How to maintain good vision amidst the myopia epidemic | Hacker News Reader

How to maintain good vision amidst the myopia epidemic

ssathe.substack.com

73 pointsplun979 comments

Article misses the mark a little bit. "Outdoors" preventing myopia isn't about focusing distance, it's about light levels. Dimmer light makes the eye think it isn't done growing, so it grows more.

You can replicate those light levels indoors, if you're bloody minded enough to do so. It's somewhat expensive but for a tech-enabled crowd not too difficult.

You need about 10x to 100x the lighting most people are satisfied with indoors, and you need to turn it on whenever you're in the room and leave it on between sunrise and sunset. This is easiest with timers and automation.

The most important thing about all of this is to realize that children NEED outdoor recess sometime between the hours of 10am and 2pm every day. They don't have to be directly exposed to the sun, but they need to be in an environment with >1000 lux, more is generally better, for a number of hours. This will prevent their growing eyes from continuing to grow indefinitely.

We know this because there was an intervention in Taiwan, which has extremely high myopia levels in children (80%+ last I heard), and it dropped myopia from ~80% to ~35% in the intervention group. That's an astounding effectiveness for something free.

Interesting, it seems really likely that more light indoors should be good. Do you have a reference, a scientific study on the topic? Thanks!

Here's a couple from a random search for the convenience of the forum:

https://pubmed.ncbi.nlm.nih.gov/29371008/

https://reviewofmm.com/light-as-a-tool-for-myopia-control/

I can't find the site that I read a while ago, it was very similar to the myticker.com site that was posted the other day for heart disease but focused on myopia.

Thanks for sharing this! I've never heard of this research, but it sounds very promising.

I also found this Guardian article from a Google search: https://www.theguardian.com/world/2025/mar/01/shortsighted-t...

It's difficult for artificial light to compete with full-spectrum natural daylight from an infinitely distant light source (sun). See previous attempts at sunlight simulation indoors.

I have fairly bad myopia (-6) and I was outside a lot as a kid. I don’t buy this argument, at least not universally.

Practically nothing in health science is universal, your anecdote does not disprove anything.

And I had fairly bad myopia before I could read or had ever seen a computer, would you like to reject the argument that reading or screens are relevant as well?

I've read a number of anecdotes about benefits of bright, full-spectrum indoor lighting and I'm increasingly sold on the idea.

The only thing that makes me hesitant is the extreme unpleasantness of direct high brightness artificial light. I wonder if an indirect lighting setup of similar brightness could be as effective.

It is. The best I've seen make use of essentially bright overcast levels of lighting, so more like 2000 lux, and it's extremely pleasant.

This guy has a pretty compelling version:

https://www.youtube.com/watch?v=6bqBsHSwPgw

If you look at his scatter pane, that's where I would go. There are companies that sell similar lights retail, but they're perhaps 3x as expensive.

I'm not sure why you're convinced that focusing distance is irrelevant. Everything I've seen indicates that it is the combination of focusing distance and light level.

Also... 100x the lighting indoors strikes me as quite difficult? Do you have any examples of a realistic setup?

Because studies that controlled for focus distance (ie compared children reading indoors v children reading outdoors) seemed to show that focus distance did not have an impact.

Late reply, but most of the pro-focusing-distance crowd agrees that it’s time in peak sun, plus a fairly small number of daily “reps” of near-far focusing that is sufficient. In other words, kids could spend 99% of the time outdoors just reading a book, and the handful of glances at a tree in the distance, stop sign, bird, etc would be sufficient. Furthermore, as I mentioned to a sibling comment, even if it is just the bright light, with no influence from the focusing (which I doubt!) the only practical way to get that light is outdoors.

Solving focus distance is expensive. If you could prevent this with something cheap, why not ?

The intervention that most advocate for is shifting kids’ breaks to be outdoors during peak sun hours. This is free ($0.) You get 100k lux, high CRI, flicker free light with no power or setup requirements. You also get birds, trees, buildings etc in the distance as “infinity” focus targets, also for free. (Reminder that “infinity” is actually fairly close!) This approach is also proven to improve myopia rates.

Custom water-cooled ultra-powerful indoor lighting setup as suggested by sibling comment: $30k/small room (far focus not included)

Think operating room or photo studio. 100w grow light panel for every 2-3 square meters - so for a typical office, 4 100w lights, with a scatter panel in front.

I really like this video for an example of how to make proper scattering effect, but you can buy similar materials that are more durable and lighter, for in e.g. a drop ceiling:

https://www.youtube.com/watch?v=6bqBsHSwPgw

That's a cool video, but a custom 500W water-cooled setup does indeed strike me as "quite difficult" for your average person. It seems that the LED in the video is the $500 YujiLEDs BC270H, which is 20,000 lumens. In other words, to match midday sun at ~120k lux, for a small room of 100 sq ft /~10 m2, where all light fell directly onto you/the floor and none on the walls, you would need 1.2 million lumens, or _sixty_ of the setups in the video, or about 30 kW continuous ignoring all cooling needs and other losses.

I completely believe him when he says that it feels like sunlight (it's a high-quality, high-CRI, extremely bright light source at infinity!) but us humans are very bad at determining brightness levels. An iPhone flashlight in your face is unpleasantly bright and yet it is a completely insignificant amount of light on an absolute scale. We humans perceive brightness on a sort of relative log scale.

The steelman argument - where someone does indeed build one 500W water-cooled setup with large dish etc - and all of this light falls into a small corner of 2m x 2m - is still only ~5000 lux, roughly an overcast day. To even get to the level of standing in the shade on a clear day - 20k lux - for a regular room, you would need an obscenely powerful setup.

---

The natural response to my comment, of course, is that "well, maybe they don't need those high levels!" The problem is that all of the research indicates that they do. You mention research on Taiwan, which I think is a perfect example. They already did try to brighten the indoors to prevent myopia - minimum government standard of 500 lux starting with a 1999 standard [1], and in many cases brighter than that. You say that they need a 1000 lux environment, which isn't much different than the current Taiwanese indoors. I, on the other hand, say they need a ~100k lux environment, which is orders of magnitude more light. The research agrees with me: it was not the 500 lux standard, but the later introduction of two hours outdoors daily that improved myopia rates [1,2.]

Mind you, this is two hours outdoors during school hours in Taiwan, which is near the Tropic of Cancer (think Mexico, Caribbean, North Africa) and thus has far sunnier winters (Taiwanese peak summer sun is 1.9x winter sun vs 4.2x in Boston, 3.7x in NYC, 10x in London [4]) despite total solar irradiation being similar to Western cities [3.]

[1] https://www.sciencedirect.com/science/article/pii/S016164202...

[2] https://pubmed.ncbi.nlm.nih.gov/34425129/

[3] https://solargis.com/resources/free-maps-and-gis-data?locali...

[4] https://weatherspark.com/y/137170/Average-Weather-in-Taipei-...

I wonder, wouldn't this mean that in nordic countries, where in winter get less than 6 hours of sunlight in total, and where that sunlight is mostly obstructed by heavy clouds, would be the place with most myopia in the world? For example in Latvia where I grew up, winters last from november to march-april, the nights are long, and it can be months without any sunlight. And it gets darker once you go further north - Finland, Norway, Sweden. But back in my preschool, we had 1-4 kids per 30 in the class, with any eye problems. I myself was among those few who had hypermedia, some even got rid of it by age 10-13. And if I look at the my parents, and grandparents - even fewer had need for eye correction.

Genetic adaptation of humans is a thing.

One way to test it out would be the rates of myopia of people from lower latitudes that have migrated to the nordics.

Valid point. I guess then in Canada they could have a lot of such cases, as it has been a major destination for migration. In any case, sounds like an good topic for a research paper

>> Dimmer light makes the eye think it isn't done growing, so it grows more.

Does that mean that populations in places with more sunlight (e.g. close to the equator) have less myopia than populations with less (e.g. close to the arctic)?

Yes, and the difference is pretty significant, but early childhood schooling rates are more significant than latitude alone.

https://nap.nationalacademies.org/read/27734/chapter/5#29

That's interesting. I seem to be the only one around my circle who like bright environments (my work area uses 2 2400 lux lamps). I find most environments too dark.

And I'm the only one who doesn't wear glasses, lol

This article is written in a way that will propagate the myth that screens are bad for your eyes. Screens are not uniquely bad. The myopia epidemic is not caused by screens per se, but by a lack of time outdoors during childhood. What is it about time outdoors that prevents myopia? It is some combination of much brighter light, broader light spectrum, and objects in your peripheral vision being farther away. I don't think it is fully known yet which of these factors is most important, and I am skeptical of claims that one in particular is to blame over the others. But ultimately some combination of these factors provides the signal to your retina to stop growing once it reaches the right size, which prevents myopia.

As long as you get a few hours outdoors most days during childhood, it doesn't really matter (from the perspective of myopia prevention) if you spend your indoor time in front of a screen or not. And if you don't get that outdoor time, avoiding screens won't save you from myopia. Screens are not really relevant here except to the extent that they encourage children to spend less time outside. You could just as easily blame HVAC or other conveniences of modern homes that make it nicer to stay inside.

It could be both. And focus distance may matter. Like, books may also cause myopia. Reading books outdoors may be a bit better than reading books indoors. Using screens at a distance could also be benign.

I keep hearing this, but I spent a lot of time outdoors as a child. Hours every day, riding bikes with friends and running around with BB guns in the woods. We played a lot of video games and read books, too, but we spent plenty of time making tree forts and "sword fighting" with old pipes. Still needed glasses by the age of 7.

Obviously, genetics also plays a role in individual cases. We're talking about the population level here, and genetics doesn't explain the myopia epidemic, because population-level genetics hasn't changed rapidly. Time outdoors has.

I believe that more screen and reading time causes more childhood myopia. That seems hard to refute. I just do not believe, without serious peer-reviewed studies, that "a couple hours a day outside" is the magic cure. Out of my friend group, 3/4 of us needed glasses, and we definitely met the "couple hours a day outside" criterion. But we also loved our Street Fighter 2.

Here's your review:

https://pmc.ncbi.nlm.nih.gov/articles/PMC9114237/

Various peer-reviewed studies exist and have been covered by pop science articles over the past 15 years or so.

Here is an example one; there are likely dozens available.

Study with 65 citations: https://pmc.ncbi.nlm.nih.gov/articles/PMC7607527/

Pop science article with more context: https://www.theatlantic.com/health/archive/2014/05/nearsight... (https://archive.is/OeuC3)

Thanks! The first study is interesting because it links axial eye growth inhibition to high light levels, not necessarily being strictly outdoors (UV) nor avoiding close-up activities like reading. Interesting.

"High light levels" makes it sound like you could just replace 50 watt bulbs with 100 watt bulbs indoors to fix the problem. It's not like that at all. Sunlight is dramatically brighter than indoor lighting, far more than people realize. It would be impractical to replicate sunlight brightness indoors for many reasons: energy consumption, the cost and size of the fixtures, the immense heat it would produce, and generally because it would be uncomfortable to have light sources that bright in close proximity to you.

And again I am skeptical of claims that it is just one factor like brightness alone. There is other research about spectrum and distant objects in view that also shows effects. So even if you did use 100x brighter lights in your house there's no guarantee you would fix the problem.

In my early teens I had 20/15 vision. By my mid teens I was into computers and wearing glasses, despite copious time outdoors.

Just anecdata, perhaps, but same.

I did nerdy kid stuff like read lots of books and use computer screens (uncommon back then, I'm 52)... but I also played outdoors for hours nearly every single day.

Ended up with vision at -6.00 by the time I was a young teenager (don't remember the age it started to slide that way but would estimate around 7-8 or so). Hasn't gotten any worse (or better) since then.

Same here. Both parents though wear glasses from young age so I think genetics will always be the main factor.

Ha! My parents also thought this was the case, I was a child before the internet and phones, my favourite hobby was playing around in the trees next to our soviet commie block.

I had an incredible childhood with building hidden dwellings in the woods, unsupervised fires and bicycle journeys, football, building ice castles etc, swimming and martial arts lessons. My parents even limited my TV time to 2h a day.

But I still had —1 myopia for every grade until 7th.

My analysis is that by that time I got into reading books - both science and fantasy, and then boom my eyesight was fucked.

Thank god for LASIK.

>My analysis is that by that time I got into reading books - both science and fantasy, and then boom my eyesight was fucked.

When I became a heavy reader I speedran long sighted to short sighted. I think 4th grade I got my long sighted diagnosis. 5th grade I started lifting heavier books. By the end of 7th I had more or less the prescription for Myopia I have now.

I don't think that's true at all. I had prefect vision up until I graduated college and started spending 10hr a day behind a screen - within two years I ended up getting glasses, although they are a mild prescription and I don't really need them other than driving at night. My friend was in a similar position and they also ended up getting almost the same prescription.

My eye doctor said it was my eyes optimizing for what they do the most. And that makes sense, I have no eye strain using a computer.

Interestingly my vision is better in the summer, and when I take holidays during the summer and spent time away from the computer my eyes essentially fix themselves. It takes a couple months back behind a screen to need my glasses again.

Counterpoint: I have spent 10hrs a day in front of screens since I graduated from college and my eyes are fine.

Definitely a genetic component as well!

Yes but it's might just be a different mechanism from childhood -> adult myopia. Where you go from perfect vision to -5

> But ultimately some combination of these factors provides the signal to your retina to stop growing once it reaches the right size, which prevents myopia.

Are you conflating retina with eyeball? In some/many cases, it’s the length of the eyeball being too long for correct focus on the retina. The retina doesn’t keep growing and cause myopia.

> In my opinion, it’s too early, too ambiguous, and the jury is out on whether myopia can actually be reversed.

We do need studies on if/why/how myopia reduction works for some people.

However, we already know a guaranteed way to increase myopia:

  1. Wear corrective lens for 20/20 vision for distant objects, e.g. driver license vision test.
  2. Keep wearing distance lens for closeup, e.g. phone at 12".
  3. Keep wearing distance lens for near work, e.g. book or laptop at 24".
  4. Keep wearing distance lens for intermediate, e.g. monitor at 36".
  5. Eye adapts (more myopia) to get 20/20 vision at daily focusing distance, e.g. work laptop.
  6. Optometrist measures that distance correction with lens is now worse than 20/20.
  7. Optometrist increases distance correction to get back to 20/20, for legal (e.g. driving) compliance.
  8. Go to Step 1.

This loop can be broken by measuring the distance in #5 and buying dedicated lens/contacts for that distance. This reduces the burden on both eye and brain.

How does one "buy dedicated lenses for that distance"? The distance between my eyeballs and my screen is 28 inches, but I do not know how to translate this into what to buy.

Ask optometrist for "intermediate lens" prescription for the distance of your screen.

Ask optician to customize the intermediate/computer glasses for your work posture, e.g. looking straight ahead (monitor) or down (laptop).

For those with more time than money, learn from opticians at https://www.optiboard.com/forums/ before ordering online.

"Cheaters": Get the lowest power reading glasses they sell at the drug store.

You can also order 0.75 diopter glasses on Amazon that work real well.

The formula is:

  your prescription - (100 / desired distance in cm).

For your PC that sits one meter away from your eyes, you'd need to subtract 1 from your real degree of myopia, e.g. for -4 degree myopia, get glasses that are -3. Don't forget to calculate individually for each eye.

As a matter of fact I'm using glasses I bought this way right now. I actually find these even more comfortable than my full degree glasses for all-day use too, in terms of eye strain.

I feel it's ridiculous that the medical industry thinks I need to wear glasses that are powerful enough to focus an image of a mountain 100 kms away all day, when my average focus distance throughout the day is probably less than one meter.

These reduced degree glasses are called differentials. If you want to go into the rabbit hole of fixing your myopia, start here: https://www.youtube.com/watch?v=XPIGDSY_xBs

Disclaimer: When driving, you have to obviously wear your full prescription glasses.

I don't currently have any known vision problem nor wear glasses, I was only looking to reduce eye strain since I regularly need to take breaks due to my eyes hurting after using the computer for too long. I have had recent eye exams and they were 20/20.

That being said I'm even less sure how to calculate it now.

The post at the top of this sub-thread is specifically about myopia. It is not applicable to eyes hurting and any calculation would not be applicable to someone without myopia, since the calculation begins with a myopia distance prescription.

So eye strain cannot be reduced without already having myopia?

Myopia or no myopia, afaict the way to reduce eye strain is the same.

My understanding is that eye strain is either caused by unbalanced lightning (e.g. bright screen in dark room), or focusing on close distance for too long without giving the muscles a break by focusing further away. The well known 20-20-20 rule tries to establish that. As a practical advice, you may try adding some small walks, getting some fresh air for a few minutes, or even looking out of the window for a few minutes throughout the day.

FYI, iPhones have a feature to tell you to use your phone further away when you use it glued to your face. If you have myopia, it should go without saying that you should never use your phone with your glasses.

> you should never use your phone with your glasses

Apple could detect that the user is wearing glasses. During FaceID registration, the phone could ask whether the glasses are for distance (myopia) or closeup/reading. If distance, the phone could offer to remind the user to remove their glasses after using the phone for more than X minutes.

I have eye glasses, but I do not use it when I am working on computer, nor when I am reading or writing a book or paper. I only wear it when I need to see things far away. (I also do not have (and do not intend to have) a driving license.)

This is also what I came up with, with my own experience. Basically, everytime I get prescription glasses for myopia, my myopia gets worse a few months later. What baffles me is that none of the professional I've seen (I think 2 ophtalmologists, 1 orthoptist, 1 optician) told me about that Now I feel truly bitter about the eyes professionals, even though I'm sure they are good at catching defunct eyes, I feel like they don't know how what to advise you, when it gets worse and worse.

Another nuance is that vision decreases during the day, so you want to avoid an eye exam late in the day when vision is weak, resulting in a stronger prescription.

Low ambient lighting and dark mode for work will increase pupil dilation and reduce focus. Better to match monitor brightness with natural ambient light levels.

Vision therapists are better at personalized treatment, https://locate.covd.org

It's worth trying to reduce myopia, if only to reduce the thickness/weight of glasses, https://hn.algolia.com/?query=walterbell%20myopia&sort=byDat...

I noticed this yes. I even had a eye exam with some eye drop that makes your muscle sore, so you can't focus closely anymore, but the doctor is 100% sure that muscles are not focusing passively

Hmm. I am 67 and require no corrective lenses. Two years ago, at my last exam, the doctor said I was “the one percent of the one percent of people” my age that do not require glasses. All of my siblings and both of my parents wore glasses.

Most of my professional life has been spent staring at screens, usually in darkened rooms, so I have no idea why my sight is still good.

I've worn glasses since I was 6. At least 3 times my glasses have saved me from eye injury.

Us four eyes are wearing safety goggles all the time. I would probably prefer perfect vision instead but blindness avoided is a blessing.

I am not unhappy with wearing glasses all the time. Sure it meant I stink at baseball, tennis, etc., as the ball trajectory is warped by my lenses, but I don't care about that.

Hmm, I wore strong corrective glasses full time as a kid and was good at ball sports. Same for my siblings.

I have astigmatism, meaning my eyes are egg-shaped. This means the glasses are shaped so that the view is "correct" only if my eyes face forward. If I look to the right or the left, the view is warped.

Normally, the brain adapts to the warping, and it also means (as I didn't notice before the doc told me) that I have a tendency to turn my head rather than turn my eyes.

But with the "warp" constantly changing, the brain cannot adapt to it and it calculates the wrong trajectory for a flying object.

Hence my utter failure at hitting baseballs and tennis balls.

The doc opened by saying "you must be bad at baseball!", guessing correctly, and then explained all this to me. He also said I must suffer from severe headaches because of it, and accused me of lying about it when I denied it(!).

Contact lenses solve the problem by moving with your eye, but I tried them and didn't like the nuisance of contacts. (This is not an issue if you have only near or far sightedness.) I could get Lasik eye surgery, but I don't even want to take a small risk of damaging my eyes.

Makes sense, we just had myopia.

Interesting that you didn't get age related presbyopia and needed reading glasses as a result.

It's one of the more annoying things about getting older, if you didn't need glasses before sometime in your 40's.

Left to their own devices (i.e. without external lens adjustments), one aging eye can specialize in closeup and the other in distance. This will lead to monocular vision that is functional for both distance and closeup. This separation can be assisted by corrective lens.

Vision therapy: https://raygottlieb.com/presbyopia

Expensive progressive glasses have neurological impact, not just optical. Better to use separate distance and reading glasses which manipulate only optics, and provide the brain with a physical signal of "mode" change.

I don’t need or use reading glasses. I have tried some +1.0 readers but they quickly cause me vertigo.

Genetically, I've dealt with myopia on the -2.x range most of my life till I had lasik around 20 years ago. However, now my eyes have diverged in the weirdest of ways. I have 20/20 in my right eye but can't read up close - due to being in my late 40's - and my left eye can read up close but I have around 20/80 for near-sightedness. I guess it's "good" I can handle any situation with one of the eyes but playing pool with depth perception sucks! Anyway, I have a new problem this article never mentioned. Floaters. My left eye is full of them and reading anything with these blobs blocking my vision is a game of moving my eye so it "shakes" things up so I can read where it was blocked. I have not found a therapy for it. Floaters is protein waste broken off in the eye and mine never settle to bottom of the eye. Don't take your vision for granted.

Try to experience an hour of 10,000 nits outdoor brightness per day.

Spending a couple thousand on LASIK was the best investment I’ve ever made. The money I’ve saved on prescription glasses alone has already paid for lot of it, and ten years later my distance vision is still nearly perfect. Now only if there was a similar procedure for my neck and posture..

Filtering glasses and large screen staying at distance is the answer

I never wore filtering glasses. Using screens at a distance made a big difference for me.

I just purchased some computer glasses that are optimized for about 38 inches. (A little short of a meter.) I get no eyestrain, and looking far away isn't awful.

I wonder what effects VR and AR will have on this.

Same. Hopefully AR/VR and other display technologies will mitigate myopia.

Why was this downvoted? VR shows an image at infinity which is much better than other display technologies, and new technologies like micro LED chips can be super bright and even rival the outdoors. Together, both hypotheses regarding myopia are addressed.

> VR shows an image at infinity

Most are in fact measured in feet, and only quite a few at that. Still better than being measured in centimeters however.

Head worn glasses simulate infinity/distance, so they do not impose focus or convergence stress on the eye.

Viture glasses ship with adjustable myopia optical correction to -5.00D (no cylinder), or they have an optional frame for custom prescriptions.

Or you could wait until you get into your 40s and your eyes will naturally become far-sighted.

Will they? How come?

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