Lecture: Evidence-Based Myopia Control

The prevalence of myopia, considered an epidemic in certain parts of the world, is rapidly increasing. This live webinar critically evaluates current methods for myopia correction and prevention as well as practical applications in a clinical setting.

Lecturer: Dr. Fuensanta Vera-Diaz, OD, PhD, FAAO


(To translate please select your language to the right of this page)

DR VERA-DIAZ: Good morning! Give me just one second. I’m going to open this. So I’m Dr. Vera-Diaz, and I’m going to talk today about evidence-based myopia control. I’m originally from Spain, but I’m associate professor at the New England College of Optometry, here in Boston, where I am today. So my work is all around myopia, from the perspective of a researcher. This is the topic I did my PhD on, as well as a teacher, and as a clinician, as we have our own myopia control clinic here at NECO. So today I would like to give a little bit of a review about myopia, so at the end, you are able to apply the concepts that we learned today to understand the etiology and development and progression of myopia, and apply it to your patients, so that you can educate the children with myopia that you have and their parents or guardians and the options for correction, as well as control of myopia. And in that process, it’s very important that you’re able to select the most appropriate myopia control method for your patient. So we’ll start by reviewing what’s evidence-based health care, and then we’ll review what myopia is and what it means. Why is it so important. And we’ll talk a little bit, briefly only, about correction, to spend most of the time on myopia control methods. Which I think is what we are mostly interested in.

>> Dr. Vera-Diaz, can you just share your screen for us?

DR VERA-DIAZ: I’m sorry? Sure, sorry about that. Share screen. There you go. Thank you.

>> Yeah, perfect.

DR VERA-DIAZ: Okay. Let me get this a little smaller. Perfect. Okay. So let’s start by evidence-based health care. What is evidence-based health care? Well, this has been defined by many, but I really like this definition by David Sackett, who was a disciple of Dr. Evans, where he describes it as judicious use of up to date evidence. What does that mean in a practical way? It means we first need to ask ourselves questions. We need to be curious. And for example, related to myopia, a question can be: What’s the best management for my patient who is a 7-year-old Asian girl, and her myopia is progressing rapidly, and she’s right now at -4 diopters of myopia? What can I do about her? So that will be my question. Then I need to be up to date with the literature, and I need to be critical with the literature. We’ll talk about that in the next slide. I also need to know whether that literature available applies to my patients. So if I’m reading a review about myopia control, are they reviewing patients who are within the same population as my patients seated in the chair? A 7-year-old Asian girl? So for best evidence, it’s very important to remember that you are gonna find in the literature lots of different types of articles and books and journals. It is very important to focus on peer-reviewed journals, and at the top of the best evidence, we have meta-analyses. These are the articles where they review all the work that has been done in a specific area. So these are very comprehensive, as well as systemic reviews. I know it’s not very easy to find these articles everywhere in the world. It depends on where you are. Thankfully, more journals are going free online. So we can have more and more access. And many institutions will also give you access to journals, even after you graduate. When we review the literature, it’s very important to be critical, so we recommend that you do not start with the abstract, but with the methods. And when you read the methods, be critical about what they did and whether you think it’s valid and relates to your patient. And be especially careful about the conclusions that you may find in the abstracts of journals, because sometimes they may not be exactly related to what the study was about, for example, in this abstract, we found that OK lens is a useful method for controlling myopia, however, this study was designed to compare ortho-K with atropine, not to determine whether ortho-K was a useful way to control myopia. So be aware and make sure you read the entire manuscript. Okay. So now let’s talk about myopia from the perspective of both a clinician and also an academic who wants to make sure we have the best evidence to take care of our patients. First of all, what’s myopia? Or myopias, because there are many different kinds of myopias. We’ll start with a review of classifications. But first, let me get some information about you. So we have our first question here. The question asks: Which of the following statements is correct? Myopia occurs because the eye does not have enough power. Or B, only high myopia poses a risk for associated ocular pathology. Or C, myopia occurs because the eye is too long for its power. I’ll give you a few seconds to answer. Drink some coffee. Excellent. So it looks like everyone is awake this morning, because most of you selected C, which is correct. Myopia occurs because the eye is too long for its power. And we will go into the other two answers and find out why they’re not correct in a few minutes. So let’s find what myopia means. Myopia is a refractive error off the eye. What happens is, instead of having the normal eye, where when the eye is looking far away at infinity, the objects are seen clearly, in myopia, because the eye is too long, then the image of the objects, when you’re looking far away, is in front of the retina, rather than at the retina. So the image the retina gets is blurry. Now, we can correct myopia with negative lenses — glasses or contact lenses, refractive surgery — we know that. So why do we care so much about myopia? If we can simply move that focal point back to the retina and get clear images with those lenses? We care about myopia for many different reasons. One of them is because it is becoming an epidemic. So the prevalence of myopia is rapidly increasing over the last several years. Especially in the last two to three decades. And this depends — the prevalence depends on what part of the world you are. It is particularly high in South and Southeast Asian countries. Where in some populations, it can get to be up to 99% of the population may have myopia. So these are very high numbers. In the US, it’s about 25% of the population. And again, it depends on which country you are. But overall, in the world, it’s about 25% at the moment. And what’s worse — if the progression keeps going the way that it’s going, the prevalence is expected to be over 50% in the year 2050. So we expect that half or more than half of the population will have myopia in a few years. So a big problem from that point of view. But as we will see later, it’s a big problem as well, because it can have serious consequences. Before, let’s talk about different types of myopias. Different types of myopia may have more serious consequences than others. We can classify myopia based on the degree of myopia. So we typically say low myopia is less than 3 diopters, and high myopia, 6 diopters or more. Everything in between will be moderate myopia. This is a very important classification, because the higher the myopia, the more risk that person is going to have, to have ocular complications related to myopia. We also can classify myopia based on the age of onset. And this is also important, because the earlier myopia starts, it’s going to end up a higher amount. So if a child starts having myopia when they are 4 or 5, they’re gonna end up probably with a high myopia at the end of their teen years. Whereas if they start when they’re 12 or 13, they probably will not end up with very high myopia. It progresses very quickly when the child is younger, and less so later on. We’ll talk about the progression in a few slides. A couple more definitions. Primary versus secondary myopia. We’re going to focus on primary myopia, because it’s the most common form of myopia that most of us have. And in the past, this used to be low myopia. But nowadays, because the myopia is increasing and it’s starting earlier on in life, we have high myopia also increasing. So we have primary myopias that end up being really high myopias, because they start very early in life, and progress very rapidly. We must not forget, though, that we can have secondary myopias. These are myopias that are caused by either systemic conditions or ocular pathologies. And we need to keep that in mind, when we have a patient whose myopia is progressing more than expected. Just keep it in the back of your head. Could there be something else going on here, besides the myopia? We think those myopias will include… Within those myopias, we include the pseudomyopia, which is basically not a real myopia, but when we do a refraction, it shows us a myopia, because the patient is overaccommodating all the time. So we will focus on primary myopias in this talk. Let’s continue to learn why it’s so important, myopia, besides the high prevalence and the fact that it’s becoming an epidemic. We’re gonna have another break and let you answer this question number two, that reads: Since myopia is simply a refractive error of the eye, you can correct it, for example, with laser refractive surgery, and if you do so, you will no longer have any complications related to myopia. And I’ll give you a few seconds. And feel free to keep posting questions as we go. Excellent. So this is not the Case. And let’s discuss why. As we go along, as I said, feel free to post questions that we can answer at the end of the talk. Myopia is a very significant problem, because the prevalence is increasing very rapidly. This means very high financial costs. Not just because we have to pay for eyeglasses or contact lenses or refractive surgery, but also because we have to pay to the doctors, we have to have time off to go to the doctors. So this is a significant financial burden for many countries. And that’s why especially countries where myopia prevalence is very high, such as China, are working really hard on improving this problem. Myopia causes impaired vision, obviously, when not corrected, but even when corrected, eyes with myopia do not have as good functional vision as eyes without myopia do. Myopia can restrict your options for certain jobs, in certain parts of the world, even if corrected. And it also does affect your quality of life. But most importantly, myopia causes a very significant risk for vision-threatening conditions. These are potentially blinding conditions that individuals with myopia are at higher risk for. So this is the most important reason why we care so much about myopia. Because if you have myopia, you have a risk for these conditions, and I will list them in the next slide. But also, if you have higher myopia, you have higher risk for these conditions. So you want to try to slow down the myopia. You’re going to try to control the myopia. Because if you end up, when you’re an adult, with 2 diopters of myopia or 6 diopters of myopia, your risk of having these conditions is gonna be very different. So again, the take-home message here — very important to try to end up with low amounts of myopia, because you’ll have a lower risk of vision-threatening conditions. There’s still a risk whenever you have myopia, because you have a longer eye, but the higher the myopia, the higher the risk. So imagine the eye as a balloon that elongates. So the layers of the eye become thinner, as it elongates. Remember, myopia is caused by an elongation of the eye. The eye becomes longer in the back of the eye. And so there is possible degeneration of the retina, the choroid, myopic maculopathy is very common in high myopias, particularly. And this can cause even bleeding of the macula, which, with the consequence of very poor vision that is irreversible, so blindness will come from this. We have a staphyloma, we can have retinal holes or tears or retinal detachments. All of this in high myopias, but the incidence is also higher even in low myopias, compared to no myopia. Other diseases associated with myopia that are very important are primary open-angle glaucoma. You have a high risk if you have myopia. PSC cataracts. You also have a higher risk of having these earlier on in life, if you have myopia. And you have a higher risk of surgery complications when you have surgery for these cataracts, if you have myopia. The good news is that if you have myopia, you have a lower risk of getting diabetic retinopathy, if you have diabetes, and you have a lower risk of getting age-related macular degeneration. When you age. So very important, myopia. Not just because we cannot see well when we have myopia, but because it increases the risk of blinding conditions. So why does this happen? Why does myopia happen? And who can get it? Let’s answer the third question for today. The question says: Only genes determine whether an individual will develop myopia or not. Is this true or false? A few more seconds. Excellent. This is not true. Because in fact, myopia is caused by — as all other diseases or problems in the body — a combination of environmental and genetic factors. But myopia in particular, the myopias that we are seeing increasing rapidly in the last decades, are mainly environmental. Yes, some patients will have more genetic predisposition than others to get myopia. But if they were not put in this environment that predisposed them to myopia, they would probably not get it. So we know, because there’s a lot of evidence in this area, and you will see throughout the slides how I have written a lot of titles of articles that I’m happy to share. So there’s a lot of evidence that myopia is primarily environmental. The changes we’re doing in our society in the last few decades, in terms of urbanization, living closer together, smaller environments, we spend less time outdoors, we spend more time reading, more time in school, indoors, playing with electronics, all of these changes are making a big difference. In the myopia incidence. So we know from animal models and human studies that myopia is a visually guided process. This means is depends on what you were exposed to see when you are a child. You will have more or less chances to get myopia. So the eye grows as we grow. The whole body grows. The eye doesn’t grow that much. Usually grows about 1 millimeter from early childhood to adulthood. But it does grow as we grow. So how much does the eye grow? So that depends on how much power it has. The eye has power from the cornea and the crystalline lens. The eye matches power from the lens. Which is fascinating, because how does the eye know how much to grow? How does the eye know how much power the eye has? How does the eye know in which direction to grow? These are questions where we don’t have final answers, but there are many scientists working on, and we do have some information, and we’re expecting to find more soon. Another very important question is: What do I need to have in my visual environment for me to have lower risk of myopia? And we again have some answers there, but we don’t have a definitive answer. We do know that spending more time looking far away and outdoors is helpful, but we don’t have specific answers about what it is that is important about being outdoors. So what are the risks for a young child who doesn’t have myopia to get myopia? Or what’s the chance that a patient sitting in your chair will have myopia? Well, first of all, young children don’t typically have myopia. Young children typically have hyperopia. And if everything goes well, when they get to their teenage years, they will have emmetropia. So no refractive error. However, as we know nowadays, many children are developing myopia in their early childhood years or teenage years. So the population where you’re gonna have the highest prevalence of myopia is gonna be in your young adult population. And this is, again, because of environmental reasons. Your older populations did not have the experiences our kids are having nowadays, and they’re less likely to have myopia. So age is very important, and family history is indeed very important. Family history, meaning parental myopia. If we have one parent with myopia, we have more chances of getting myopia than no parents. And if we have two parents with myopia, we even have more chances to have myopia. Now, this may make you think… Well, myopia is genetic. Because I’m inheriting the genes from my parents. But actually, it is not clear. Although part is genetic, a large part is environmental. Because you don’t just inherit the genes. You also inherit the habits from your parents. So if your parents are highly educated, you’re likely to be highly educated. If they spend a lot of time reading, you’re likely to spend a lot of time reading, and so on. In fact, there are studies that show that the amount of time that children spend in near-work activities or outdoors is related to their parents’ myopia. So as parents, we influence our children’s habits, and therefore whether they get myopia or not — it’s not only whether we pass on our genes, but also we pass on our habits. The other factor that’s very important in myopia is race. There is no doubt that Asian populations have a higher chance of getting myopia. And as I said earlier, South and Southeast Asian populations are the highest risk. This is followed by Caucasian populations. African-American populations tend to have a lower risk. Now, when we talked about age, we said that the normal condition is that children have hyperopia when they’re young. So when they’re babies, toddlers, when they’re preschoolers, the norm is that they will have some hyperopia. And as the eye grows, that hyperopia goes away, and they shall end up with emmetropia. But if you have a young child, younger than five or six years of age, and that child has already gotten rid of much of their hyperopia, so they have no hyperopia when they’re 5 or 6, or too low amounts of hyperopia when they’re 5 or 6, this means it’s very likely that they’re going to get myopia later on. So it is preferable that children maintain the normal level of hyperopia. Depending on the age, it’s between 1 and 2 diopters of hyperopia. Otherwise they have higher risk of getting myopia later on. Now, so far, we’ve talked about things that we can’t really do too much about. But now let’s talk about environmental factors that we can do something about. The first one is near work. And this one has been studied for decades — and we’ll say even centuries. It is well established that near work is related to myopia. Now, whether this near work is causing myopia or not is a different story. But it is associated with myopia. There are hundreds — thousands of studies on this. I’ll just mention one of these. It’s not that new, but it’s very significant. For example, in this Israeli population of children, age 14 to 18 years of age, they compare girls and boys in general schools. They found that girls and boys in general schools had a similar percentage of myopia. In fact, girls had a little bit more. However, when they compared girls and boys in orthodox schools, they found that the rate of myopia in orthodox schools for boys was much, much higher. And the conclusion was that these orthodox boys are required to spend many more hours every day reading than the girls. Only when they are in these orthodox schools. Not in the general schools. So this is related to the amount of near work that they’re doing. Another study — and again, these are just two examples, but there are many, many more — is this other study — this one is from Singapore. Where they looked at the prevalence of myopia relating with the years of schooling. So one here will be they have no education. And at the end here, 8, 9 will be they have gone to university, and have at least 3 to 5 years of university degrees. And as you can see in the grey bars, the more years of education you have, the higher prevalence of myopia. So again, myopia related to near work and myopia related to education. As we do a lot of near work, during our education years. What’s interesting as well from this graph, as I said earlier, is not just myopia prevalence that’s higher with more years of education. But also high myopia. The black bars here. So the prevalence of high myopia. And as you can see, the prevalence of high myopia is much higher for those individuals who have had more years of education. So something happens when children and young adults go to school. And we spend many years educating ourselves. Whether it’s near work, per se, or not, it is not completely clear, but it is related to the fact that we are in school, that we are studying, that we’re spending a lot of hours doing that. Obviously we’re not going to ask our children not to go to school. That will not be good for anybody. It is very important to make sure that we all receive proper education. So what we need to do is look at other factors. So in the last decade or so, many studies have shown that perhaps when we go to school more, what’s happening is that we are spending less time outdoors. So the studies have found a relationship between amount of time spent outdoors under the sunlight, and the development of myopia. They have found that children who spend more time outdoors when they are little — they have less chances to develop myopia later on. And what’s very interesting is that they have found that to be an independent factor from near work. So even if you spend quite a bit of time doing near work, here, high amounts of near work, if you spend quite a bit of time outdoors as well, you have less chances of having myopia. Your biggest chances of having myopia later on is if, as a child — and this relates to children between 3 to 8 or nine years of age — in these early ages, if children spend a lot of time reading, looking up close, studying, and they don’t spend time outdoors — that’s when they have a high risk of having myopia later on. And this is related as well to living in urban societies, rather than rural societies. There are many, many studies supporting this outdoors implication in myopia development. So because we can modify near work and outdoors, I will talk later on in the presentation about how we can modify these factors to help our children. Who have a risk for myopia. There are many other factors that have been investigated as risk factors for myopia. For example, gender. Gender, it’s not a risk factor for myopia. Obviously girls develop quicker than boys, and therefore they may get myopia earlier on. So depending on what age population you look at, you may find that more girls have myopia, just because they grew up quicker. Pupil sizes don’t seem to play a role. Don’t seem to be any differences in pupil sizes among different refractive groups. Or intraocular pressure. Or intelligence. And again, there are differences in years of education, but not necessarily intelligence. Other factors such as diet have been investigated with non-conclusive results. Size — by size I mean the body size, the height, and the body mass index. These do not show conclusive results either. So we know who is more likely to get myopia. So once our patients get myopia, what do we expect is gonna happen with them? How fast do we expect it’s going to progress? As I said earlier, this depends on the age of the patient. So younger patients will be more likely to progress more quickly. And the summary of the literature that I have reviewed is that it depends on the racial background of the child. Asian children will progress a little more rapidly than Caucasian children, for example. But the progression rate for younger children is about 1 diopter or a little more than 1 diopter per year. And for older children, it will be about half a diopter per year. We have some graphs here. This one from Donovan et al., from 2012, shows exactly what I’m saying up there. So if you have a 7-year-old child who comes in and you prescribe glasses for myopia, if the child comes in a year’s time, you’re likely to find that that child has about 1 diopter, 1.25 diopters more. If you find that the child has 3 diopters more, you probably need to think something is not quite right here. Now, if you have a child who has 10 or 11 years of age, and you prescribe glasses for myopia, when they come back in a year, you expect that they will have about 0.5 to 0.75 diopters of myopia more. So as children get older, we expect that their myopia will progress more slowly. This is very important as well, when you’re reading studies on myopia progression and myopia control methods. Because yes, as you do interventions to control myopia, such as atropine, and the child grows up, you need to take into account the fact that as the child grows up they will anyway slow down the progression of myopia. You also need to take into account that it’s not just important to know how the refractive error changes in diopters, but also how the eye growth changes. How the axial length changes. Very important in myopia control. The length of the eye. This is what we are trying to control. Because that is what’s causing vision-threatening conditions such as myopic maculopathy or retinal detachments. It’s the fact that the eye grows too long. So what we care is not just so much that the myopia doesn’t get much higher in diopters, but also that the eye doesn’t get much longer. So we will see an increment, as we’re seeing this year, on devices to measure the axial length in clinics. So myopia progresses very rapidly during the childhood and teenage years, and when does it stop? Well, it’s gonna depend on an individual basis. There are some children who will stop when they are young teenagers, 14, 15 years of age, and there are others that will progress until they’re in their 20s, even up to the mid-20s. So we do expect myopia to progress, and to later on in life — particularly if the individual is still studying, still going to school, college — the myopia is likely to continue to progress, until their 20s. Another very important concept to consider when you are trying to decide on a myopia control method for your patient. Is my patient likely to have to continue this myopia treatment method until their 20s? We’ll talk more about that later. And as we said earlier, earlier onset myopias, that start earlier, are gonna end up with more final myopia. So what we really want is… Either we slow down the progression of myopia, so that we end up with less myopia when we are adults, so less risk of blinding conditions, or we can also try to push the onset of myopia later, so that rather than starting having myopia when we are 4 or 5, we start when we are 10 or 11, so we end up with less myopia when we are adults. And more on that later. And usually myopia stabilizes in childhood years, until we are older and we get cataracts that we may have another myopic shift. So now that we have a good idea on what myopia is, and why it happens, let’s talk briefly about how we can correct it optically, before we go into methods to control it. Remember, when we’re trying to correct any refractive error — not just myopia — our main goal is to provide clear and comfortable vision for our patients. Not just clear vision. We’re not just trying to put that focal point at the retina, but we want our patients to have comfortable vision, good visual function, and good visual performance. And for that, we always have to consider their needs. Each individual patient’s needs. Myopia is probably the simplest of the refractive errors to correct. We usually do an objective refraction, ideally with retinoscopy, followed by a subjective refraction, and we typically prescribe the full amount of myopia. Now, it’s very, very important that we do not overminus. So that’s why you need to do binocular subjective refraction, to control accommodation, and not overminus. And if you’re not sure you’re controlling accommodation with dry binocular subjective refraction, you need to do a wet refraction, with cyclopentolate or atropine, or any other methods you have available. Very important to not overminus. But also, we typically prescribe the full amount of myopia. Let’s talk a little bit more about that. In adults, we do. We prescribe the full amount of myopia, just because we want them to perform well, so it depends on their visual needs, but as long as they have clear vision and they’re comfortable, we will prescribe the full amount of their myopia. Always careful not to overminus. For children, it’s a little bit more tricky. Particularly because children are very good to adapting. So children will take any glasses or contact lenses, any methods you give them to correct myopia, and they will be happy with them. They will not complain. Which is good and it’s bad. So children may take a prescription that is really wrong for them, and wear it for a long time, without any complaint. That’s why you have to be particularly careful when prescribing for children. Because if you prescribe wrongly, if you overaccommodate by a lot, based on animal studies, we expect that the progression of myopia is going to increase more rapidly. So we do not want to overprescribe for myopia. We do not want to say… Oh, well, in six months, he’s gonna have 0.5 diopter more myopia. Let me give him 0.5 diopter more myopia now, so he doesn’t have to change glasses. We do not want to do that. We do not want to overprescribe. Now, a question that is of interest for most of you I’m sure is: Should we underprescribe or not? And this is a very, very important question. For which I have some evidence to support my opinion, but not as much as I would like. There are some studies that have shown that undercorrection of myopia does not have an effect on the progression of myopia. There are two of the studies that are typically cited. There are other studies in Asia also that have shown the opposite. And personally, based on the evidence that we have, I do not think it’s sufficient to say that undercorrection is a problem. Of course, we want to make sure the visual function of our patients is good. So if you decide to undercorrect by a little bit, that would have to be only by a little bit. Because visual performance has to be adequate for the child’s age. So always consider the child’s visual demands. If you have babies, then their visual demands are very limited. So you will not correct myopia unless it’s high. Unless it’s stable, persistent. You want to keep a close eye with young feints. You want to keep a close eye with young infants. See them every two months, if possible. If it’s high myopia, unilateral myopia, then you want to correct it. And the same goes for older children. We always want to consider visual demands. Not just in school. They have to see everything well in school. They need to be able to see the board and the projected slides. But they also need to be able to play the sports they want to play. You don’t want them not to be able to go out and play sports, because you don’t want to correct their myopia, and then you’re hurting them more, because they’re not going out, and therefore their myopia is getting worse. So the recommendation is: Full prescription of myopia. There may be a small amount of overminusing in young children, but overall, full prescription of the myopia is what we recommend, based on the evidence we have. I do believe we still need more evidence on the role of undercorrection of myopia, particularly for children and teenagers. And as you know, we can correct myopia optically. Here we’re not talking about treating myopia, but just correcting it optically. We can use glasses. We can use contact lenses. Different types of contact lenses, with advantages and disadvantages of each. We can use refractive surgery and orthokeratology. These are methods that are becoming more and more common to correct refractive errors. What’s very important to keep in mind is: We are only correcting the refractive error. We are not treating the underlying problem. So if you have a myopia of 6 diopters, and you have refractive surgery, and now you can see 20/20 or 6/6 without any glasses, that’s wonderful. But your eye is still a myopic eye of 6 diopters. So you still have the same risks for all those vision-threatening conditions we talked at the beginning. Keep that in mind when you are treating your patients. So if you have a new patient who tells you they’ve had refractive surgery, and if you cannot measure the length of the eye, which would be ideal, then at least you have to know how much myopia they had before their surgery, to get an idea on how much risk they have for these conditions. Okay. So let’s talk now about myopia control. We have different methods for myopia control. But let me allow you to look at this question. Number four. The following interventions have been shown to halt the progression of myopia. You may select more than one, if you think more than one is appropriate. And what’s important here for the question is is that we’re looking for interventions that have been shown to stop the progression of myopia. I’ll give you a few more seconds. OK lenses refer to orthokeratology lenses. Excellent. So we have a range of responses here, which I expected. Many of you selected time outdoors and atropine. Some of you selected ortho-K and multifocals, and some selected none of the above. So as we are going to see over the next few slides, in fact none of these treatments has shown to completely stop the progression of myopia. I know that’s bad news. But there is some good news. And they are useful, even if they don’t completely stop the progression. Because they can slow it down. So let’s start talking about lifestyle modifications. Outdoors, one of them. But lifestyle modifications. They are simple methods that we can recommend to all our patients. They don’t have any cost. And any patient can follow these advices. So in our myopia control clinic, we recommend these lifestyle modifications to all our patients, regardless on whether they also go to one of the optical or pharmaceutical interventions or not. Outdoors. As we said earlier, outdoors has been shown to protect against the development of myopia later on. So if you have young children who spend more time outdoors, compared to those young children who spend less time outdoors, the ones who spend less time outdoors would be more likely to get myopia later. Now, what is of interest is what happens once you have myopia. Because children who are going to come to your clinic are usually going to already have myopia. There is not evidence — or at least not enough evidence — to show that time outdoors helps with progression of myopia. So if the child already has myopia, we don’t have enough evidence to show that they will be less likely to progress if they spend more time outdoors. These are the articles, and this is a review. And some of them showed that spending time outdoors helped slow the progression of myopia, but most of them showed that it did not make a difference. So the conclusion for this is that we do not have sufficient evidence to recommend our parents of children who have myopia that children should spend more time outdoors. However, as a health care professional, and given that spending time outdoors has many good consequences for the physical and mental health of our children, I do not have an ethical problem recommending time outdoors, always educating parents to the fact that we do not have sufficient evidence to support this recommendation. So we do recommend that children spend time outdoors. And ideally at least two hours a day. That’s what has been shown to have an effect in the development of myopia. Definitely if you have patients with myopia and they have younger siblings who do not yet have myopia, there it is very important to recommend the parents to change their habits and make sure the kids spend more time outdoors. With all the issues we need to have, of wearing a hat, sunscreen, sunglasses, if you spend more time outdoors as a young child, you are protected from developing myopia later on, even if you use a hat or sunglasses. So those are very important to recommend. Time outdoors. Very important. And why is the outdoors important? Well, we have some evidence that lighting is key. We don’t know exactly what aspect of lighting. Is it that the intensity of lighting is greater outdoors? That is the case. It could be part of it. But it could be that lighting outdoors is very different from indoors. The spectral composition is very different. The sunlight has a very wide range of wavelengths, whereas indoor lighting has a very narrow range of wavelengths. So sunlight, very important — with caution. These may also have an effect on circadian rhythms. So the eye is supposed to be growing at certain times of the day. And if we don’t spend enough time outdoors, our eye may not have a good rhythm, so it may not know when it’s supposed to grow, and it may grow all day. There are other differences between outdoors and indoors, related to the dioptric demand. For example, when we are outdoors, most things are far away, so we don’t need to be accommodating much, and we don’t need to be changing the focus on the accommodation of our eye. Others have studied the effect of vitamin D. There’s no conclusive evidence yet, but it’s there. As well as the effect of pupil size and physical activity. These have been found most likely not to have an effect. Because there are studies showing that physical activity indoors and outdoors is very different. So spending time outdoors is important for our young children with myopia. How about near work? We have seen that near work is associated with myopia. And increases the risk of myopia development. And perhaps progression. We do not know for sure. But given that there is this very high association that has been there for years, that we have the very high association with education, what we do is we recommend our children to spend as much time outdoors as they spend doing near work activities. So yes, children need to continue to do their homework. No excuse for not doing homework. And for not working in class and not studying. But let’s try and have them outdoors more hours, so that they balance the hours that they are doing near work with the hours that they are outdoors. So rather than watching TV or playing video games, they could be outside playing with their friends or playing soccer, doing other things. I know if there are children listening to this, I’m not gonna be very popular, but this is very important for myopia. In fact, in some parts of the world — particularly in China — they’re coming up with strategies where they’re changing their curriculum, their educational curriculum, entirely because of this, and they’re having children do more activities outdoors. Educational activities, but outdoors, in the forest and the trees. They are learning about science, for example. They’re also building classrooms where children get more sunlight into the classroom. The glass classrooms. Something that is going to be changing over the next few years, and we need to consider not only as health care providers, but as educators, the importance of outdoors and sunlight. We also recommend that children do not do near work too close to their eyes. So it depends on how big the child is, but at least we recommend around 14 inches viewing distance, 30 centimeters between their eyes and the reading material, whether it’s electronic or in paper. We recommend good lighting. They could read outdoors. That would be ideal. And we recommend that they have some breaks every 45 minutes or so. Just have a minute or two looking far away and relaxing their eyes. Ideally looking through a window. So these lifestyle recommendations are very simple. We can educate our parents and children with myopia. And they are simple changes that they could be doing, without any financial cost. Now, if they can afford it, we can offer them some optical and pharmaceutical interventions to control myopia. And… Check how we’re doing with timing. So the optical interventions that we have are divided in glasses, contact lenses, and different types of contact lenses. First of all, glasses. Multifocal or progressives or bifocal glasses have been used for decades for progression of myopia. There are many studies that are very robust, such as the COMET study, that began with the lead of Dr. Gwiazda, that have shown that wearing spectacle glasses with near adds can help slow down the progression of myopia. Unfortunately, the effect is pretty small. And it was concluded that it’s not clinically significant in that particular study. But other studies later on have found bigger effects. For example, the Cheng studies, where they used bifocal glasses with prism, they found a 1 diopter change — a 1-diopter difference in progression in three years between the kids who wore single lenses and bifocal lenses with this prism. So kids will end up with 2 diopters versus 3 diopters. That is a difference that can be significant for parents and you as a health care professional. These spectacle lenses have been shown to have more of an effect in children who don’t accommodate well. So they have a large lag of accommodation. And children who have esophoria or esotropia at near. Just so you know, the standard contact lenses — either standard soft contact lenses or gas permeable lenses — do not have an effect on progression. So either wearing glasses or standard soft lenses or standard gas permeable lenses, the progression of myopia is going to be the same. How about ortho-K lenses? Orthokeratology, as I said earlier, is used to correct myopia, but it can also be used to slow down the progression of myopia. In most countries, it’s not approved for that purpose, but it is used widely. It is used because there have been studies — in particular, there are three randomized controlled trials that have shown after two years that they slow down the progression of myopia. And it is important that these studies occur in longer term. So we don’t yet have data longer term, which is very important. We hope to have that in the next year or so. And what’s important is that studies have shown that there’s less progression of refractive error, so less progression of myopia in diopters, but also less progression in the elongation of the eye, which, remember, is what we care about. So these studies involve measurement of the length of the eye. Very important measurements. So that we know the eye is actually growing less than when they don’t wear this correction. So there are many studies. Not all of them that have measured the length of the eye. Some like this one I’m showing here did not. But many studies have shown less elongation of the eye after two years, when we’re in ortho-K. As we said earlier, we do not know what happens after that. There’s one cohort study, five years, and one, also, cohort study a little longer. But there’s no randomized clinical trials longer than two years, at the moment. And that’s where we are hoping to get soon to see what happens in long term. We also need to know what happens once the kids stop wearing the ortho-K. Because what we have seen in many treatments to control myopia is that the treatments seem to work more in the first year or two. Hence the importance of having long-term studies. And also, the ones we stop the treatment — those kids that were in the treatment seem to progress more rapidly and catch up with the kids that were not in the treatment. So we need more studies in ortho-K. We still do treat our kids with progressing myopia with ortho-K lenses, when it’s good for them and their family. First of all, it’s an expensive treatment, so they need to be able to afford it. And then they need to have certain characteristics related to the amount of myopia, the shape of the cornea, their habits, et cetera. But if it’s a good fit for the child and the family, we do recommend ortho-K, because it may slow down the progression of myopia. By the way, studies… The first few studies were done mostly in Asian populations, but now we have studies in other populations. The effect seems to be a little greater in Asian populations, but it is also there in other populations. So ortho-K is one of the treatments that we recommend to our patients. The other one is the special design soft contact lenses. Or multifocal contact lenses. But these are not just the typical multifocal contact lenses that we prescribe for our presbyopic patients. Sometimes they are, but sometimes we prescribe them for another purpose. I’m not going to go into detail on this, unless people ask me. But the reason we prescribe these multifocal contact lenses is so we can provide different correction in different parts of the retina. This is not easy to achieve. We are not sure exactly what we are doing. But there have been studies with multifocal contact lenses. Most of them in center-D design. They used these Acuvue lenses, and found that after one year, there was less progression of the myopia in the children with bifocal versus single vision contact lenses. It’s only one-year study, but it’s promising. We again need longer studies. The only one longer study we have so far is about the MiSight Lens from CooperVision. We have Paul Chamberlain from CooperVision presented the data or at the Academy of Optometry meeting a month ago, and he showed data from three years, and it seems to be pretty promising. There is a difference of about 0.75 diopters of change between the kids who were wearing the MiSight and a regular contact lens. This has not been published in a peer-reviewed journal yet, but we are looking forward to that information. There are a lot of researchers working in different designs of contact lenses that may impact the effect of the clarity of the image in the retina, and therefore may impact the progression of myopia. So stay tuned for that, because there will be more coming up very soon. Again, we need longer studies that are double blind studies, with the appropriate protocols, et cetera. So those are the two main optical means that we use to try to control myopia. Again, they will not likely stop the progression of myopia. And they will hopefully slow down the progression. We cannot guarantee that they’re going to work for every child. So we have in our myopia control clinic — we have parents and children signing an informed consent, where we educate them on what we know and what we don’t know, to make sure they understand that we cannot guarantee they’re going to have an effect in their children’s myopia. Lastly, let’s talk about pharmaceutical interventions. I’m sure you’ve all heard about atropine. Because atropine, which is a pharmaceutical compound that has been used for decades, it has been shown in the last few years to slow down the progression of myopia. The ATOM studies are the main studies we have for atropine. The initial study was for two years, here on your left. And they had kids that used just placebo drops, here in the triangle, versus kids with different amounts of drops. And what they found — that it didn’t matter the concentration of the atropine. They all slowed down the progression of myopia at two years. Now, what happened after that? Well, they had a one-year washout period. And what they found was that the lower percentage atropine, 0.01%, very small concentration of atropine, had less of a rebound effect than the higher concentrations of atropine. So here we have, after one year of not using atropine, those kids who used 0.01 progressed less than those who had used higher concentrations of atropine or placebo. The difference is about 0.7 diopters at 3 years. So whether this is clinically significant or not is something we need to consider. They continued with a follow-up study, where they had some of the kids with atropine again — this time only the three lower concentrations of atropine, for ethical reasons, based on their previous results — and they found that the 0.01% was actually after the five years, again, the concentration of atropine that had most of an effect. Now, unfortunately, these effects did not show as much of a change in the length of the eye. And this is very important, because remember, what we care is about the length of the eye. We don’t want those eyes to get too long, because if they do, they’ll have risk of complications. So there are other groups that are investigating the effect of atropine, different concentrations, as well as the effect of other drugs. When we use drugs, we always have to consider side effects. And I need to speed up a little bit here, so I’ll just briefly mention that other drugs have been investigated, but right now atropine is the only one that’s currently investigated in humans. So atropine is a very promising treatment. However, why are we not finding the effect in the axial length? Is it because the atropine is mostly affecting the front part of the eye and the ciliary body? And maybe changing the tonic accommodation of the patients? Questions to be answered in the future. Other interventions that you may hear about for myopia control are vision therapy. Many devices that they may sell in internet, to treat myopia. I will encourage you to be very critical with all of this. Vision therapy does work if you have an accommodative problem. It doesn’t treat the myopia. It treats the accommodative problem. But all these other treatments — there’s no evidence that they work. I know I’m running late, but I wanted to mention about surgery. Because we are having so many people with high amounts of myopia. We are looking into this very drastic surgical operation, where they are trying to actually prevent the eye from growing longer, by putting belts and some liquids behind the eye, et cetera. So there are many studies on this already in humans. To try to prevent the elongation of these very highly myopic eyes. In conclusion, we have a myopia epidemic in most parts of the world. Our children are becoming myopic earlier on, and therefore they’re having higher amounts of myopia when they are adults. Which means they are at higher risk for complications associated with myopia. So as health care providers, we must evaluate the possibility of those complications and always do a dilated fundus evaluation of the eyes of these patients. We do have a number of promising control myopia methods. Increased time outdoors. We know it is useful in prevention. We don’t know about progression of myopia. But we can educate our patients. We have low percentage atropine, that we have seen an effect in the dioptric power of the eye, but not so much in the length of the eye. We have ortho-K. We need longer term studies and double blinded studies in ortho-K, but it’s a promising intervention method. As well as the multifocal, bifocal, or special design soft contact lenses. We need more long term double blind studies, but the results so far are promising, because they are affecting not just the dioptric change of the eye, but the axial length. We recommend it to children with esophoria and esotropia. Now, can we retard the onset of myopia? This is something that researchers are working on. It is harder, because if a child does not have myopia, it is difficult to justify an intervention, when they don’t have a problem yet. But it’s something that we are hoping to see some results soon. Thank you very much for listening. I know I presented a lot of material. Let’s see. Do we have time for one or two quick questions?

>> We do have time if you have time. There were 17 questions submitted. So if you want to just… Open those up, and…

DR VERA-DIAZ: Okay. Do you know where the questions are?

>> They’re on your side, in the Q and A box.

DR VERA-DIAZ: Okay. Let me make this bigger. There it is, yes. Thank you. One question I see here is: When should we stop atropine? So if you initiate treatment with atropine, 0.01%, which many of us are doing, does this child need to continue using atropine all their lives? I mean until they become an adult, and therefore they don’t have a risk for myopia progression? So… The answer is that we really don’t know what is best. But we at least recommend two years of use of atropine, because based on the ATOM study, they found an effect after two years. If you remember that graph I had a few slides ago, after two years, when they discontinued the atropine, those kids that used 0.01% had an effect a year later, compared to the placebo. So at least two years is what we recommend to the parents. If we don’t have any side effects and everything is good and we see there is an effect in the progression of myopia, we do recommend to continue with that. What we do in our clinic is we evaluate the kids who have been treated for myopia control very closely and see if the treatment they have has an effect or not in the myopia progression. So we look every six months whether there is a change in the axial length that is less than we would expect or change in refraction that is less than we would expect, and if so, it’s good. But if the treatment doesn’t seem to be having an effect in that child, then we consider changing to a different type of treatment. Very important. One treatment may work better for a child than another, and we don’t have enough evidence to know for all of them. So we try if the child is already more than 14 years of age. This is a very good question, thank you. So these methods to control myopia are shown to be more effective in young children. And that’s when it will be best to use them. Because that’s when we can prevent them from getting higher amounts of myopia. That’s when myopia is progressing more rapidly, when they are young. 5, 6, 7, 8 years of age. But if I have a 14-year-old whose myopia is progressing more rapidly than it should be, I will still recommend the myopia control treatment, if the parents can afford it and it’s a good fit for the family. I have a question about near devices and the use of smartphones. Which… It is becoming very popular in our young teenagers, and even in children nowadays, to already have mobile devices that they have with them most of the day. So yes, this is part of the near work. The devices per se, the smartphones per se, have not been investigated. But since they’re near work activities, they are used close up, then we assume that they will have the same effect of any other near work activity. And we recommend that they are not used as much. We cannot stop kids from using devices at near. Because it’s the way we communicate these days. And it’s just the way society is going. But remember to encourage kids to spend more time outdoors. So if they are going to be using their smartphone or tablet, then they need to compensate that with time spent outdoors. This question… It’s very tricky. Evidence is changing year and year. How to decide on best evidence? And this is the biggest problem we encounter as providers. Right? Because yes, we want to keep up with the best evidence. But every year, we have actually thousands of papers on myopia. The last few years — I don’t have numbers right now — but the last few years has been a very steep progression on the number of articles on myopia progression and myopia control that have come out. And so obviously it’s a very hot topic, of interest for many people. So I think what’s most important is to try and focus on meta-analysis, comprehensive reviews, from well known peer-reviewed journals. Also ask colleagues who are experts in the area, and have the time to spend more time on this. Maybe such as myself. As always, don’t just trust what I say, but go to the literature. So yeah, reading the meta-analyses, and reading the systematic reviews will be the best. And being very cautious, remember, when you’re reading about whether the research was sponsored by a company, in which case, you know, just a word of caution. And with how long it’s been, if they had double control or not. Also, one thing that is very important is: Many of these studies report the progression of myopia in percentage. And this is a big problem. This is a problem, because the percentage is gonna depend on how much myopia you have. So if I only have 1 diopter of myopia, 25% change is only 0.25. But if I have 4 diopters of myopia, 25% change is 1 diopter. So we strongly recommend — and we’re hoping — we’re working in some international guidelines that we’re hoping to get out soon — we strongly recommend that all publications related to myopia control, myopia progression — they have to give the raw data in terms of how many diopters, how many millimeters, has that child changed over the last year, over the last two years, over the last three years. It’s very important to have the amount. And then if people want to report percentages, that’s fine. But we do need to know the amount of diopters of change. Because that’s what we care. If after three or four years we only have a quarter diopter difference between treated and not treated eyes, we probably cannot justify that treatment. Right? But if after three years, we have over one diopter difference, maybe we can justify that difference. So that’s a very important question. Okay. I have someone asking about sun exposure. Whether it is protective or problematic? Oh, it’s protective of myopia, definitely. So we need sun exposure for our children when they are young. With caution. Not to expose them in the middle of the summer, middle of the day sun. So mornings and late in the day is when is best, and making sure you have sunscreen and hat and sunglasses. But expose them to the sun. Have them out there playing in the fields. Playing in the parks. Playing wherever you can. Depends on where you live. With friends, which is also probably a good thing. Playing with other kids, rather than being on the phone. But that’s beyond my expertise. I’m not gonna go there. And I will answer one more question. So… Atropine. And combinations of atropine and ortho-K. First of all, atropine has not been approved for myopia control, except, I believe, in Taiwan and Singapore. So in most countries, it is not approved for myopia control, per se. However, in some countries, like in the US, we can use off-label medications when we as health care providers have sufficient evidence that this will be beneficial to our patients. So that’s how we use atropine in the US and in other parts of the world. So depending on your confidences as a health care provider, you may or may not have access to atropine. If you don’t have access to atropine in your country, you could work with other providers who do have access to it. It is not too expensive. It is cheaper than multifocal contact lenses and ortho-K, for sure, but still involves a cost. And whether combined treatments are better than single treatments — we do not yet have enough evidence of that. So since I have a child who is progressing very rapidly, should I tell them to use atropine and ortho-K and multifocal? I can use everything combined, right? We don’t recommend that, just because there’s not enough evidence that it’s gonna benefit. And each of these treatments have potential side effects. That we have to consider, to not overtreat the child. So we recommend to start with one treatment, and follow up the child very closely. If after six months or a year we do not see the effect we expect from that treatment, then we can consider either adding another treatment or changing the treatment. Perhaps changing the treatment is more recommended than adding another treatment. And I don’t know if there is a chance for maybe people to post the questions later on, and I can answer if more questions are coming. I will be happy to answer them in the web page, if we can later.

>> Yeah, I can send them to you, and you can answer them by text, and we can send them out.

DR VERA-DIAZ: Perfect. I’m sorry I cannot get to answer all the questions. I know there are lots of questions in this topic. But I will be more than happy to answer them offline later. Thank you for your interest. Be tuned, be critical, and let’s see what we can do for these kids. Thank you so much. Have a wonderful day.

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December 18, 2017

Last Updated: October 31, 2022

1 thought on “Lecture: Evidence-Based Myopia Control”

  1. 1. What is the mechanism of multifocal lenses that may slow progressing myopia?

    The mechanism for multifocal contact lenses in myopia control is the same for orthokeratology – “peripheral retinal defocus theory”. The hypothesis of this theory is that paracentral hyperopic defocus encourages the axial length increase so those areas are in focus (the eye grows so the retina is at the focal point). Increased axial length results in myopia progressing and central blur, we correct the vision and the process happens again. Soft multifocal contact lenses provide a relative hyperopic prescription in the peripheral aspect of the lens, focusing paracentral beams on the oblate shaped retina.

    2. What are the numbers of myopia and myopic ansimetropia that may cause amblyopia?

    Bilateral myopia greater than -8.00DS and anisometropic myopia greater than -3.ooDS.

    3. The effect OK contact lens is flattening of cornea to treat myopia and slow progressing it?

    The mechanism for orthokeratology myopia control is the same as multifocal contact lenses – “peripheral retinal defocus theory”. The hypothesis of this theory is that paracentral hyperopic defocus encourages the axial length increase (the eye grows so the retina is at the focal point). Increased axial length results in myopia progressing and central blur, we correct the vision and the process happens again. Orthokeratology lenses achieve this by creating a steepened peripheral cornea, focusing paracentral beams on the oblate shaped retina.

    4. When you treat myopic children, what do you do to slow progressing of myopia? You use atropine or OK contact lens?

    Atropine in very young children – it is easily administered by parents on weekends (if the child won’t have drops I tell parents to instill a drop whilst they are asleep – kids sleep through just about anything!) Once the child is old enough to handle the lenses and take responsibility for them I move them to Orthokeratology lenses for two reasons, it gives them clear vision without glasses and it is more of a long-term solution as myopia is expected to progress until 17 years of age and there a not strong studies on the long-term (beyond a few years) effects of bilateral weekend atropine use.

    5. You use bifocal glasses if the patient has esotropia at near? You advise the patient to remove glasses at near and don’t wear bifocal glasses? What is your opinion?

    If the patient has an esotropia at near then we have a bigger problem than myopia and I would pursue treatment of the esotropia rather than the myopia. The myopia is the least of my problems if they have strabismus. If the child has a esophoria I would prescribe BF or progressive lenses (I prefer progressive lenses as they are more attractive for older kids) and that way they do not have to bother taking their glasses on and off. Additionally, the level of their myopia may be more than what I want to prescribe at near.

    6. Myopia usually doesn’t cause asthenopia, when does myopia cause it?

    Sometimes when you make a large change to a patient’s glasses prescription, especially if there is a large change between eyes.

    7. What dose peripheral defocus mean?

    Paracentral hyperopic defocus occurs in a myopic eye when corrected with negative lenses because of the oblate shape of a myopic eye.


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