Am I understanding this right? The choroid layer behind the retina gets slightly thinner when we look at dark details on a bright background, and slightly thicker when we look at bright details on a dark background, and somehow this causes an opposite effect in the overall eye growth over time. So spending a lot of time looking at dark letters on a bright background would cause the eye to become too long and unable to focus on objects far away.
Is there an explanation for why the choroid changes its thickness, and why this change would create an opposite effect in eye growth over a longer period?
So, they eye works pretty much like a camera - but it's not a camera: it's a complex dynamic self-assembling, self-tuning adaptive structure.
The fact that it's geometry is roughly static around a focal length that has sharp focus on the retina is a wonder of homeostasis with at least three known tuning loops:
1) the lens
Moving on swiftly...
2) a slower feedback loop adjusting the choriod (hence focal length) in the order of hours.
3) an even slower loop adjusting the eye geometry over longer periods of time.
The story so far:
We hack our visual sense to be a data channel for symbolic information.
This incidentally messes with the above homeostatic loops causing myopia.
We then hack the eye's optics to correct the immediately problem without fixing the cause and oppose the corrective process by adding glasses or contacts.
We end up at a myopic static point where the balance of forces match.
I remember recently reading about the myopia increase in China and it was largely attributed to children staying much more inside, out of the sunlight, causing the eye to under-develop iirc.
They can test this if they tried getting students to try studying outside under natural lighting for a while. Though in China that may be impractical depending on the city.
Myopia is actually caused by your eye being "too long", and means the lens focuses light in the middle of your eye, rather than on the retina. It seems that sunlight ceases the development of your eye, rather than encouraging it.
Perhaps we evolved to "make use" of UV light to halt our eyes growth.
I read that it isn't a sunlight issue, but an overall brightness issue. If that is true, reading on a bright screen might be better than reading a book.
When I was a teenager I preferred white text on a black background. (Think of the DOS terminal.)
In my very early 20s, I suddenly found white text on a black background extremely irritating. Suddenly, my vision was filled with persisting horizontal lines. (Like what you get when you look quickly at a light bulb.)
Maybe it's because DOS was really grey on black, but on the web, people typically do bright white on black?
I've always preferred a sepia type color scheme. The HN default colors are pretty close to perfect for me. Solarized Dark color scheme is about as dark as I like to get. Going full black background on white text has always been hard for me to read.
When I was a teenager I took a big dose of what I thought was blotter acid. I ended up with HPPD and ever since I have trouble looking at dark text on a white background. Sucks... I used to be a speed reader and now I'm maybe only a little faster than average.
My normal color scheme is a slightly modified 'desert' theme that comes with vim.
Web era began around the rise of LCD displays. CRTs are too non-linear for most people to tolerate black on white, so its a status symbol from around the turn of the century to do white on black.
Not helping matters is the rise of glossy distraction screens, again before the turn of the century the status symbol was ultra low glare matte screens to avoid eyestrain and with the conversion to everything must be shiny its hard to look at a black background reflecting tons of distracting moving shadows so everything must have a white light blackground to cut thru the bright distracting reflections.
> CRTs are too non-linear for most people to tolerate black on white
What does non-linear mean? And what do you mean tolerate?
Before LCD screens all Macs were black-on-white and people loved it. The first Macs were monochrome. I don't recall anyone ever having a problem with it.
Also, I don't remember any matte CRTs -- they're all glossy because their surface is glass.
Also early computers with monochrome CRTs often shipped with actual silk screen pressed between the case and CRT. It was a trade-off, you'd lose a bit of sharpness but there would be no room reflection whatsoever. The Kaypro 10 was a dream machine in its time, it had a bare CRT with a 'matte' glass surface that had been slightly etched. Sharp characters with no layer of silk in the way.
I still emulate the Kaypro 10 with its dull/bright green on black phosphors for coding.
> Web era began around the rise of LCD displays. CRTs are too non-linear for most people to tolerate black on white, so its a status symbol from around the turn of the century to do white on black.
How does this account for things like Atari TOS, MacOS, OS/2 or any early version of Windows that all mainly use black on white for text? The "web era" depending on how you define it could of course have coincided with the LCD era (though in my experience happened more than half a decade earlier, which is generations in computer technology time) but the web didn't somehow invent black text on white backgrounds.
I still prefer dark background with white text to this day, even when the web came around I tried to keep all my software/OS with dark background/white text. To this day I'll try to use "night mode" if available.
It's so much less strain on the eyes, especially during the night or after waking up. Going from darkness to a blazing white screen literally hurts in the eyes.
When I'm forced to use black-on-white (i.e. when browsing most of the web), I find that reduced brightness and increased monitor colour temperature helps a lot.
"One would therefore expect that dark text on bright background would stimulate myopia development and bright text on dark background would inhibit myopia."
Yeah - my eyesight is already really bad, but hopefully there will be something like a Kindle Paperwhite with dark theme so my future children won't have to suffer the same.
Stylus Chrome extension has alternative styles for loads of websites. Eg I make GitLab dark with light text using a downloaded style sheet that someone made, and my HN as well.
Ugh. Dark themes. Can't get used to them. Fine for general terminal use, but impossible for me for larger amounts of text. Can't really articulate why, but it's uncomfortable for me.
I'm not sure anyone's 100% sure, but from what I've read the leading hypothesis is that white light spreads in the retina and is more sensitive to lens distortions (and the pupil is larger when looking at a black screen, so even more distortion). So white letters essentially smudge more in the eye against each other and require more work to decipher, while black letters don't. (White light surrounding black letters could make them "shrink" with the same effect, but this doesn't seem to harm legibility.)
Which is also why it's more relevant to body text, as opposed to display text which is larger and thus less susceptible to the problem.
Could be CRT vs. LCDs. Family all have bad eyesight but my younger sister who spends every waking hour gaming doesn't need glasses. I spent less time on the computer when I was her age but I had a CRT monitor.
I am a 99% sure that "some people are just immune." I have friends my age who played games way more with perfect eyes. I also have a friend who drank soda at work all day and never had a single cavity.
There are a few gym protocols used to train / flex / exert the eyes’ muscles and revert myopia gradually. An expert tutor acting under your doc’s supervision is needed, though.
Nah, there are more recent studies based upon first principles and less stretching protocols than Bates. Still not accepted best practice, though, so individual mileage may vary, my myopic eyesight improved enough to give them a pass.
Not quite true. The ciliary muscles and suspensory ligaments in your eye are largely responsible for ensuring the accommodation-convergence reflex (the process by which your eye focuses on objects at different distances) works properly. It's not a priori non-sensical to assume that actions (exercises, drugs, etc.) that affect the ciliary muscles could change the accommodative properties of the eye sufficiently to decrease the effects of myopia - in fact, that's a part of what happens when you get atropine drops during an eye exam.
Note that this is not an endorsement of Bates' or any other method supposed to implement this in practice. I'm just noting that putting "muscles" and "myopia" in the same sentence isn't non-sensical.
In most cases, myopia is caused by physical properties of the eye (wrong length, etc.). Relaxing the ciliary muscle actually increases the focal distance, so I don't see how muscle-oriented exercises would help.
> in fact, that's a part of what happens when you get atropine drops during an eye exam
Even a fully paralyzed ciliary muscle cannot overcome a wrong geometry of your eye. Whether atropine has any real effect on myopia is controversly discussed.
I agree with everything you said except the last sentence. The (temporary) effect of atropine is well known and uncontroversial, anyone with severe myopia will tell you the same thing - after it takes effect, you'll be able to easily read the Snellen chart with a weaker prescription than you needed before, in my case by about 1D (the extent varies substantially obviously).
As for the rest, like I said - I don't endorse any of the proposed exercise regimens or see much support for them. I was simply pointing out that muscles do affect eyesight and briefly explained how.
> anyone with severe myopia will tell you the same thing
I doubt that. Yes, small children tend to have high ciliary muscle tone, resulting in errors of 0.7D in average. That's well known and that's the reason for cycloplegic refraction. But what's the effect for adults? 0.2D on average?
I've had high myopia since childhood and for me the effect hasn't diminished (comparing between my annual checkups). I don't know any reliable statistics for this, however, only anecdotal experiences and consultations with my various ophtalmologists over the years. Do note that I'm only talking about cases of high myopia (in the 6-12D range at least), I don't know if the effect is as perceptible to someone with better eyesight.
> in fact, that's a part of what happens when you get atropine drops during an eye exam.
Atropine works by temporarily blocking the contraction of the muscle sphincter pupillae (which along with dilator pupillae is responsible for the contraction of the pupil). The cilliary muscle isn't involved. The rest of your comment stands, though.
It is my understanding that atropine (like scopolamine, cyclopentate, etc.) effectively paralyzes the ciliary muscles by blocking muscarinic receptors. This enables an ophtalmologist to measure the "true" refractive error of the eye.
Atropine is also a mydriatic agent (dilates the pupils) and this lets you better see the retina, but that's a different effect than the one I was referring to.
Also I wonder if this means TV and Video Games etc. aren't as bad for eyesight as they should have the same visual statistics as natural scenes (as they display natural scenes more or less) despite TV being demonised as bad for eyesight for generations.
Whereas when you think about it staring at dark symbols on a bright background is really unnatural and therefore it is reasonable that it can affect visual development.
So does this mean that my preferred color scheme of light text on a dark background might be accelerating my presbyopia? I'm at the perfect age for it to start(43), but it sure seems to be progressing fast.
As a German speaker, this title seems very Denglish-ey to me. Is this phrasing valid in English? It seems like the object of 'to make' is necessary and missing, whereas in German it is perfectly normal and correct to phrase things this way (e.g. Tofu macht satt, or Schnaps macht betrunken, whereas in English you'd say: tofu makes you full/is filling, or shnaps makes/gets you drunk).
Not trying to nitpick, just curious if this is actually correct grammar or not.
I’m also a native speaker, and I find this construction recognizable from some literature. Just searched for examples of whether a grammar teacher would allow transitive verbs without direct objects, and I found one of the answers here suggesting it’s ok in English because the object can be inferred from context:
Is there an explanation for why the choroid changes its thickness, and why this change would create an opposite effect in eye growth over a longer period?