Marks Daily Apple
Serving up health and fitness insights (daily, of course) with a side of irreverence.
28 Jun

Seeing the Light: Why Sun Exposure May Be Good for Your Eyes

iStock 000011181239XSmallHaving immersed myself in all things Primal for so long, I find myself viewing nearly everything through the prism of human evolution. Is this food, activity, environmental stimulus, or social more an evolutionary novelty? If so, might it possibly conflict with or impede our pursuit of good health? Is it benign? An improvement, even?

Grok logic will only get you so far. It’ll give you a nudge in the right direction – that is, headed straight to honest inquiry and further research – but it’s not enough. You shouldn’t rest on your laurels if Grok logic suggests what you’re doing is right, and you shouldn’t make big changes just because Grok logic suggests you’re doing something wrong. Instead, use those insights to generate hypotheses, then try to explore them. Research, read, ask more questions. At least, that’s what I try to do. It’s awfully tempting to just go with conjecture (especially if it turns out to be right on a fairly regular basis!).

That little preamble was just my way of setting up yet another question with roots in evolutionary conjecture: does the avoidance of sunlight via indoor living, sunglasses, and general heliophobia have an impact on eyesight, and more specifically nearsightnedness? Going purely by Grok logic and what we know about sunlight’s interaction with other aspects of our health, I think it’s a reasonable question. To whit:

Sunlight and skin – Sunlight exposure is required for vitamin D synthesis. When UVB hits our exposed skin, vitamin D is synthesized and distributed throughout our body. Vitamin D is an essential pro-hormone, necessary for musculoskeletal health, immune system robustness, as well as protection from heart disease and cancer.

Sunlight and circadian rhythm – We need exposure to light at certain times of the day in order to regulate our circadian rhythms. Without daytime/morning light, or with too much evening light, our internal clocks – and general health – go awry.

Given those two extremely basic, widely-accepted interactions between sunlight and our bodies, coupled with the fact that the eye’s express function is to interact directly with light, I think Grok logic regarding the sun and our eye health might be onto something. But we can’t be sure, remember, without confirming through other sources.

So let’s look into those other sources.

I’m sure you’ve heard of myopia. You may have it yourself or know someone who does. In case you don’t, myopia is nearsightedness, which is characterized by blurry vision when looking at distant objects. If it weren’t so easily countered with prescription eyeglasses, myopia would probably be classified as a public health epidemic. It’s that common, and it’s getting worse.

In fact, the latest statistics indicate that 41.6% of Americans aged 12-54 suffer from myopia, way up from 25% in the early 1970s. That’s an awfully big percentage of the tribe that can’t throw a spear, shoot an arrow, spot prey, or see the enemy coming from afar. That’s a ton of squinters who require assistance. In other words, if myopia were just an unfortunate part of growing old (to the ripe old age of 12!), we probably wouldn’t have made it this long.

No, there’s probably an environmental component to the rise of myopia. Genetics could play a part in determining susceptibility to myopia, and probably do, but an environmental factor is likely to be a trigger for the “myopia gene’s” expression. Could sunlight be just such an environmental factor?

Kathryn Rose, a visual disorder researcher, thinks so. First, she points to the weak or inconsistent epidemiology that attempts to link time spent on the computer, watching television, reading, and studying to the development of myopia, instead suggesting that the real problem is lack of sunlight. In cases where digital media usage or inside work appears to be associated with myopia, Rose thinks it’s actually a measure of displaced outdoor time.

Then she points toward the epidemiology exploring the link between time spent outdoors and myopia prevention, which is much stronger. Let’s take a look at a few studies:

In Chinese school children, myopia progression was inversely correlated with outdoor activity.

Near work (studying, reading) did not correlate with myopia progression, but American kids who played fewer sports outdoors had more myopia.

In Taiwanese rural children, outdoor activities might be “an important protecting factor for myopia.”

In teens from Singapore, outdoor activity appeared to protect against myopia progression.

Parental myopia status interacts with risk, too, though. In one study, kids with two myopic parents were at the greatest risk of developing myopia themselves, more so if they did not engage in outdoor sports. Kids with no myopic parents and who played a lot of sports outside had the lowest risk. Genetic predisposition expressed by an environmental trigger, anyone?

Of course, any good Primal thinker knows that epidemiology, like Grok logic, only goes so far. It’s certainly interesting, and it can inspire new avenues of inquiry, but science cannot live on epidemiology alone. You need something else to look into, like perhaps a physiological mechanism. Rose’s proposed mechanism was retinal dopamine, a “known stimulator of eye growth whose release is stimulated by light.” A lack of retinal dopamine – from avoiding the outdoors – means excessive eye growth. This is bad, for the eye is a delicate, extremely complex structure with many components, and a lot can go wrong if those components grow faster and bigger than they’re supposed to grow. Like the progression of myopia, which is characterized by excessive eye growth.

But wait – isn’t excessive amounts of light one of the big issues with modern living? Even if we stay indoors most of the day working, browsing, or watching TV, we’re still parked in front of a screen beaming light into our eyes and we’re still immersed in artificial overhead lighting. If all that light is enough to disrupt our circadian rhythms and ruin our sleep patterns, why isn’t it enough to stimulate retinal dopamine release?

It’s the magnitude. Try looking up at the sun in the afternoon. I mean really give it a good, long look. You can’t do it (in fact, that is definitely bad for your eyesight!) for more than a second or two, tops. If you squint, you might make three. Now try the same with an illuminated lightbulb. It’s easy and nearly painless. It doesn’t compare. To quantify the massive gulf between sunlight and artificial light, let’s look at another study. Researchers trying to study the link between light exposure and myopia exposed chicks to various amounts of light. Normal laboratory lighting was 500 lux, “intense” laboratory lighting was 15,000 lux, and sunlight was 30,000 lux. Only intense lab light and sunlight were able to retard the development of myopia, while normal lab lighting – which is still quite bright and very similar to standard office lighting conditions – did not adequately protect. Oh, and good news for you sunglass wearers: the chicks who were continuously exposed to bright lighting while wearing “translucent diffusers” also showed resistance to eye lengthening and myopia.

To get an idea of how many lux you can expect to “get” in various situations, check out the Wikipedia article on the subject. Prepare to marvel at the insane brightness of the outdoors and the comparatively piddling illumination found indoors. Note that direct sunlight is ridiculously bright (up to 130,000 lux), while just being outside in “full daylight” will provide plenty of light for your retinal dopamine labs. No need to stare at the sun or avoid dark forests. Just be outdoors and the sun will take care of the rest. If you can see stuff, that means light is getting to your eyes, it’s from the sun (and thus bright enough) and you’re good to go.

Of course, us oldsters might be too far gone for sunlight to have an effect on nearsightedness. Myopia develops early (hence the inclusion of 12 year-olds in myopia statistics), so it’s absolutely crucial that kids get plenty of time outdoors. I’d say “as much as possible,” but if you want a specific number, Kathryn Rose suggests between 10-14 hours a week as a bare minimum. Barring that, I suppose you could blast your toddler in the face with a halogen bulb every couple hours. No, but really: let those kids get outside, get dirty, play with bugs, climb stuff, and get some sun. Although the chick study showed that sunglasses may not be problematic, I don’t think kids need ‘em, and they might still interfere with normal eye development. They’d just fall off, anyway, unless you hooked the kid up with some Horace Grant-style goggles.

Given all that, I think it’s safe to say that sunlight exposure probably plays a role in the development of nearsightedness. It’s not the only player – physiology is rarely that simple – but it appears to be a major factor. Anyway, I think we’ll have a better idea in the coming years. My Pubmed trawling pulled up a ton of very recent studies on the subject, all in the last few years or so, so we can probably expect more definitive answers in the near future.

Are you nearsighted? Did you play a lot outdoors as a kid? What’s your family history of myopia – do your parents have it too? Let me know in the comment section!

You want comments? We got comments:

Imagine you’re George Clooney. Take a moment to admire your grooming and wit. Okay, now imagine someone walks up to you and asks, “What’s your name?” You say, “I’m George Clooney.” Or maybe you say, “I’m the Clooninator!” You don’t say “I’m George of George Clooney Sells Movies Blog” and you certainly don’t say, “I’m Clooney Weight Loss Plan”. So while spam is technically meat, it ain’t anywhere near Primal. Please nickname yourself something your friends would call you.

  1. I think there’s a much larger genetic component as opposed to an exposure component. For example, people within the LDS religion have what I would consider an abnormally high incidence of eyesight issues – I’ve never seen more children in glasses than in SLC.

    Hal wrote on June 28th, 2011
  2. Very interesting. I am definitely outdoorsy and played a lot outside but I’m still very nearsighted.

    Lia wrote on June 28th, 2011
  3. I am extremely nearsighted, and I played outside constantly (and mostly barefoot) as a kid. I was also fed properly. I have one myopic parent and one with normal vision. I’m inclined to agree more with Loren Cordain on this one — I think it’s something to do with sugar and carbs making IGF-1 levels surge, which in turn elongates the eyeballs. Combine that with some genetics, and you have a perfect setup for myopia.

    lyra wrote on June 28th, 2011
  4. I am nearsighted–became that way at the age of 21. Lived in the tropics and had plenty of sun exposure until age 18, at which time I arrived in the Northeast of this country for college. Needed glasses within 3 years–coincidence or not? It was about the same age as my father first needed glasses for myopia. Interesting hypothesis. My daughter is severely nearsighted–since before age 7. I didn’t consciously keep her from going outside to play, and she did, but she also was and is a bookworm and spent a lot of time indoors reading. My son still has 20/20 vision and did and does spend oodles of time outdoors, so my experience at least doesn’t contradict the hypothesis!

    Margaretrc wrote on June 28th, 2011
  5. Doesn’t surprise me at all. I am a freelance writer and editor, so I stare at a computer screen all day long. When I work at home, I prefer to work next to a window rather than turn on a lamp. My vision is 20/30 (farsighted), and I’m just fine without glasses. Right now, I am working at a client’s office, in an interior room with no access to natural light. Working under fluorescent light all day is really rough on my eyes. I need to wear +1 readers (optometrist’s suggestion) just to get through the day. I go outside at lunchtime just for a few minutes to give my eyes a break. Sunlight really helps.

    onewomanband wrote on June 28th, 2011
  6. Very interesting article. I wonder if at 30, my nearsightedness can be even slightly abated by getting more sunlight. I’ve been getting ALOT more sunlight lately (I have trouble sleeping and am trying to get a bigger dose to see if it helps), it will be interesting if my eyesight has improved at all on my next eye test.

    Peter wrote on June 28th, 2011
  7. Both of my parents are myopic, my Mother has worn glasses since she was 11 or 12. Neither my sister or I wear glasses. We were outside all the time when we were young.

    bbuddha wrote on June 28th, 2011
  8. As children, we spent pretty much all of our time outdoors; playing indoors just wasn’t done in those days in my neighborhood (during the 50s.) Sadly, I’m myopic and have been since an early age. My brother was far-sighted. Must be in the genes.

    Shari Ciancio wrote on June 28th, 2011
  9. I doubt this, too. I noticed my eyes getting bad while I was a caddy the summer before my 8th grade year. If you don’t know what being a caddy is like, it’s basically spending all day, every day during the summer outside carrying a 40lb golf bag. Plenty of good sun for 10-14 hours every day. I did it the summer before as well.

    The African kids have many other factors going on besides playing outside all day. In addition to caddying, I played video games at night on a small screen for a couple hours, or I watched TV, or I read. All of those things, when done for long periods without breaks/refocusing, can weaken your eye muscles. I doubt the kids mentioned above have access to those activities as often, which is why their eyesight is better overall.

    Andrew wrote on June 28th, 2011
  10. Got myself some sweet pterygiums from not wearing sunglasses!

    Not cool..

    http://en.wikipedia.org/wiki/Pterygium_(conjunctiva)

    Benji wrote on June 28th, 2011
  11. Sunlight is certainly important and may impact the development of myopia as you suggest. However, Loren Cordain, Ph.D. has made reference to hyperinsulinism contributing to myopia. Perhaps those who played outdoors as children but still became myopic were eating a Standard American Diet with too many simple carbs, milk, candy, etcetera, all which boost insulin levels. Good sun exposure may not have been enough to overcome dietary trauma.

    Robb Russell, D.C. wrote on June 28th, 2011
  12. I’m extremely nearsighted. I started getting that way in the 3rd or 4th grade, and my vision got worse until I reached my full growth as a teenager. I played outside a lot as a kid; everybody did back in those days. After I started wearing glasses, I probably did become more of an indoors person, but it was a gradual process. My sense is that developing an interest in “close work” like reading was more an effect than a cause of nearsightedness. I really didn’t become much of a reader until I’d been myopic for several years. My father had 20-20 vision, only needing glasses for reading when he became middle-aged. My mother is slightly nearsighted. My theory is that someone as myopic as I am would not have survived to reproduce in primitive times. But in modern times, I did, and one of my kids is as nearsighted as I am, and the other is mildly nearsighted.

    Jim Anderson wrote on June 28th, 2011
  13. I have done a lot of work in 3rd world countries. One thing that I noticed that the adults that I worked with, that grew up in near poverity had great eyesight. 20/20 or better. In addition to the sunlight theory, I wonder if that since their parents could not afford glasses at an early age, if their eyesight corrected itself as they grew older?

    In other words, kids bodies change and perhaps blurred vision at some point is just part of the growth process. If you put a crutch (glasses) on during that growth process, it keeps the eyes and muscles from developing as they should.

    Randal wrote on June 28th, 2011
  14. My eyesight started to deteriorate (myopia) when I moved from Brisbane in Australia (lots of sunshine and an outdoors lifestyle) to the UK back in 2005. Every six months (and sometimes more frequently) I’d have to get re-tested, and sure enough, a new prescription was required.

    Three months ago I moved to Malta and within a month noticed that my vision was improving. Today, I’m walking down the street, watching television etc quite well, without glasses!

    Sure, some things are slightly fuzzy, and legally I wouldn’t be able to drive without glasses as I still can’t read a number/license plate clearly at 20 feet, but it’s a HUGE improvement and I put it down to the better quality light.

    Josh wrote on June 28th, 2011
  15. Seems bogus to me, growing up in Florida I was outside a lot and theres plenty of sun around. In fact, I would be one to argue that I think the bright Florida sun may have caused my condition because its not like I had money to wear sunglasses between the ages of 6-12 (when I found out I was nearsighted). My eyes were always very sensitive to the sun and I always sneeze if I look in the general direction of the sunlight when I first walk out into it. I always remember the hottest and brightest afternoons having problems being outside, especially in the heat of the day when the sun was super bright, but I wanted to be playing outside so I just endured it. I always wear sunglasses now to prevent my eyes from straining and since that time my eyes stopped getting worse until I had them corrected with laser surgery earlier this year. I will always wear sunglasses to protect my eyes outdoors. The bright sun hurts your eyes, it doesn’t help them in any way.

    JJ wrote on June 28th, 2011
  16. Myopic? Check (-9 now)
    When? First glasses around age 9
    Parents? One myopic, but half mine.
    Outdoors as a kid? Check.
    Grew up before PC and outside the US, where there was not much of any TV either.

    Easily did the 10-18h outside per week, so the link in my case is weak…

    Chris T. wrote on June 28th, 2011
  17. Myopic? Check (-10 now)
    When? First glasses around age 9
    Parents? One myopic, but now at only half mine.
    Sibling, ditto me.
    Outdoors as a kid? Check, plenty.
    Grew up before PC and outside the US, where there was not much of any TV either.

    Easily did the 10-18h outside per week, so the link in my case is weak, as seems to be the case for many of the other posters with similar constellation.

    Chris T. wrote on June 28th, 2011
  18. I worked outside as a child on a working farm, we irrigated our fields, and of course I took care of that from the age of 12. So in addition to being short-sighted, 20-400 in my left eye, I have a cataract growing on my right lens (as well as all sorts of precancerous growths on my arms). Gee THANKS!

    Otto Cilindri wrote on June 28th, 2011
  19. I don’t know, Mark. Neither of my parents are nearsighted, nor are any of my siblings. I am and also astigmatic. I grew up in a foreign country and literally lived and played outdoors constantly–in a very sunny country.

    I understand that stress can play a big role in unleashing myopia, and there were some stressful aspects to my childhood in that my parents didn’t always get along, nor did I get along very well with one parent–who was stressed for various reasons. Asian kids are very stressed by very high scholastic standards and pressures.

    John wrote on June 29th, 2011
  20. Well as far as genes are concerned I was pretty much destined to develop myopia – the wearing of glasses or contacts is rife in my family, and has been for a few generations, beyond the two world wars in fact. But as far as immediate family goes, my dad developed myopia in his teens, my mother even now (in her late 60s) only needs reading glasses. My eldest brother had perfect eyesight, my next brother has slight myopia (he’s supposed to wear glasses, but doesn’t as he forgets about them, due to only really needing them for watching television), my next brother after him has perfect eyesight, and I developed myopia in my mid-teens – it stayed fairly mild, like my brother for about a decade, and since has been gradually worsening (thanks left eye for being weaker than the right and confusing my poor brain LOL). As kids (as far as I know, cos I’m the baby and there’s a lot of years between me and my brothers) all of us but the youngest of my brothers spent as much time as possible outside as kids, my mum often goes on about making us all go out to either play or help her with the garden as soon as it was warm enough for us kids to go out in just our underpants (usually April-ish), maybe only for an hour or so, but it was every day, for about 6 months of the year (we still got plenty of outdoors time the rest of the year, but we were a little more covered up!) from babies til we got to the age where we started wanting to do our own thing; for me that was around age 9 and I retreated to my room… I knew my eyesight was changing when we went on holiday one year and during the journey, I couldn’t make out trees in detail on the horizon, or read signposts before my parents whilst travelling in the car. Not long after that, I started getting headaches at school, as I couldn’t read the board, even sat at the very front of the class. So did 6 years of being mostly indoors trigger that gene in me, I wonder… However, interestingly, although I still don’t get outside as much as I would like, I do willingly spend much more time outdoors than I used to, and yet my eyes are STILL getting worse. I’m actually due to see the optician this summer for a check-up and I will be interested to know if there’s been any change…

    Jo wrote on June 29th, 2011
  21. “Sunlight and circadian rhythm – We need exposure to light at certain times of the day in order to regulate our circadian rhythms. Without daytime/morning light, or with too much evening light, our internal clocks – and general health – go awry.”

    I’m wondering more about this; I’m from the norhtern part of Sweden, above the arctic circle, and how do you explain the circadian rhythms in our part of the world? In summer, there’s sunlight all the time, and in the winter we ha approx 2 hours a day with sunlight, everything else is dark.

    Apart from this question, I also wonder what you think of lazer eye surgery? I had myopia, like everyone else in my family (mom, dad, 3 siblings), but had surgery in january. Yes, everything matches our family – practically no outdoor playing when we were little, so I think you (and studies/research) are spot on. But eye surgery isn’t really grok logic, and how do you think it effects other parts of the body?

    I’m just trying to se things the same way as you do – evolution came first.

    Hanna wrote on June 29th, 2011
  22. Plese do not listen to Mr. Sisson’s misguided advice. Unfiltered sunlight and vitamin D may be beneficial for the skin, but not for the eyes. You may develop growths on the surface of your eyes called pterygia (surfers get them) early in life. Later, cataracts develop sooner and after a certain age, unfiltered sunlight (particularly the UV-blue spectrum) will accelerate aging in the back of your eyes. Mr. Sisson is confused and cannot discriminate between sunlight for skin and for eyes. Yes, play outdoors, natural vitamin D is essential for life. But your babies should be given sunglasses.

    Bill Sardi wrote on June 29th, 2011
  23. When I was 15 they told me I needed glasses. But I knew about muscles and that the eye is focused by muscles.
    I knew that if I wore glasses those muscles would get weaker. Would your legs get stronger if you started using a walker?
    So I ignored them. I never wore glasses. I had 20/30 vision at the time. Now I am 40 and have 20/20 vision.
    The whole glasses thing is a scam, plain and simple, because after you weaken your eyes with glasses, a few years later you end up needing…..yes! a new prescription! And how much are those lenses? How much are those frames? We can put the computing power of a 1960s supercomputer in your pocket for under 500 dollars but hey those glasses that you need are so simple, very old technology, and way overpriced. Glasses – especially on the young – will be known in the future (if the same people who control the world now are NOT in control then)as one of the “great lies”.

    Doktor Jeep wrote on June 29th, 2011
  24. Do the eyelashes on the eye of this picture have mascara on them? If so that’s a coincidence because I just discovered that mascara makes my eyes very dry. I guess I already have problems with dry eye and it makes it worse. I never wore mascara until recently, because I have dark lashes anyway. I usually only wear in on an occasion. I had no problem with dry eye for a few weeks. Then a date night with husband proved that something in my mascara is making my eyes dry! Waste of money and time anyway, so into the garbage it went!

    tbird wrote on June 29th, 2011
  25. If sunlight hurts your eyes, wear sunglasses. Grok would have, if there ever was such a figment of Mark’s imagination. The first thing I do when I walk outside on a sunny day is sneeze.

    Besides, hasn’t anyone ever seen what the Eskimos used to wear to prevent snowblindness? A type of primitive sunglasses.

    Grok is a crock.

    Rex wrote on June 29th, 2011
  26. I had painful dry eye syndrom and it was progressing toward sjogren’s syndrom and nothing the doctors gave me helped at all. Once I switched to primal lifestyle, it went away. They are both a result of INFLAMMATION due to grain and HFCS. My guess is that myopia is also caused by inflammation/non-primal diet.

    Bert wrote on June 29th, 2011
    • Eight yrs ago I was about to get a lip biopsy to test for Sjogren’s Syndrome. I cancelled the test as I started to salivate and tear as soon as I stopped eating gluten. Two years ago I transitioned to a primal lifestyle. I am not myopic but I did have one sister with high myopia.

      Anne wrote on June 29th, 2011
  27. HOW to improve vision NATURALLY?

    Improper vision habits and mental stress causes eye muscles to deform. Light is therefore unable to focus properly on to the retina causing vision problems such as myopia and astigmatism.

    There`s a natural method for regaining perfect vision without contacts or glasses called: THE BATES METHOD. It teaches you relaxation techniques such as palming, breathing and other healthy vision habits.

    Just learn to let go and let your eyes do their thing.

    APinto wrote on June 29th, 2011
  28. Here are 15 more articles on Vitamin D and UV and vision related diseases
    http://www.vitamindwiki.com/tiki-browse_categories.php?parentId=70&sort_mode=created_desc

    Henry Lahore wrote on June 29th, 2011
  29. Mark,
    I practically lived outside as a kid. Football was definitely a year round sport as a kid.

    I had no issues with my eye sight until I started using computers, which was my early teens. As you can expect, I am nearsighted. My uncle, 13 years older than me, also started needing glasses for distance right at the same time, which is when he started using computers more.

    I don’t know about you, but my n=2 study says computers are what made me nearsighted.

    Ryan Denner wrote on June 29th, 2011
  30. played outside constantly as a child. am over 50 now and just barely myopic …just starting really…and not bad, noticing a difference on highways, but again, minor.

    jude wrote on June 30th, 2011
  31. Dang it, Mark! My girlfriend already thinks I’m weird for all the primal living I do. I don’t know what she’s going to say when she finds out I don’t wear sunglasses anymore. But, as a sciency type of guy, I can’t refute the data.

    No shades at the beach tomorrow!

    Matt wrote on June 30th, 2011
  32. Reading the study on Children of Chinese Origin Living in Singapore and Sydney, I was wondering if the reason for Myopia could also partly be the amount of chronic stress. The children that play more outside, may also be the ones who experience less stress. That may also explain why so many frustrated CNN commenters claim to have been outside a lot, but still myopic.

    I stumbled upon a paleo article on myopia published in 2002, which cites studies that hunter-gatherers hard had any myopia.

    Victor Venema wrote on July 2nd, 2011
  33. Without glasses I can see clearly at 5 inches from my nose, but I was very much an outdoor child. However I agree with the hypothesis. I feel humans were never intended to be indoors away from the sun as much as we generally are now.

    My mother’s nearsightedness and my father’s astigmatism gathered in my eyes.

    Becky wrote on July 5th, 2011
  34. There must be a moderate amount that does the trick, because I was raised in the pre-give-a-crap-about about sun exposure, or fancy sunblock lotion era and was told daily to stay outside until the sun went down my whole childhood. Those massive amounts of early childhood sun exposure didn’t negate my nearsightedness in the least… all the better to check out my extensive sunburn scarring, I say!

    Rich wrote on July 8th, 2011
  35. I had 20/10 vision as a child, up through junior high, while living in a small mountain town, where even the junior high and early high school kids played outside a ton: skateboarding & tubing the river in summer, snowboarding & sledding in winter, bikes all year ’round, small game hunting, you name it. 12-14 hours a week outside? Heck, it was 12-14 hours a day for a lot of us, at least in summer & on weekends. And I was doing a lot of reading throughout this time, I was an avid reader of newspaper & books since elementary school. So no, near-point accommodation was not the factor here.
    So when did my vision slide to 20/20 in one eye & 20/40 in the other? In junior year of high school, when I got a car, and quit skateboarding & biking everywhere. I did spend a lot of time outside after that, but.. it was after dark, and a keg was usually involved. And that’s a whole ‘nother ball of wax, you see.

    So, there you have it, another n=1 anecdotal story that fits the data very well.

    Epilogue: I’ve had good success in improving my eyesight in both eyes since then, now about 20/15 in the left and 20/25 in the right. It changes a lot though. My eye exercise & nutrition regimen was to eat a lot of beta carotene-rich foods, do some exercises for accomodation & focus, and slowly
    decrease my prescription with the help of my optician, who slowly ground down my prescription until it was not needed. Even for visually demanding activities like hunting, I can now hunt & shoot a gun very accurately at 100+ yards, no correction needed, and a compound bow to 60+ yards. This is great, because no glasses or contacts are ever as good as a bare eye in low light conditions.
    It would be great to see a post on Grok’s eye exercises!

    Luke wrote on July 15th, 2011
  36. does anyone know if sunlight can work wonder for presbyopia as well? ^_^
    (Lady Grok does not like reading glasses!)

    PHK wrote on July 15th, 2011
  37. Hey,

    I am short sighted. Played a lot outdoors as a kid but both parents short-sighted too. Genetics won this round I reckon Developed it in late-teens/early 20s.

    Rory Mulhern wrote on July 19th, 2011
  38. I was an extremely active kid who was *always* outside and was still in glasses by 12 years old.

    Perhaps kids play fewer outside sports due to the onset of myopia which makes it more difficult to excel at physical activities?

    sqt wrote on August 16th, 2011
  39. So to state the obvious, we know that there must be genetic predisposition. Clearly, some people are luckily not susceptible to myopia no matter how much indoor reading or junk-food eating they do. My theory: For those with the “bad” genes (which express themselves through a weakened sclera or accomodative lag or both, but especially the latter), I believe myopia begins with so-called “pseudo-myopia” caused by “accomodative spasm” (lens remains in focused state) after prolonged near work. But contrary to what is commonly theorized, this in itself does not cause axial elongation of the eye and permanent elongation through increased intra-ocular pressure. If anything, I would think the spasm would PREVENT further nearsightedness because any blur on the retina at that point would be myopic blur and under this condition the eye stops growing. However, glasses move the focal plane back to the retina and at this point no amount of focus (accomodation) will bring the closest objects into focus since the lens was already focusing to some degree during the fitting of the glasses and further focusing is beyond its range. Therefore, the only way for the eye to regain emmetropia is through axial elongation, and this is where the retinal defocus pathways come into play. I have read that cycloplegic refraction is not guaranteed to eliminate the spasm to allow for measurement of the true prescription (which indicates that the “spasm” is not so much a ciliary muscle (lens muscle) spasm as it is a condition of the lens retaining its shape after the near-work), so my theory is feasible even under those conditions. So from there on out, most of the myopia increases are probably due to further axial elongation. It’s possible that the lens also changes more and more over time but it has no muscle acting on it to thicken it (it thickens when the ciliary muscle relaxes). I have read convincing arguments that the lens can be shaped through vitreous fluid pressure during focusing, but it is indisputable that myopic eyes are on average longer than emmetropic eyes, so I think it’s safe to say that elongation is a main factor. Anyway, by moving the focal plane back, you are back at square one and near-work again causes a lot of retinal defocus which leads to even more axial elongation (and possible lens thickening, according to some). How many diopters you will max out at is a function of how strong your sclera is, so both the onset and the limit of myopia is genetic, but the progression itself I believe to be caused by the “treatment” which is glasses. The actual RATE of progression is where nutrition, near-work, ad other environmental factors come into play.

    I have two brothers. One got glasses at the same age I did and progressed to near-severe myopia just like me within a matter of years. One refused to wear glasses and never progressed beyond 20/40. There are other stories describing the same thing right here on this site. You be the judge. Nutrition (and by extension sunlight) plays a role in lense and scleral structure and is a contributing factor in the rate of progression, but I can guarantee you that if you put -3.00 glasses on 100 different people, each with different diets (some “primal”, some high-carb), they’ll all end up as -3.00 myopes sooner or later. The high-carb, book-worm, basement-dwelling types might beat the rest to the prescription, but they’ll all get there. They tested this on monkeys and they all got nearsighted to -3.00. Note that my argument is not applicable to those with congenital conditions that caused myopia. Also, I believe they have already compared incidences of myopia between countries at different latitudes and concluded that the varying amounts of sunlight did not have a statistically significant effect. (Also, it is common knowledge among the scientists that Eskimos have a very low incidence of myopia).

    Scott wrote on September 17th, 2011
  40. I just heard a report on the BBC, which lead me to Google, which lead me here.
    It seems the correlation between exposure to outside light and myopia is becoming well recognised. The report was about the results of a study, the aim of which was to try to understand the high rates of myopia in Asia and SE Asia. Too much indoors time, studying, napping during daylight time and more study at night. Singapore (where I am) was of special interest because of the racial mix. All races are being affected equally, because the lifestyle (study patterns in particular) are identical for all races here.
    My daughter is myopic and getting worse. I’m going outside.

    Yee Mei wrote on May 4th, 2012

Leave a Reply

If you'd like to add an avatar to all of your comments click here!

© 2014 Mark's Daily Apple

Subscribe to the Newsletter and Get a Free Copy
of Mark Sisson's Fitness eBook and more!