity and Meditation on Intra-Ocular Pressure

Mittal Sanjeev K.umar, Mittal Sunita, Verma Punam, Deepak Desh, Jain Nidhi, Garg Neeru

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A Study Showing Influence of Autonomic Nervous Activity and Meditation on Intra-Ocular Pressure

Mittal Sanjeev K.umar1,, Mittal Sunita2, Verma Punam2, Deepak Desh3, Jain Nidhi2, Garg Neeru2

1Ophthalmology, Shri Guru Ram Rai Institute of Medical & Health Sciences, Dehradun, Uttarakhand, India

2Physiology, Shri Guru Ram Rai Institute of Medical & Health Sciences, Dehradun, Uttarakhand, India

3Physiology, Veer Chandra Singh Garhwali Government Medical College, Shrinagar, Uttarakhand, India

Abstract

Purpose: Maintenance of normal intra-ocular pressure (IOP) involves aqueous humour dynamics at several steps, like active secretion of aqueous humour by ciliary body, its flow along pupillary area and ultimately its drainage through trabecular meshwork, schelemm’s canal and collector channels. Almost each of these steps is influenced by autonomic activity (sympathetic and parasympathetic). This autonomic activity, which is otherwise not under voluntary control, can be modified with the help of meditation. Meditation is said to be ‘a wakeful hypo metabolic state of parasympathetic dominance’. The present study is aimed to assess the influence of meditation on autonomic activity and intra-ocular pressure so that a regular regime of meditation may be recommended in Glaucoma prone persons or combined with the Glaucoma treatment. Methods: The study was carried out on 40 healthy non-meditator male subjects and 20 healthy meditator male subjects of the age 40-50 years who have been performing regular meditation for at least 5 years. Their IOP was recorded in each eye. All these subjects were catagorized into 3 groups based upon 2 criteria, viz. non meditators versus meditators and secondly, normal IOP versus border line IOP amongst non meditators. Thus 3 groups were formed, viz. Group A: 20 Non-meditator persons with normal IOP Group B: 20 Non-meditators who had borderline IOP Group C: 20 Meditators who had normal IOP Subsequently a battery of tests were undertaken to assess autonomic activity in all the groups after seeking their consent and making them familiar with the tests. Results: The values observed in different tests in meditator group (Group C) showed parasympathetic dominance and blunted sympathetic drive in comparison to both subgroups of non-meditators (Group 1 & Group 2). Conclusions: This study can help us in clinical practice by this fact that regular meditation in ‘glaucoma suspect’ & ‘ocular hypertensive’ patients can bring down IOP due to improved parasympathetic tone and reduced sympathetic tone.

Cite this article:

  • K.umar, Mittal Sanjeev, et al. "A Study Showing Influence of Autonomic Nervous Activity and Meditation on Intra-Ocular Pressure." Neuro-Ophthalmology & Visual Neuroscience 1.1 (2014): 1-7.
  • K.umar, M. S. , Sunita, M. , Punam, V. , Desh, D. , Nidhi, J. , & Neeru, G. (2014). A Study Showing Influence of Autonomic Nervous Activity and Meditation on Intra-Ocular Pressure. Neuro-Ophthalmology & Visual Neuroscience, 1(1), 1-7.
  • K.umar, Mittal Sanjeev, Mittal Sunita, Verma Punam, Deepak Desh, Jain Nidhi, and Garg Neeru. "A Study Showing Influence of Autonomic Nervous Activity and Meditation on Intra-Ocular Pressure." Neuro-Ophthalmology & Visual Neuroscience 1, no. 1 (2014): 1-7.

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1. Introduction

Glaucoma is a clinical condition characterized by increased intra ocular pressure (IOP) and optic nerve head changes leading to visual field loss. It is one of the most important causes of blindness in India. Maintenance of normal intra ocular pressure depends on active secretion of aqueous humor by ciliary body, its flow along pupillary area and ultimately its drainage through trabecular meshwork, schelemm’s canal and collector channels. Almost each of these steps are influenced by autonomic (sympathetic and parasympathetic) activity [1-6][1].

In human body, organs other than skeletal muscles are innervated by autonomic nervous system (ANS) and through this, body functions are carried out without conscious control. Functionally the two divisions of ANS i.e. sympathetic (catabolic division of nervous system) and parasympathetic (anabolic division of nervous system) are essentially antagonistic and work to maintain the perfect homeostasis in body. Even noninvasive assessment of autonomic functions provide important tool to understand the etiology and the remedy of certain diseases [7, 8]. More recently, raised intraocular pressure has been found to be associated with autonomic dysfunction [9, 10, 11].

Meditation practices originated from ancient India are now known across several parts of the world. A lot of studies have been performed on meditation in India and in some parts of world. Meditation is said to be a wakeful hypo metabolic state of parasympathetic dominance. It has been observed that many functions that are not under voluntary control (like heart beats, pulse and respiration) can be influenced by meditation [7, 8, 9].

Considering the facts that autonomic (sympathetic and parasympathetic) activity has a role in aqueous inflow and outflow, and medtation has been found to influence autonomic activity, the present study is aimed to find the role of meditation on intraocular pressure. This will help us to assess whether a regular regime of meditation may be recommended in Glaucoma prone persons or it (meditation) may be combined with Glaucoma treatment.

2. Material & Methods

The study was undertaken on 40 healthy non-meditator male subjects of 40-50 years of age with similar socio-economic status and physical activity and 20 healthy meditator male subjects of the similar age group and doing meditation for at least 5 years for 8-10 hours per week (Subjects chosen were from YSS Dhyan Mandali, Dehradun). No food, coffee, or nicotine was permitted for 3 hours before the tests. After seeking their consent all the persons were familiarized with the tests beforehand. None of the patients were taking any long term medication neither for hypertension, diabetes mellitus, thyroid disorder nor did they have history of undergoing for any intra-ocular surgery.

3 groups were formed, viz. Group A: 20 Non-meditators, those who had normal IOP Group B: 20 Non-meditators who had borderline IOP and Group C: 20 Meditators who had normal IOP.

Over all mean ± s.d of age in total subjects was 47.44±1.3 (Group A = 46.52±1.6, Group B = 47.66±1.0 and Group C = 48.12±1.4)

2.1. Intra-ocular Pressure Recording

Intra ocular pressure (IOP) was recorded in both the eyes of each subject almost at the same time of the day using a Goldmann applanation tonometer. Two readings were taken in both the eyes keeping an interval of half an hour in order to be more accurate. The subjects, in whom IOP was found to be borderline raised for the first time, were kept in Group B. After IOP measurement they were subjected to visual field evaluation (30-2 program over Humphrey’s automated perimeter, Carl Zeis) and fundus examination using +90 D lense. The subjects with normal fundus and visual field were only included in study group B.

2.2. Assessment of the Autonomic Nervous System Activity

Subsequently a battery of tests were undertaken in all the groups to assess both the components of autonomic activity viz sympahtetic and parasympathetic. A number of simple well established tests of autonomic nerve function based on cardiovascular reflexes allow quite an accurate assessment of the autonomic nervous system. Tests included for assessing autonomic activity were:

1. Sympathetic activity: Changes in the blood pressure responses show normal sympathetic activation; a) Hand Grip Test, b) Cold Pressor Test.

2. Parasympathetic activity: Changes in heart rate during Valsalva manoeuvre, as well as during deep breathing reflect parasympathetic modulation. c) Valsalva Ratio in Valsalva Manoeuvre; d) E: I Ratio in Deep Breath Test [15, 16, 17, 18, 19].

Basal parameters for each of the aforementioned tests were recorded. Subject was made to lie down supine on the bed for at least 10 minutes to attain the basal state. Each test was performed after a resting period of 10 minutes, in supine or sitting position as required.

A basal value of blood pressure-systolic and diastolic (SBP and DBP) was recorded by automatic blood pressure instrument (National) and Heart Rate (HR) was measured from the R-R interval of ECG recording in Lead II (By BPL Cardiart machine).


2.2.1. Hand Grip Test

After recording of basal Systolic Blood Pressure (SBP) and Diastolic Blood Pressure (DBP), subject was asked to hold the dynamometer in right hand (dominant) and to press its handle as hard as possible. Assess this maximum developed tension. After that subject is asked to maintain a tension of 30% of the maximum voluntary capacity for 3-5 minutes or as long as effort was possible by the subject. SBP and DBP were recorded from the inactive arm just before the release of hand grip, after 1 min and 5 minutes of the release of hand grip. The sustained hand grip results in increased cardiac output. This happens due to sympathetic activation mediated through the adrenergic receptors of ANS, thus leading to peripheral vasoconstriction, and increase in SBP and DBP. The rise should be within 15-20 mmHg. The value of rise in SBP & DBP as 11-15 mm Hg is border line and 10 mm Hg or less is sympathetic insufficiency. The test result is presented as the difference between Blood Pressure (SBP and DBP) recorded ‘during manoeuvre’ and the ‘basal’ value.


2.2.2. Cold Pressor Test

After recording of basal SBP and DBP, subject was asked to immerse his left hand upto first crease of the wrist in cold water of 8 Celsius for 2 min or as long as effort was possible. SBP and DBP were recorded from the right arm during the immersion of hand. Due to activation of afferent pain and temperature fibres from the skin and due to emotional arousal, reflex sympathetic activation takes place, which results in increased SBP and DBP. A rise in diastolic blood pressure is calculated. It should normally exceed 15 mmHg. The rise should be within 15-20 mmHg. The value of rise in SBP & DBP as 11-15 mm Hg is taken as borderline and 10 mm Hg or less is sympathetic insufficiency. The test result is presented as the difference between the highest SBP: DBP (during manoeuvre) and basal SBP: DBP.


2.2.3. Valsalva Manoeuvre -Valsalva Ratio

It is a voluntary forced expiratory effort by a subject against a resistance and reflects parasympathetic (cardiovagal) activity.

Subject is asked to be seated and to blow in the mouthpiece with both nostrils clipped. Mouthpiece is connected to aneroid manometer and subject is asked to raise the pressure to 40 mm of Hg and to hold/strain for 15 sec and then to release the strain. An unremitting ECG is recorded during rest, strain and within 45 sec of release.

The change in heart rate during the Valsalva manoeuvre was used as an index of response and expressed as the Valsalva Ratio. This is the ratio of the longest R-R interval ‘after the Valsalva’ to the shortest R-R interval ‘during the Valsalva’. A ratio of <1.20 is defined as abnormal, 1.21-1.45 as borderline and >1.45 as normal parasympathetic activity.


2.2.4. Deep Breath Test

Normal variation of heart rate with respiration is known as sinus arrhythmia. Inspiration increases and expiration decreases heart rate. This is primarily mediated by parasympathetic (vagal) innervation of heart as sinus arrhythmia is abolished by parasympathetic block but not by sympathetic dysfunction. During deep breathing (6 breaths per min) the difference of maximum and minimum heart rate is pronounced and is known as Deep Breath Difference (DBD). Respiratory arrhythmia declines with age. Difference of more than 10-15 beats per minute is regarded as normal. After the age of 50 years, DBD should not be less than 5 beats per minute.

After recording of resting ECG for 1 min, subject is asked to lie supine and to breathe deeply through the nostrils for 60 sec, at a rate of 6 breaths / min as 5 sec is given for each phase of inspiration and expiration. Continuous recording for ECG is done during deep breathing, and after 1 min of deep breathing. Heart Rate changes during the deep breathing expressed as the expiratory-inspiratory ratio (E: I ratio), longest R-R interval during expiration/ shortest R-R interval during inspiration. For calculation, sum of 6 longest RR intervals are divided by 6 shortest RR intervals. Normal E: I ratio in young person should be higher than 1.2.

It is ensured before starting the test that resting respiratory pattern should be normal and mean heart rate should not fluctuate.

Statistical analysis was carried out by SPSS version 7 by using T test, multivariate analysis, Univariate analysis and Post Hoc Test. Further Post Hoc test-Scheffe's method was used to make inter-group comparison. Statistical significance was defined as p<0.05.

3. Observation and Results

3.1. Intra Ocular Pressure

Mean ± s.d. of intra ocular pressure in both the eyes is reflected in Table 1. It shows that non-meditators Group A has normal IOP, Group B has borderline raised IOP and meditators Group C has normal IOP nearing lower side of normal range. The values of IOP were found statistically significantly lowest in meditators than in non-meditators of Group A & Group B.

Table 1. Mean ± s.d. Intra Ocular Pressure in three groups

3.2. Sympathetic System Evaluation

Mean ± s.d. of basal SBP and DBP were highest in Group B followed by Group A and Group C, indicating lowest sympathetic tone in Group C [Table 2].

Multivariate analysis of sympathetic tests showed statistically significant difference in both SBP and DBP parameters during basal and manoeuvre phases in all three groups (SBP 2,240=20.032, p value. 000 and DBP 2,240= 83.79, p value. 000) [Table 3].

Multiple group analysis (post hoc-Scheffe Test) showed a rise of SBP & DBP ‘during manoeuvre versus basal level’, which was statistically significantly lower in Group C in comparison to both Group A and Group B. However there was no statistically significant difference of rise in SBP & DBP between Group A & Group B [Table 4].

Thus this can be inferenced that meditators had significantly lower sympathetic response in comparison to non-meditators.

Table 2. Sympathetic System Evaluation: Mean ± sd of HGT and CPT

Table 3. Multivariate analysis of Sympathetic tests in different Groups and phases

Table 4. Sympathetic System; Post Hoc Test (Scheffe Test)

3.3. Parasympathetic System Evaluation [Table 6, Table 7 & Table 8]

Mean ± s.d. of Valsalva Ratio and E:I Ratio were highest in Group C followed by Group A and Group B, indicating more parasympathetic tone in Group C as shown in Table 5.

On univariate analysis of parasympathetic tests; Valsalva ratio and E: I ratio showed statistically significant difference in all three groups (Valsalva Ratio 1,60=41537.432, p value. 000 and E:I Ratio1,60= 117.600, p value. 000) as shown in Table 6 and Table 7.

On multiple group analysis (post hoc-Scheffe Test); Mean ± s.d. of Valsalva and E:I ratio were statistically significantly higher in Group C in comparison to Group A and Group B. There was no statistical significant difference in valsalva and E: I ratio between Group A and Group B as shown in Table 8.

Thus this can be inferenced that medidators had significant higher parasympathetic response in comparison to non-meditators.

Table 5. Parasympathetic System Evaluation: Mean ± s.d. of Valsalva Ratio and E:I Ratio

Table 6. Univariate analysis of Parasympathetic tests (Valsalva Ratio) in different groups and phases

Table 7. Univariate analysis of Parasympathetic tests (E:I Ratio) in different groups and phases

Table 8. Parasympathetic System; Post Hoc Test (Scheffe Test)

4. Discussion

In the present study, intra ocular pressure (IOP), sympathetic and parasympathetic systems were evaluated in non-meditators and meditators by forming 3 groups: Group A (Non-meditators with normal IOP), Group B (Non-meditators with marginally raised IOP), Group C (Meditators with normal IOP). It is interesting to note that mean IOP in both eyes was lower in meditators (group C) compared to non-meditators (group A and group B). Statistically also, non-meditators (group A and group B) showed significantly higher sympathetic tone and significantly lower parasympathetic tone in comparison to meditators (group C). Further in Goup B little raised sympathetic and reduced parasympathetic tone in comparison to Group A reflects marginal systemic autonomic dysfunction

The role of the ANS in the regulation of aqueous inflow and outflow is well recognised and more recently it has been found that rise in IOP is associated with autonomic dysfunction [12, 13, 14]. The ciliary body is innervated with both sympathetic and parasympathetic nerve endings. The catecholamine neurotransmitters released from the sympathetic nerve endings stimulate the adrenergic receptors on the ciliary epithelium, which in turn increases aqueous humor secretion. The parasympathetic fibres secrete acetylcholine, which in turn stimulates cholinergic receptors on the ciliary muscles. The resulting effect is ciliary muscle contraction with reduced resistance to the trabecular aqueous humor outflow. The uveo-scleral outflow of aqueous humor also gets increased [6]. Current medications prescribed in the treatment of glaucoma i.e. guttae adrenaline, guanethedine, timolol and pilocarpine act primarily via autonomic effects in the anterior segment of the eye [4].

Meditator are usually saints and ascetics people, who are inaccessible to the scientific world, but recently in India meditation has been re-popularized among the masses and the number of common people practicing it has risen up again. Meditation leads to variation in physiological responses of the subjects by influencing ANS and thus achieving parasympathetic dominance with better control over sympathetic activity.

A number of simple well established tests of autonomic nerve function based on cardiovascular reflexes allow accurate assessment of the autonomic nervous system.

Various studies suggest that systemic parasympathetic neuropathy occurs in 58% cases of closed angle glaucoma and 42% of ocular hypertension patients [20, 21].

Based upon the aforesaid facts it can be implied that meditation can help in regulation of IOP by affecting autonomic nervous system activity.

Meditation may also be of clinical usefulness in other diseases associated with increased sympathetic nervous system activity.

A number of physical ailments i.e. Obsessive Compulsive Neurosis, Epilepsy, Sleep, Addiction and behavioral disorders are reported to get improved by reduction in sympathetic drive [22, 23, 24]. Few studies exhibit that yogic practices including meditation and deep breathing relaxation exercises bring not only control over sympathetic drive but also induce parasympathetic dominance [8, 9]. The hypometabolic state seen during practice of meditation differs from that seen during sleep, but is consistent with an integrated hypothalamic response, recently termed as 'the relaxation response' [25]. This hypothalamic response probably represents a state of decreased sympathetic nervous system activity. Hence it can be inferred that regular practice of meditation can control ‘uncontrollable’ ANS.

5. Conclusions

This study brings this fact that autonomic nervous function plays an important role in control of IOP and thus may contribute as a significant factor in the pathogenesis of Ocular Hypertension and possibly in Primary Glaucomas

Further this study can help us in clinical practice by the fact that regular meditation in ‘Glaucoma Suspect’ & ‘Ocular Hypertensive” patients can bring down IOP due to improved parasympathetic and reduced sympathetic tone. It can be hypothesized that Primary Glaucomas without anatomical abnormalities related to resistance in aqueous outflow facility, might also have some beneficial effect by meditation.

We know for a fact that risk of glaucoma is also based on non-IOP factors. But, the only modality of treatment available to reduce risk is to lower IOP.

Therefore meditation practices may be helpful as an adjuvant to medical therapy.

The present study had a limitation that no female subject was included in this study. Secondly, the age group of participants had not been wide. The effect of meditation practice in ‘established cases’ of Primary Glaucomas, opens scope for further research study.

Acknowledgements

The authors express gratitude towards members (the meditators) of YSS Dhyan mandli for their participation in this work, and Ms Gauri for assisting in written work.

Statement of Competing Interests

The authors have no competing interests

List of Abbreviations

Systolic Blood Pressure (SBP), Diastolic Blood Pressure (DBP), Deep Breath Difference (DBD),

Expiratory-inspiratory ratio (E: I ratio), standard error of the means (SEM).

References

[1]  Barany EH, “Transient increase in outflow facility after superior cervical ganglionectomy in rabbits”, Arch Ophthalmol, 67 (3). 03-11. 1962.
In article      
 
[2]  Richardson KT, “Parasympathetic physiology & pharmacology”, Surv Ophthalmol, 14. 461-76. 1970.
In article      
 
[3]  Sears ME and Barany EH, “Outflow resistance and adrenergic mechanisms”, Arch Ophthalmol, 64. 839-48. 1960.
In article      CrossRef
 
[4]  Nagataki S and Brubaker EF, “Effects of pilocarpine on aqueous humor formation in human beings”, Arch Ophthalmol, 100. 818-21. 1982.
In article      CrossRef
 
[5]  Mapstone R, “Autonomic effects on aqueous outflow”, Res Clin Forums, 3. 35-9. 1981.
In article      
 
[6]  R.R.Alligham. Shield’s text Book of glaucoma: The Autonomic innervation of the ciliary body, Lippincott Williams Wilkins, India, 2011.
In article      
 
[7]  Patel C, Marmot MG, Terry DJ, Carruthers M, Hunt B, Patel M, “Trial of relaxation in reducing coronary risk: four years follow up”, BMJ, 290. 1103-06. 1985.
In article      CrossRef
 
[8]  Bellavere F and Ewing OJ, “Autonomic control of the immediate heart rate response to lying down”, Clin Sci, 62. 57-64. 1982.
In article      
 
[9]  Clark CV and Mapstone R, “Autonomic neuropathy in ocular hypertension”, Lancet, 11. 185-7. 1985.
In article      CrossRef
 
[10]  Mapstone R, “Mechanisms in ocular hypertension”, Br J Ophthalmol, 63. 325-30. 1979.
In article      CrossRef
 
[11]  Clark CV, Mapstone R, “Anterior Segment Autonomic Dysfunction in Ocular Hypertension”, Documenta Ophthalmologica, 64 (2). 201-7. 1986.
In article      CrossRef
 
[12]  Wallace RK, Benson H, Wilson AF, “A wakeful hypometabolic physiologic state”, Am J Physiol, 221. 795-99. 1971.
In article      
 
[13]  Jevning R, Wallace RK, Beidebach M. A, “wakeful hypometabolic integrated response”, Neurosci Biobehav Rev, 16. 415-424. 1992.
In article      CrossRef
 
[14]  Baghchi BK, Wenger A,”Electrophysiological correlats of some yoga exercises”, Electroencephalography and Clinical Neurophysiology, 9. 132-149. 1957.
In article      
 
[15]  Jain AK, Manual of Practical Physiology: Autonomic Nervous System Testing, Arya publication, India, 2009, 279-84.
In article      
 
[16]  Low PA, “Testing the autonomic nervous system”, Semin Neuro, 23. 407-21. 2003.
In article      CrossRef
 
[17]  Agnieszka Zygmunt, Jerzy Stanczyk, “Methods of evaluation of autonomic nervous system function”, Arch Med Sci, 6 (1). 11-18. 2010.
In article      CrossRef
 
[18]  Ewing OJ, Irving JB, Kerr F, Wildsmith JAW, Clarke BF, “Cardiovascular responses to sustained handgrip in normal subjects and in patients with diabetes mellitus-A test of autonomic nerve function”, Clin Sci Mol Med, 46. 295-306. 1974.
In article      
 
[19]  Levin AB, “A simple test of cardiac function based on the heart rate changes induced by the Valsalva manoeuvre”, Am J Cardiol, 18. 90-9. 1966.
In article      CrossRef
 
[20]  Chowdhury D, Patel N, “Approach to a Case of Autonomic Peripheral Neuropathy”, JAPI, 54. 727-32. 2006.
In article      
 
[21]  Freeman R, “Autonomic peripheral neuropathy”, Lancet, 365. 1259-70. 2005.
In article      CrossRef
 
[22]  Roth B, Creaser T, “Mindfulness meditation based stress reduction experience with a bilingual inner city program”, Nurse Prctitioner, 22. 31-33. 1997.
In article      CrossRef
 
[23]  Khanam AA, Sachdeva U, Guleria R, Deepak KK, “ Study of pulmonary and autonomic functions of Asthma patients after Yoga training”, Indian J Physiol Pharmacol,, 40. 318-24., 1996
In article      
 
[24]  Panjwani U, Selvamurthy W, Singh SH, Gupta HL, Thakur L, Rai UC, “ Effect of Sahaj Yoga practice on seizure control & EEG changes in patients of epilepsy”, Indian J Med Res, 103. 165-72. 1996.
In article      
 
[25]  Beary JF, Benson H, “A simple physiologic technique which ellicits the hypometabolic changes of the relaxation response”, Psychosomatic Medicine, 36. 115-20. 1974.
In article      
 
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