Myopia, is a product of human adaptation to nature, to adulthood, a little myopia is not only harmless, but also some benefits. But some children are nearsighted, watching the degree is constantly increasing, every time you change the mirror, parents will feel worried, in the end how to do, in order to make myopia degree growth slower?
There are many reasons why the degree keeps increasing, at least the following seven can be found, find the right way.
First, not wearing glasses will increase the number of degrees.
Why? Wearing glasses can improve vision, vision to 0.6, can focus at a distance, relax the ciliary muscle. When you look close, the ciliary muscle strains, just like a leather band being stretched. If you can get it to relax, you can keep the same length for a good long time. If your vision is less than 0.6 and you don’t wear glasses, you can’t focus at a distance because the image is blurry, and the ciliary muscle can’t relax. This state of looking close will then remain. Imagine pulling a leather band without relaxing it, and then releasing it after 3 months, you will find that it has grown longer than before and can never go back. In 3 months, myopia will only grow by 0.25D, but in the long run it will grow by 1.00D per year, and only with glasses can this pathway be stopped. If caught in time, a ciliary muscle paralysis optometry and a complete relaxation of the ciliary muscle when the child is just developing blurred vision may nip pseudomyopia in the bud. This time, the medication will not only give accurate information about the refractive status, but also have a therapeutic effect. By paralyzing the ciliary muscle every 3 months, some children can even delay wearing glasses for more than a year. Remember one thing, if your vision does not reach 0.6, you must wear glasses and they need to be on your face all the time. Glasses that are used only for classes and not worn when you go out are not only not relaxing, but may add to the importance of fatigue.
The second important factor is occult strabismus.
In the case of hidden internal strabismus, when the near use of the eyes is too long, both eyes will be staggered inward and blurred vision occurs. In order to be able to see clearly, one tries to make both eyes see together with some effort. As a result, the stronger the inward strabismus, the stronger it becomes. At this time, a series of symptoms of visual fatigue and even transient high eye pressure may appear. We compare occult internal strabismus to a pile of dry firewood under the roof, and when you read and write close to your eyes, the visual fatigue that occurs over time is like scratching a match and throwing it into the pile. This rapid increase in myopia is like a house on fire, burning itself. How can we prevent this danger? We can’t remove the firewood, nor can we stop children from reading and writing near the eyes (scratching matches), but we can set a high threshold to prevent matches from being thrown easily. children before the age of 9, if there is a hidden internal obliquity, can’t read and write for more than 1.5 hours a day; children over 10 years old can’t use their eyes for more than 3 hours a day, which is obviously not enough for children to learn. We use an additional lens with ortho-spheres plus prisms, which is placed over the glasses normally worn for reading to see near, and the original glasses with the upper half spoke to see far. This ensures that the adjustment is reduced at all times, prolonging the appearance of visual fatigue, and does not increase irregular astigmatism and reduce the best corrected visual acuity (which often occurs when students wear gradual multifocal lenses for a long time) due to the long-term wearing of lenses with two diopters. These glasses are only used for patients with occult internal strabismus or a tendency to have occult internal strabismus, which certainly does not lead to occult exotropia.
Some occult exotropia may also lead to increasing myopia. Since both eyes cannot be used at the same time when looking at distance, using only one eye, the fatigue time will also be less than half of the time when both eyes are used at the same time; the regulation accumulated when looking at near, one eye will not have the opportunity to relax when looking at distance. These two factors drive the increase in myopia, and post-lens training is an effective way to address this pathway of myopia growth.
What is accommodation training? It’s simple. It’s distance and near vision training. The specific method is to use your finger to point to a distant target, which is best to identify clearly within 9 seconds, and then gradually move your finger closer to 30cm in front of your eyes for 3 seconds, 15 minutes a day. Since children now do not have enough time to see far, we advocate that the training time be extended to 40 minutes, which can be done in several sessions. This was a big project done at the initiative of a president of the Soviet ophthalmological society. He involved 50,000 people in the training and 50,000 people in the control for five years. The end result was that there was no significant difference in the prevalence of myopia between the two groups, but the difference in high myopia between the two groups was significant (about 23 times). In other words, a large group of children who did this training avoided high myopia. To date, this is the only training method that has an evidence-based medical basis in myopia prevention and control. Other devices designed to simulate this training have not been validated. This is because the equipment on the tabletop, cannot simulate natural conditions.
The third factor is large astigmatism.
Astigmatism of more than 1.50 Dc is called large astigmatism, and it is difficult to match the corrected state to the state of the eye when wearing lenses for large astigmatism. Because the lenses are regular, the larger the astigmatism of the human eye, the more difficult it is to be regular. According to some statistics, for every 1.50Dc increase in astigmatism, there may be 20% of points where the eye does not match the lens. At this point only central matching can be considered, and deviation from the center is either overcorrection or undercorrection. Developing children can be very sensitive to overcorrection of the wearing glasses (more on this below). Undercorrection, of course, can have additional problems. This problem may be solved with a rigid gas permeable contact lens (RGP), which eliminates some of the astigmatism through the tear lens and also allows the corneal surface to become more regular, improving the quality of vision. Double aspheric RGP is more effective. He can not only make the lens relatively stable on the eye and solve part of the corneal astigmatism, but also correct myopia in which the central prescription is greater than the peripheral prescription without peripheral overcorrection. However, if the astigmatism is too large, or not on the cornea, this RGP can not help.
The fourth factor is refractive error.
Refractive aberrations after wearing glasses, due to the lens degree difference is too large (bifocal refractive error is refractive aberration, generally more than 2.50 Ds will cause discomfort wearing glasses), magnification is different (imaging in the retina image diameter difference > 5%), the imaging of the two eyes can not be fused in the center, giving up the simultaneous vision. Often one eye is fixed to see near and the other eye to see far or both eyes are used alternately. It is well understood that with only one eye looking near, the myopia in this eye will continue to increase over time. Both eyes alternate gaze why will also rise myopia? One is that one eye has not been able to relax, the second is that the fatigue of monocular gaze will not exceed half of the simultaneous vision of both eyes. After the appearance of visual fatigue has not completed the homework, and then insist, will soon find that myopia increased again. There are three solutions: first, keratoplasty (to be mentioned later), second, RGP, and third, keratoconus surgery, which, because of its close proximity to the cornea, allows a person to receive a refractive error of 20.00D or more. The keratoconus procedure allows for a greater refractive error. The eye care community has now relaxed the age limit for keratoconus surgery for children with refractive partials.
The fifth factor is prolonged near eye use.
A prolonged near-eye time or a prolonged cumulative daily eye time can lead to visual fatigue. Continued near eye use in a state of visual fatigue will not only deepen myopia, but may also lead to a series of more serious problems, such as high eye pressure, dry eye, retinopathy and so on. In a good eye environment, a normal person can spend up to 6 hours a day near the eyes, but more than this time will also get myopia. 9 years old before not more than 3 hours, 6 years old before not more than one and a half hours. Conditions such as occult strabismus, large astigmatism, and refractive error may result in binocular interference or monocular gaze. There is a classic analogy of “two minus one is less than one” when both eyes cannot be used properly or when only one eye is used. Thus, it seems that eye problems, near eye time is reduced by at least half. How to solve these problems? The first step is to create a good eye environment and to solve the hidden strabismus, refractive error and large astigmatism. If they are not completely solved, they can only limit the time they spend using their eyes. Children with problems can only use their eyes for less than half the normal amount of time (3 hours) until the problem is solved. If the age is less than or equal to 9 years old, cut it in half again (1.5 hours). This is definitely not enough time for the child to study. In order to accomplish normal study tasks, the above problems should be solved first. It should also be noted that the time spent on reading and writing should not exceed 40 hair minutes at a time.
The sixth factor is paracentric defocus.
What is paracentral defocus? Simply put, it means that peripheral myopia is worn large. The human eye does not always grow into a spherical shape, and the posterior pole is somewhat flat in the center, and somewhat pointed. The flat ones may have a smaller central deviation than the periphery, and the sharp ones may have a larger central deviation than the periphery. Generally, in the population, one third of each. After wearing the lenses, it is definitely difficult to see according to the peripheral prescription. Although you can see clearly with the central prescription, the peripheral prescription is too large. The children who are still developing, the eyes will soon adapt to the glasses, the periphery will rise, the periphery rose, the central will not rise. This way the water rises, myopia will keep increasing. Even if they don’t read or write, they will. There are some irregular lenses where the periphery is significantly larger than the center. These lenses will lead to gradual myopia deepening even if they are used for children whose center and periphery are the same and who do not read or write. How to solve the paracentral defocus? Four solutions: first, keratoplasty, second, dual aspheric RGP, third, frames with decreasing peripheral prescription, and fourth, strict restrictions on the use of poor quality lenses with greater peripheral myopia in children and adolescents.
What is Keratomileusis? Why does keratoplasty solve paracentral defocus? Keratomileusis is a hard, gas permeable contact lens for nighttime wear that can be used to address myopia up to -6.00D through epithelial migration and short-term changes in corneal refractive power. The keratoplasty lens only changes the refractive state of the central 3mm area and the 5mm overcorrection area, and the periphery is still the same, unlike the central and peripheral areas which are the same, or even higher, when wearing a frame. By solving the peripheral overcorrection, the increasing myopia caused by this factor can be controlled.
Why do double aspheric rigid contact lenses also limit this paracentral out-of-focus myopia? Contact lenses can make and keep the large areas in the center and not overcorrect the small peripheral areas. For this type of paracentral defocus myopia, the effect is ideal and is not limited by the number of prescriptions. However, it requires lenses to be worn all the time during the day and the rate of loss is higher than night wear.
What if I can’t wear contact lenses? What’s the deal with peripheral decreasing prescription frames? Do they work? There are many contraindications to contact lenses, so if you cannot wear them, the only option for children whose central refraction is greater than their peripheral is these peripherally adjusted myopic lenses. Many designs of lenses are available with large central diopters and small peripheral diopters. However, the child has a limited ability to adapt and cannot always keep the visual axis squarely in the center. When the visual axis is off-center, not only will they not be able to see clearly, but the large central prescription will fall on the small peripheral prescription and the effect will be greatly reduced. The effect will be reduced to one third of the effect of keratoconus.
Also pay attention to the measurement of lenses for children, even if the central and peripheral prescriptions of the child’s eyes are equal, it is important to pay attention to whether the glasses will lead to peripheral overcorrection. Resolutely eliminate the use of poor quality lenses for children where the peripheral myopia is greater than the central myopia.
Which of these methods of resolving paracentral defocus should be preferred? If you have the conditions to do the shaping, it is ideal; for those who can’t do the shaping, because the degree is too large, or astigmatism exceeds the standard, you can choose the double aspheric RGP; for those who can’t accept contact lenses because of the shape of the cornea, crystal astigmatism, tears or eye surface, etc., you can only wear the kind of frame glasses with decreasing peripheral degree. Of course, this kind of glasses has a little flaw besides being a little less effective. It is that after wearing them for a long time, the child will not look smart enough. Because after wearing these glasses, always use the method of turning the head to find the center of the lens is the most clear.
Another question, how can I find the paracentral out-of-focus? There is a device for measuring peripheral refraction under astigmatism and aberrometry that can find the difference between the peripheral part and the central refraction.
The seventh reason is the growth and development factor.
For children between the ages of 6 and 12, the eye axis increases by 2 mm. for every 1 mm increase in the eye axis, the myopia increases by 3.00 D. The changes in the cornea and lens offset some of this. This 3.00D change is present in almost every developing child. This means that there has to be +3.00D to +4.00D of hyperopia by age 6, and some hyperopia by age 12. During this age, farsightedness decreases by 0.50 Ds per year. developmental rates greater than this can lead to premature myopia, even if it turns out to be normal. In addition to congenital factors, very few children are born with myopia. The refractive state of the child after birth is about +2.00D to +3.00D; between 4 and 6 years of age is about +3.00 to +4.00; and +1.00D of hyperopia is retained at 12 years of age. This is the refractive state that people who have maintained good vision throughout their lives walk through. Most myopia occurs during development. If you enter myopia too early and do not find the cause in time, myopia will continue to follow this path. almost 100% of children who develop myopia before the age of 6 will reach high myopia; about 80% of children who develop myopia before the age of 9 will develop high myopia; and about 60% of those who develop myopia before the age of 12 will enter the ranks of high myopia. Knowing these developmental stages should show the state, you can predict the future development trend, and at the same time there are ways to take various intervention measures as early as possible.
Of course, these seven factors are not the only ones that cause myopia to increase. There are more than 20 proven factors, such as genetic factors, environmental factors, lighting factors, form deprivation factors, imaging factors, regulation factors, regulation disorders, drug factors, pathological factors, crystal factors, void factors, etc. The above seven factors are only those for which solutions have been found, and they are also the factors for the development of most myopia. Only by considering the whole picture and finding the real cause can we make the right decision. Trying to solve all problems with one solution can only be a nice fantasy. Saying that one solution is good and thinking that everything can be done, you may be on the wrong path. What works for the development of myopia caused by one factor does not necessarily work for another. An approach that works for someone else that is not right for you not only delays the opportunity for effective control, but can go further and further in the wrong direction. It’s like hidden internal vs. hidden external obliquity. Most of the increasing myopia is the result of multiple factors acting at the same time, and only by finding all of them and blocking all the triggering factors at the same time, it is possible to limit the increase in myopia to a minimum.