vision loss
Introduction
Introduction Refers to the naked eye far vision is not up to normal standards. Low eyesight is judged by one eye, and the naked eye vision does not reach the normal standard eye.
Cause
Cause
the reason
1, light pollution
Many families like to paint the walls very white, but parents don't know that white walls reflect a lot of light, stab the children's eyes, and white pages are too much reflection of light, which is also an important cause of low vision.
2, the posture is not correct
Observing the children's reading and writing posture in the natural state, it is found that most children are too close to the book when reading and writing. The sitting posture is better, the posture of holding the pen is poor, and the posture at the beginning of drawing and writing is better. Poor persistence, better posture in other parts of the body, and poor wrist posture.
3, use the eyes unhygienic
Parents do not pay attention to the child's eye hygiene. Children spend too much time reading and writing at home, some children sitting on the squat or toilet to draw and write, some squatting in bed to read books, and some sharing towels with adults, causing trachoma. The current biggest impact on children's vision is to watch TV over-the-counter, as well as long-term Internet access or long-term use of mobile phones and other electronic products. Parents do not affect their work in order to make their children not be noisy, let them watch cartoons when they go home. Some VCD films are serial dramas. I watched a plate but I didn't have to watch it again. It was an hour or two. The children watched before dinner and watched after dinner. Some parents also let their children play computer, which has a serious impact on children's sleep and vision.
Environmental facilities and equipment are not up to standard
Some children's garden desks and chairs are either high or low, which does not meet the height requirements of children. Some children have insufficient lighting or lighting equipment in the activity room. Some have no curtains. Children read books, draw and write in direct sunlight. The greening in the park is not up to standard and so on.
Predisposing factor
1. Genetic factors
According to a large number of survey data, the more consistent conclusion is that high myopia is related to heredity, and there is a big difference in moderate myopia. The genetic type of high myopia, the majority of survey data concluded that autosomal recessive inheritance. Therefore, the father and the child can have myopia at the same time. Genetics are often mutated by the objective environment, the influence of living conditions, which increases the complexity of the inheritance.
2, environmental factors
Environmental factors are mainly close-range work and poor working environment. This is the oldest theory. Although there are still some controversies to this day, from a large number of domestic and foreign research reports, it is recognized that genetics and environment are the main causes of myopia. And pointed out that environmental conditions are the objective factors that determine the formation of myopia.
However, under the influence of close reading or close work, why can it produce myopia? There is no consensus on this, mainly the following theories:
(1) Regulation theory: Most of myopia occurs in adolescence. Because the eyesight of young people is particularly strong, they are highly adaptable to close work and study, so it is not easy to get tired. However, the ciliary muscles are over-stressed for a long time, and the ciliary muscles may become fatigued or even paralyzed and have modulated myopia. If they are not eliminated in time, they may become irreversible true myopia. Or affect the extension of the eye shaft by other means.
(2) Radiation theory: When using the close-range work adjustment, it is also necessary to strengthen the convergence function of both eyes at the same time, which can cause the eye muscle to pressurize the eyeball and cause the extension of the eye axis.
(3) Environmental adaptation theory: In childhood, the eyeballs are small, and most of them show hyperopia. As the age increases, the eyeballs increase to the frontal state. In this development process, too much reading is done at a close distance, and the eyeball becomes myopia in order to adapt to this adjustment. This theory is subject to many oppositions, but it is very malleable during development and has a significant impact on the development of myopia.
3, other external factors such as lighting, reading posture, contrast, small word blur, too close distance and long reading time can affect the above factors.
4. Nutritional physiology
From some data analysis, the lack of trace elements such as cadmium, strontium and zinc and the weakness of the body can also affect the occurrence of myopia. In short, it can be seen from the above that there are many factors that can be caused by myopia, both external factors and internal physical factors, rather than a single factor.
Most of the students' low vision is myopia. The influencing factors of myopia occur include environmental factors, physical nutrition factors and genetic factors, among which physical factors account for a large proportion.
Examine
an examination
Related inspection
Vision eye examination
Vision includes far vision and near vision, as well as a preliminary impression of visual impairment. Poor vision, near vision, may be myopia, astigmatism and so on. Poor near vision, good distance vision, may be hyperopia. Those over the age of 40 are considered to be presbyopia. Far and near vision are not good, can be hyperopia or astigmatism, or refractive interstitial opacity, fundus or optic neuropathy, intracranial lesions. If there is ciliary congestion, keratitis, iridocyclitis, and glaucoma should be considered. A sudden visual impairment, which may be a central retinal artery occlusion, ischemic optic neuropathy. Visual acuity rapidly diminish within a few days, possibly central retinal vein occlusion, retinal detachment, vitreous hemorrhage, eye and craniocerebral trauma, poisoning, acute intracranial lesions, etc. No light perception may be caused by optic atrophy and eyeball atrophy. Eyeballs, absolute glaucoma, cortical blindness, etc. After giving a preliminary impression of the above-mentioned vision, it should be checked step by step from the front to the back according to certain steps.
Diagnosis
Differential diagnosis
Can be differentiated from visual impairment.
Eye functions include shape, color perception, and light perception. Vision is a function that more accurately represents the shape and can be divided into central vision and peripheral vision. Central vision is obtained through the center of the macula, which refers to retinal function outside the macula. Therefore, vision is one of the specific manifestations of visual function. Visual impairment, although very mild, also indicates that vision function has been affected.
