abstract

Myopia is also called myopia, because you can only see near but not far. When the eyes are at rest, the parallel light from infinity is refracted by the refractive system of the eyes and then converged into a focus on the retina, forming an unclear image on the retina. Hyperopia is obviously reduced, but myopia is still normal.

Treatment measures

1. True myopia

(1) lens correction Before fitting glasses, we must first check the film to find out the true degree of myopia. For teenagers, optometry should be performed under ciliary muscle paralysis to control adjustment and eliminate pseudomyopia. The principle of optician should adopt the lowest lens that can also correct myopia to the best vision. Generally, myopia below 6.00d should be fully corrected and worn frequently; If people with high myopia want to get better eyesight, they must be completely corrected, but it is often unbearable. Therefore, in order to maintain the comfort and binocular vision function, they have to reduce the lens power (generally between 1.00d~3.00d ~ 3.00d).

⑵ Contact lenses Wearing contact lenses can increase the visual field, have a good cosmetic effect, and can significantly reduce the anisometropia of both eyes, thus maintaining the visual function of both eyes. Teenagers are nearsighted, wearing contact lenses can not only increase their eyesight, but also oppress the cornea and prevent the development of myopia. But we must pay attention to cleaning, disinfection and maintenance, and change them frequently as required.

(3) Hyperopia glasses Patients with high myopia or macular degeneration can often wear hyperopia glasses for study or close work. The magnification of this kind of glasses is 1.8 times, so the far vision can be enhanced by 2% ~ 3.5%, and the near vision can be enhanced by up to 5 times. Because the field of vision is too small, you don't need it when you walk.

⑷ Radial keratotomy was first tried by Soviet scholar Kranov (1970). There have been many reports in China. The method is to make 8 ~ 16 radial incisions with a depth of 0.36 ~ 0.50 3 ~ 5 mm between the corneal center and the corneal limbus. After corneal surface incision, corneal curvature becomes flat, thus reducing myopia. It is generally believed that 3.00d myopia can be corrected. Because the long-term effect of this method is uncertain, and the indications and contraindications should be strictly selected, there is the possibility of surgical complications. Therefore, it is still difficult to implement it universally.

5. Scleral shortening is the most commonly used surgical treatment method, which has been widely used because of its reliable effect from high myopia.

[6] Corneal grinding is a method of lamellar resection from the center of cornea with specially designed instruments. After low temperature treatment, the removed corneal piece is ground on a very fine lathe to achieve the required diopter, and then stitched back to its original position to correct high myopia. However, the operation is extremely complicated and dangerous, and it is difficult to popularize.

2. Treatment of pseudomyopia Pseudomyopia is due to the fact that when the eyes are far away, they still maintain a certain adjustment. In other words, this is a refractive state in which the eyes adjust and relax slowly when looking from near to far. It increases with the extension of near-sight time and the increase of adjustment power, and decreases or disappears with the degree of far-sight and adjustment relaxation. Therefore, pseudomyopia has the characteristics of disappearing after treatment (including rest), but it can recur after treatment. Various methods may have certain effects, but not all of them can last. Therefore, treatment should be based on the following principles. (1) is harmless to eyes, even if it is used for a long time, it has no effect on visual development. ② Because pseudomyopia can be improved by itself, the methods used should have scientific basis, and objective methods should be used to prove that pseudomyopia has relaxing and regulating effects. It is not reliable to evaluate the curative effect only by improving vision. (3) It is simple and feasible, and can be popularized in a large area.

At present, the methods used are:

⑴ Use various methods to improve visual excitability and lower visual threshold, such as Qigong, cold water bath, taking irritating drugs, etc. This therapy can improve both hyperopia and visual acuity, and it is not an ideal treatment.

⑵ Local treatment with drugs: Atropine drugs, for example, have a rapid and obvious relaxation and adjustment effect, which is a unified method to distinguish true from false myopia. However, these drugs are inevitably accompanied by side effects such as difficulty in seeing near and photophobia. Some people try to relax and regulate it with a lower concentration without side effects, but the research results show that with the disappearance of side effects, the curative effect will also disappear.

⑶ An instrument that uses optical principle to relax and adjust.

⑷ Physiotherapy: such as overlooking, atomization, crystal exercises, etc. Everyone should have a distant goal as an attraction for relaxation and adjustment, and should not be treated in a nearby environment such as evening self-study. 1983 Xu Guangdi designed a binocular combination method to prevent and treat pseudomyopia, and now it is changed to Xu-myopia prevention instrument. It installed two sets of flash bulbs in a box of 10×9×3cm3. In one group, two lights are located at the farsightedness of both eyes to simulate the function of distant targets. When this group of lights flashes, the observer automatically closes its image and leads the eyes to infinity. According to the joint movement relationship between adjustment and set, the adjustment is relaxed while the set is dispersed. The other group is that a single light bulb is located in the center of two combined lights, which is the target that both eyes can see at the same time. When the two groups of quasi-lights flash alternately, the observation eye will follow the light to see near rather than far, so that the inner and outer muscles of the eye can move together to achieve the purpose of treating pseudomyopia and preventing true myopia in the near environment.

It is worth mentioning that there are different types of eyelet glasses to treat myopia. It is well known that pinhole mirror can improve vision. Recently, it has been reported that if the pinhole diameter is 0.5mm, the visual acuity of all kinds of ametropia in 5.0d days can be maintained at about 0.5. However, pinhole only increases the image depth and thus enhances vision, and has no preventive and therapeutic effect on myopia. Moreover, although there are many small holes in these lenses, the distance between the eyes changes with the observation distance when students wear these glasses in class. Even if there are many small holes, they can't keep their eyes single. Only the dominant eye or dominant eye is engaged in monocular vision, and the other eye is in a state of inhibition. The visual interference caused by this is secondary, and the most important thing is that if the eyes are in a depressed state in adolescence, the development of eye vision will be affected. Therefore, it is ineffective and harmful to treat myopia with locked glasses, and it cannot be tried.

etiology

In the past, there were different views on the causes of myopia, but they all came down to internal and external causes. A brief introduction is as follows:

1. Internal reasons

⑴ Genetic quality: It has been recognized that myopia has a certain genetic tendency, especially for high myopia. But for general myopia, this tendency is not obvious. People with genetic factors have an earlier onset age, mostly above 6.00d, but there are also people with high myopia and no family history. High myopia belongs to autosomal recessive inheritance, and general myopia belongs to polygenic genetic disease.

⑵ Developmental factors: Infants are farsighted because of their small eyeballs, but with the growth of age, the axial length of the eyes is gradually elongated until puberty. If it develops excessively, it will form myopia, which is called simple myopia, starting from school age. Generally, it stops developing when it is under 6.00d and around 20 years old. For example, it made rapid progress in childhood, even faster when it reached 15 ~ 20 years old, and then it slowed down. This kind of myopia is often higher than 6.00d and can reach 20 d ~ 25 d or 30 d. This kind of myopia is called high myopia or progressive myopia or pathological myopia. This kind of myopia can occur and degenerate in old age, so vision can gradually decline, and glasses can't correct vision. Myopia is rare at birth, but a few are congenital.

2. External factors are environmental factors. People who are engaged in writing or other close work are more nearsighted, and young students are more nearsighted. The prevalence rate has increased significantly since the fifth and sixth grade of primary school. This phenomenon shows that the occurrence and development of myopia is closely related to close work. The eyeball of teenagers, in particular, is in the stage of growth and development, with strong adjustment ability and large ductility of the ball wall. The adjustment and assembly of the external muscles (mainly the internal rectus) exert certain pressure on the eyeball during close work such as reading and mailing room, and the intraocular pressure increases accordingly. With the continuous increase of work, the frequency and time of adjustment and assembly also increase gradually, and the ciliary muscle and external muscle are often in a state of high tension, and the adjustment function is over-exerted. However, after rest or using ciliary muscle erosion agent, vision may be improved and fully recovered. Therefore, some people call this kind of myopia functional myopia or pseudomyopia. However, under the long-term mechanical compression of extraocular muscles, the sclera tissue is gradually elongated, the axial length is elongated, and the degree of myopia is getting deeper and deeper, which can no longer be alleviated by atropine. Especially in adolescence, not paying attention to visual hygiene is the direct cause of myopia. Failure to pay attention to general health will promote the development of myopia.

Recently, someone observed "the role of environment and genetic factors in myopia" by the method of "prospective study" The method is to follow up the students with normal vision for two years, and analyze and judge various factors affecting myopia. The results are as follows: in terms of genetic factors, the ratio of the new prevalence rate of myopia among children whose parents are not nearsighted, one parent is nearsighted and both parents are nearsighted is1∶ 2.6 ∶ 3.8; Environmental factors: the ratio of the new myopia prevalence rate to the reading time after class1~ 2h: 3h: 4 ~ 5h is 1∶2. 1∶3.2. Therefore, heredity and environment are two important factors that affect students' myopia.

In addition, in a broad sense, the pollution of trace elements in the atmosphere, the change of nutritional components, and teaching AIDS that do not meet the requirements of ergonomics are also objective factors, and it has been reported that they affect students' myopia. But these factors are secondary to myopia caused by myopia.

clinical picture

First, the classification of myopia

1. According to the degree of myopia

(1) within 3.00 d is called mild myopia.

⑵ Those with 3.00 d to 6.00 d are moderate myopia.

⑶ High myopia above 6.00 d is called pathological myopia.

2. According to the refractive components

(1) Axial myopia is caused by the overgrowth of the anterior and posterior axes of the eyeball.

⑵ Curvature myopia is caused by excessive curvature of cornea or lens surface.

⑶ Refractive myopia is caused by the high refractive index of refractive stroma.

3. Pseudomyopia, also known as accommodative myopia. It is caused by looking too far and not relaxing. It is essentially different from true myopia with changed refractive components.

Second, clinical manifestations of myopia

1. The most prominent symptom of myopia is decreased far vision, but near vision can be normal. Although the higher the degree of myopia, the worse the vision, but there is no strict proportion. Generally speaking, for myopia over 3.00d, the distance vision will not exceed 0.1; 2.00d is between 0.2 and 0.3; 1.00d can reach 0.5, and sometimes it may be better.

2. Vision fatigue is especially common in low-level people, but it is not as obvious as hyperopia. It is caused by the uncoordinated regulation and collection. In high myopia, because the gaze target is too close to the eye, the collective effect cannot match it, so monocular gaze is often used, but it will not cause visual fatigue.

3. The eye position does not need to be adjusted because of myopia, and the collective function is relatively weakened. When the balance of muscle strength cannot be maintained, the visual function of both eyes is destroyed, only one eye depends on the object, and the other eye leans to the outside, which becomes a temporary alternating strabismus. If the visual function of strabismus is extremely poor and the deviation occurs earlier, strabismus can lose its fixation ability and become monocular exotropia.

4. The eyeball is highly myopic, mostly axial myopia, and the anterior and posterior axes of the eyeball are elongated, and the elongation is almost limited to the posterior pole. Therefore, exophthalmos, deep anterior chamber, large pupil and slow reflex are common. Because there is no adjustment stimulus, the ciliary muscle, especially the annular part, becomes atrophied. In extreme high myopia, the lens can't support the iris at all, thus causing mild iris tremor.

5. The fundus changes are not obvious in low myopia, and the fundus changes can be caused in high myopia due to the excessive elongation of the axial length.

⑴ Leopard-shaped fundus: Retinal blood vessels become thinner and straighter after leaving the optic disc. At the same time, due to the extension of choroidal capillaries, it can affect the nutrition of retinal pigment epithelium, make the surface pigment disappear, expose choroidal vessels, and form a leopard-like fundus.

⑵ The choroid around the optic disc of myopic arc spot is pulled away from the temporal side of nipple by scleral tension, exposing the sclera behind it and forming white arc spot. If the posterior pole of eyeball continues to expand and extend, choroidal detachment gradually extends from the temporal side of nipple to the periphery of optic disc, and finally forms annular spots. Irregular pigments and sclerotic choroidal vessels can be seen in this position.

⑶ Irregular, isolated or fused white atrophic spots can appear in macula, and sometimes bleeding can be seen. In addition, there are occasional degenerative lesions near the macula, which are black annular areas, slightly smaller than the optic disc, with clear boundaries and small annular bleeding at the edges, which are called Foster-fuchs spots.

(4) Postscleral staphyloma. If the extension of the back of the eyeball is limited to a small part, a sharp protrusion can be seen from the slice, which is called retroscleral staphyloma. If this atrophic lesion occurs in the macula, it can be combined with central vision surgery.

5] Cystic degeneration of serrated edge.

6. Complications and sequelae

⑴ Vitreous liquefaction, turbidity and posterior detachment: floaters are the most common symptoms, and patients feel black spots fluttering in front of their eyes. Like a mosquito flying. It is often accompanied by the light, sparks and other feelings in front of you. Especially high myopia is more obvious.

⑵ The crystal is turbid.

⑶ Retinal hole, retinal detachment.

⑷ Glaucoma Some people use applanation tonometer to investigate and prove that the prevalence rate of high myopia open-angle glaucoma is 6 ~ 8 times higher than that of normal people.

5. The prolonged dark adaptation time is due to the pathological changes of pigment epithelial cells in high myopia, which will inevitably affect the photochemical reaction process of visual cells.

prevent

The causes of myopia are very complicated, and there are two main factors: heredity and environment. At present, genetic engineering cannot be used to transform genes, so the prevention and treatment of myopia should focus on improving the visual environment.

1. Do a good job in publicity and education and set up special institutions to prevent and treat myopia. Make the prevention and treatment of myopia organized and planned. Check students' eyesight regularly, establish students' eyesight files, and check and correct those who find that their eyesight is declining in time.

2. Improve the visual environment

(1) Daylighting and lighting in classrooms should be standardized. The ratio of window light transmission area to indoor building area shall not be less than 1: 6. Don't reflect light on the blackboard, keep the bag black or dark green. Desktop illumination shall not be lower than 100lx. The light should come from the left or the front left. When writing, don't let the shadow of your hand cover the light.

⑵ Desks and chairs should meet the requirements of ergonomics, and be suitable for children's height and age characteristics, so that they can maintain correct posture and posture during class or homework. Reading. When writing, the distance between the eyes and the desktop should be kept at about 30cm and not less than 23cm.

⑶ Develop good reading and writing habits and postures: homework time should not be too long. After studying for 45 minutes, you should rest 10 ~ 15 minutes or look far away, so that the ciliary muscles can get a proper rest. It can also be used to do eye exercises. Don't read in bed, don't read in walking and moving carriages, don't read and write in strong sunlight or dim street lights, and don't watch TV programs at close range for a long time, so as not to cause visual fatigue and adjustment tension.

3. Pay attention to exercise and nutrition, reduce the burden of study and enhance physical fitness.

4. Reduce the influence of genetic factors. Myopia is closely related to heredity. Both parties are highly nearsighted, and the genetic probability after marriage is extremely high. Pay attention to eugenics.