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!

About the Author

Mark Sisson is the founder of Mark’s Daily Apple, godfather to the Primal food and lifestyle movement, and the New York Times bestselling author of The Keto Reset Diet. His latest book is Keto for Life, where he discusses how he combines the keto diet with a Primal lifestyle for optimal health and longevity. Mark is the author of numerous other books as well, including The Primal Blueprint, which was credited with turbocharging the growth of the primal/paleo movement back in 2009. After spending three decades researching and educating folks on why food is the key component to achieving and maintaining optimal wellness, Mark launched Primal Kitchen, a real-food company that creates Primal/paleo, keto, and Whole30-friendly kitchen staples.

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151 thoughts on “Seeing the Light: Why Sun Exposure May Be Good for Your Eyes”

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    1. I think the more you avoid sunlight the more sensitive you become to it and the worse your vision gets. Think of the person held in an underground dungeon for years, we all know somebody who has done that, now think about how it went for them when they were released and were crying out because of the bright lights. Anywho, maybe try closing your eyes and facing the sun for 15 minutes and see what it does.

      Lactose intolerance comes from consuming milk that has been cooked (pasteurized ) and therefore has all of the digestive enzymes killed. Try adding probiotics to your milk. Then it turns into a kefir type drink and it keeps reproducing (adding milk) at room temp and you keep reproducing those expensive probiotics for the price of milk.

      I wouldn’t assume that milk has puss in it. Dang. That’s criminal. When a cow has mastitis and goes on anti-biotics she is pulled out of circulation. It is illegal to slaughter or use product from sick animals. Cripes, reading this sounds as if cows are laying in poop. Just remember that an unhealthy animal will not be profitable to the producer so even if they hate all people and would prefer to poison them … it is not a money making proposition.

      People who make a living from animals usually love animals! When you love your animals you love taking good care of them.

  1. “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…..

    1. 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.

    2. 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.

      1. 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.

        1. 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.

        2. 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.

  2. 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.

  3. 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!

    1. Wow! yes I too sneeze when going into bright sunlight. No other known allergies except to wheat.

    2. 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?

    3. 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.

      1. 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.

      2. 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.

      3. 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.

      4. 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.

        1. 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!

    4. 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. 🙂

      1. 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.

    5. 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.

      1. 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.

    6. 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.

  4. 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.

    1. 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?)

    2. 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.

  5. 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.

  6. 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.

    1. 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…

    2. 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.

      1. He liked to play on the computer, he now works for Bioware designing video games.

  7. 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.

  8. 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.

    1. 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.

      1. 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.

  9. I heard in a Robb Wolf podcast that grain consumption that causes an autoimmune response has a causative effect on myopia.

  10. 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.

  11. 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 🙂

  12. 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.

  13. 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 ! 🙂

  14. 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.

    1. 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.

      1. 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.

    2. 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.

      1. 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.

        1. 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.

        2. I have green/blue eyes. Maybe I am more photosensitive than others. *shrug*

    3. 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.

      1. 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.

      2. 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.

  15. 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?

  16. 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.

  17. 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).

  18. 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.

    1. I doubt that hundreds of millions of years of successful eye evolution could be undone by genetic drift in a few decades.

  19. 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!

    1. Hello Laura,

      According to Walter Wood in his book
      The Ultimate Unification of Diet, Health and Disease sugar and refined carbs stimulate excessive insulin secretion. Insulin stimulates secretion of IGF (insulin growth factor) which in turn stimulates abnormal lengthening of the eyeball. Scientists have discovered that the fundamental defect in myopia is an eyeball lengthening of the eyeball, which causes light to fall in front of the retina instead of on it.

      The author is also in favor of the hypothesis that light (or sunshine) helps the eye modulate growth but rejects the notion that near work is a primary cause of myopia.

  20. 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.

    1. 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.

  21. 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.

    1. 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.

  22. 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.

  23. 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.

    1. 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.


    2. I read somewhere on the internet there is a similar YOGA technique involving palming which promotes better vision…

  24. 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?

    1. “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.

    2. Agreed. If you are outdoors, you can’t help but look into the distance at least some of the time.

  25. 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.

  26. 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. 🙂

  27. 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.

  28. 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.

  29. 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.

    1. 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.

  30. 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.

  31. 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.

  32. 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.

  33. 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.

  34. 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.

  35. Yes! Which is why it’s a bit unfortunate that there are several photos of you wearing sunglasses – and Richard Nikoley too.

  36. 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.

  37. Very interesting. I am definitely outdoorsy and played a lot outside but I’m still very nearsighted.

  38. 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.

  39. 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!

  40. 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.

  41. 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.

  42. 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.

  43. 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.

  44. 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.

  45. 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.

  46. 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.

  47. 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.

  48. 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.

  49. 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.

  50. 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…

  51. 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.

  52. 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!

  53. 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.

  54. 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…

  55. “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.

  56. 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.

  57. 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”.

  58. 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!

  59. 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.

  60. 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.

    1. 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.

  61. 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.

  62. 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.

  63. 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.

  64. 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!

  65. 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.

  66. 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.

  67. 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!

  68. 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!

  69. does anyone know if sunlight can work wonder for presbyopia as well? ^_^
    (Lady Grok does not like reading glasses!)

  70. 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.

  71. 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?

  72. 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).

  73. 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.

  74. There could be something to the light-exposure hypothesis; my own myopia onset at about 7th grade, correlating both with loss of elementary school recess, starting to become a Coke-aholic, and a lot of reading. My eyes gradually got worse, to about 20-200 & 20-150. Stayed at that level until two years ago, when I started going without my glasses except for reading (use a pair of 1.50 diopter reading glasses from the $0.99 store) and driving. Now my eyes test at about 20-40, presumably due to just a readaption. Amazing, since I never bought into those ‘throw your glasses away after doing these simple exercises’ books that were popular years ago.

    I read some years ago of a study claiming a relationship between sugar consumption and myopia, supposedly from the loss of chromium from the body. I wonder if that was ever supported in subsequent studies.

  75. Im 19, i started to use glasses at 12, my family didn’t have myopia, they are clean, and yes, i didn’t use to play outdoors, i spent a big time playing computer and family game. I wasn’t a very social boy.
    After 12,the story changed, i began to be outside more often and get more friends, and my myopia’s progress stoped. How i know that? I went to the doctor 4 month ago because i broke my glasses, he prescribe me the same that when i was 12 1(L), 0,75(R)

    Just a coincindence

  76. I was diagnosed with Myopia, 2 years ago. Since then, my vision has been getting worse, and despite of 3 months ago the prescription values were -0.75(L)/-0.5(R), I feel that overnight, I dont see perfectly, even with glasses.
    Anyway, my question is about other thing…
    I recently started to do outdoor sports and usually I just have time to do them at the evening, or at night, when the sky is completely dark. I dont wear the glasses during that time, even knowing that my vision at distance is clearly blurry.
    Should I wear them?
    Is an obligation that I should take into account, when doing sports?
    This situation, by being at night, can bring risks, since can worsen more?

    I am aware that those questions should be made to an ophthalmologist, but is only to find an opinion. Thanks!

    1. Myopia usually refers to nearsightedness. If distant vision is good, then you don’t need glasses for those purposes. If, however, your distant vision is blurry (as you indicate), not wearing glasses for evening sports could be risky or even dangerous depending on just how bad your vision is and what sports you’re involved in. Have you considered contact lenses? They might work better for you than glasses.

      Whatever is causing your vision to worsen is definitely a question for an opthalmologist, not a web site, and you should get it checked ASAP. There could be something else going on with your eyes.

      1. Since I was diagnosed with Myopia (2 years ago), I have already consulted 5 different ophthalmologists, just to be sure of what was going on… At daytime, I see well, with or without glasses, but at night I really have to use them, because my vision at distance is blurry.
        At night, when I do sports (started recently), like running or jogging, I never wear them, even knowing that I see worse, because it is darker… in that situation, I dont know if it’s a risk or not.
        I’ve never used contact lenses, and for now, I do not plan to use them.

  77. There is a russian eye doctor Oleg Pankov who is famous for treating myopia in people ( Along with doing eye exercises he has people looking at the evening sun (even with their eyes closed if it’s too bright). Seems to be the same concept, and reported to be effective. Great article, Mark

  78. My family all has perfect or almost perfect vision. I had perfect vision until 10th grade when my eyesight got slightly worse. I think it was due to the fact that I had to do a lot of work for my college applications. Most of the teachers knew that the students eyesight got worse during that period and everyone thought it was because of all the late night reading and computer work. However, my eyesight was still around -1.25 which was fine by me ( a jump that happened in 2 years btw, I was -0.25 before that). In uni however, I was in a city where the weather was atrocious and rained everyday. I also had classes twice to three times a week and barely spent any time outdoors at all. My eye sight jumped from the -1.25 before college to the -3.25 I have now. -2 in 4 years, I started uni at 19. Around 20 most opticians will tell you your eye sight will no longer change much. Everytime I’d ask if its’ gonna stop getting worse, they’d say yes, this is the final change you’re getting too old for that. I’m 23 now and it’s still changing. There’s nothing otherwise wrong with my eyes btw, since I wear contacts I get in depth eye check ups. It’s funny actually, how little they know about what causes myopia. They just throw glasses/contacts at you as if it solves everything. It’s a huge problem that affects the lifestyles of millions of people around the world and there’s been literally no breakthroughs as to what exactly causes this!

  79. Interesting post.

    But too late for me as I am an (older) adult.

    From what I can tell from reading here and there, it was originally thought that “close work” – – lots of reading – – and maybe lots of reading in poorly-lit places – – caused near-sightedness. And since atropine empirically helps slow the progression of near-sightedness (by paralyzing the ocular muscles which pull and tug at the cornea to help it focus), it was concluded that “eye strain” caused by too much “close work” caused myopia.

    And this was the thinking up until maybe a decade ago.

    But within the past 5 years or so, it seems there is now research that:

    -disruption of a higher mammal’s circadian rhythm …

    -reduces dopamine within the eye …

    -and the reduced dopamine level permits the eye to continue growing (“over-growing”) axially (meaning, the eye-ball continues to elongate excessively … apparently in youth an eye-ball “grows” … elongates … during the day but usually contracts at night) …

    -which in turn causes it to be difficult for the cornea to correctly focus incoming light rays onto the correct spot on the retina …

    -and there it is, myopia.

    More specifically, you can read the words of the Australian researcher herself in, “New research an eye opener on cause of myopia” – By Greg Hughes and Pauline Chiou – CNN – June 1, 2011:

    ” … the effect of light was mediated by retinal dopamine, a known inhibitor of eye growth whose release is stimulated by light … “.

    So yes, in a way, “close work” and “eye strain” were causes of near-sightedness … BECAUSE they almost always occurred over long hours inside a classroom, or library, or at one’s desk at home, reading under lamp-light. The actual cause seems to be significant lack of real sunlight (as you mentioned), which in turn disturbed our circadian rhythm, which in turn allowed the eye-ball to over-elongate.

    And so, 75% of college students in Taiwan are near-sighted, and many studies show that the higher one’s educational attainment is, the more near-sighted they usually are.

    I’m stable now at around -8.00 diopters in both eyes, but it would have been nice to know that maybe getting an hour of sunlight each day, regularly, back when I was 8 years old (and keeping up with it constantly and consistently), could’ve kept me at minimal near-sightedness …

  80. Hi, This is so interesting.
    I had a overprotected mother who would never let me go outside and play. I was only playing with my sister who is a years younger than me. I was born with a lot of vision problems but nobody in my family has any issues with their vision. I have antisemitism and myopia. I thought the reason was lack of vitamin A. I don’t really know what to think.
    As i mentioned before, my sister and I are a year apart and we have been raised together the same exact way, I started wearing glasses when I started elementary school and never did any exercise or has surgery at all. I am not doing any surgery. I have been reading about improving the vision with exercises.
    Hope it works. I know it has worked for people that have been consistent with the exercises.

  81. I don’t know about the sun connection but I do want to point out that a moderate myopia isn’t really that big of a deal. Without my glasses I can’t read text several inches high across a room, but if I didn’t need that level of visual precision for situations like work and driving (neither of which are very groklike) , I could otherwise function quite adequately in life.

  82. I’m 24 and have problems seeing far off, when I was a child I stayed in doors alot. I watched movies and would have my room completely dark now when I go outside I’m taking the sunglasses off. I’m trying to help my vision and I think its working but I’m not for sure.

  83. I was myopic well before my one-room-country schoolteacher phone my mother and suggested getting my eyes tested about 1948 when I was eight years old. Every year I needed a new prescription with stronger glasses until I was 17, when I supposed it was because I’d outgrown that tendency (but I was also in college, spending fewer hours in a classroom, walking outside between classes, etc.) My vision changed little until early 1980s when I was using a computer most of the day at work and taking computer programming classes (for fun) on my own time, when my eyes started doing what they’d done as a kid! The optometrist was amazed that I could clearly read fine print with the greater concave lenses (at age 42, when most people need bifocals even if they’d never needed correction for vision before), but realizing that the eyestrain from over-correction for close work had been a problem as a child, I found some old glasses that focused right for close work and asked him to give me bifocals blended top to bottom with that correction, and they needed no change for 13 years. Now I insist on single-vision glasses just the right correction for computer work and gladly change glasses for that. (The age-related changes are such that I can read in bed without glasses, holding the book a bit closer than recommended, but don’t have to close one eye to avoid seeing double anymore.) So I suspect that some children automatically look up and far intermittently while reading and others, who don’t are more likely to be myopic.