Impact of Retinal Stimulation on Neuromodulation
by Deborah G Zelinsky, OD
Since retinal signals are processed by many regions of the brain—not just the visual cortex—the implication is that retinal stimulation can affect other physical, physiological, and psychological processes, such as motor control, biochemical activity, and cognitive abilities.
Historically, experts have considered the retina as a sensory system, feeding information into the brain’s visual cortex. However, research has now demonstrated that the retina is a bidirectional neural interface that is an actual part of the central nervous system (CNS) (Vaney 1999). Since retinal signals are processed by many regions of the brain—not just the visual cortex—the implication is that retinal stimulation can affect other physical, physiological, and psychological processes, such as motor control, biochemical activity, and cognitive abilities.
During the past decades, researchers have discovered a retinal cell type that responds to luminance (external light) levels. These photosensitive cells combine the external luminance information with signals obtained through eyesight and not only send this combined feedforward information to the brain but concurrently receive feedback signals from the body (Chen et al 2011, 2013, Schmidt et al 2011).
The mixture of feedforward and feedback signaling enables the retina to be used as a two- way, noninvasive portal for influencing and monitoring body functions and thought processes, largely beneath the level of consciousness. Because of the retina’s critical role in brain function, therapeutic eyeglasses—an important tool in neuro-optometric rehabilitation—may be used to modify processing in a range of physical and mental health disorders. These individualized lenses can change the dynamic relationship between the mind’s visual inputs and the body’s internal responses by altering spatial and temporal distribution of light on the retina. The novel use of light to affect the nervous system has already been successfully applied to a range of dis- orders, including jaundice (Tayman et al 2010), jet lag (Parry 2002), seasonal affective disorder (Lavoie et al 2009), brain injury (Naeser et al 2011, Sinclair et al 2014), and spinal cord injury (Alilain et al 2008, Alilain and Silver 2009). Neuro-optometry also uses light to modulate brain and body functions.
This chapter presents both the theoretical framework and empirical evidence to support the use of customized eyeglasses for altering brain function. The underlying premise is that there exists a hierarchy of separate, yet interdependent, cortical and subcortical pathways, which are linked to various visual systems. The main emphasis of this discussion is on the retina’s complex connections with systems other than the conscious eyesight. Those subconscious and unconscious systems can be altered by changes in the amount, frequency, intensity, or direction of incoming light to the eye.
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~ Norman Doidge, M.D. & Clark Elliott, Ph.D., and Patricia S. Lemer praise her accomplishments
“Zelinsky fit Elliott with a series of eyeglasses designed to improve the perceptual damage that made his life so difficult… Getting fitted for Zelinsky's eyeglasses is like no eye appointment you've ever had… Now, Elliott says, he is almost entirely symptom-free, able to problem-solve, multi-task and find his way easily — all abilities he lost in the auto accident in 1999. When he put on his Phase VI glasses he felt something that he hadn't felt for years: “I felt normal.”
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“One brilliant Chicago-area optometrist I know, Deborah Zelinsky OD, FNORA, FCOVD, has developed a unique, patented, easy-to-administer evaluation called the Z-Bell Test. This test measures the efficiency of integration between visual processing and listening….A 2014 study at Vendarbilt University found that children with autism do not synchronize their seeing and hearing…I have watched Dr. Zelinsky administer this test to disbelieving coleagues, who were astounded by its accuracy and results…Over the past two decades, the Z-Bell Test has become internationally recognized by the scientific community.”
– Patricia S. Lemer, Licensed Profesional Counselor (LPC)
“I visited Dr. Zelinsky, and she showed me how she can use optical lenses to alter sensory filtering, by directing light to different retinal cells and brain circuits. This can influence activity in the brain and the hypothalamus to better regulate body chemistry, sensory integration, and even some auditory processing. [Dr. Zelinsky] works frequently with patients working with learning and cognitive disorders as well as TBIs.”
– Norman Doidge, M.D.
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