By Deborah Zelinsky, O.D.
In the words of journalist and author Susannah Cahalan, “Hormones get no respect,” but anyone who has sustained a head injury or concussion is likely to agree with biochemist Barry Sears, Ph.D., that those disrespected chemicals “control your life.”
In fact, traumatic brain injury (TBI) can throw hormones out of balance, causing a cascade of symptoms ranging from cognition difficulties, poor memory, and confusion to psychiatric and psychosocial disorders – mood swings, anxiety, stress, depression, changes in personality – and actual physical conditions like diabetes, obesity, nausea, dehydration, sleep problems, hyponatremia (low sodium), and adrenal insufficiency.
Statistics indicate about 1.5 million Americans are diagnosed with a TBI annually.
Scientists from the Uniformed Services University of the Health Sciences investigated the effects of mild blast injury on the neuroendocrine stress response. Their 2017 article suggested TBI disrupts the hypothalamus-pituitary-adrenal (HPA) axis, thereby altering stress hormones and increasing risk for anxiety and other neuropsychiatric disorders. The hypothalamus, a structure located near the middle of the brain, regulates basic functions such as the body’s stress response, cardiorespiratory function, circadian rhythm, body temperature, appetite, and thirst, “telling” the pituitary gland when to release hormones. The hypothalamus also plays a role in the control of behavior and emotions.
Authors of a study published in a 2019 issue of the International Journal of Molecular Sciences report more than 25 percent of brain-injured patients develop some form of post-traumatic hypopituitarism – a deficiency in the pituitary gland’s production of one or more hormones, with the most affected being growth hormone. If the hypothalamus is not functioning efficiently, the pituitary will not necessarily receive appropriate signals and will not release the hormones the body needs. For instance, lack of sufficient growth hormone can lead to anxiousness, anxiety, worry, and low self-esteem, as well as fatigue, headaches, and changes in adult body fat and muscle. The presence of chronic hypopituitarism “impairs [a patient’s] recovery and rehabilitation,” the researchers say.
Hormones also shift posture, according to researchers from Uppsala University in Sweden. Writing for an August 2021 edition of eLife, the authors indicate a TBI prompts the body to release hormones that result in movement deficits or disorders on both sides of the body.
So, you might ask why an optometrist is discussing endocrinology issues?
Because the retina is composed of brain tissue, serving as an interface between internal functions and the external world. More than a million signals leave the retina after the transformation of external light into electrical signals. Those signals travel along communication pathways further in the brain, and one of those retinal pathways is routed directly to the hypothalamus (the retino-hypothalamic tract). Selective stimulation of the retina apparently influences activity in the hypothalamus.
Using eyeglasses to selectively stimulate retinal signals can change the body’s movement, posture, adrenaline production, sleep, and other physiological processes. When light is dispersed on certain portions of the retina, posture reflexes are triggered to shift posture or move in a certain way beneath the level of consciousness.
Any discussion of hormonal imbalances and their impact on posture must include eye position, which optometrists measure during examinations. Unlike persons who are calm and whose eyes readily move around, patients with an overabundance of stress hormones are put into constant fight-flight-or-freeze mode, with increased tension in muscles that control eye movement, thereby limiting overall eye movement. When eye position is too limited, peripheral eyesight fails to function effectively, and such failure can disrupt visual processing, skewing how a person responds to motion, sounds, and light.
Indeed, the majority of signals from the environment come via the peripheral receptors in the retina. Peripheral eyesight governs a person’s judgment of the speed, size, location, and shape of objects and provides the information needed to strategize and act. In combination with central eyesight, peripheral sight enables the shifting of gaze quickly and accurately. When eye movement is restricted, incoming information is limited, and responses are often neither relaxed nor effortless.
Should the neurological, chemical, and muscular changes set in motion by a TBI become chronic, the hypersensitized patient with impaired peripheral eyesight may develop post-traumatic stress disorder – or PTSD. PTSD decreases awareness of – and attention to – one’s surroundings, often resulting in spatial dysfunction and disorientation. Those changes in perception can, in turn, cause mood dysregulation and difficulty in thinking logically.
All of which might cause one to ask if victims of TBI can ever find relief and a return to near normalcy even after years of struggling with symptoms, including the hormonal dysfunction of a damaged or disrupted brain.
Fortunately, scientific advances have given today’s optometrists the tools necessary to prescribe therapeutic eyeglasses designed for peripheral retinal processing. These are not intended to bring the clarity of a person’s central eyesight to 20/20. Rather, they selectively stimulate retinal communication pathways in the brain by changing the amount, intensity and angle of light that disperses across portions of the retina. The ultimate goal is to rebuild the patient’s visual processing skills by either restoring informational roadways in the brain damaged by TBI or constructing new ones that circumvent injured or disrupted areas.
Frequently, people are told no eye or brain damage has occurred as a result of their head trauma. Yet, their symptoms linger, because the head injury has pushed various systems of the body out of synchronization. Each system functions well on its own, but they are not working together in a unified fashion. Restoration of some visual processing skills can be achieved through normalization of peripheral eyesight and re-integration of sensory systems, thus helping bring other basic physiological and biochemical functions – like hormone production – back into balance.
Individualized glasses are certainly not magic, but they are often a wonderful adjunct to collaborative TBI protocols. The bottom line: if you believe out-of-whack hormones to be the cause of your persistent moodiness, just know you might be able to use a pair of therapeutic eyeglasses to change them.
Deborah Zelinsky, O.D., is a Chicago optometrist who founded the Mind-Eye Connection, now known as the Mind-Eye Institute. She is a clinician and brain researcher with a mission of building better brains by changing the concept of eye examinations into brain evaluations. For the past three decades, her research has been dedicated to interactions between the eyes and ears, bringing 21st-century research into optometry, thus bridging the gap between neuroscience and eye care. www.mindeye.com/tbiquiz