myopia
Introduction
Introduction to myopia When the eyeball is in a state of static regulation, the equal light from 5 meters passes through the refraction of the eye, and the focus falls on the retina to form a clear image. The eye with such a refractive state is called the emmetropia. The focus is on the front of the retina, which does not accurately form a clear image on the retina, called axial myopia. It is highly adaptable to scattered light from nearby targets, and as long as the target moves to a certain distance in front of the eye, clear vision can be obtained. Therefore, the nearsightedness of the nearsightedness is clear and the distance is blurred, and the concave spherical lens can be corrected. basic knowledge The proportion of illness: 3% Susceptible people: no specific population Mode of infection: non-infectious Complications: retinal detachment, retinal tears, open angle glaucoma, glaucoma, flying mosquitoes
Cause
Myopia
Genetic quality (30%):
Myopia has a certain genetic predisposition, which has been recognized, especially for high myopia, but for general myopia, this tendency is not very obvious. Those with genetic factors are older, more than 6.00D, but there are also High myopia, no family history, high myopia is autosomal recessive, general myopia is a multifactorial genetic disease.
Developmental factors (30%):
Because the eyeball is small, the baby is farsighted, but as the age increases, the axis of the eye is gradually lengthened, and the puberty develops normally. If it is overdeveloped, it forms myopia. This kind of myopia is called simple myopia, mostly in school age. At the beginning of the period, it is generally lower than 6.00D. It will stop developing until about 20 years old. If it progresses very slowly in childhood, it will progress faster when it is 15 to 20 years old, and then slow down later. This type of myopia is often higher than 6.00D. To 20D ~ 25D or 30D, this kind of myopia is called high myopia or progressive myopia or pathological myopia, such myopia can be delayed and degenerative in later years, so the vision can gradually decline, the glasses can not correct vision, rarely in There are myopia at birth, but very few are congenital.
Environmental factors (30%):
People who are engaged in writing work or other close-up work have more myopia, and there are more myopias among young students. Since the fifth and sixth grades of primary school, the prevalence rate has increased significantly. This phenomenon indicates the occurrence of myopia. The relationship between development and close-up work is very close, especially in the eyes of young people. It is in the stage of growth and development, the adjustment ability is very strong, the stretch of the ball wall is also relatively large, and the adjustment and collection of reading, sending and receiving rooms, etc. The effect is that the external muscles (mainly the internal rectus muscles) exert a certain pressure on the eyeball, and the intraocular pressure also increases accordingly. As the operation increases, the frequency and time of adjustment and collection gradually increase, the ciliary muscles. And the extraocular muscles are often in a state of high tension, and the excessive exertion of the regulation can cause ciliary muscle spasm, causing temporary vision loss, but after rest or use of the ciliary muscle erosion agent, vision may improve in complete recovery, so Some people call this kind of nearsightedness as functional myopia or pseudomyopia, but the scleral tissue is gradually extended under the long-term mechanical compression of the extraocular muscles. The length of the eye axis is deepened, and the degree of myopia is getting deeper and deeper, and it can no longer be alleviated by atropine, especially during adolescence, not paying attention to visual hygiene. It is the direct cause of myopia. Not paying attention to general health can promote myopia. development of.
Recently, some people have used the "forward-looking research" method to observe the role of environmental and genetic factors in the development of myopia. The method is for students with normal vision, who are affected by myopia after two years of follow-up. Various factors were analyzed and judged. The results were as follows: in terms of genetic factors: both parents had no nearsightedness, and one of them had myopia. Among the children with myopia, the ratio of new prevalence of myopia was 1:2.6:3.8; Aspect: The ratio of new prevalence of myopia after reading time is 1~2h:3h:4~5h is 1:2.1:3.2. Therefore, genetics and environment are two important factors affecting students' myopia.
In addition, in a broad sense, the pollution of trace elements in the atmosphere, the change of nutrients and the teaching aids that do not meet the requirements of ergonomics are also objective factors, and there are reports that affect the occurrence of myopia in students, but these factors are close to Compared with myopia, it is secondary.
Prevention
Myopia prevention
There are many ways to prevent myopia. Any measure that can help reduce vision fatigue and relax eye adjustment can be tried. Of course, other ways can be explored. But they should be scientific, reasonable, and beneficial.
1. Prevent the occurrence of myopia
There is a certain regularity in the occurrence of myopia, and attention should be paid to visual health care during the pre-existing period, usually including preschool, growth and development, pregnancy, perinatal period and certain systemic diseases. Simple myopia has a clear external cause, that is, long-term use of the eye, so reducing the visual load is the key to preventive work. Through regular monitoring of vision changes and qualitative examination of vision, early detection and identification of targets can be identified. According to the epidemiological survey, the following subjects are more likely to develop myopia, which can be used as a key prevention target: 1 have poor eye hygiene habits and excessive close workers. 2 parents are nearsighted. 3 The visual instability has dropped from 1.5 to 1.2 or 1.0 (in fact, there may be myopia). Preventive measures include continuous short-term use of eye time should not be too long; active participation in outdoor activities; can take a far-reaching method, or a variety of vision and adjustment-collection training method, in order to increase the line of sight frequently, broaden the horizon, relax Adjust to maintain normal visual function. Usually, you must ensure adequate sleep, work and rest, balanced diet, and reasonable nutrition. Life must be regular and maintain physical and mental health. Pay attention to prevent all kinds of abnormal stimuli and risk factors, such as chronic poisoning of organic phosphorus. Try to avoid the formation of shadows on the retina, such as early correction of corneal astigmatism. Do not read under shock or shaking conditions or at dusk. Lighting requirements are adequate and standard, and the light should not be too dark or too strong. The brightness and color tone of the TV screen should be moderate and normal, and the image should be adjusted in time when the image is unclear, or the line of sight can be shifted. Use the correct reading posture. The read and write distance is kept above 1 foot. Improve learning conditions (clear print requirements, font standards) and writing conditions (clear handwriting, white paper). Actively treat systemic diseases and other eye diseases. Especially when adolescents suffer from systemic fever, they should protect their vision and pay attention to eye hygiene. Pathological myopia can be prevented by genetic counseling. If both parents are pathological myopia, nearly 100% of children will develop the disease. Prevent infection during pregnancy and avoid poisoning, allergies and other abnormal stimuli. Premature infants should pay attention to care and reduce oxygen intake as much as possible.
2. Prevent the development of myopia
For all myopia, especially pathological myopia, we should try to prevent the myopic diopter from deepening and maintain or strive to improve visual function. In addition to the above methods for preventing the occurrence of myopia, special attention should be paid to the rational use of the eye, and appropriate work should be selected to avoid excessive use of the eye and poor visual stimulation. Correct correct refractive error and wear appropriate glasses. Pathological myopia requires frequent wearing of the mirror, and the choice of use. Contact glasses can also be worn. Measures that may slow or halt the development of myopia, including optician (double-focus lens, oxygen-permeable rigid contact lens), drugs, and surgery.
3. Prevention of complications of myopia
The main cause of blindness in myopia is its complications, such as amblyopia, retinopathy and glaucoma. Various methods to prevent myopia from deepening should be taken actively and conscientiously. In addition to requiring patients to pay attention to changes in vision, they should also pay attention to any other abnormal phenomena in the early stage of the eye, such as flashing, fly (mosquito), visual field defects, visual acuity (especially near vision), progressive or sudden decline , as well as eye swelling, pain and night blindness. If you have a complication at a glance, you should observe the other eye in particular. Check at any time and find out early. Including changes in intraocular pressure, visual field, and axial axis. Perform other special eye examinations as necessary. Pathological myopia has a higher incidence of open-angle glaucoma. The changes in fundus and visual field can mask glaucoma lesions. Because the eye wall hardness is low, the measured intraocular pressure is low, which can delay the diagnosis of glaucoma. alert. A flattening tonometer should be used to measure intraocular pressure in pathological myopia to rule out the effect of eye wall hardness. In addition, it is necessary to avoid various predisposing factors and reduce the bad stimulation to the eyes. Minimize intense physical activity.
4. Promote eye exercises
(1) Eye exercises: The Ministry of Education and the Ministry of Health have designated eye exercises for students in school. Although some scholars have different views on their effects, as long as they can do it according to the regulations, it is beneficial to the health of the eyes.
(2) Far-reaching method and crystal gymnastics: These two kinds of eye-operating exercises are based on the "long-term view of the main cause of myopia", and they can be designed to prevent the occurrence of myopia. This type of method is described in detail in all popular science books for prevention and treatment of myopia.
(3) Finger exercises: There are two ways to do this, which are described as follows:
1 Target finger exercises: Straighten your right index finger and place it vertically 15 to 25 cm below the eyes. When the two eyes are looking at an object other than 10m away from the distance, the two eyes are in a far-sighted state. At this time, the eyes of the two eyes are scattered, so that the lines of sight of the two eyes are parallel, the eyes are adjusted to zero, and the pupils are enlarged. When both eyes look at the front finger, the two eyes are in a near-reflex state. Depending on the distance between the index finger and the eye, such as at 15 cm, a 6.6D adjustment and a 6.6 meter angle (ma) collection can be produced. If the two eyes alternately look at the distant object and the near finger, it is inevitable that the muscles inside and outside the eye will move together. This is a very reasonable eye movement to prevent myopia.
2 Finger exercises without far targets: Place one finger vertically in front of both eyes. When the two eyes are gazing at the near finger, the binocular single vision is formed so that the eyes are in a close state. According to the distance between the finger and the eye, a synergistic exercise of close proximity of the intraocular and extraocular muscles of the two eyes can be performed. But when the subject went to see the distant target in the imagination, and consciously did not look at the near finger, the eye axis of the two eyes rotated outward. Since there is no gaze target in the distance, the near fingers are seen as two blurred fingers that intersect left and right. Suddenly looking at the front of the finger, and suddenly looking at the distant target in the imagination, you can carry out the finger operation without the far target. If you move your finger up and down at the same time, you can exercise the eye and muscles of both eyes. This method is simple and convenient to do at any time and place. If it can be adhered to, it is indeed a good method for economic and effective in the prevention and treatment of myopia.
Complication
Myopia complications Complications retinal detachment retinal break open angle glaucoma glaucoma floater
1. Vitreous liquefaction, turbidity and post-dissociation: The most common symptoms are floating mosquitoes. The patient feels that there are black spots floating in front of the eyes. It seems that the mosquitoes are flying. It is often accompanied by the light in front of the eyes, the spark of Mars, etc., especially the high myopia. The eyes are more obvious.
2. The crystal is turbid.
3, retinal tears, retinal detachment.
4, glaucoma: Some people have used the applanation tonometer to prove that the prevalence of open-angle glaucoma in high myopia is 6-8 times higher than that of normal people.
5, dark adaptation time prolonged: due to high myopia pigmentation epithelial cells after the lesion will inevitably affect the photochemical reaction process of the visual cells.
Symptom
Myopia symptoms Common symptoms Arotropia myopia lens dislocation or subluxation lens protrusion lacquer crack pattern myopia arc eyeball function reduction... tremor yellow vision fatigue
First, the classification of myopia
1, according to the degree of myopia
(1) Within 3.00D, it is called mild myopia.
(2) Those with 3.00D to 6.00D are moderate myopia.
(3) Those above 6.00D are high myopia, also known as pathological myopia.
2, according to the refractive component
(1) Axial myopia is caused by excessive development of the anterior and posterior axes of the eyeball.
(2) Curvature myopia is caused by excessive curvature of the cornea or crystal surface.
(3) Refractive myopia is caused by excessive refractive index of refractive interstitial.
3, pseudo-myopia, also known as accommodative myopia, is caused by the adjustment of the distance is not relaxed, it is essentially different from the true myopia of refractive changes.
Second, the clinical manifestations of myopia
1. Vision
The most prominent symptom of myopia is reduced distance vision, but near vision can be normal, although the higher the degree of myopia, the worse the vision is, but there is no strict proportion. Generally speaking, myopia above 3.00D, far vision will not exceed 0.1. ; 2.00D is between 0.2 and 0.3; 1.00D is up to 0.5, and sometimes it may be better.
Far vision is reduced, but near vision is normal
- average; - 50% confidence limit;
··95% confidence limit.
2, visual fatigue
Especially in low-grade people, but not as obvious as hyperopia, due to the inconsistency between adjustment and collection. Because high-vision myopia is too close to the eye, the collective effect can not be matched with it. Therefore, monocular gaze is used instead. Does not cause vision fatigue.
3, eye position
Since the nearsightedness of the myopic eye does not need to be adjusted, the collective function is relatively weakened. When the balance of muscle strength cannot be maintained, the visual function of both eyes is destroyed, and only one eye is viewed from the other, and the other eye is biased to the outside to become a temporary alternation. Strabismus, if the visual function of the oblique eye is extremely poor, and the deflection occurs earlier, the oblique eye loses the fixation ability and becomes monocular external strabismus.
4, eyeball
High myopia, mostly axial myopia, the anterior and posterior axis of the eyeball is elongated, and its elongation is almost limited to the posterior pole. Therefore, the eyeball is more prominent, the anterior chamber is deeper, the pupil is large and the reflex is slow, because there is no adjustment stimulation. The ciliary muscle, especially the annular part, becomes atrophic, and in extremely high myopia, the crystal can not support the iris at all, and mild iris tremor occurs.
5, the fundus
The fundus changes in low myopia are not obvious. High myopia can cause degenerative changes in the fundus due to excessive elongation of the eye axis.
(1) Leopard-like fundus: the blood vessels of the retina become thin and straight after leaving the optic disc. At the same time, due to the elongation of the choroidal capillaries, the nutrition of the retinal pigment epithelial layer can be affected, so that the superficial pigment disappears and the choroidal blood vessels are exposed, forming a leopard. Streaked fundus.
(2) The choroid around the optic disc of the myopic arc is pulled away from the temporal side of the nipple under the traction of the scleral stretch, causing the sclera behind it to be exposed, forming a white arc spot, such as the posterior pole of the eyeball continues to expand and extend, then the choroid The disengagement gradually extends from the temporal side of the nipple to the periphery of the optic disc, and finally an annular plaque is formed, in which irregular pigments and hardened choroidal blood vessels are visible.
(3) The macular part may form irregular, white or fused white atrophy, sometimes bleeding. In addition, there are occasional degenerative lesions near the macula, which is a black ring-shaped area, slightly smaller than the optic disc, and the boundary is clear. A small rounded hemorrhage can be seen at the edge, called the Foster-Fuchs spot.
(4) Post-scleral grape swollen extension of the posterior part of the eyeball. If limited to a small part, a sharp protrusion can be seen from the slice, called the posterior scleral staphyloma. This atrophic lesion occurs at the macula and can be combined. Central vision operation.
(5) Cystic degeneration of the serrated margin.
Examine
Myopia examination
Eye examination includes naked eye vision, corrected visual acuity, intraocular pressure measurement, etc., and computer optometry, dilated pupils, corneal map, corneal thickness gauge, slit lamp, etc., cornea, refractive interstitial, fundus, corneal thickness And the radius of curvature, etc.
Diagnosis
Myopia diagnosis
To identify true and false myopia, in addition to hospital optometry, a simple method to hang an international standard eye chart at 5 meters, first determine the vision, and then wear a 300-degree reading glasses, look into the distance, the eyes will slowly appear Cloudy scene, after half an hour to remove the glasses, and then check the vision, such as increased vision, can be considered pseudo-myopia; if the vision still or vice versa, you can do this once a day, for three consecutive days, such as vision If there is still no improvement, it can be determined as true myopia.
