Do you wear glasses or contact lenses? (If so, click here). Use a hearing aid? Use a crutch or brace to walk? Based upon recent breakthroughs from the science of neuroplasticity, there may be a way to permanently eliminate the need for these aids — without the use of surgery or other artificial means.
Crutches or Stimulators? Correction by the use of compensatory devices or “crutches” is the usual approach to treating physical deficits such as motor weakness, difficulties with balance or coordination, or poor eyesight or hearing. While physical therapy is often prescribed to aid in recovery from stroke or acute conditions of motor weakness, it is typically continued only for a few weeks until improvement is seen to plateau. With more chronic conditions such as deteriorating eyesight, or impaired balance and weakness due to neurological conditions, such as Parkinson’s disease or multiple sclerosis, physical therapy is typically regarded to be of limited value.
The conventional medical model for treating impaired strength is to prescribe an external device or “crutch” to compensate for the deficit, which is generally considered to be permanent or untreatable as an organic condition. This is true for just about any physiological weakness, whether it involve muscle weakness, imbalance, loss of dexterity, or diminished sensory acuity in vision or hearing. In the case of a muscular weakness or unsteady gait that impairs the ability to walk, this might involve the use of canes, crutches, braces, or even a wheelchair. In the case of visual impairments such as near- or farsightedness, eyeglasses are prescribed as optical crutches; hearing aids are indicated for auditory impairment. Such “corrections” never actually “correct” the original impairment, but rather provide a compensation that readily restores the lost function through artificial means.
In point of fact, however, crutches such as canes, eyeglasses or hearing aids actually promote increasing weakness and dependence!
The approach of is Hormetism entirely different– it addresses the root cause of the deficit by applying a stimulus–a controlled stressor–to build strength and overcome the original organic weakness. It pursues a more “effective” long-term adaptation, rather than a more “efficient” short-term correction. It does not take the easy road to an illusive quick fix, but embarks upon an intensive, sustained, and systematic effort to build new strength or rebuilt that strength that has been lost.
Plasticity and Adaptation. Homeostasis is the capacity of an organism to regulate itself in response to an external stressor. It is based on dynamic biochemical mechanisms that keep the internal environment of the organism in a relatively constant state. Typical homeostatic adjustments take place in “real-time”, in a matter of minutes or hours. When we exercise, we sweat to cool down the core body temperature. Our blood is buffered against swings in acidity or alkalinity. The response of the immune system to an allergen or foreign infectious agent can be quite rapid. Plasticity can be thought of a “long term homeostasis”, in which the adaptations involve remodeling or rebalancing the organism in order to be able to better cope with sustained stresses. Plastic adaptations are not transitory adjustments like sweating or shivering, but persist for at least some time after the stressor is removed. Plastic remodeling involves tissue repair and growth, reshaping or rewiring, and is manifest in multiple physiological systems, including muscle and bone tissue, the circulatory system, and even the nervous system. Plasticity is also evident in longer term rebalancing of certain non-structural control systems such as the endocrine and immune systems.
Without plasticity, organisms would be “brittle”, with little prospect of significant recovery from injury. The capacity for wholesale plastic remodeling in response to injury has been recognized in certain primitive organisms, such as worms. In the case of humans and other mammals, it was believed until recently that the capacity for plastic change was very limited, particularly in older adults. But in the last 30 years, there has been a revolution in the understanding of plasticity, that has given rise to a host of new rehabilitation therapies. The most remarkable of these involve neuroplasticity, often involving significant changes to the brain and nervous system. The brain was once thought to be fully formed and unchangeable except for a malleable phase during childhood and, to a lesser degree, adolescence. The last several decades of research have overturned this belief.
An outstanding tour of the exciting advances in rehabilitation therapies based upon neuroplasticity can be found in Norman Doidge’s well-written book, The Brain That Changes Itself. Doidge engagingly summarizes the advances in neuroscience that have come from challenges to the assumption of neural hard-wiring by some of the lead neuroplasticians, including Michael Merzenich, Paul Bach-y-Rita, V.S. Ramachandran and Edward Taub. He presents these scientific and intellectual advances through a series of fascinating stories about people who regained lost function, including dramatic recoveries from balance disorders, phantom limb pain, obsessive-compulsive disorder, addictions, autism and learning disabilities. In recounting these hopeful rehabilitations, Doidge tracks not only the behavioral improvements that result from therapy, but in many cases also the accompanying physical changes to brain circuitry.
I would like to take some time here to elaborate on how Hormetism and the science of neuroplasticity provide a basis for dramatic reversal of two persistent conditions: the ability of stroke victims to walk again, and the ability of nearsighted and farsighted individuals to regain normal eyesight without glasses, contacts, or laser surgery.
Constraint-induced (CI) movement therapy. Some of the most impressive successes of applied neuroplasticity involve the recovery of stroke victims. Doidge relates the case of Dr. Michael Bernstein, an eye surgeon, who was paralyzed on his entire left side after a massive stroke. An MRI brain scan depicted extensive damage to his cerebral cortex. After a week in intensive care, he had a week of physical therapy, occupational therapy and speech therapy, followed by a few more weeks of outpatient care. Then he was sent home. But this typical course of treatment left Dr. Bernstein significantly impaired. He could not walk without a cane, and had minimal dexterity in his left hand. He had lost his ability to perform surgery, play tennis, drive, or even feed himself.
Bernstein was lucky however. He was one of the first beneficiaries of a new therapy developed by Dr. Edward Taub, a professor of psychology at the University of Alabama. Taub’s constraint-induced (CI) movement therapy enables patients to recover lost motor functions through weeks or months of painstaking exercises specifically designed to re-educate their brain circuitry. In conventional physical therapy, stroke patients respond to lost function by compensating, for example by relying upon the stronger hand or leg to take over some or most of the work performed by the damaged limb. But Taub reasoned that this compensation leads to “learned non-use” of the affected limb or part. So he developed methods of forcing use of the the underutilized body part, by preventing compensatory use of the stronger body part. For example, a stroke patient with a weakened hand would be required to wear a mitt on the strong hand to prevent it from taking over the job of the weakened part. (This very nicely exemplifies the constraint principle of Hormetism: restricting the strong part of a system in order to focus the full impact of the stimulative stress on the weaker part needing to be strengthened).
Taub’s patients engage in repetitive manual tasks, such as stacking blocks or putting coins into a piggy bank, for six hours a day over a period of weeks. The difficulty of the tasks is increased incrementally. It is an exhausting regimen; by comparison conventional rehabilitation sessions last no more than an hour and occur only a few days per week. The result: controlled studies of stroke patients who undergo CI therapy show that 80 percent of them can improve substantially. It certainly worked well for Dr. Bernstein. After his therapy, he was able to return to work and play tennis three times a week.
What is particularly remarkable with successful CI patients is the evidence that the brain remodels itself in the process of retraining, recruiting alternate neural pathways to take over the function of those damaged by the stroke. Paul Bach-y-Rita, another pioneer of neuroplasticity, recounts the case of his own father’s disabling stroke. His father Pedro, a famous poet and scholar, suffered a totally disabling stroke which left him paralyzed. Paul’s brother worked with him intensely for hours a day, first getting him to crawl, playing games with marbles and washing pots and pans. Eventually he could stand on his own and walk, and gradually he learned to use his hands and fingers, and started to speak again. “After a number of months he wanted to resume his writing. He would sit in front of the typewriter, his middle finger over the desired key, then drop his whole arm to strike it. When he mastered that, he would drop just the wrist, and finally the fingers, one at a time. Eventually he learned to type normally again.” Eventually, at age 68, Pedro was able to resume full-time teaching at City College in New York, and he started traveling and hiking again. At age 72, while hiking in the mountains of Colombia, he had a heart attack and died. Through his medical connections, Bach-y-Rita had an autopsy performed. “Ninety-seven percent of the nerves that run from the cerebral cortex to the spine were destroyed–catastrophic damaged that has caused his paralysis.” With the years of physical effort, Pedro’s brain had reorganized itself, recruiting alternate neural pathways to take over the function of the brain areas severely damaged by the original stroke.
Eyesight without glasses. Corrective lens–eyeglasses or contact lenses–are almost universally regarded as the best way to overcome visual problems based upon refractive errors (changes in the shape of the lens), such as myopia (nearsightedness) and hyperopia (farsightedness). Before resorting to external crutches, why not consider consider the possibility of changing the eye itself? (Of course, laser eye surgery offers to do just that. But eye surgery is not risk-free, and in this respect is analagous to gastric bypass surgery or liposuction as a means of losing weight. The body is a dynamic system and it can rebound or otherwise defeat surgical attempts at correction: there is a significant incidence of weight regain after gastric bypass and visual problems resulting from Lasik eye surgery ).
What are the prospects for improving visual acuity without corrective lenses? A number of “systems” have promised “eyesight without glasses,” but some of them are suspect. The Bates method is perhaps the most famous of these approaches. William Bates (1860-1931) contended that visual problems were a result of eye strain. He believed that the eye changed shaped when attempting to focus, thereby inducing muscular tension. Bates developed a number of techniques, such as “palming” and movement exercises, to help relax the eye, and “visualization” to enhance memory of colors and shapes. But the jury is out on whether the Bates method is effective or scientifically sound. Wikipedia pans the Bates method:
“Despite continued anecdotal reports of successful results, Bates’ techniques have not been shown to objectively improve eyesight, and his main physiological proposition – that the eyeball changes shape to maintain focus – has consistently been contradicted by observation. In 1952, optometry professor Elwin Marg wrote of Bates, ‘Most of his claims and almost all of his theories have been considered false by practically all visual scientists.’ Marg concluded that the Bates method owed its popularity largely to ‘flashes of clear vision’ experienced by many who followed it. Such occurrences have since been determined to most likely be a contact lens-like effect of moisture on the eye.”
Whether or not the Wikipedia review is fair, it is clear that Bates approach does not use the principles of Hormetism. Bates advocates relaxation, not the systematic application of stress. And there is nothing in his method that suggests a basis for permanent remodeling or adaptation of the eye or any of its visual structures.
Anti-corrective lenses. But there is an approach to eyesight without glasses that I believe is scientifically sound: anti-corrective lens therapy or, as it is called in the case of overcoming myopia, “plus lens therapy”. Strange as it may seem, this involves wearing the opposite type of glasses normally prescribed, making it initially less comfortable to focus. Specifically, so-called “plus” lenses are employed to overcome nearsightedness (myopia) and “minus” lenses to overcome farsightedness (hyperopia). I can attest the effectiveness of plus lens therapy out of personal experience, because this approach helped to free me of the eyeglasses I used to wear for myopia since I was 15 years old. I used to need glasses to drive or to view PowerPoint presentations. I was able to give up my glasses about five years ago after only a few months of using these lenses, in combination with certain eye exercises, and my eyesight continues to improve every year.
It is not exactly clear who originated the use of anti-corrective lenses. I first came across them through a commercial product called “Vision Freedom”, offered in the 1980s and 1990s by Brian Severson, an airplane pilot from Victor Montana. More recent related websites include a method for overcoming myopia using Plus Lens Therapy, and a theoretical discussion by Otis Brown. The aggressive use of plus lenses to arrest and reverse myopia is advocated by a small but well informed group of optometrists and academic researchers such as Alan Sherman of SUNY.
The exact scientific explanation for why anti-corrective lenses work is not fully clear, so I will first describe the method and later provide a speculation as to why I think it works. The use of anti-corrective lenses is almost the polar opposite of the “relaxing” Bates technique. Essentially, anti-corrective lenses apply visual “stresses” in a systematic way, in order to stimulate improvements the ability of the eye to see in focus.
Comparing the eye to a digital camera, Severson observed that the eye will attempt to “autofocus” on any image that is slightly out of focus, but will not even attempt to focus on objects that are significantly out of focus. Furthermore, he found that the focal range can be extended by a simple technique.
Step 1. Find your starting range of focus:
“Take off your prescription lenses and put this page right on the end of your nose. Now push the print slowly away until it becomes clear and in focus, and stop. Now close each eye and see which one is sending the clear image to your brain. You have just entered the range of focus of your better close vision eye. It dominates for all close work…Now open both eyes, and slowly push the print away until the very first indication that the print is no longer perfectly clear and in focus, and stop…You have just found the limit of your range of focus for that eye”.
Step 2: Push your eyes to increase their range of focus.
For myopes, this is done by repeatedly pushing a printed page just slightly outside the range of focus, and allowing it to sharpen up or “clear”. (For hyperopes, the page is pulled closer until it blurs, then allowed to clear). The eye gradually adapts to increase its range. This can be done with different objects at different ranges. So it can be done with fine print close up, but also with larger objects in the distance. It is especially useful to focus on sharp lines, such as overhead electrical transmission lines, and houses or trees with sharp edges.
For myopes, the process can be accelerated using plus lenses, the “reading glasses”, available in most pharmacies, that hyperopes typically use for close reading; conversely, hyperopes can accelerate the process by using minus lenses that myopes use for vision distance. Myopes can improve their vision by starting with the strongest plus lenses they can wear that will maintain their reading or computer just within their focal range. (Hyperopes do the converse). If the myopia or hyperopia is extreme to the point where anti-corrective lenses do not allow a reasonable focal range, then it may be preferable to use reduced prescription lenses, i.e., lenses in which the diopter have been somewhat reduced. With time and success, these can be progressively weakened, and a move can be made to anti-corrective lenses.
For the focusing exercises, one should periodically push the book or computer slightly out of focus and wait for the image to clear again. This will cause a slight feeling of discomfort, but the eye will focus as long as the distance is just slightly out of the comfort zone. This procedure can be followed for hours or more during everyday activities such as reading and computer work, watching TV, walking or driving. The anti-corrective or reduced prescription lens diopter rating (the plus or minus number) should be selected so as to make the eyes slightly uncomfortable, while still allowing clear focusing. Different lenses may be needed for different activities, and the strength may need to be increased over time.
If the right and left eyes are uneven in strength, it may be necessary to match different corrections to each eye (buy two pairs and pop out and replace one side), or to cover the stronger eye with a patch or diffuser. Much as with CI movement therapy, this follows the principle of “constraint” to ensure that the primary stress is focused on the weaker eye, stimulating it to do most of the focusing, until it catches up with the stronger eye. We don’t want the weak eye to coast along with a “free ride” or only the stronger eye will benefit.
The use of anti-corrective lenses is a classic case of the five general principles of Hormetism, as outlined on the Overview page of this website: (1) the viewing distance is adjusted to simulate real-world conditions as closely as possible; (2) a constraint (an eye cover or plus lens) is imposed on the stronger eye to focus the stress on the weaker eye; (3) the intensity is adjusted to be somewhat uncomfortable, but still short of “failure”; (4) adequate recovery is allowed during rest periods between sessions; and (5) gradualism is observed by progressively increasing the focal range over time in order to force adaptive remodeling of the eye.
Mechanism. Severson and others believe that Plus Lens Therapy works by strengthening the eye muscles:
“Your eye muscles instantly change the shape of your eyes thousands of times each day to focus, as clearly as the muscle strength will allow, on different objects…Stronger eye muscles will greatly increase your “range” of focusing ability.”
However, this reasoning does not appear to be physiologically sound. Myopia is caused by a lengthening of the eyeball, so distant images are not properly focused on the retina, but rather on the vitreous layer in front of it. Conversely, in hyperopia, the eye is too short, and close-up images tend to focus behind the retina. In both cases, there is not much that can be done by the eye muscles, whether it be tensing them or relaxing them, to actually change the shape of the eye.
One clue to the mechanism is that adaptations are not instantaneous, but occur gradually over weeks or longer. Another clue is that one frequently sees a double-image–a combination of the old blurry image and a new sharper image–during the period of adaptation. The sharper image is at first faint, but becomes stronger over time. Eventually, it displaces the blurry image. This was my experience. After days of working on pushing my range, I would look, for example, at electrical power lines and see a double sharp-blurry image. The sharpness and darkness of the power lines increased over several weeks. Now I see them sharply.
Retinal remodeling. I do not think the double imaging I saw is consistent with the short term strengthening of muscles, because the images were simultaneous. A better explanation may derive from the theory of neuroplasticity: the retina actually undergoes persistent changes in shape as retinal tissues grow and develop in response to stimulation of photoreceptor cells. There is strong evidence that myopia develops in the first place as a response to environmental stimuli, such as reading and close work, that stimulate ocular elongation. A very plausible theory of how myopia develops has been proposed by Hung and Ciuffreda (of Rutgers and SUNY. Their paper on the incremental retinal-defocus theory of myopia development (IRDT) summarizes research regarding how visual stimulation regulates ocular growth. Specifically, when close work (or use of minus lenses) causes the image of close objects to be out of focus on the retina, the is a decreased in the rate of release of retinal neuromodulators. This in turn reduces the rate of retinal proteoglycan synthesis with a resultant weakening in the structural integrity of the scleral (the thick white sphere of dense connective tissue that encloses the eye and maintains its shape). This causes the sclera to begin growing faster, which leads to elongation of the eye, and myopia. Hung and Ciuffreda explain how the eye grows in the appropriate direction under a wide range of experimental conditions, and specifically how repeated cycles of “near work” lead to decreaseed “retinal-image defocus” and increased axial growth that leads to permanent myopia.
The process of retinal remodeling, while it may take weeks, can get started almost immediately in response to stimulation. In a study of chicks fitted with either plus or minus lenses, Zhu X et al. at City University of New York detected rapid changes in choroidal thickness of the retina in response to brief periods of defocus. In their article (“In matter of minutes, the eye can know which way to grow”), the CUNY researchers reported that wearing positive lenses for 10 minutes caused an increase in choroidal thickness and a concomitant decrease in vitreous chamber depth, whereas wearing negative lenses for 1 hour caused significant changes in the opposite direction. The longer the lens wear, the more extensive and persistent were the changes in the choroidal and vitreous layers.
The IRDT theory of myopia, buttressed by experimental evidence that exposure to visual stresses (slightly out of focus images) can drive almost instantaneous remodelling of the eye, provide a scientific basis for how anti-corrective lens therapy might work. I admit it is not a fully substantiated theory, but it is a promising one that deserves further investigation. It explains how repeated efforts to focus on images just slightly outside of the focal range can drive plastic remodelling of the shape of the eye. But there is one more mystery: how to explain the transient “double vision” of focused and unfocused versions of an object that arise in the process of adaptation?
Again, for this explanation we turn to the science of neuroplasticity. The retina is not single plane, but rather a tissue of some depth, consisting of multiple layers of sensitive photoreceptors cells (rods and cones) and intermediate conductive fibers. In fact, the photoreceptors perversely evolved for various reasons to be at the back of the retina, with the “wiring” actually in front of them. But the photoceptors are distributed over multiple layers. Presumably, the most active receptors are those which are usually stimulated by well-focused images. After all, those are the ones whose signals the brain can interpret, and they receive the most reinforcement. For a myope, these will tend to be the receptors in the focal plane of close objects, toward the back of the retina. Because the myope is doing a lot of close work and spends less time looking in the distance, the closer retinal cells get less stimulation and suffer from underuse. However, if these closer layers can gradually get more stimulation, or example by using plus lenses, they will adapt to increase in sensitivity and the strength of their signalling to the visual cortex will gain prominence. At some point, weak signals from this forward layer (on which there is a sharper image) will be sent simultaneously with the stronger signals form the backward layer (on which the images are blurred). During the period of adaptation, activation of multiple layers will be perceived as a double-image. Eventually, and with time, the sharper forward layer will dominate over the backward blurry layer. And as the overall shape of the eye is remodeled as the eye grows in response to focusing on distant objects, the focal “strain” on the eye will be reduced, and a new equilibrium shape will take hold. This hypothesis is unproven, but is consistent with known mechanisms, and could be tested experimentally.
The science of neuroplasticity can not only provide guidance on how to restore normal eyesight, but it suggests the possibility of developing extraordinary visual acuity. Doidge describes Anna Giselen’s study of the Sea Gypsies of Thailand, a nomadic tribe of people who “learn to swim before they learn to walk” and dive for pearls to depths of over 75 feet, unaided by scuba equipment. Their visual acuity underwater is uncanny, as they are able to read placards placed underwater at distances more than twice those of Europeans. Apparently they are able to exert voluntary control over the shape of their lenses and the size of their pupils, features normally assumed be under the control of involuntary reflexes. After observing this, Giselen found that Swedish kids could learn the same tricks and voluntarily constrict their pupils to see under water, “one more instance of the brain and nervous system showing unexpected training effects that alter what was thought to be a hardwired, unchangeable circuit.” (Doidge, p. 289).
July 5, 2010 update: A new post on this topic has been added here which contains some additional information regarding a controversy over whether or not plus lenses improve eyesight in myopic children. A re-analysis of the original data showed the importance of using plus lenses only while doing near work — they should not be worn all the time! If these guidelines are followed, good results can be expected.
If this topic interests you, please comment below, or check out the Rehabilitation Discussion Forum., where a number of people have reported their success with using the Hormetism method for improving eyesight, manual dexterity, and other areas of overcoming the need for corrective devices.