I. What is refractive error? What is myopia?
When the eye is at rest, parallel light from a distance (5 meters away) enters the eye and is focused on the retina after passing through the refractive system (cornea, lens, vitreous), which is called “orthophoria”. As shown in the figure.
However, when light is not focused on the retina for various reasons, it is called “non-orthoopic eye”, which is a refractive error that includes myopia, hyperopia and astigmatism.
What about myopia? When parallel light enters the eye and passes through the refractive system of the eye, the light is focused in front of the retina but not on the retina, forming an unclear image on the retina, this refractive state is called myopia. As shown in the figure.
And when parallel light enters the eye, after passing through the eye’s refractive system, the light is focused behind the retina but not on the retina, and this refractive state is called hyperopia. As shown in the figure.
Second, what causes myopia?
Myopia can be caused by many factors, mainly the following.
1. Genetic factors.
The prevalence of myopia varies among various ethnic groups, and there are differences between families, and high myopia is mostly related to genetics.
2, environmental factors.
There are many environmental factors that have an impact on myopia, the main one being the increase in visual nearness load. Animal experiments and epidemiological data confirm that long and intense myopic work is closely related to the occurrence of myopia. The eye of adolescents is in the stage of growth and development, with strong adjustment ability and large extension of the spherical wall. The adjustment and convergence during close work such as reading and writing cause the extraocular muscles (mainly the internal rectus muscle) to exert certain pressure on the eye, and the intraocular pressure rises accordingly. As the frequency and duration of accommodation and convergence gradually increase, the ciliary and extraocular muscles are often under high tension, and the scleral tissue, under the long-term mechanical pressure of the extraocular muscles, gradually extends the spherical wall and elongates the eye axis.
There are many other theories about the mechanism of myopia, but they are all under study and have not yet been fully understood.
3. Can myopia be cured?
Myopia is an irreversible change in the anatomy of the eye due to the elongation of the eye axis. So far, there is no effective treatment, and it is better to wear suitable glasses.
What is pseudomyopia?
Pseudomyopia is relative to true myopia. Pseudomyopia is just a myopic phenomenon, and there is no difference between true and false myopia. Pseudomyopia is a phenomenon of myopia. It is common in young students who are looking at near objects, and due to the strong degree and long duration of close work, the ciliary muscle over-contracts causing regulatory tension or regulatory spasm, and when they turn to look at distant places, they cannot relax the regulation quickly, resulting in symptoms such as dizziness, eye swelling and vision loss. This increased refractive power of the eye, which puts the eye in a myopic state, is called pseudomyopia. Both pseudomyopia and true myopia are characterized by symptoms such as visual fatigue, poor distance vision and good near vision. However, pseudomyopia is a functional change, without the problem of the anterior and posterior diameter of the eye becoming longer. After the ciliary muscle paralyzing medicine is ordered to the eye, most of them can be converted to farsighted or orthoptic eyes.
Features.
1. Reduced distance vision and normal near vision.
2.Far vision is unstable and easily fluctuates.
3. The symptoms worsen with the tension of regulation and decrease with the relaxation of regulation.
4. Various methods of treatment are effective, but effective when treated, and can be repeated if not treated.
How to identify pseudomyopia?
Every parent wants their child to have pseudomyopia rather than true myopia, but how can the two be distinguished? The classification criteria for true and pseudomyopia issued by the Chinese Medical Association in 1985 can be used as a basis.
1. Pseudomyopia: Myopia disappears after the pupil is dilated with a diluent and becomes orthopia or mild hyperopia.
2.True myopia: Myopic refractive error is not reduced or is reduced by less than 0.5 degrees after the pupil is dilated with a diluent.
3.True myopia with pseudophakic component: Refractive error of myopia is significantly reduced (by ≥0.5 degrees) after using a dilating agent, but still does not return to proper vision.
Because pseudomyopia can be restored through rest, it does not attract the attention of most people, and it is usually the parents who find that their child’s vision is significantly reduced and does not recover for a longer period of time before they go to the hospital for examination. But at this point, it is often not pseudomyopia anymore. This is why it is important to protect the eyes during the fluctuating vision stage to prevent pseudomyopia from becoming true myopia. Therefore, educating children and adolescents to develop habits to protect their eyesight from an early age and to avoid constant tension due to over-regulation of the ciliary muscles of the eyes is the key to preventing the occurrence of myopia. Protective measures include: good reading habits; a good reading environment; a healthy body, moderate exercise and rest; attention to nutritional balance; regular eye examinations; and eye medication.
V. Do I need to wear glasses often?
Some people with glasses often do not wear them, or use the eyes to wear when not take off, said that they are afraid of glasses continue to deepen the degree. In fact, this concern is no scientific basis. We say, myopia is deepening for its own reasons, mainly with not pay attention to eye hygiene, the eye itself the front and rear diameter becomes longer, and whether often wear glasses is not related. In fact, when the human eye looks at external objects, the distance and angle are changing all the time, and there is no difference between “using” and “not using”. The youngsters with mild and moderate myopia, because they usually use their eyes more, the ciliary muscle function is not stable, except for physical education and other strenuous sports, glasses should be worn often. After wearing suitable glasses, seeing things becomes clear, so that the tense ciliary muscles are relaxed, and to some extent play a preventive and controlling role in the deepening of myopia, which brings great convenience to study, work and life.
Six, wear glasses, myopia will not develop?
No. Wearing glasses makes the refraction of the eyes less progressive. Wearing glasses corrects the refractive power of the eyes and improves vision, but it does not change the anatomy of the eyes and does not have a therapeutic effect on the eyes. As I said before, myopia is caused by many reasons, some people think that with glasses everything is fine, is “insured”, so do not pay attention to eye health, writing or reading books are still very close, reading time is too long, several hours without rest, lying or walking while reading books, lighting is not enough to read books. Although you can also barely see clearly, but the need for excessive regulation of the ciliary muscle, over time, resulting in visual fatigue, vision loss, myopia increased. Therefore, if the various factors that cause myopia are not removed, these factors will also have an effect on the eyes, so that the degree of glasses continue to deepen.
Are the advertised treatments for myopia effective?
In recent years, due to the development of eye care devices, a variety of eye care devices have appeared on the market. Many teenagers come to the hospital and ask: Can myopia treatment devices treat myopia? How does it work?
Generally speaking, myopia treatment devices have a positive effect on regulatory myopia (pseudomyopia) and true myopia with a pseudo component in the pseudo component. For pathological myopia (high myopia) and true myopia (those with organic changes in eye structure) determined by dilated eye examinations, the application of the treatment instrument can eliminate visual fatigue and stabilize myopic refractive error, and sometimes there seems to be an improvement in vision after a course of treatment. The effect is not considered to be obvious, and there is no significant change in myopia with objective astigmatism. Therefore, the effect of myopia treatment instrument should be analyzed objectively, and the objective degree of myopia after pupil dilatation (ciliary muscle paralysis after optometry) should be used as the standard, not the naked eye visual acuity as the standard to judge the change of refraction before and after treatment, so as to make an objective and scientific evaluation of the effect of treatment instrument for myopia.
At present, there are many types of eye care devices, but the principle and effect are similar, so myopic patients can choose according to their own situation.
Prevention of myopia
1. Since myopia is related to genetic factors, marriage of highly myopic people of both sexes should be considered.
2.After 50 minutes of continuous close work, you must take a break and then do 10 minutes of far-seeing to relax eye muscle tension.
3. When reading, the head should be slightly tilted forward, but not too much downward to avoid head or eye bruising. The trunk should take a sitting position.
4, tables and chairs should be in line with the human physiological height, so that the distance between the object to be seen and the eye in more than 30 cm, bed or walking when reading and other bad habits should be avoided.
5, the print must be sharp, the font size is appropriate; such as writing with pencil to hard thick black is better.
6, reading or near work must be fully illuminated, the light must be in the upper left side and avoid all dark shadows.
7, avoid direct sunlight and some glare glare.
8, pay attention to dietary hygiene and nutrient intake, control the intake of sugar and fat, increase the content of fiber components, and supplement trace elements.
9, strengthen physical exercise, do more suitable, regular outdoor activities, such as: swimming, running, gymnastics. Eye exercises are safe, effective, simple and easy to do.
10.Regular vision examination, if there is a decline, should be quickly diagnosed and treated.
Eight, what is astigmatism?
The cornea without astigmatism has a smooth spherical surface, and light can be concentrated into a point after refraction by the cornea. A cornea with astigmatism has a shape like the surface of a rugby ball, and the bending force is different in all directions, so the light is refracted through the cornea and focused in different places and cannot be concentrated into a clear image. Nearsightedness is the inability to see distant objects, while astigmatism is the inability to see distant and near objects no matter how hard the eye tries.
Astigmatism is mainly due to different degrees of curvature of the corneal surface, mostly due to congenital factors, and a large degree of astigmatism. Some mild astigmatism is physiological in scope and generally does not require correction. Acquired astigmatism is mostly due to diseases of the corneal surface. Other diseases of the lens, such as senile cataracts, can also cause astigmatism, but the magnitude is usually small. The main symptoms of astigmatism are similar to those of other refractive errors, including visual fatigue, eye pain, and headache. The severity of symptoms is inversely proportional to the degree of astigmatism, with milder astigmatism potentially causing significant symptoms. However, because the adjustment cannot compensate for the refractive abnormalities in two different meridians at the same time, it not only fails to make the image clear, but also increases the factors that lead to visual fatigue. Therefore, astigmatism can also cause fatigue symptoms when using distance vision, such as watching movies. So for mild astigmatism, as long as there is visual fatigue and vision loss, you should wear glasses to correct it.
Astigmatism has another characteristic, because it is caused by the inconsistency of the curvature of the meridian on the surface of the cornea, so it is not affected by the length of the eye axis. It is not like myopia, which will continue to deepen, but will remain stable at the original level without major changes.