Mindfulness meditation helps reduce intraocular pressure in glaucoma

Stress and glaucoma

In the forms of primary open-angle glaucoma (POAG, Primary Open-Angle Glaucoma), the reduction of intraocular pressure (IOP, Intra Ocular Pressure) is currently the only approach to prevent further damage to the optic nerve head.

Pathology

Glaucoma is a chronic degenerative disease affecting the optic nerve, characterised by damage to its nerve fibres and consequent visual field damage. If left untreated, the progressive reduction of the visual field can lead to blindness.

Glaucoma is a major social problem: it is the second leading cause of blindness in the world and affects about 60 million people, rendering more than 8 million of them blind. Moreover, about 50% of glaucoma sufferers are unaware of it.

It is a sneaky disease as one often notices the disease when visual changes are already very advanced, whereas previously one did not experience any symptoms. However, if diagnosed early and properly treated, it can be effectively kept under control, allowing good vision throughout life.

Risk factors

Numerous risk factors correlate with the onset of the disease. Among these, the main ones are:

- elevated intraocular pressure (IOP),

- advanced age,

- familiarity.

The IOP value is determined by a fluid circulating within the eye, the aqueous humour. In a healthy eye, the ratio between the aqueous humour produced and the aqueous humour excreted is such that a constant intraocular pressure is maintained, usually between 11 and 20 mmHg. In the presence of glaucoma, on the other hand, this ratio is altered due to a reduction in the elimination of aqueous humour that occurs at the level of the trabecular meshwork (structure that allows this fluid to escape from the eye).

Classification

Glaucoma can be classified in several ways:

- Depending on the aetiology, glaucoma can be primary, when it occurs in the absence of other ocular or systemic pathologies, or secondary, when associated with pre-existing pathologies;

- Based on the altered outflow of the aqueous humour, we distinguish between open-angle glaucoma, due to increased resistance to outflow at the level of the trabecular meshwork, and angle-closure glaucoma, where there are anatomical problems that prevent the aqueous humour from reaching the trabecular meshwork;

- Based on the value of the main risk factor, IOP, there is high-pressure glaucoma and normal-pressure glaucoma.

Added to these are congenital or acquired glaucoma, if IOP is elevated from birth, and infantile glaucoma if it occurs during the first years of life.

Symptoms

The increase in intraocular pressure and the resulting damage to the optic nerve are not perceptible and, therefore, the main symptom is a progressive narrowing of the visual field. Unfortunately, in the early stages, it is not possible to realise this limitation without an eye examination.

Diagnosis

There are several tests that can be used to rule out or diagnose the presence of glaucoma:

1. the tonometry, which is used to measure intraocular pressure;

2. l'ophthalmoscopywhich allows an objective examination of the optic nerve;

3. the perimeter (or visual field examination), which allows an assessment of overall visual function;

4. the pachymetrywhich assesses corneal thickness;

5. OCT, which evaluates the retinal nerve fibre layer.

Apart from measuring IOP, some of these tests are necessary to monitor the evolution of the disease.

Treatment

Glaucoma therapy involves two types of approach, pharmacological and surgical.

Pharmacological treatment is the first choice and uses anti-glaucomatous drugs aimed at reducing the main risk factor for glaucoma, intraocular pressure.

These drugs are taken as chronic therapy, i.e. administered regularly and consistently throughout life. Full adherence to therapeutic prescriptions is essential for the treatment to produce its effects.

In the event that drug therapy alone fails to achieve a certain target pressure, parachirurgical therapy (laser treatments) or, alternatively, surgical treatment is possible. The most common surgery is called trabeculectomy and involves the creation of an artificial aqueous humour outflow channel.

Stress and glaucoma

It is not yet clear whether the stress is only the consequence or even one of the causes of glaucoma.

Glaucoma patients have high levels of anxiety and depression associated with poor psychosocial functioning and, moreover, the stress due to early vision loss and the somatic/biochemical changes associated with it are known "risk factors' for glaucoma progression.

On the other hand, others mechanisms underlying POAG, such as ischaemia, oxidative stress, glutamate excitotoxicity, loss of neurotrophin, glial inflammation/activation and vascular dysregulation, are in turn influenced by stress.

Mindfulness meditation and IOP

The practice of Meditation Mindfulness (MM, mindful meditation-"pay attention in a particular way: intentionally, in the present moment and in a non-judgmental manner'.*-), is among the oldest, most used and effective techniques for evoking a relaxation response (RR).

In this regard, various scientific studies have focused their attention on the different mindfulness meditation techniques demonstrating their positive effects on preventing and/or improving mental stress. The effect of MM was documented not only by subjective reports and quality of life (QOL), but also by tests measuring positive influence on various biomarkers: lowering the levels of cortisol (thus also lowering IOP and improving vascular function), improved perfusion and oxygenation of the brain, increased neurotrophin levels, improved parasympathetic activity and reduced oxidative stress, glutamate excitotoxicity and proinflammatory processes.

Biomarkers and stress

Considering the similarity in alterations between the biomarkers of glaucoma and those of the stress response, it can be assumed that the stress plays a major role among the factors contributing to the development and/or progression of glaucoma. Based on this consideration, a recent study, published in Journal of Glaucomaevaluated the effect of the relaxation response, achieved through the mindfulness-based stress reduction (MBSR) method, on glaucoma biomarkers and IOP.

The prospective study

To this end, the research team carried out a prospective randomised study of 90 patients with POAG, assigned to a control group or a mindfulness meditation group subjected to daily 60-minute sessions for 21 days. IOP, quality of life (QOL) and stress-related serum biomarkers (cortisol, ?-endorphins, IL6, TNF-?, BDNF- brain neurotrophic factor, etc.) were assessed and compared in these two groups.

The results

The comparison between the groups revealed a Significant lowering of IOP in the meditator group correlated with significantly lowered levels of stress biomarkers.

 The study concludes that a short course of MBSR in individuals with POAG can be recommended as additional therapy for POAG.

*Jon Kabat-Zinn, MBSR protocol scientist and theorist, 1994.

Dada T et al. Mindfulness Meditation Reduces Intraocular Pressure, Lowers Stress Biomarkers and Modulates Gene Expression in Glaucoma: A Randomized Controlled Trial. J Glaucoma. 2018 Dec.