Abstract: long time continuous close reading, writing, playing computer and mobile phone, eyes are in a state of tension for a long time. There is little outdoor exercise, and the 2-hour telescopic time can not be guaranteed every day, and the eyes can not be relaxed and rested.
“the child is 10 years old. He always squints when looking at things. After optometry, he found that the child has 100 degrees of myopia.” Ms. Lin, the provincial capital, recently worried about her son’s myopia. “Neither of us has myopia, but how can he have myopia?” Ms. Lin wondered whether the child’s condition was serious and needed treatment. To this end, the author visited Sun Wei, director of optometry expert of the affiliated ophthalmic hospital of Shandong University of traditional Chinese medicine, and asked him to take his parents with “myopia baby” to understand the “past and present life” of myopia.
what is myopia
the human eye is like a camera. Myopia is that when the eye looks far, the image falls in front of the “film”, the feeling is blurred, and becomes clear when it gets close.
the following symptoms need to be vigilant against myopia.
█ like to watch TV
█ can’t see the blackboard clearly, or always copy the wrong blackboard
█ close to the book when reading and writing
█ like to squint when looking at a distance, or hold the bridge of the nose
█ eyes are prone to fatigue, Why do you often rub your eyes
at present, there is no definite conclusion about the causes of myopia, which can be roughly summarized into the following aspects:
█ looking close for a long time
reading, writing, playing computer and mobile phone for a long time, and your eyes are in a state of tension for a long time. There is little outdoor exercise, and the 2-hour telescopic time can not be guaranteed every day, and the eyes can not be relaxed and rested.
█ poor reading and writing posture
incorrect reading and writing posture and pen holding posture will cause the eyes to bear the triple burden of posture, line of sight and distance, induce myopia and deepen the degree of myopia.
█ incorrect glasses
the parents obtained incorrect proximity prevention information, resulting in the wrong concept of proximity prevention. After the child suffers from myopia, many parents are unwilling to wear glasses for their child. They think that the more they wear, the deeper they wear, they can’t take them off. Vision care institutions exaggerate publicity and prevent confusion. Many myopia prevention and control products in the market have no scientific basis. The unqualified rate of optometry and glasses in optical shops is as high as 85%. The non-standard prevention and control leads to the deepening of children’s myopia.
█ retinal hyperopia defocus
ciliary muscle regulation function disorder, poor regulation sensitivity, resulting in retinal hyperopia defocus, resulting in eye axis growth and myopia.
█ form deprivation
reading and writing under strong and weak light, reading in the carriage, long bangs or inverted eyelashes, uncontrolled Internet watching TV, playing the piano and other bad eye behavior, which limits the full input of visual perception, interferes with the quality of peripheral retinal imaging, blurred retinal imaging, and will lead to the occurrence and development of myopia.
█ axial growth
poor reading and writing posture, non-standard optometry and glasses, resulting in hyperopia defocus of peripheral refraction relative to macular fovea, which promotes the compensatory growth of axial myopia and deepens axial myopia.
█ patients with high myopia inherited
have a higher probability of myopia in their offspring.
what are the common myopia? The
axis is too long – the axis of axial myopia
axis is the length of the camera from the lens (cornea) to the film (retina). Generally, the normal value of ocular axis after 7 years old is 23.5 ~ 24mm. For every 1mm increase of ocular axis, myopia increases by 300 degrees. Axial myopia accounts for 90% of myopia.
corneal over bending – curvature myopia
normal corneal curvature radius is 7.8mm, and the shape is close to the spherical surface. If the cornea is over bent, the curvature radius will become smaller, and the corneal shape will be convex, which is manifested as myopia. RGP or MCT is the best.
when the lens adjustment cannot be relaxed, it will show the same symptoms as myopia – blurred vision, clear vision near, and the result of direct optometry will be higher than the actual power. After the examination of the ciliary paralysis (mydriasis), the regulation effect was relieved, and the high myopia degree disappeared. This part of myopia is called pseudomyopia.
pseudomyopia can be eliminated after ciliary muscle paralysis, but it will show true myopia and cannot be eliminated if direct pupillary optometry and glasses are provided. Children under 15 years old should have binocular visual function examination or mydriatic optometry to rule out pseudomyopia. Classification of
█ mild myopia: < 300 degrees
█ moderate myopia: 300 ≤ degrees < 600 degrees
█ high myopia: ≥ 600 degrees
the main cause of myopia growth is the elongation of
eye axis. Myopia increases by 300 degrees for every 1mm extension of the ocular axis.
teenagers are in the stage of growth and development, and the ocular axis will grow with growth and development.
retina is located in the inner wall of the eyeball. It has photosensitive and conductive functions. It is the “film” of this advanced camera. When the image does not fall on the “film”, it is called defocus. At this time, the eyes feel as if it is blurred.
█ hyperopia defocus
are divided into myopic defocus (falling in front of the retina) and hyperopia defocus (falling behind the retina) according to the position of the image.
myopia are often accompanied by insufficient adjustment ability. They use their eyes at close range for a long time, and the object image falls behind the retina for a long time. The eyeball has the characteristic of focusing growth, that is, in order to see the object clearly, it will “look for” the image behind, resulting in the extension of the eye axis and the growth of myopia. Insufficient adjustment of
, glasses for pseudomyopia and high degree of myopia glasses will lead to hyperopia defocus and accelerate the development of myopia.
█ peripheral retinal defocus
wear frame glasses and the image falls on the central retina, but due to the characteristics of optical glasses, the peripheral image still falls behind the retina, which is called peripheral retinal defocus.
peripheral retina also plays an important role in the extension of ocular axis, so peripheral hyperopia retinal defocus is also the main reason for the growth of myopia.