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I get a fair number of emails from folks who wonder about their eye health in a Primal context. A while back I looked at the potential role of sunlight in preventing myopia, but that was just the tip of the iceberg. The post got people thinking. What are the other factors and theories behind the myopia surge? And as for readers' individual circumstances, were they really destined to wear glasses? Is there anything they can do once they're already living with a vision prescription? Glasses or no, what can we do to support the well-being of our eyes throughout our lifetimes?
As is customary, let's revisit the Primal backdrop. In hunter gatherer days, of course, our ancestors depended upon good vision for survival. If you can't see well enough to decipher the outline of a hungry predator watching you, you're probably not going to make it very long. Likewise, if your vision doesn't allow you to participate effectively in either hunting or foraging expeditions, your chances are likewise diminished. Although you might have survived young childhood under the watchful eye of tribal caretakers, you probably wouldn't have made it long enough to procreate.
That doesn't mean there was absolutely zero variation. Research a couple years back showed that men tend to have better distance vision and women have better near vision. The researchers related the discrepancy to our respective roles in hunting and gathering. Men, the primary hunters, required the ability to see clearly across a vast field to bag the dinner. Women as primary foragers benefited from strong visual acuity up close as they located and then discerned edible from inedible plants.
Although we can't submit Grok to the standard eye exam, study of existing traditional societies reveals an unsurprising picture. As Dr. Loren Cordain notes (PDF), research involving modern hunter gatherers reveals near perfect eyesight in studied groups. Among vision impairments that do exist, myopia (nearsightedness) is the most common. Statistics for myopia in these traditional groups settle out at zero to three percent and consist of almost exclusively mild cases.
Fast forward to today's modern societies, and we find a much different picture. The numbers for myopia, for example, have skyrocketed in the last thirty years across the developed world, and children oddly appear to be the hardest hit. Singapore is often cited as the worst off. As many as 80% of 18-year-old military conscripts exhibit myopia as do 20% of children under seven and 70% of those graduating college (PDF). In Sweden, 50% of 12-year-olds have myopia (PDF).
In the U.S., the prevalence of myopia is 42% in people 12 to 54-years-old and 34% in 12 to 17-years-old. As for other visual impairments, more than 17% of people over the age of forty are diagnosed with cataracts. For age-related macular degeneration, it's more than 6%. For diabetic retinopathy, there's another 3.4%. For glaucoma, it's about 2%. Add it all up, and that's a whole lot of us voted off Grok's island.
As much as genetics matter, we're clearly looking at a whole other animal here. Enter environment. Although you might not hear it often enough, diet for one thing plays a significant role in eye conditions. Cordain among others has emphasized the role of carbs, particularly fast-acting carbs, in the development of myopia, for example. Insulin spikes don't do your eyes good any more than they do the rest of your body. Insulin influences the release of growth related hormones, which is telling when you remember that myopia stems from unchecked growth that throws off the precise balance of eye structure and development. When it comes to full-blown diabetes, retinal damage caused by diabetes is now the leading cause cited in new blindness cases in American adults. Diabetics are also twice as likely to develop glaucoma, another major cause of blindness in the U.S. Myopia and hypothyroidism, both on the rise, are also known risk factors for glaucoma. Among risk factors for "age-related" macular degeneration are obesity, high blood pressure, low antioxidant diet, and inactivity. This just keeps getting better.
Even if we avoid the major pitfalls and walk away from the optometrist's office empty handed, what about the everyday eye strain and headaches that many of us experience? Although frequent reading has long been tied to eye problems, our growing array of electronic devices is upping the ante on dysfunction. Studies have found some 64-90% of computer users suffer from a host of pains, including "eye strain, headaches, ocular discomfort, dry eye, diplopia, and blurred vision." (From a personal standpoint, the back and tops of my eyes feel like they're being crushed from inside my skull from time to time. So I got that goin' for me, which is nice.) Smart phones seem to be the worst culprits (although electronic readers might not be far behind).
Researchers have identified a couple of reasons behind smart phone eye strain. Because of the tiny screens and smaller fonts used on smart phones, the researchers found people generally hold their smart phones closer to their eyes than they would printed text. Study results showed people held their phones an average of only 12.6 inches away from their eyes while reading website text and 14 inches when looking at a text message. (The average distance for printed text is nearly 16 inches.) The researchers noted that font size on smart phones were an average of 20% smaller than printed text. In some cases, viewed fonts were 70% smaller. (Time for that monocle.) What does this mean for us techno-suckers? Because of the size and distance, our eyes have a harder time focusing on the print. The strain involves two processes called accommodation, the adjustment from near to far distance, and vergence, eye movement toward and away from one another.
Modern lifestyles are especially setting up our children for strain as well as poor eye health. The diminished physical activity level and high screen time of many children's days have been connected with narrower blood vessels in the eyes, a characteristic of various common eye problems. Research at the University of Sydney associated every additional hour of screen (or otherwise sedentary) time each day with vessel narrowing of 1.53 microns, a measurement reflective of a 10 millimeter (mm HG) rise in systolic blood pressure.
What gives here? Well, a few things. Yes, we live longer than we used to. Research supports genetic correlations with all of the aforementioned eye disorders. However, environmental and lifestyle factors are known risk factors for all of these diseases as well. Sure, our genetics might predispose us to type 2 diabetes or AMD, but our health in both those areas isn't black and white. When it comes to eye health as in any other aspect of health, our individual health efforts can make an impact. This isn't to say any given person will be able to achieve perfect vision solely with a healthy lifestyle, but who wouldn't want to make the most of what they have? We can take steps to preserve our vision, whatever it is at this moment, and stave off future dysfunction.
Our factory setting rests at good vision just as it does good overall health - within the context of our ancestral environments and lifestyle. When we live the life our genes expect, our body is able to work optimally. We increase our chances of vision preservation and decrease our chances of developing serious eye disorders.
Studies show that overall nutrition plays a crucial and evolving role in eye health. Breast feeding, for example, appears to offer some protective benefit against myopia, likely due to the advantages of omega-3 fatty acids. Continuing a diet rich in omega-3 fatty acids reduces the risk of developing AMD and can even stem the progression of AMD once it begins. Cutting out carbs, particular refined grain, can also "stall" AMD in its tracks. (It seems we're looking at dynamic physiological interaction here.)
Antioxidants are likewise essential to eye health. Studies show the B vitamins and vitamin D is also important to the development and progression of AMD. Subjects of one study whose antioxidant intake was high were less likely to develop lens damage and certain kinds of cataracts.
What the body requires of and how the body processes antioxidants for the purpose of eye health appears to change over the course of our lifetime. The carotenoids have long been recognized for their role in maintaining optimum eye health. As we age, they may become even more essential. Lutein and zeaxanthin, researchers believe, help protect the eyes by countering the damage of free radicals and blue light. With a lifetime of exposure, our need for these carotenoids likely rises.
Finally, want another reason to enjoy that glass of red wine? Resveratrol, a 2010 study suggests, helps curtail uncontrolled blood vessel growth in the eyes, a process implicated in diabetic retinopathy and AMD.
Then there's the question of lifestyle as a whole. Compare the sedentary lifestyles we live today with the continually active lives of our ancestors. Inactivity is a risk factor for many eye disorders, and the "near work" of reading, texting, and other activities undoubtedly explain much of the modern explosion in myopia rates. Though individual genetics contribute a predisposition, the lives we choose to lead have their say as well. In the instance of myopia, for example, we may all in a sense be predisposed as a species. As researchers from the Australian National University explain, "high heritability sets no limit to the potential for environmentally induced change." With the advent of "education and urbanisation," we're seeing that "[a] propensity to develop myopia in "myopigenic" environments thus appears to be a common human characteristic. We're designed to look out across a vast savannah, not be limited to the dimensions of a living room, let alone a smartphone screen. Clearly, we need to expand our visual horizons.
As is so often the case, living as close as we can to our genetic expectations goes a long way toward countering the strains of modern patterns and supporting our inherent functioning. Eating Primal, getting sunlight, staying active, and enjoying a visual life of distant, outdoor scope all become part of a more natural, Primal kind of prescription for maintaining the best eye health we can.
I have read stories of bad eyesight actually being reversed.
Because this effect was a secondary result of the therapy that was being tested, accurate records were not kept. But it gives us another potential factor that tends to get ignored in medicine.
This phenomenon is sometimes called "stress." In some forms of Transactional Analysis it is called the "hook." In Dianetics it is called a "key-in" or "restimulation."
In all these models some environmental stimulus results in the person unconsciously contacting some past experience and using it to make choices, rather than relying on rational thought in present time. This can happen suddenly, or gradually over a number of years in the case where a person has some habitual behavior that is restimulative (like watching TV or reading). The theory is that the being starts to live in moments where it had to focus on something very close and thus gradually loses the ability to see things at a distance clearly.
It is difficult to "key out" restimulation once it has become chronic, but it can be done. And doing that has had some amazing results, including improved eyesight.