Abstract: refractive myopia refers to myopia caused by the change of refractive factors such as lens within the normal range. The refractive components of the eye are abnormal, or the combination of components is abnormal. The parallel light enters the eye and focuses in front of the retina after refraction by the refractive system to form myopia.
myopia is a very common phenomenon, and with the increase of myopia, more and more people go to do vision correction and vision maintenance. However, most people don’t know anything about their own situation when they go to do vision correction or vision maintenance. Generally speaking, the characteristic of myopia is that they can only see near but not far. Without adjustment, the distant parallel light enters the eye through the pupil and cannot form a clear image on the retina before focusing on the retina, which is a problem of the optical structure of the eye. Although they are all myopia, the types of myopia are different. Some people are myopia with astigmatism, while others are simple myopia. In the types of myopia, axial myopia and refractive myopia are often heard. What is the difference between the two?
01. Refractive myopia
refractive myopia refers to myopia caused by the change of refractive factors such as lens within the normal range. The refractive components of the eye are abnormal, or the combination of components is abnormal. The parallel light enters the eye and focuses in front of the retina after refraction by the refractive system to form myopia. Strictly speaking, refractive (or photorefractive) myopia should refer to myopia caused by the change of refractive factors such as lens with constant axial length (or within the normal range). Its essence is to emphasize the role of environmental factors. This kind of large-scale vision maintenance institutions with general myopia can recover vision without changing diopter.
02. Axial myopia
axial myopia is the most common myopia. Generally, it refers to that other refractive components are basically normal, but the eye axis increases. When the parallel light enters the eye, it focuses in front of the retina to form myopia, resulting in blurred vision. When the eye axis increases by 1 mm, the degree of myopia increases by 300 degrees. Children and teenagers are studying in school. They spend a long time reading, writing and other near work, which is easy to lead to axial myopia.
in recent years, children with high myopia have increased, and the average value of normal ocular axis has moved up to the upper limit. Visual function exercise is generally needed to control the development of ocular axis and promote the tendency of ocular axis to normal development. The reason why
take the standard length of children’s ocular axis from 1984 to 86 is that in recent years, there is a growing disparity in the development of children’s ocular axis. There are many people whose preschool ocular axis reaches 24mm for adults. The standard axis length is the average of children over 5 years old with visual acuity of 1.0, The upper limit mean value is the mean value above the mean value (the axial development of children with normal vision naturally slows down and tends to the mean value), which should belong to the physiological difference between early and late development. Visual function exercise can inhibit the axial development and make the elongation slow or stop.
03. The risk of axial myopia
Axial myopia occurs in adolescents. In the stage of development and growth, myopia deepens year by year and progresses rapidly with age. It is often accompanied by fundus changes and vision is not easy to correct. Once high myopia is formed, the eye is easy to develop into irreversible pathological myopia.
whether axial myopia or refractive myopia, they are generally true myopia and need visual correction and visual rehabilitation. Many parents responded, “why does the degree of children increase instead of decrease after visual rehabilitation in vision maintenance institutions?”, It should be emphasized here that axial myopia is common for teenagers. Children with abnormal axial development enter vision maintenance institutions for vision rehabilitation. Although it is difficult to restore the axial length, it can greatly slow down the growth rate of axial and visual acuity; If children with axial myopia do not do visual rehabilitation, the degree will soar in a short time. Over time, it will lead to serious consequences and even blindness. Therefore, it is very necessary to enter vision maintenance institutions for visual rehabilitation.