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

Having 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. Interesting. I have terrible vision, but am also very sensitive to light.

    Lauren wrote on June 28th, 2011
  2. “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.”

    I am with you 110% here Mark. Its how I do things. I form a hypothesis based on evolution and then experiment on myself.

    My latest experimentation is raw cheese from grass-fed cows milk. Unfortunately even a little bit seems to give me acne. I have known that dairy causes me to breakout but I wanted to see if cheeese was an exception. I woke up with 2 whiteheads this morning after consuming a little cheese for just 2.5 days!

    I thought there was a good chance of this happening due to the fact that Grok did not eat dairy and the fact that most of us are lactose intolerant, including myself.

    I seem to do fine with butter and whey… but maybe not?! I wonder if I ditched butter and went with Ghee if I would have shiny skin?! Butter does have a touch of lactose…..

    Primal Toad wrote on June 28th, 2011
    • We’re casein free at our house. It’s the protein in milk that gets my husband and daughter. Parmesan cheese seems to be my husband’s personal kryptonite, he gets some in a dish, and he’s got chills, hacking cough, and fuzzy brain for several days.

      Elisabeth wrote on June 28th, 2011
    • Everything grok did and benefitted from does not apply to everyone today. I eat yogurt on an almost daily basis and my skin has always been perfectly fine. I know many other people who eat cheese and yogurt well into their 30s and 40s without any issues at all. N=1 in your case.

      Morgan wrote on June 28th, 2011
      • I said… “most of us are lactose intolerant.” Right? Oh, yea, I did.

        That would be 50.00000001%. I think the number is around 75%. I may be fine with yogurt because of the probiotics and semi low lactose content. I am not sure.

        I may still be fine with cheese. I mean, it could have been something else that caused the 2 whiteheads. I’ll never know for sure.

        N=1 in everyones case. We are all different and thus need to experiment on ourselves to figure how we are different.

        Primal Toad wrote on June 28th, 2011
        • Didn’t mean to sound like I was attacking you, I was more so attacking the idea that everything grok did was best for all of us, which I believe is a bit too pervasive around here.

          Morgan wrote on June 28th, 2011
        • Remember if it’s store bought, pasteurized yogurt, clabber, buttermilk, you name it…there is puss and blood in it, too.
          It’s a toxic soup that has to be pasteurized because of the conditions and health of the cows and the enviroment they stand in, regardless if it says ‘organic’.

          Most people are allergic to that toxic soup, not the actual lactose. Unless you have a test done, there is no need to assume you’re allergic to lactose…dead bacteria mimic a virus that your body tries to get rid of, too.
          There are many, MANY reasons you ended up with white heads.

          Primal Palate wrote on June 29th, 2011
  3. On bright sunny summer days, sunlight hurts my eyes. Not looking at the sun, just being out in it. I look terrible in hats, but it beats painful squinting.

    I have one nearsighted eye and one farsighted eye, which is the same as my mother. They compensate for each other very well, and I don’t need to wear glasses (though I did from age 12-17). I played outdoors a lot as a child, but bright sun has always been pretty uncomfortable.

    Omnomnivore wrote on June 28th, 2011
  4. I love the sunshine… it makes me feel better all over :)

    Jeanna wrote on June 28th, 2011
  5. They’d just fall off, anyway, unless you hooked the kid up with some Horace Grant-style goggles.

    Oh boy… I remember Horace Grant from the Chicago Bulls – MJ days! He played for the Charlotte Hornets too, didn’t he?

    Sunlight also hurts my eyes. And, if I am indoors for a while, say an hour or more and go outside in bright sunlight then I always sneeze immediately. Usually twice. I do not have allergies of any kind and never have. I just always sneeze when going from a dark room to bright sunlight.

    Does anyone else do this?

    My father and brother have contacts and also have glasses… I do not have either and my eyesight still remains golden. I think its improving too from living primal. Surprise!

    Primal Toad wrote on June 28th, 2011
    • Wow! yes I too sneeze when going into bright sunlight. No other known allergies except to wheat.

      Deb wrote on June 28th, 2011
    • Yes, sunlight makes me sneeze too. More so when I was younger.

      Harry wrote on June 28th, 2011
    • Yup, me too. No one ever believes me that it will happen until I show them. I read somewhere that it is a protection mechanism to prevent you from looking at the sun too long. Many people will sneeze if you ask them to look almost directly at the sun, but I guess some of us are more sensitive. Incidentally, I have no vision problems, coincidence?

      Stephen wrote on June 28th, 2011
      • It’s actually a genetic allele, whether people do this or not.

        cTo wrote on June 28th, 2011
    • Ha, glad to see others are in the same boat as me. I will add that sometimes I go out in the sun and I kind of have to sneeze. If I look up at the sun or face towards it then the sneeze comes on even more and then BAM! I let it out.

      Its not just sunlight either… it can actually happen in side with artificial lights.

      Primal Toad wrote on June 28th, 2011
      • Sneezing caused by bright light is a common thing. It’s thought to be a result of cross-talk in the nerves when the optic nerve gets overstimulated (bright light) and some of that signal stimulates the trigeminal nerve that runs right near it.

        Alex wrote on June 28th, 2011
      • you have lighter eyes right? I think this happens more often with people who have ligher eyes. My eyes are green and I can sneeze when I first look into the sun after being indoors for a while. When I was young, I would wake up to use the bathroom at night and sneeze from exposure to the bathroom light.

        Morgan wrote on June 28th, 2011
      • I totally sneeze from bright sunlight, bright snow and lightbulbs. If I need to sneeze but can’t quite, I just look at a lightbulb;) It’s an inherited trait. My dad also does this.

        Erin wrote on June 28th, 2011
      • I, too, will sneeze right when going out into the bright sunlight. I’m almost 67 years old and it’s been something I’ve done all my life and still do! If I get up at night to use the bathroom, same thing – I’ve learned not to look in to the overhead light otherwise I’ll sneeze my head off!

        By the same token, have you ever felt like you needed to sneeze – maybe something like dust or whatever was up your nose but you couldn’t quite get past it? Well, all I have to do is look at a bright light (sun, light bulb, whatever) and it’s achoo-land for me!

        My 4 year old granddaughter is the same – we take her out for a walk and the first thing she does when she gets outside is sneeze! She has dark brown eyes so the lighter-colored eye theory may not be applicable here! I have green eyes so maybe it applies to me, but DH has blue eyes and he’s not affected at all.

        PrimalGrandma wrote on June 28th, 2011
        • Sunlight doesn’t make me sneeze by itself, but if I find myself feeling like I need to sneeze, I’ll look to the sun and it always helps me out! Bright indoor light isn’t as quickly effective, but will do in a pinch.

          My husband thinks this is nuts. Now I can tell him why!

          MamaGrok wrote on June 29th, 2011
    • It an example used of simple Mendalian inheritance. It is dominant. I learned it as Achoo syndrome, but the fancy name is now “Photic Sneeze Reflex”.

      According to Wiki, the condition affects 18-35% of the human population.
      The first mention of the phenomenon is probably in the later work attributed to Aristotle(between the third century BCE to the 6th century CE).

      And yes, I sneeze when I suddenly step into bright lighting too. :-)

      Elisabeth wrote on June 28th, 2011
      • Very interesting indeed! So about 1/4 on average I guess. Cool camp of “buttercups.” -Robb Wolfs favorite word.

        Primal Toad wrote on June 28th, 2011
      • I wonder if you can have a mild form of this if you are a “carrier” of the gene. If I need to sneeze, I look at a bright light to help it happen but I don’t sneeze just from looking at a bright light. Very interesting stuff.

        fritzy wrote on June 28th, 2011
    • Sunlight feels great on my eyes, so good that I actually used to enjoy looking into it feeling no or little discomfort for quite a long time(i know this was bad). I have green eyes and also sneeze when looking at the sun after being indoors for a while. When I was young it I would sneeze just after turning on the light to the bathroom during my nightly middle of sleeptime visits.

      Morgan wrote on June 28th, 2011
      • Sungazing is an ancient practice that is potentially very good for our eyes and general health :) Though it is usually done within an hour of sunrise or sunset to get a lower dose of light.

        Melody wrote on May 1st, 2015
    • Both my son and I sneeze when we go from dark to light. I assumed that it was due to the release of moisture from my eyes that seem to drain into my sinus. That tiny bit of moisture is enough to make us both sneeze. That’s also what makes my nose run (tears) when I go from warm to cold or from cold to warm. So I carry hankies everywhere I go. My dad used to say regarding food “it’s not good unless it makes your nose run.” Ahahahahaha, I guess it’s a family thing.

      2Rae wrote on July 16th, 2013
  6. My dad had perfect vision, but my mom is practically blind without glasses. By the time I was 7, I had glasses to correct nearsightedness, and have worn glasses or contacts my entire life.

    I heard a theory once that prior to WWI and WWII, there were less people who needed glasses, but that military service and many deaths essentially helped cull good vision out of our “herd”. Men with bad vision weren’t accepted into the military at that time, so they stayed home and made babies while men with good vision went abroad and got killed. Not sure how true that is, though.

    Melissa wrote on June 28th, 2011
    • I would also assume, evolutionarily speaking, that before the invention of glasses, people with myopia would have had less of a chance to procreate. What self-respecting Grokina wants to be saddled with the mate who can’t hunt or even gather?

      Since myopia is no longer detrimental to mating (for which I’m selfishly glad!) the genes would get passed on a lot more.

      (I wonder though, if slight myopia would be an asset for working with your hands? I know that I am able to focus more closely to my face than people with normal vision, possibly there was at one point a benefit, but myopia has gone overboard since then?)

      Melissa wrote on June 28th, 2011
    • Just another theory from conventional wisdom that assumes that primitive man had just as many plagues as modern man (that is, every man has two or three major ones!), but that natural selection kept the plagued from breeding. The theory is that it’s all genes.

      No, it’s genetic expression. Our modern diet & environment are distorting our genetic expression. Genes determine who among those with bad environmetal factors will develop what ailment. Myopia is connected with insufficient sunlight, excess carbohydrate intake, & excessive near work. It is nearly 100% preventable if you are somehow able to avoid those factors.

      MamaGrok wrote on June 29th, 2011
  7. Retina illumination causes retinoic acid synethesis.

    Last summer I got tons of FL sunlight and ate much liver. Upon going back to NJ and an office, I developed a very slight visual problem (sensitivity to car lights at night) after 6 weeks. I was still eating liver but instead of sunlight, I was supplementing D3. I’m still trying to figure out what’s going on–it’s a little better.

    john wrote on June 28th, 2011
  8. Started wearing glasses when I was 12 years old. I was born in 1951 and played outdoors most of the time when weather permitted. My father had myopia at about the same age, he was born in 1923 and spent very little time indoors. Mother had perfect eyesight until she reached her mid 50’s. Older brother has myopia, started wearing glasses at age 10 years, also spent a lot of time outdoors. Younger brother, perfect eyesight until mid 50’s. My son has perfect eyesight and hardly every played outdoors, my daughter has myopia from about age 12 and played outdoors most of the time. Their father had perfect eyesight until mid 50’s and only needs reading glasses.

    I don’t think sunlight has anything to do with having myopia.

    Deb wrote on June 28th, 2011
    • In your case, maybe not. Seems like your dad passed on some pretty bad eye genes. Doesn’t mean it’s not true for others, though. And who knows? Your vision could have been even worse…

      Uncephalized wrote on June 28th, 2011
    • Why did your son hardly ever play outdoors? Just curious, I think things like this are interesting, especially when a boy does not play outdoors.

      Obviously genetics plays the largest role here. Your experience is one family out of millions, it doesn’t mean anything.

      Morgan wrote on June 28th, 2011
      • He liked to play on the computer, he now works for Bioware designing video games.

        Deb wrote on June 28th, 2011
  9. From my experience(actually my brother’s), I would argue sunlight was a much less significant player. My brother and I spent equal time outside growing up.

    My eyesight at 40 years ols is 20/20, but he was in glasses in his teens, then contact lenses, and a few years ago corrective surgery (LASIC ?sp?). In his case, genes seem to have had a bigger impact on his eyes.

    That being said, my two year old daughter is outside as much of the day as she can be given the Dallas temps this summer. I think its important for a number of reasons and her eyesight is one of them.

    Thanks for another thought provoking article.

    WS wrote on June 28th, 2011
  10. I read a study a lot of years ago that correlated myopia to young children sleeping in light at night. Nightlights were a culprit.

    Lord knows I spent plenty of time playing outside. Neither parent had myopia. But I didn’t have a nightlight, and I had bad myopia.

    Mark Luedtke wrote on June 28th, 2011
    • I wrote that wrong. I DID have a nightlight.

      Mark Luedtke wrote on June 28th, 2011
    • They later learned that myopic parents tended to leave the light on in the kids’ rooms so the myopic parents could see at night. Myopic parents beget myopic kids. The nightlight had nothing to do with the kids’ myopic progression.

      Karen wrote on June 28th, 2011
      • That’s interesting since neither of my parents was myopic. In fact out of my extended family, only one other cousin, out of several dozen relatives, was.

        Mark Luedtke wrote on June 28th, 2011
  11. I heard in a Robb Wolf podcast that grain consumption that causes an autoimmune response has a causative effect on myopia.

    Mark wrote on June 28th, 2011
  12. My sisters and I played outside a LOT, however we lived north of 60 and for half the year, there was no light to play in 5 out of 7 days of the week (as we were in school, under fluorescent lights). During the summer we were outside almost constantly though, and had strong daylight the entire time. It would be interesting to see if latitude and school time have any effects in studies.

    That having been said, I’m only barely myopic at nearly 40 and don’t wear glasses regularly. One of my sisters is the same, the other has worn glasses since she was a teenager. Our father was far-sighted and our mother didn’t start wearing glasses regularly until she was in her late 40s.

    Sarah wrote on June 28th, 2011
  13. I think you have to include the declining amounts of Vitamin A in the form of Retinol and lower Omega 3’s and higher Omega 6’s into consideration. I certainly think we overdo sunglasses and staying indoors but I know as a kid I was always the one with my hands in the butter dish and I practically survived on egg sandwiches for years at a time and I was the only one of my siblings (4 other girls) who hasn’t ever needed glasses or braces. My mother has always had horrible vision and had horrible teeth, now my father had perfect vision and perfect teeth but I was the only of my sisters to be that way and I certainly attribute it to the butter and eggs :)

    Evelyn wrote on June 28th, 2011
  14. My mom has trifocals, my dad is legally blind without his glasses, my sister is nearsighted and has astigmatism (sp), and I am nearsighted. My brother (has a different father) does not need corrective lenses. I have to other sisters (different mother), they both are nearsighted. I have another brother (also a different mother) who does not need glasses.

    Time spent outside? I would venture a guess that my two brothers spent the most time outside “being boys,” but I do think I spent a fair amount of time outdoors.

    My husband has perfect vision. He spent a lot of time outside as a child, but now prefers to be in front of a computer in a dark room.

    Ali wrote on June 28th, 2011
  15. Hello, I think it is not only the sun, but the outdoor activity. Because in those researches, outdoor means, not the city , but the great outdoors, objects far away, big blue sky, so that the eyes can rest. My wife cured her eyes with intense outdoor landscape viewing when she was a teenager. So go out ! :)

    Mustafa Korkut wrote on June 28th, 2011
  16. I am very, very nearsighted. When people who boast a -2 diapoter Rx tell me they are “blind as a bat” I want to hit them–my most current Rx had me at a -7 in both eyes, and I wear large, chunky black frames specifically so I can find them if they fall off; otherwise they’re lost in a blur. Having worked in optics for a few years in college, I’ve seen people with worse prescriptions…but not many and rarely in people as young as I am. About all I can say is that I don’t have an astigmatism and I’m a good candidate for Lazik, which I will probably invest in at some point. My glasses are extremely expensive, and I’m genuinely concerned about the risks of what would happen if mine, say, broke in a public place and I wasn’t carrying spares (I keep an old pair in my glove compartment, in fact. Just in case.)

    I didn’t play outdoor sports, but I was a very active child and I was outside several hours a day.

    I have worn glasses since I was seven.

    Interestingly however I didn’t initially near them for nearsightedness, although I am profoundly nearsighted now. I needed them to correct a focus issue, because my eyes did not refocus properly and this meant I had a difficult time visually tracking things (…which is likely why I didn’t play sport. I was more likely to get hit by a ball than do anything else with it.) The solution to this was to slap me in bifocals, which forced my eye muscles to “exercise.” It did work. I wore them for two years, but by the end, when I didn’t need them for my focus issues anymore I needed them for nearsightedness.

    I’ve had ophthalmologists (whom I see because I’m at a truly absurd risk for a retinal detachment–one doctor told me it was less a question of “if” it will happen but “when”) tell me that they suspect that early intervention was, in fact, what triggered the nearsightedness and caused it to worsen: there’s apparently some evidence that vision correction causes, in some people, vision to further degrade, particularly when you hit a certain point, as I have. So it’s very possible that while Grok might’ve hard a hard time counting the leaves on the top of a tree, he probably wouldn’t regularly walk into things and fail to identify close friends sitting across the room, as I sadly do without either my glasses or my contacts.

    I don’t have a great answer for this: my inability to see clearly was impacting me at school when they finally put me in lenses for my developing nearsightedness. So obviously it needed to be corrected. But I also wish that I wasn’t so nearsighted anything further than five inches from my nose gets lost in a complete blur.

    A.K. wrote on June 28th, 2011
    • I hear what you are saying. I’ve had corrective eye wear since I was 8 and that’s 30 years now. And without them I can’t see closer than a few inches from my nose.

      I wonder if there are any studies on glasses vs. contact lenses on how much they block the eyes of sunlight.

      Trevor wrote on June 28th, 2011
      • I don’t know about sunlight, though doctors will tell you that UV blocking is important in tinted lenses. This makes good intuitive sense: your pupils dilate when they’re in shade, which means if you’re not compensating for the increased UV exposure, you could do damage to your eyes. Either let your pupils constrict, or wear UV protected lenses to compensate. Sensible. You’d be surprised how often I sold sunglasses and had people try to haggle me out of the UV protection on the lenses to save a few bucks (no company I know of will sell tinted lenses without UV protection, anyway.)

        I DO know they do research how much oxygen the eyes get, and that’s important. That’s a big part of why your eye doctor will tell you not to sleep in your contacts. When you’re not blinking, you’re not rewetting them properly for one, and for another, you’re not letting your eyes “breathe.” You’re also risking anything that gets on the contact being in contact with your vulnerable little eyeball for extended periods.

        I worked for three eye doctors, and all of them told patients who asked for the “long wearing” contacts that you can wear, say, for several days or a week at a time that they did not advise the patient did so regularly. We did have one patient once in long-wearing contacts who, because she was a hairstylist, ended up with an awful eye infection because the chemicals she worked with got into the lenses, and because she didn’t take them off for days, well…it wasn’t pretty.

        A.K. wrote on June 28th, 2011
    • I know what you mean about people who think they’re blind! My most recent prescription has me at -7 (R) and -9 (L). On the rare occasion that I wear my glasses to work rather than contacts, people are shocked at how thick and distorted they are.

      I too wonder whether wearing glasses made my eyes worse, but if I couldn’t read the blackboard from my desk at school at the age of 7, they were probably necessary.

      I did notice that when I stopped wearing glasses and started wearing contacts my eyes became a lot more sensitive to sunlight. I’ll get headaches and eye strain outside on a bright day (not even necessarily sunny, just bright) if I don’t wear my sunglasses.

      Hopefully, before long some superstar scientist will come up with a way to fix the genes involved, and people will only have to worry about environmental factors.

      Melissa wrote on June 28th, 2011
      • Do you have blue or green eyes? People with blue or green eyes tend to be far more photosensitive than people with brown eyes, whether or not they also have a vision issue.

        Your comment that the sun seems “brighter” with your contacts on is something I heard all the time. It’s well known. Lenses, even untinted ones, are not truly clear. There’s some distortion you have to “look” through and that provides some small amount of “shade”, or so one of the docs I worked for said. It may not be much, but eyes are very sensitive. It can make a difference.

        A.K. wrote on June 28th, 2011
        • I definitely wonder if eye colour has any influence. My father still has perfect vision, while my mother is mildly myopic. Out of 4 siblings, my brother who has very light blue eyes, and myself with light green eyes, both ended up myopic too. My other 2 brothers, one with dark blue eyes, and one with brown eyes, both have perfect vision. Or maybe that’s just genetic pot luck.

          Having lived in Australia, where the light is sheer and stunningly bright, I’ve been schooled in the importance of good sunglasses. However, now that I’ve returned to Ireland, and it’s Summer, I find it odd how I’m often the only person wearing sunglasses – I feel like people must think I fancy I’m a celebrity, since sunglasses are so unusual here. :( When it isn’t raining, it can get pretty sunny.

          I wonder if sunglasses could increase your risk of myopia, because you’re not letting enough light in. But I have a feeling the reason being outdoors helps your eyesight is more due to the use of distant vision, which gives your eyes a pleasant break from close work – as someone else mentioned in the comments.

          kerrybonnie wrote on June 28th, 2011
        • I have green/blue eyes. Maybe I am more photosensitive than others. *shrug*

          Melissa wrote on June 28th, 2011
    • Sadly I am one of those in the minority with an even worse prescription than you. I get jealous of people with -7 prescriptions who are actually candidates for LASIK. My current contacts are -11 and -11.5 glasses are usually 1-2 diopters lower. I started wearing glasses at age 8 and have been in double digit prescriptions since High School :-( Both parents have excellent vision excepting mild presbyopia. One sister has perfect vision and one has a moderately high prescription.

      stephanie wrote on June 28th, 2011
      • OUCH. You have my sympathies.

        A.K. wrote on June 28th, 2011
      • I feel for you. I used to be that bad in high school, college and my 20s too. In my 30s my eyes started getting better. I’m -9 now. It’s amazing how much of an improvement that is.

        If the nightlight wasn’t the cause, I have no idea what it could have been. I didn’t eat or play any different than anybody else in my family. We were outside playing all the time. And we don’t have a history of myopia in the family.

        Mark Luedtke wrote on June 28th, 2011
        • My eyes are green. Maybe light eyes in the sun too much as a child?

          Mark Luedtke wrote on June 28th, 2011
      • Years ago, an eye doctor told me that a high fever in early childhood can lead to high myopia later on. He said that was often the case when parents with normal vision had a child that was a high myope. Something to do with collagen formation.

        lyra wrote on June 29th, 2011
  17. What about the possible role of vitamin D? Less time outside may also mean greater vitamin D deficiency. Or perhaps those with myopia cannot use the vitamin d they have?

    Anne wrote on June 28th, 2011
  18. My vision changed when I was in high school, and I’ve worn glasses or contacts ever since. Most folks with myopia see a generally slow and steady decline of their vision over the years, but mine has remained essentially unchanged for about a decade, and the changes before that were minimal. (A lot of my peers are getting bifocals and reading glasses, meanwhile.) Yes, I feel lucky to have kept my vision stable, but wonder how the sunlight theory would fit? Can it help maintain vision once it’s degenerated to a certain level? I am also very fair and sensitive to light, but do enjoy being outside for yard work or running or whatever when I can. Could there be a minimum amount of sunlight, which if combined with proper diet, is actually protective of vision for adults?

    Jim wrote on June 28th, 2011
  19. I developed myopia in grade 7 and when I was in grade 9 I started to do as much research as I could about the causes. Like you I realized that if 40% of the population can’t see well without glasses then as a genetic trait is should have disappeared long ago.

    My physics teacher in high school taught at a rural school in Africa for a number of years and told us a story about how he was fascinated that none of the kids wore glasses. So he tested them all.. not one had poor eyesight, and many could see better than 20/20.

    I started to test my eyesight daily at home and trying different things to see if there was an effect.

    I tested exercising the orbital muscles, sunlight exposure, relaxation exercises, focal distance exercises and progressive prescription changes. I even tried hypnosis.

    The only correlation I was able to measure was that after several days of skiing my vision would be slightly better. And on the other side, a weekend spent in front of a computer screen would result in noticeably worse eyesight.

    My theory after all this was that for the majority of people with myopia (those who develop it after birth) it is a result of muscle adaptation. In the same way that people can’t do the splits unless they regularly stretch the leg and hip muscles the muscles that control the lens will adapt to limited movement if they don’t get used regularly and often.

    but the eye is delicate and it is difficult to stretch those muscles that control focusing. Sunlight may offer some help here as the muscles which dilate the pupal will actually pull on the rest of the internal eye muscles. However sunlight alone is not enough to reverse myopia. You also need to be constantly be focusing on things at or beyond your focal distance. Hence why skiing worked so well for me – outside in bright sunlight made even brighter because of the snow and the requirement to always be focusing on trees, people and bumps coming at me fast as well as long distance views of the horizon. Over the course of a day skiing my eyes would feel sore from use.

    Unfortunately there is very little research going on in this area. Optometrists are happy to continue seeing patients and prescribing corrective lenses or selling surgery.

    Matt wrote on June 28th, 2011
  20. Great info, one question though:

    What about those of us with blue eyes? Mine are particularly light blue almost grey in some light…but they’re extremely sensitive to bright sunlight.

    This doesn’t stop me from being outside whenever possible, but it means that I wear sunglasses most of the time (when I remember them anyway).

    Jesse wrote on June 28th, 2011
  21. I have my doubts about the validity of this… in my opinion genetics are the determining factor. As a boy, I spent the vast majority of my time playing outdoors, and yet ended up with glasses by the age of 7. My current Rx is -5.5 and -5 diopters, and I am convinced that if not for corrective lenses, people with eyesight as bad as mine would not be able to properly take care of and fend for themselves in this world.
    It’s simple: Grok’s brother Grolk, with very poor vision, had a far greater chance of perishing due to predation, accident, unable to see prey, etc. Bad vision was a handicap, and as such was essentially weeded out of the genetic pool. Now, I have no way to back this up, but my hunch is that if you went back even a couple hundred years to when life was a lot tougher and eyesight more essential for survival, poor vision was rare. Only the advent of modern technology, medicine, and opthalmology has made it possible for men like myself to live normal lives with vision that would cripple us without lenses.

    Ginger Thickbeard wrote on June 28th, 2011
    • I doubt that hundreds of millions of years of successful eye evolution could be undone by genetic drift in a few decades.

      DeyC3 wrote on July 3rd, 2011
  22. I also have terrible eyes, and have worn glasses since 2nd grade. My mother’s are worse than mine, but my father’s are better than 20/20. I definitely lost the genetic lottery there. Tons of time spent outside as a kid, and I wouldn’t even wear the (prescription) sunglasses, despite my father’s nagging. Many is the time that I reflected on how lucky I am to live in an age with corrective lenses, lest I be eaten by a bear, or a useless burden on my family.
    I recently read an article (over at Archevore, I think) which said that the eye is particularly sensitive to insulin, and excess insulin causes elongation of the eye, leading to myopia. I would like to know more about this mechanism, as my husband also has poor eyesight, and I’d like to think our future children could avoid that trap!

    Laura wrote on June 28th, 2011
  23. Just this weekend I read on another blog a study linking our time spent indoors and myopia. That’s a tough one for me to swallow. I spent nearly all of my time outdoors as a child. I had a huge backyard in California and my parents were in their 40s so they pretty much left me to play outside with my brothers all day every day.

    I was severely nearsighted by the time I was 10. My brothers and sister had absolutely perfect eye sight. I had celiac disease too which none of them seemed to have developed. I was also the last of 5 kids.

    Maybe sunlight plays somewhat of a role, but it’s not the whole story. I’d like to read an article that explores nutritional deficiencies and myopia, or the ill effects of having too many children (Weston Price talked about that), maybe diabetes or insulin spikes has something to do with it (which is an epidemic as large as myopia). Maybe I’ll look into this one myself one day.

    Peggy The Primal Parent wrote on June 28th, 2011
    • It is my understanding, as per science magazine blurb circa 10 years ago, that myopia is caused by insulin levels in childhood and has been on the rise for 300 years following the trend towards increasing refinement of carbs. That myopia has increased so much since the Lipid Hypothesis caught traction suggests that, indeed, a lowfat, high-carb diet is to be implicated. For too many reasons to get into here (including Global Dimming), I think sunlight is barking up the wrong tree.

      DeyC3 wrote on July 2nd, 2011
  24. This is an example where correlation is being confused with causation.

    An alternative hypothesis is that kids who are myopic don’t enjoy outdoor sports and activities so much, so tend to spend more time indoors playing with things close up.

    All epidemiology tells you is that An and B tend to occur together – not that A causes B. Instead, B may cause A.

    Tim wrote on June 28th, 2011
    • Yours is, indeed, another plausible hypothesis, and you are totally right that we can’t jump from correlation to causation. It would be interesting, however, to compare incidence of myopia in tropical versus more northern climes. It wouldn’t prove anything, but could either support or disprove the hypothesis.

      Margaretrc wrote on June 28th, 2011
  25. I completely agree with this article! I went for about a year of wearing no sunglasses while driving, used natural light as much as possible, and tried to stay away from the computer as much as possible (that’s hard when you are a graphic designer!). After that year, my eyesight actually improved quite a bit. I didn’t change any other factors like diet or exercise, so it has to be the wonderful sun! Great article.

    Kate wrote on June 28th, 2011
  26. NATURAL VISION IMPROVEMENT!! Sorry I had to break out the caps lock on that. I used to be moderately nearsighted -3.5 diopter 20/ 400 I think, and my wife told me about a book. Natural Vision Improvement by Janet Goodrich. I am not sure if it is still in print but I did the exercises in the book as well as other NVI type exercises I found via the “Bates Method” or Thomas Quackenbush. (good luck being a doctor with that name) and have improved my vision to about 20/40. The last bit has been stubborn.

    Essentially it comes to learning how to RELAX your eyes. Myopia is caused by straining and staring.

    One of the exercises is sunning and palming where you close your eyes and face the sun and let your eyes relax.. Then you cup your palms in front of your eyes and relax into the darkness. alternating back and forth a few times a day.

    I could go on and on, but just wanted to say that myopia can be helped as well as far-sightedness. The optometrists seem only to want to put you in glasses, some are sympathetic to NVI though. I would love to hear other success stories if they are out there.

    Matthew Muller wrote on June 28th, 2011
    • Iiiiiinteresting. I’ve been dealing with anxiety-related issues since college, and my eyesight (which was myopic but stable during college) has been steadily plummeting during this entire time. Additionally, I have been dealing with issues of excess muscle tension in other parts of my body, also related to anxiety.


      cTo wrote on June 28th, 2011
    • I read somewhere on the internet there is a similar YOGA technique involving palming which promotes better vision…

      Isis wrote on June 30th, 2011
  27. I’ve always thought that eyesight deterioration might also be related to the time we spend focusing on nearby objects.

    It seems that “time spent outdoors” doesn’t necessarily pinpoint sunlight as the active ingredient; the outdoors imply both brighter light and larger focus depth (on average).

    Are there any studies separating the two elements, e.g. a study showing that reading outdoors does not affect eyesight?

    Alex wrote on June 28th, 2011
    • “I’ve always thought that eyesight deterioration might also be related to the time we spend focusing on nearby objects.”

      That’s what I thought. I think it’s true because my vision was fine until I started to do massive online gaming (shush…all of you lol).
      I don’t online game anymore but I still do research every day. I also had a computer job for many years contributing to the problem.

      I stopped wearing my eyeglasses for neasightedness because it can cause the retina to detach from the eyeball and cause blindness. I don’t even miss my glasses, I see fine, and the mild double vision I have on objects far away doesn’t bother me. Sunshine and eating primal for over a year now has done nothing to improve vision. I’ve read that concentrating on looking at something in the distance can improve vision…maybe it’s true but how do I reverse this 20 year long damage done to my eyes?
      I’d have to stare into the distance for the same amount of time to correct my internal lense.

      Primal Palate wrote on June 28th, 2011
    • Agreed. If you are outdoors, you can’t help but look into the distance at least some of the time.

      Karen wrote on June 28th, 2011
  28. I used to play outside all the time. It’s only in the last 5 years that I found out I was nearsighted. I did however go through that whole “it’s the 90’s, I’m grunge, I’m depressed, and I want it to rain all the time” phase (which actually lasted until I was like 35). I spent a lot of time avoiding the sun because pasty white is the new tan. Or so I thought.

    PJ McNiel wrote on June 28th, 2011
  29. Sunshine makes me HAPPY! :-)

    Primal Palate wrote on June 28th, 2011
  30. Only started wearing glasses in my 30s, and it was for farsightedness…which, oddly, makes computer work (my dayjob) hard (hm!).

    I can actually still see fairly well, I just get headaches if I stare at computer screens too long. On weekends I don’t bother with contacts unless I intend to watch a lot of TV or play on the computer…and I usually don’t. I’d rather be outside or reading a book (which doesn’t require glasses) than doing what I do in my dayjob. :)

    Steph wrote on June 28th, 2011
  31. An issue like this gets pretty complicated. On the one hand if the statistics are truly accurate, then there is obviously some social factor at large which is contributing to the general increase in myopia. Does this effect certain geographic regions however? It would be tough to really make the conjecture that people are spending more time in-doors that lets say 50 years ago.

    Personally I developed myopia when I was twelve, spend almost all my time outside, my parents are big nature buffs, and that obviously didnt make a difference in my vision impairments.

    There are so many factors that effect individuals which could lead to a greater chance of myopia. Spending more time outside may in fact be better. These kind of tests should be recreated in different regions however, such as iceland and nordic countries where they go through months of continual light and continual dark.

    GymyGym wrote on June 28th, 2011
  32. I grew up in farm country in NZ and spent a huge amount of time outdoors playing in the dirt, but my eyes suck 😛 But it runs in the family and we had poor nutrition too.

    Nion wrote on June 28th, 2011
  33. I think there’s too many confounding effects here to isolate sunlight as the main reason why spending more time outdoors correlates with less myopia, and why the rates are increasing.

    The eye appears to regulate it’s own growth… by generating varying growth hormone levels in response to focus. In our natural environment, we would have had much less opportunity for up-close focusing, so the system evolved to operate in an environment with predominantly distant focusing. If instead your dominant activity is up-close focusing, this system cannot regulate eye growth correctly. High insulin levels from a high-carb diet also seem to disrupt the system (Cordain et al

    So at the same time we’ve been going outdoors less, focusing up close more, and getting more sunlight. Myopia rates could be increased by some or all of these, plus as-of-yet unidentified factors.

    Myself, I developed myopia around age 13 despite spending much more time playing outdoors than most children. But I *also* spent virtually all of my indoor time focusing very closely: reading or on the computer.

    healthyengineer wrote on June 28th, 2011
    • Glad to see the insulin link. If hyperinsulinemia is warping lens development, those who were spent more time active outdoors would be expected to be less susceptible to the same high carb diet. Perhaps this also explains the rise in the glasses-IQ association–a strangely intuitive but false stereotype that psychologists have struggled to explain. Sunlight may play a role but I think it is far more likely that time indoors means time spent reading or playing video games instead of running and playing outside. And since everyone in The Zoo is suffering from excessively carb-rich diets, exercise will show a protective effect. If this hypothesis is true, it may appear to be an interaction between diet and exercise. But if excessive insulin is the culprit, anything that increases it (refined grains, sitting) will be bad and anything that decreases it (exercise, fasting) will be better.

      DeyC3 wrote on July 3rd, 2011
  34. These studies showed that statistically the kids who spent more time outdoors were less nearsighted. Any one person may still become nearsighted no matter how much time spent outdoors, but on average, fewer will become so.

    Karen wrote on June 28th, 2011
  35. Both of my parents have perfect eyesight, as does my sister. Despite an entire life spent outdoors (in TX), but habitually reading anything I could get my hands on since 4, things started going blurry for me in high-school, but I’ve remained at 3.25 since then. I’m staying away from corrective keratome procedures, as it’s still too “new” to log long-term effects, for my comfort.

    nbongo wrote on June 28th, 2011
  36. My family seems to be the exception to this theory. I have six siblings and two parents, ranging in age from 43 to 82. I note this because, as children, all we ever did was play outside. After all, there was no such thing as cable TV or any other electronic distractions. Even in the winter, we were outside in the snow. My father worked as a landscape contractor for 30 plus years, and most of us worked with him during the summers.

    Eight out of nine of us have required vision correction. I used to wear -10 and -12 contact lenses before I had LASIX 13 years ago. I still get lots of sun, take fermented cod liver oil and high vitamin butter oil daily, and eat a primal diet. Even so, I recently had to get my first pair of glasses since my surgery.

    Obviously, in my family’s case, genetics is a strong influence.

    AnnieC wrote on June 28th, 2011
  37. I played a lot outside as a kid. One of my eyes is near sided and the other is far sided. Its kind of crazy.

    Gary Deagle wrote on June 28th, 2011
  38. wonder how much it has to do with only having to focus on things within a 20ft (or smaller) radius when you’re indoors all the time.

    ottercat wrote on June 28th, 2011
  39. After discovering that my niece and nephew had been in a foster home for 2 years I took them both into my home. At the ages of 6 and 3 they had spent all their lives with a junk food diet, computers, TV’s, Gameboys – anything to keep them quiet – firstly by their parents and then their foster carer. Luckily both children were ‘skinny’ but their other problems started to add up – the 3 year old was in 12-18 month clothing, who couldn’t get warm, couldn’t walk more than 100 yards before becoming exhaused and the 6 year old had, hypermobility, fallen arches and severe myopia – that hadn’t been dealt with. The optician felt that with all the changes these poor children had gone through he would let her settle in her new home and new school and review it then, not wanted to add to the stigma of wearing glasses in a new school.

    6 months later – My boy had caught up, in height and weight, to within 6 months of his age and my girl – hypermobility was sorted, arches had developed and no longer needed glasses. The optician was astonished – he had never seen anyone’s eyesight return to near normal. He continued to examine every 6 months for another year, then to yearly. We are now 5 years down the line and still no glasses are required!! The change in their lifestyle? Real food – meat, veg, limited TV, outdoor play, bare feet whenever possible, sun caps not sun glasses, walking a mile to school and back every day, scooters, bikes, skipping ropes. I truly believe their change in lifestyle saved them in more ways than one.

    SuzieP wrote on June 28th, 2011
  40. Yes! Which is why it’s a bit unfortunate that there are several photos of you wearing sunglasses – and Richard Nikoley too.

    GWhitney wrote on June 28th, 2011

Leave a Reply

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

© 2016 Mark's Daily Apple

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