High myopia is defined as myopia of more than 6 diopters (600 degrees). The vast majority of myopic eyes are below 6 diopters, called ordinary myopia, which is a physiological variation. As children grow older, their eyes slowly grow, and thus the refractive state of the eye is constantly changing. If you don’t pay attention to eye hygiene in general, you are bound to have various effects on this process. Many ophthalmologists have conducted surveys in some schools and found that there are very few myopic eyes in kindergarten children, not many myopic eyes in elementary school, and gradually more myopic eyes in middle school, and even more in high school and college. Rural schools are less myopic than urban schools. Why is the prevalence of myopia related to ageing? This means that myopia is related to long-term close study and work. If you do not pay attention to eye hygiene during this period of growth and development, excessive application of regulation will inevitably affect the development of the eye over the years, resulting in a longer anterior and posterior diameter of the eye and a deepening myopia. Myopia is generally more stable by the age of 20, and the number of diopters is below 6. Some people continue to progress after the age of 25, even to 20 diopters or more, the eye is very large, the anterior and posterior diameters are significantly longer, the posterior part of the eye expands, can form a posterior grape swelling, affecting the function of the retina, choroid and vitreous, resulting in retinal degeneration, choroidal atrophy, vitreous liquefaction and a series of pathophysiological changes, even with glasses, vision correction Even with glasses, the vision cannot be corrected to the normal level. Therefore, high myopia is called “pathological myopia” or “degenerative myopia.