More excerpts from the book.
“Now you already have quite a bit of insight on the topic of myopia. What you just spent a short time reading is material that most people never learn about at all. Well done! It’s also things that took me the better part of a decade to find, verify, sort through misinformation and pseudo science. It’s certainly not easy to get the full picture, so don’t feel bad if all this seems so obvious in hindsight. Things always make sense after you know them, and it might appear that it should have been simple to see from the start.
But here we are. You know that the chain store optometry office is in all likelihood actually a glasses sales retail shop. You know that the diagnosis is biased towards selling you things. That should take off some of the pressure in taking too much stock in the story of “permanent myopia”. And you also now know what to make of the whole “myopia is genetic” story. Yes it is, and also no it isn’t. It will affect your child most certainly, in terms of how much environmental stimulus will affect the eye (more on that soon). But you aren’t powerless to stand by and watch your child’s eye become less and less able to see clearly.
And that’s where we are now. We unmasked a lot of the stories and now it’s time to look at how that myopia actually happens. This will put us on a path to start looking at ways to prevent more myopia and an answer to the question whether myopia can be reversed.
A quick aside here. I remember talking with this very old French optometrist in Phnom Penh, Cambodia. He said this to me, something that really struck a cord. “There is no illness
Let’s talk about that now, the eye, and how it actually works. And bear in mind that we want to get into this topic not in a way to impress you with all my jargon or confuse you into accepting some kind of authority. Rather I want you to understand how the eye works, in respect to understanding myopia. So we’ll stay jargon free here, though I’ll give you some references to more detailed biology reading if you want to continue reading.
First you already know that the eye adjusts for focus. In order to see clearly far away and up close, the eye has to adjust a lens that sits in the front of the eye. It’s sort of like a camera, where the lens has to move in order move the focal plane from a far point, to a near point for clear focus. So when you look far away the lens in your eye is actually shaped differently than when you look up close. It happens so quickly that you don’t even notice, but for every change in distance the lens in your eye adjusts to give you clear vision for that exact distance.
The way the lens shape is changed, is by a circular muscle (the focusing muscle, or “ciliary) around the lens. It’s a beautiful construct, adjusting your lens many hundreds of thousands of times each day, every day, your whole life.
This muscle is a key to understanding myopia. We will talk about this in more detail in a bit, but there is a difference between early myopia, before the first glasses, and progressive myopia, after the first glasses.
The first kind of myopia is called pseudo myopia quite often, in medical literature (“pseudo”, as in, not real). If you are into researching medical literature and clinical studies you might also like the keywords “ciliary spasm”, and “near-induced transient myopia”. There is actually a shocking amount of research that shows how your child’s eyes first become myopic. But, more on that later. Let’s get back to the eye.
The focusing or “ciliary” muscle works like any other muscle in your body. It’s designed to be relaxed most of the time, and tense, “working”, some of the time. Like when your arms are resting by your side, there’s no effort involved. When you move something, or pick something up, the muscles have to work briefly, before returning to a state of rest. If you spent all day with your arms stretched out in front of you, your muscles would get quite sore. In fact, I bet you can’t keep your arms stretched out in front of you for very long, before your muscles start to let you know that they aren’t liking all that effort. And if you manage to keep your arms stretched out way, way past that, eventually you’ll get a muscle spasm. Right? So far, pretty simple.
Now here is where things get interesting. Your child’s eyes, your eyes, are designed to mainly look in the distance. Far away, or some middle distance, people you are talking to, things you are looking at. Most of our eyesight, for most of human existence, happened at distances further than at least about 1 meter. You might look closer to prepare food or play with things, or build something. In all those cases your ciliary muscle continually adjusts in shape, a little more distance, a little less distance, always in motion. And more often than not, the muscle will be relaxed when looking at a distance.
This is very, very important. The focusing muscle is relaxed when you look at a distance. The close you look, the more tense the muscle gets. It is at its most tense when you look at something just a few centimeters from your eyes.
And here is the other part of the puzzle: the ciliary muscle doesn’t have a feedback mechanism to tell you that it’s tired. Your arm muscles will have a burning sensation when you keep them outstretched too long. Your eye’s focusing muscles, they don’t have this feedback loop. We don’t know why, but the important thing is that your child doesn’t get the “ow” feeling from staring at a book at 20 centimeters up close, even though those focusing muscles are very tense and getting quite exhausted.
Is it dawning on you, what is happening? And again here, as with all other parts of the book, I’m trying to keep things to where you can verify the information easily, and see ho the puzzle pieces fit. There is no debate about this ciliary muscle activity. Nobody will dispute that it’s relaxed when you aren’t focused up-close. Nobody will debate that a muscle that stays tense for long periods of times will eventually spasm. And lots and lots of studies talk about pseudo myopia and NITM (near-induced transient myopia) which is caused by looking up-close for too long.
So far not complicated. You may even have read advice talking about taking breaks from close-up vision. That alone though won’t prevent your child’s myopia. We have to dig deeper yet.
There is a second part of how the eye creates focus. Immediately you have the focusing muscle. But the eye is an amazing system. It’s designed not just for immediate focus, but it also has a system built in to account for environmental changes, and changes due to your child growing. Something here that is worth knowing: Your child’s eyeball has the lens in the front, with the focusing muscle, and then on the backside, inside the eyeball is the retina. This is where the millions of rods and cones take the image projected on it, and send it on to your child’s brain. Like a tiny movie theater inside your child’s eyeball, the light travels through the lens, through the eyeball, and is projected onto the retina.
Now imagine this: At birth, your child’s eyeball is about 16 millimeters long. By age three, your child’s eyeball is about 22.5 millimeters long. It is fully grown by about age 13, at about 24 millimeters. So here we find out that your child’s eyeball changes in length. Most babies are actually farsighted, the opposite of myopic. As the eyeball changes in axial length, it creates emmetropia, the natural state where your child can see both near and far clearly. Even more fascinating is that this eyeball growth is dynamic. Studies find that axial change is based on environmental stimulus, the child’s eye actually adjusting based on the actual image.
Back in 1973 a study was published using avian eyes (very similar to human eyes), related to this subject. It found that environmental stimulus caused the bird’s eyeballs to elongate, creating extreme myopia in a very short period of time.
Since then many studies confirmed that the environment causes the axial length of the eyeball to change. This is true for basically all types of eyes similar to humans.
A 2004 study published in Neuron combines the insights from the past decades, discussing these very key insights that science has came to understand about the development of the human eye.
“As with other organs, the eye’s growth is regulated by homeostatic control mechanisms. Unlike other organs, the eye relies on vision as a principal input to guide growth. In this review, we consider several implications of this visual guidance. First, we compare the regulation of eye growth to that of other organs. Second, we ask how the visual system derives signals that distinguish the blur of an eye too large from one too small. Third, we ask what cascade of chemical signals constitutes this growth control system. Finally, if the match between the length and optics of the eye is under homeostatic control, why do children so commonly develop myopia, and why does the myopia not limit itself? Long-neglected studies may provide an answer to this last question.”
That’s not the most easy to read structure, but it’s incredibly important as a summary. To understand myopia, to understand what goes on with the eye, it’s worth re-reading this one. “The eye relies on vision as a principal input to guide growth.”
Genetics play a role, as we looked at earlier. We have the focusing muscle that affects immediate focus. But now we have the third piece of the puzzle, the system that runs the long term focusing bias of your child’s eyes. We now know that the actual eyeball changes in length, first from birth, and then to account for how the child actually sees the environment.
Things are getting interesting!
You probably realize by now that this is quite the rabbit hole. I’m tempted to show you dozens of studies that all delve into this subject. They aren’t so easy to read (I will link some to you at the end for further reading), but they all come to the same conclusions. The eyeball isn’t disconnected from the experience of seeing. It is in fact completely connected to the experience. It will grow or shorten, based on its environment.
Here is another tidbit you might find interesting. One single millimeter, the smallest increment on a metric ruler, how much do you think that this one millimeter of eyeball length affects your child’s vision? Remember, the whole eyeball is going to be about 24 millimeters.
I will tell you. One millimeter of axial change (length change of the eyeball), equals three diopters of change in vision. Three! That’s quite a lot, for a tiny bit of change in length.
Think about all of this. The way we get glasses prescriptions at the optometrist, we never learn about all of these systems that keep the eye in balance, and vision clear. The lens, the focusing muscle, the retina, and the eye’s ability to understand the environment and actually adapt in length. It’s a staggering amount of sophistication that runs your child’s vision. And we haven’t even looked at the brain yet, which is by far the largest piece of eyesight!
All this, and you get a ten minute eye exam, and a pair of lenses stuck in front of the eye. Once you start to appreciate all the beautiful complexity of the system, it’s awareness of it’s own environment, does two pieces of curved plastic really seem like the best possible answer?
The important thing to get out of this chapter is just a basic understanding of your child’s eyes. I want you to know that those eyes aren’t at all broken. On the contrary, they are actually very much working as they should, adapting to their environment. They are full of mechanisms to make sure focus happens, and by the very fact that myopia happens, you are getting confirmation that the eye is working as it should. The eye is changing as intended. The problem here isn’t your child’s eye, at all. Remember what I said, about their being no cure for myopia, because there isn’t any illness? Well, here we are getting closer to this truth. Your child’s eyes are just fine. The problem, as you are probably realizing by now, isn’t to be found in the child’s eyes at all. Rather, the problem is the environment.
Which of course is the best of news. You can’t change the eyes of your child. But you can change the environment. And as your child’s eyes are obviously working properly, once we give them a healthy environment, we’ll get the sort of healthy vision you have been wishing for all along.
Let’s look at the environment, now!”
Tasty, tasty nuggets! ;-)
Enjoying these bits? If you’ve previously posted in the forum on your own progress, consider putting that on our new Facebook account.
Why the nudges? Here is a bit of the backstory:
Alex promised Neha to get some feedback posted on Facebook. He isn’t looking so great right now since that promise has resulted in … zero feedback so far. Neha asks, Alex, what’s going on there? Does nobody care? Something else? She has been working on promoting #endmyopia, and getting a lot of feedback asking for Facebook. But then our Facebook is looking less than entirely encouraging so far. It doesn’t end up being so ideal! :-(
So we put together a program (Keep Your Access), to provide some incentives beyond just asking for your help.
But I know how it is. I personally don’t even use Facebook, and going out of my way to post something for somebody else is rather a stretch. So don’t feel bad if you are one of those who enjoys the site but hasn’t really felt compelled to add something.