Shedding Light on Myopia

March 18, 2015 7:24 PM

Nature reviews the rise of short-sightedness and the connection to outdoor light exposure.
posted by parudox (36 comments total)

Huh. I already knew that I wasn't short-sighted because I sat around reading too many books, but I never would have guessed that I was short-sighted because I mostly read them inside.
posted by jacquilynne at 7:38 PM on March 18, 2015 [5 favorites]

How is outdoor fight exposure a factor? I tried to read the article but the words were too small.
posted by uosuaq at 7:44 PM on March 18, 2015 [15 favorites]

Thank heavens I spent much of my childhood reading in the tops of trees.
posted by kinnakeet at 7:53 PM on March 18, 2015 [3 favorites]

Ah, this explains so much. As a nearsighted kid with many nearsighted family members and friends, I used to idly wonder how the hell societies got anything done back in the days before glasses when, as I imagined, about half the population would have been seeing anything beyond arm's length as a blur. I speculated that the people who got famous as incredible archers were just the ones who happened to have 20/20 vision.

This makes a lot more sense.
posted by ostro at 8:14 PM on March 18, 2015 [9 favorites]

Omg I was just thinking about this today! There was an article in the NYTimes re a study a few years ago linking the two! I think it was in their health blog. Darn if I recall exactly but definitely NYTimes!
posted by discopolo at 8:14 PM on March 18, 2015

Reading comprehension fail...

I thought this was about how living in the age of computers causes increased levels of hyperbolic behavior.
posted by Reasonably Everything Happens at 8:52 PM on March 18, 2015

I assume the same effect is seen in adults as well? If so, I sure hope that natural light that comes through windows is enough to keep the badness at bay. I hate getting blinder, but I might hate being cold more.

Also, it would be great if someone would start building computers with high quality reflective/transflective displays. I wouldn't have to hide from the sun so much if it didn't make it near impossible to read my laptop's screen!
posted by Kilter at 8:55 PM on March 18, 2015 [2 favorites]

ostro: "I used to idly wonder how the hell societies got anything done back in the days before glasses"

They didn't, in relative terms. Presbyopia reduced the intellectual productivity of societal "senior" citizens (ie, 40+) to a tremendous degree.That's why the widespread adoption of corrective lenses was one of the major factors in the European emergence from medievalism.
posted by meehawl at 9:43 PM on March 18, 2015 [30 favorites]

I know the article is trying to say that book-reading isn't the issue, but it admits that people are becoming more myopic because they are spending more time in front of a screen. How is that any different from the thought that it comes from books? In both cases you are focusing the eyes at close range for extended periods of time. And way more people spend more hours on the internet today than they ever spent reading novels.
posted by rancher at 9:53 PM on March 18, 2015

If the environmental cause is looking at a screen, I'm curious why prevalence didn't spike early in the 1950s and 60s, when television became ubiquitous.
posted by a lungful of dragon at 10:06 PM on March 18, 2015

rancher, the study corrected for that.

In the early 2000s, when researchers started to look at specific behaviours, such as books read per week or hours spent reading or using a computer, none seemed to be a major contributor to myopia risk.... After five years, one in five of the children had developed myopia, and the only environmental factor that was strongly associated with risk was time spent outdoors

The association with screen-reading vs. book-reading is cultural, not a scientific conclusion. As noted, it began centuries ago, and just became conventional wisdom. Certainly, I was exposed to the criticism of "watching television too close to the screen" as a child.
Now if only people would .... read their screens.
posted by dhartung at 10:16 PM on March 18, 2015 [3 favorites]

I know the article is trying to say that book-reading isn't the issue, but it admits that people are becoming more myopic because they are spending more time in front of a screen. How is that any different from the thought that it comes from books?

They mention that sometimes higher book or screen usage has been correlated with more time indoors (see the Yeshiva example), but the important factor is how much time kids spend indoors, not what they're doing. The article is all about how outdoor light exposure is what matters.

If you read your books or use your screens outdoors you're not at increased risk. Therefore, it's not because of books.
posted by Kutsuwamushi at 10:16 PM on March 18, 2015

my guess would be that it's not book or screen reading that damages the eye, per se, (in fact it's probably strengthening the near-focusing muscles) but the lack of distant objects to focus on that's causing the far-focusing muscles to weaken...like working out your triceps, but not your biceps.
I wonder if it would be more beneficial, long-term, to take these kids bird-watching rather than immediately getting them fitted for glasses.
posted by sexyrobot at 10:27 PM on March 18, 2015 [3 favorites]

"If you read your books or use your screens outdoors you're not at increased risk. Therefore, it's not because of books."

But that's kind of my point. No one reads these things outdoors. Especially since you can't see many screens outdoors due to glare. The amount of people who regularly do these activities outdoors would surely be too few in number to conclude that the main factor was indoor vs outdoor exposure.
posted by rancher at 11:07 PM on March 18, 2015

my guess would be that it's not book or screen reading that damages the eye, per se, (in fact it's probably strengthening the near-focusing muscles) but the lack of distant objects to focus on that's causing the far-focusing muscles to weaken...like working out your triceps, but not your biceps.

Myopia is caused by an elongated eyeball, not weak muscles, as the fine article states. The light-dopamine-growth connection mentioned is a much more likely hypothesis.
posted by benzenedream at 12:45 AM on March 19, 2015 [1 favorite]

"Myopia is caused by an elongated eyeball, not weak muscles,...."

When I don't work out, my butt and boobs become elongated downward.
posted by rancher at 1:14 AM on March 19, 2015

Okay, so, myopia is not caused by weak muscles, but by how the eyeball is growing. From the article:

But what scientists really needed was a mechanism: something to explain how bright light could prevent myopia. The leading hypothesis is that light stimulates the release of dopamine in the retina, and this neurotransmitter in turn blocks the elongation of the eye during development. The best evidence for the 'light–dopamine' hypothesis comes — again — from chicks. In 2010, Ashby and Schaeffel showed that injecting a dopamine-inhibiting drug called spiperone into chicks' eyes could abolish the protective effect of bright light.

Retinal dopamine is normally produced on a diurnal cycle — ramping up during the day — and it tells the eye to switch from rod-based, nighttime vision to cone-based, daytime vision. Researchers now suspect that under dim (typically indoor) lighting, the cycle is disrupted, with consequences for eye growth. “If our system does not get a strong enough diurnal rhythm, things go out of control,” says Ashby, who is now at the University of Canberra. “The system starts to get a bit noisy and noisy means that it just grows in its own irregular fashion.”

I started with glasses at age 7, in second grade. I'm likely someone with a much more genetic predisposition to myopia, because during much of my school years, my vision changed so rapidly I would need a new prescription sometimes twice a year. (I got plenty of time outdoors as a kid, between recess in school and outdoor free range childhood in the desert southwest (where there is plenty of sunlight).) That actually all stopped when I was a teenager and got contact lenses.

I got hard contacts. Not even gas permeable, just hard plastic lenses. Had to work up into wearing them, but got to where they were what I reached for at the bedside when my alarm went off. Didn't even own a pair of glasses for many years. And those little pieces of plastic held my eyeball in shape for a long time. No kidding. Same prescription for 15+ years. And then I started wearing glasses again for reasons I can't remember, and gave up the contacts altogether, and I've had to get a new prescription about every 18 months since then.

My most recent glasses are -10.25 and -10.75, really REALLY strong. I don't even think I could get LASIK, because I don't think there is enough cornea to be shaped to correct for that. And I seriously need to get a whole new round of vision correction because I am not seeing well anymore.

*sigh*

Interesting article. I hope it helps kids who don't have whatever genetics I have from getting myopia that could possibly be prevented.

(Go play outside anyway! It's fun)
posted by hippybear at 1:42 AM on March 19, 2015 [6 favorites]

My people!

Fascinating stuff, thanks for posting.
posted by Klaxon Aoooogah at 2:06 AM on March 19, 2015

Vision problems are now identifiable for kids earlier.

My husband and I both got glasses around 3rd grade (my eyesight is corrected by implanted lenses--nearsightedness even worse than hippybear's!), but the testing is now more sensitive for children.

There are 3 kids in our daughter's preschool class who have glasses, including our daughter (now 5). And no, none of them spend all day indoors at school watching tv or playing with computers. Even during Maine winters the kids play outside, walk to the Children's Museum, walk to parks and feed ducks, sled, etc.

I agree that all kids should spend time being active outdoors, but I am skeptical about the conclusion based on the preliminary findings described.
posted by miss tea at 3:26 AM on March 19, 2015

My most recent glasses are -10.25 and -10.75, really REALLY strong. I don't even think I could get LASIK, because I don't think there is enough cornea to be shaped to correct for that. And I seriously need to get a whole new round of vision correction because I am not seeing well anymore.

hippybear: You could get laser eye surgery - it just would make your prescription less, not eliminate your need for glasses. I know, because I looked into it several years ago, when I had a similar prescription to your own (slightly stronger now).

I know my myopia is genetic: both of my parents have myopia. But I'm fascinated by the increased prevalence - epidemiology on a human time scale.
posted by jb at 4:25 AM on March 19, 2015

A friend of mine (with good vision, naturally) made this postulate at least a decade ago to me. Interesting.
posted by eriko at 6:01 AM on March 19, 2015

I was outside all the time as a kid (though I wonder about the 8 hours a day of school for nine months every year -- that is a lot of indoor time) and still ended up super nearsighted. Maybe it was genetic, or maybe all those months of school was what did it.
posted by Dip Flash at 6:10 AM on March 19, 2015

And I thought it was the other way around - a predilection to being outside and playing sports was because our vision didn't suck.

Time to lobby to move to a windowed cube farm.
posted by tilde at 6:12 AM on March 19, 2015

I've noticed that people (ex-husband, family members, good friends) who are near-sighted tend to be much more into having curtains/blinds/shades in their homes that block their view of the outdoors, even when there is no real need for privacy- as in very rural areas, in suburbs with big lots, or in high-story apartments in low-story areas. I'm far-sighted, so I'm always looking for the far horizon out windows and I avoid covering them as much as possible.

Both of my parents, who were born in the 1920s, as well as most or all of their siblings, were near-sighted. They grew up before tv/home computers and spent time outdoors playing sports, playing in the yard, and walking to school. Obviously there's gotta be some genetic component. Meanwhile, I was by far the most bookish of my siblings, but they are both near-sighted and I'm not. Did I spend more time outdoors? Maybe. Maybe it was my better vision that made me more adventurous in the outside world than my siblings.
posted by mareli at 7:56 AM on March 19, 2015 [1 favorite]

people (ex-husband, family members, good friends) who are near-sighted tend to be much more into having curtains/blinds/shades in their homes that block their view of the outdoors,

I've noticed this with family members and tenants. It's a bit odd to me to put a dresser, a TV, or a media shelf right in front of a window (especially one that already has a blind), but that's the way they arrange their rooms more and more. Causation, correlation, etc.

A friend of mine (with good vision, naturally) made this postulate at least a decade ago to me.

I feel the idea has been out there for some time; during the spate of articles about the 2013 study, I remember feeling it wasn't that new a hypothesis.

The amount of people who regularly do these activities outdoors would surely be too few in number to conclude that the main factor was indoor vs outdoor exposure.

But that's why their study corrected for screen usage. The correlation they found wasn't based on screen time of any kind, but on indoor/outdoor time. I'm sure there may be more rigorous ways to study this and that will happen now, but as a first look into the issue it's more than enough to conclude that this is well worth investigation.
posted by dhartung at 12:16 PM on March 19, 2015

Researchers first demonstrated this in chicks, a common lab model for studying vision. By fitting chicks with goggles that alter the resolution and contrast of incoming images, it is possible to induce the development of myopia while raising the birds under controlled conditions in which only light intensity is changed.

Where are the pictures of this? C'mon, Science! You had one job!
posted by robocop is bleeding at 1:16 PM on March 19, 2015 [1 favorite]

jacquilynne: Huh. I already knew that I wasn't short-sighted because I sat around reading too many books, but I never would have guessed that I was short-sighted because I mostly read them inside.

I've tried reading books outside - LOTS of them! - but inevitably I get too curious, and open them up.
posted by IAmBroom at 1:41 PM on March 19, 2015

hippybear: My most recent glasses are -10.25 and -10.75, really REALLY strong. I don't even think I could get LASIK, because I don't think there is enough cornea to be shaped to correct for that. And I seriously need to get a whole new round of vision correction because I am not seeing well anymore.

My eyes' (natural) vision is worse than that by a full diopter, and I had ICL. EXPENSIVE, and insurance won't cover the $10k, but it was worth it for me.
posted by IAmBroom at 1:44 PM on March 19, 2015 [1 favorite]

I first got glasses when I was 7. That's also around the time when I finally learned to enjoy reading and started spending time not running around outside. And honestly, it took until I was 10 or so to really start spending a great deal of time indoors.

I hate being an outlier here.

On the plus side, I've needed only very small adjustments in my glasses for the last 8 years or so.
posted by Hactar at 2:35 PM on March 19, 2015

I have extremely poor vision, -13, -13.75. I've been told the only vision procedure I can get is lens replacement, as if I had cataracts. I'm pretty sure I have both a genetic and situational predisposition to poor vision, since my family also have glasses, but I spent the most time inside reading.
posted by stoneegg21 at 5:19 PM on March 19, 2015

I have extremely poor vision, -13, -13.75. I've been told the only vision procedure I can get is lens replacement, as if I had cataracts.

Your eyes may have a feature that precludes it, but the usual option for people with high myopia and thin corneas (precluding lasik) is ICL, as linked above by IAmBroom -- it adds a lens inside your eye, but does not remove your natural lens, like cornea surgeries usually do.
posted by Dip Flash at 9:16 PM on March 19, 2015 [2 favorites]

Three or more hours of daily outdoor time is already the norm for children in Morgan's native Australia, where only around 30% of 17-year-olds are myopic. But in many parts of the world — including the United States, Europe and East Asia — children are often outside for only one or two hours.

There's no sensible cost-benefit discussion in this article, which simply implies that your children should be soaking in the sunlight to health up them eyeballs. But myopia is a cheap- and easy-to-correct health problem. Meanwhile skin cancer is epidemic in Australia: "Two in three Australians will be diagnosed with skin cancer by the time they are 70."

For those keeping score, cancer is many times more likely to kill you than wearing glasses.
posted by dgaicun at 10:51 PM on March 19, 2015

does not remove your natural lens, like cornea surgeries usually do.

If I were to go in for cornea surgery and found they'd replaced the lens of my eye, I'd be fucking pissed. (I think you meant to type "cataract" there, maybe.)
posted by hippybear at 12:38 AM on March 20, 2015

If I were to go in for cornea surgery and found they'd replaced the lens of my eye, I'd be fucking pissed. (I think you meant to type "cataract" there, maybe.)

Good grief, yes. At least I used the word for an actual eye part, rather than "chorizo" or some other random word that begins with C. Cataract surgery often (though not always) involves removing the damaged lens and replacing it with a new one; vision correction surgery (ICL) involves inserting a corrective lens but not removing or touching the natural lens.

Thanks for noticing that mistake.
posted by Dip Flash at 6:09 AM on March 20, 2015

For the record, ICL surgery is incredibly easy. A tiny incision (much smaller than the "contact lens"!) is made on the edge of the iris, well outside your vision path, is made, and sealed with two sutures.

Quite literally, the nurse measuring the exact curvature of my outer eye with a special device was far more annoying than the surgery. Back to work the next day.

And when they led me back from the surgery table to the post-op room chair, I read "EXIT" on the sign over the door - the first distant thing in my adult life I had ever read.
posted by IAmBroom at 9:14 AM on March 20, 2015

dgaicun:
Australia and New Zealand are also under the ozone hole. Countries that still have a functioning ozone layer have rates of skin cancer many times less.

What you don't want, is to be burned lobster red, or have skin peeling. Again, this greatly increases your skin cancer risk. However, regular sun exposure, even tanning without major sun damage, may actually have a protective effect against cancer. One possible mechanism is Vitamin D. Most people seem to be deficient in it these days (again, you get it from being outside in the sun), and deficiency is linked with higher overall rates of all cancers.
posted by Elysum at 3:16 PM on March 20, 2015