The Amazing Connection between the Heart, Eyes, and the Brain
Genoveva Uzunova, M.D., Ph.D.
Physician -Scientist Studying and Developing Pharmacological and Non-Pharmacological Treatments for Psychiatric, Neurologic, Immunologic, Rare Disorders, Artist, Ballerina, Art Therapist, Positive Psychiatry Enthusiast
by Genoveva Uzunova, M.D., Ph.D.
For American Heart Month, I wrote a brief article that highlights the amazing intimate connection between the heart, the eyes, and the brain.
I wrote an article and because the topic is very dear to my heart, I also made a brief accompanying video:
This connection is well known in medicine and, being a medical doctor and a scientist, I think that it is essential to highlight it during heart month, it may be important not only in ophthalmology, cardiology, and endocrinology but also in neuroscience, psychiatry, patient management and drug development. The eyes also connect to the brain, and therefore the eyes are an outward and visible manifestation of the communication between the heart and the brain. Exploring better the connection between the heart, eyes, and brain will provide a better understanding of the role of the heart in eye and brain disorders and provide new reliable diagnostic, prognostic, and therapeutic biomarkers.
I will express views based on biomedical science and observation from life. In Medical School I wanted to be an ophthalmologist and took extracurricular activities in ophthalmology. There I learned about a notion that has existed since ancient times that “the eyes are a window to the soul”.
“Who would believe that so small a space could contain the image of all the Universe?”
Leonardo da Vinci (about the eye)
1452-1519
What does the soul consist of? The heart is part of the human soul, although the soul is larger. It includes the brain, specifically the pineal gland, the kidneys, the entire human organism, and even something more, and this is a biomedical, philosophical, and religious matter. Much literature has been published on this topic.
Below I provide some interesting reading on the seat of the soul, by no means exhaustive, only as a starting point.
Following is an article on the medical students’ concept of the soul, its’ seat in the brain or the heart, and how this affects the attitude of medical students to anatomy dissections and pathology:
Here is some reading on philosophical views of the human soul:
An article on views of the human soul from different religions that may have significance for medicine:
It is evident that this is a vast unresolved question.
My modest opinion about the seat of the soul is that it may have changed through the ages, and may be individual to an extent. In ancient times education was not such a great part of our lives and society as it is today. Therefore, perhaps people listened more to their hearts. Now, the general notion is that the mind is powerful and can let us create whatever we can imagine. Perhaps, it is important to take into consideration the desires of the heart, which are motivated by love, compassion, joy, and hope. Circuits reorganize and new connections form, exercise causes muscles to strengthen and therefore it is possible perhaps to change the seat of the soul depending on the motivation for one's actions.
Let’s start exploring the anatomical and physiological connections between the eye and the heart.
By looking at the fundus of the eye, the so-called ophthalmoscopy or fundoscopy, the physician can diagnose pathological heart conditions as the vasculature of the eye and heart share similarities. Therefore, it has been noted that the “eyes are a window to the heart”. This may be viewed in a biomedical and psychological aspect. Of course, ophthalmoscopy allows the physician to diagnose many eye, brain, endocrinology, and other medical conditions.
Here is a brief overview of the eye fundus anatomy:
Here is an article summarizing the vascular connection between the eye and the heart:
As the article suggests, “There is interplay between cardiovascular functions and risk factors and the occurrence and progression of many eye diseases. In particular, arteriovenous nipping, narrowing of retinal arteries, and the dilatation of retinal veins are important signs of increased cardiovascular risk.”
By observation and examining of the eyes, and performing ophthalmoscopy, it is possible to detect eye vascular abnormalities in diabetes Type I and II and diabetic retinopathy:
The eye and the heart connect besides through the blood vasculature, through the nervous system. https://www.ncbi.nlm.nih.gov/books/NBK53329/
?A manifestation of the eye-brain-heart connection is the oculocardiac reflex:
The oculocardiac reflex has an afferent limb beginning with the trigeminal nerve (cranial nerve V) and an efferent limb the vagus nerve (cranial nerve X). The afferent pathway is initiated by the activation of the stretch receptors in the ocular and periorbital tissues. The ciliary nerves relay the sensory message to the ciliary ganglion, from where the impulses are relayed through the ophthalmic division of the trigeminal nerve to the Gasserian ganglion, followed by the trigeminal nucleus, which is the CNS termination point of the afferent limb of the oculocardiac reflex. In the CNS, the information is processed, and the trigeminal nucleus communicates with the visceral motor nucleus of the vagus nerve. This stimulates the efferent limb,?causing impulses to transit through the brainstem, and be transmitted to the myocardium to synapse as the sinoatrial node and activate the vagal motor response. The resultant effects include negative chronotropy, leading to bradycardia.
From this reflex, it is evident that there is an intimate heart-eye-brain connection. Factors that activate the afferent limb such as mechanical or emotional stimuli may activate this reflex.
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We know that using eye-tracking methods, we can detect changes in autism.
By looking at the expression of the eyes, it is possible to conclude about the physical, emotional, and mental state of a person. Perhaps the connection between the eyes and the heart (center of emotions) provides clues as to the inability of children with autism to detect the emotional state of others. Of course, brain regions involved in emotional regulation such as the amygdala are important but likely they are not acting on their own. Moreover, scientific studies show cardiac involvement in autism. https://pubmed.ncbi.nlm.nih.gov/36964783/
If we can perceive the emotional states of a person from the expressions of their eyes, this means we can detect the functioning of the heart, as the heart is involved in regulating emotions.
This is a science paper, although from mice, on how the heart can directly influence emotions.
Another example of the amazing connection between the eyes and the heart is observed in Grave’s disease and hyperthyroidism, in which there are eye symptoms such as pressure in the eyes, bulging eyes (exophthalmos), double and blurry vision, and cardiac symptoms such as tachycardia, irregular heartbeats (arrhythmia), and psychiatric symptoms such as anxiety, trouble sleeping, shakiness.
It is not my goal to list in this article all conditions of the heart that may be detected by examination of the eyes.
I would rather like to bring attention to the important and sometimes underappreciated connection between the eyes, the heart, and the brain.
We know that looking into someone’s eyes connects you to their soul, heart, and mind and you are prone to bond and fall in love. What are the biological anatomical and physiological correlates?
Perhaps the so-called “inner eye” is the heart, in addition to the pineal gland, which has been referred to as the “third eye”?
“Strive to see with the inner eye, the heart. It sees the reality not subject to emotional or personal error; it sees the essence. Intuition then is the most important quality to develop.”
―?Muata Ashby,?Egyptian Book of the Dead: The Book of Coming Forth By Day
Therefore, we can look in new light at the quote:
“It is only with the heart that one sees rightly for what is essential is invisible to the eye”.
Antoine de Saint-Exupery “The Little Prince”
The eye also has a connection to the brain through the optic nerve.
Emotional states such as peacefulness, love, happiness, hope, excitement, anger, fear, and surprise, which may be detected in a person’s eye are largely attributed to emotional centers in the brain. However, they may also be due to emotions directly experienced in the heart, and relayed to the brain, knowing the close connection between the eyes and the heart via vasculature and nervous system.
Perhaps the great artists see with their hearts and convey with their art their hearts’ vision that touches the hearts of people.
“..For it is the heart by whose virtue and pulse the blood is moved, perfected, made apt to nourish and is preserved from corruption and coagulation…It is indeed the fountain of all life, the source of all action.”
William Harvey
1578-1657
Another example of the eye-heart-brain connection and the importance of the heart for brain functioning comes from learning. Why do we (or at least I and some other people) learn a lot faster when we love the subject we are reading, writing, and learning about if we love the teacher and the way they present and teach the material? Why can’t these learning and memory be properties of the heart, just as much as of the brain? From here we can see the role of the heart in dementia.
This article is a summary of just a tiny part of the eye-heart and brain connection, which involves also neurotransmitters, neuromodulators, hormones, and the immune system. But it is essential to have it in mind when we develop new treatments for brain disorders, if the main causative factors are located within the heart, the medications may not be entirely effective and the therapeutic effects may not be long-lasting.
In conclusion, I would like to share a beautiful quote from a textbook on physical examination and diagnosis that I bought from a course I attended on clinical skills at The Icahn School of Medicine at Mount Sinai in New York City in 1999. It shows that it is important to “have a heart”, care for others, and have an interest in humanity to be a good physician, treat human illnesses, and develop new drugs. My article may not be perfect, but it is my ongoing never-ending questioning of how can we develop better treatments and alleviate human suffering.
“One of the essential qualities of the clinician is interest in humanity,
For the secret in the care of the patient is in caring for the patient”
FRANCIS WELD PEABODY
Perhaps, my colleagues will recall that I take time when examining a patient, taking the patient’s history, and at every visit to ask pertinent questions and to learn as much as possible about the factors that may contribute to their mental illness.
Your comments are highly welcomed!
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