New Research - Tear Production and the Parasympathetic Nervous System

New Research - Tear Production and the Parasympathetic Nervous System

Tear Production and the Parasympathetic Nervous System

By Dr. Diana Driscoll, Optometrist, FAAO

Are your eyes experiencing difficulties in maintaining moisture? While remedies like eye drops, ointments, and punctal plugs may offer temporary relief, they fail to tackle the underlying issue of reduced tear production. These solutions view the lack of tear production as solely an eye condition. However, when considering the body as a whole and gaining an understanding of the neurology of tear production, it becomes evident that eye problems may represent just one aspect of a broader systemic process. And patients' symptoms narrate this story.

The Neurology of Tear Production

Your lacrimal gland produces the majority of your tears (your basal tears). It is the lacrimal gland’s job to manufacture tears as required. Your parasympathetic nervous system orchestrates this operation and also plays roles in relaxation, food digestion, inflammation control, and self-soothing.

A chemical compound named acetylcholine serves as the bridge of communication between the parasympathetic nervous system and its organs or glands.

Upon receiving an alert for more tears, the lacrimal nerve discharges acetylcholine, prompting the lacrimal gland to produce the much-needed moisture. A decrease in acetylcholine or inefficient release from the nerve leads to decreased tear production and symptoms of dry eyes.

➢ The lacrimal nerve and its neurotransmitter, acetylcholine, control the neurology of tear production.

Support Your Parasympathetic Nervous System

With time and ongoing inflammation, the secretion of acetylcholine diminishes. Genetic factors, malabsorption, and dietary habits can also impair our ability to produce sufficient acetylcholine. Consequently, the parasympathetic nervous system becomes less adept, causing a decrease in tear production.

But what else is affected? TThe vagus nerve, which is the body's anti-inflammatory nerve, also utilizes acetylcholine and is influenced by low parasympathetic nervous system function. Additionally, the vagus nerve allows every aspect of digestion to function, and slows the heart rate when appropriate – it allows us to relax.

Acetylcholine is also the major neurotransmitter that the brain uses for short-term memory and executive function (the ability to organize many thoughts). When this neurotransmitter is affected, sharp cognition becomes more difficult.

➢ The neurotransmitter, acetylcholine, controls both the vagus and lacrimal nerves and allows good brain function.

A Glimpse into the Roles of the Parasympathetic Nervous System

The parasympathetic nervous system allows us to relax. This is why it is called the “rest and digest” system of the body. It regulates the body, moderates the heart rate, balances breathing, and aids in stress recovery.

The vagus nerve is a pivotal part of the parasympathetic nervous system, critical for normal digestion – from the initial swallowing of food to its journey through the digestive tract, and the functioning of the stomach, gallbladder, and pancreas. The vagus nerve also acts as the body's anti-inflammatory control. While short-term inflammation aids recovery from ailments or injuries, its chronic presence causes damage. Through the vagus nerve, the parasympathetic nervous system maintains an inflammation equilibrium.

Healthy eyes require both balanced inflammation and regular tear production, that is, they rely on both the vagus nerve and the lacrimal nerves.

The Connection Between Inflammation and Tear Production

Systemic and localized inflammation can diminish acetylcholine release, leading to reduced tear production. By supporting the parasympathetic nervous system, tear production is normalized in two ways:

  1. Direct enhancement of basal tear production (through the lacrimal nerves).
  2. Indirect support of healthy eye tissue by regulating the inflammation that diminishes tear generation and increases discomfort (through the vagus nerve).

When two these aspects are enhanced simultaneously, the result is remarkably effective!

For normal tear production with controlled inflammation, supporting the parasympathetic nervous system (both the vagus and lacrimal nerves) is crucial.

And because acetylcholine also drives cognition, short-term memory, proper digestion, and the ability to relax, patients often feel better overall!

Is dry eye disease more than just an eye disorder?

Dr. Diana Driscoll, an esteemed eye care professional, has been awarded four patents to date relating to acetylcholine, the vagus nerve, and an innovative dry eye remedy rooted in the parasympathetic nervous system. This cutting-edge discovery is changing lives every day.

REFERENCES:

Hodges, R. R., & Dartt, D. A. (2003). Regulatory pathways in lacrimal gland epithelium. International review of cytology, 231, 129-196. [Full Article]

Dartt, D. A. (2009). Neural regulation of lacrimal gland secretory processes: relevance in dry eye diseases. Progress in retinal and eye research, 28(3), 155-177. [Full Article]

Kossler, A. L., Wang, J., Feuer, W., & Tse, D. T. (2015). Neurostimulation of the lacrimal nerve for enhanced tear production. Ophthalmic plastic and reconstructive surgery, 31(2), 145. [Full Article]

Arenson, M. S., & Wilson, H. (1971). The parasympathetic secretory nerves of the lacrimal gland of the cat. The Journal of Physiology, 217(1), 201-212. [Full Article]

Zoukhri, D. (2006). Effect of inflammation on lacrimal gland function. Experimental eye research, 82(5), 885-898. [Full Article]

Pramanik, T., & Ghising, R. (2009). Salivation induced better lacrimal gland function in dry eyes. Nepal Med Coll J, 11(4), 258-260.[Full Article]

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