Abstract: one of the sequelae of high myopia (myopia greater than or equal to 600 degrees) is the increased risk of retinal detachment due to the growth of ocular axis. Therefore, after laser myopia surgery, although you can see clearly without glasses, the risk of retinal detachment has not been reduced at all.
Statistics in 2016 showed that the incidence rate of myopia in China was 67.1% among people aged 7 to 18 years. Why is myopia so common? What factors will affect the development of myopia? Is pseudomyopia a kind of myopia?
what is myopia?
the eye is like a camera. The whole transparent medium of the eye includes cornea, crystal and vitreous. Together, it is equivalent to a lens, and the retina is equivalent to a negative film. When the light is concentrated by the transparent medium of the eye and falls on the retina, we see a clear image. The axis of myopia is too long, so the light from afar can not reach the retina, so it is blurred.
to correct myopia, you can put a concave lens in front of the eye, which makes the light refocus on the retina. Whether it’s frame lenses, contact lenses, or laser myopia surgery mentioned before, it uses this principle to correct myopia. Strictly speaking, these methods are only treatment, but not cure myopia, because the length of the ocular axis has not become shorter.
one of the sequelae of high myopia (myopia greater than or equal to 600 degrees) is the increased risk of retinal detachment due to the growth of ocular axis. Therefore, after laser myopia surgery, although you can see clearly without glasses, the risk of retinal detachment has not been reduced at all.
By the way, low myopia refers to less than 300 degrees, and moderate myopia is between 300 and 600 degrees. The risk of retinal detachment in low and moderate myopia is higher than that in emmetropia (neither myopia nor hyperopia), but lower than that in high myopia.
pseudomyopia vs true myopia
We often see that various articles mention pseudomyopia. What else can pseudomyopia develop into true myopia. True myopia is, of course, myopia caused by the lengthening of the eye axis. What is pseudomyopia?
means that the length of the eye axis is normal, but the eye’s ability to focus light is too strong, so the light is still concentrated in front of the retina. There is a small circular muscle called ciliary muscle in the eye. Its function is to adjust the curvature of the crystal. When the eyes of normal people look far away, the ciliary muscles relax and the crystals are flat; When looking close, the ciliary muscles contract, the crystals become convex, and the eye’s ability to gather light becomes stronger. In this way, both far and near light can converge on the retina. When
look close, the contraction of ciliary muscle leads to the strengthening of crystal cohesion. This process is called regulation. Like other muscles in the body, the ciliary muscles are tired and sometimes spasm. If the eye is always in a state of contraction, and the converging light force of the eye is too large, the distant light will converge in front of the retina, resulting in the same blurring of distant vision as myopia.
pseudomyopia is essentially a kind of maladjustment of eye regulation. Teenagers study for a long time, and their eyes are still in the process of development, so the imbalance of adjustment ability occurs from time to time. Therefore, for children and young people to wear glasses, the standard method is to paralyze the ciliary muscle with mydriatic eye drops, force it to relax, and then optometry, otherwise it cannot be accurate.
what harm does myopia have?
answer 1 Can’t be a pilot?
answer 2 Can’t find a boyfriend?
put aside jokes. Many people think myopia is no big deal. It’s just that it’s inconvenient to wear glasses. Moreover, there are all kinds of contact lenses and laser surgery.
but myopia, Especially for high myopia (greater than 600 degrees), the growth of ocular axis will increase the risk of various eye diseases, including retinal detachment, scleral neovascularization, cataract, glaucoma and macular atrophy, which can cause permanent blindness.
The incidence rate of myopia is very high, and 1/5’s myopia is high myopia. The number of people who are very large is the risk of permanent blindness. Wearing glasses and laser surgery did not reduce these risks because the axial length of the eye did not change.
what factors will affect the development of myopia?
myopia is caused by the interaction between gene and environment. The risk factors of myopia development include:
1 Family history. Both parents are myopic, and the risk of children’s myopia is more than twice that of children whose parents are not myopic. This is well understood. The role of genes cannot be ignored. In addition, there are some environmental factors. For example, myopic parents generally spend a long time reading, and children are more likely to like reading.
2. Time for close eye use. The nature of work, education level and so on are self-evident.
eye diopter at the age of 3.6-9 years. The fact is that the average diopter of the baby’s eyes at birth is 200 degrees hyperopia. Pay attention to hyperopia rather than myopia. Then at 18 months, the great difference between people basically disappeared. Everyone was almost stable at 125 degrees hyperopia. This process is called emmetropia. Emmetropia refers to the state that the growth and development of the eye reaches emmetropia, and the focusing ability of the eye is consistent with the length of the eye axis.
statistics show that if the diopter of the eye at the age of 6 is 75 degrees hyperopia, the risk of myopia will be greatly reduced in the future; On the contrary, if it is lower than 75 degrees hyperopia, the risk of myopia is increased.
4. Race. The myopia preference coefficient of Asians is greater than that of whites and greater than that of blacks. It is unknown whether it is related to gene or cultural and environmental differences, which may be related.
5. Outdoor activity time. The latest research shows that outdoor activities, whether sports or meditation, whether overlooking or reading, will reduce the probability and degree of myopia development. What is the specific mechanism? Enhanced circadian rhythm? More overlooking the distance, more clear vision through the small pupil in the outdoor sun? Ultraviolet radiation? Or is it due to the synthesis of vitamin D? It’s not clear yet. Maybe it’s for a variety of reasons.