How many degrees of myopia is considered high myopia? Does high myopia have any adverse effects on the eyes? High myopia is defined as more than 6 diopters (commonly known as 600 degrees). People with high myopia should not play strenuous sports, mainly to avoid retinal detachment. It is generally believed that the greater the degree of high myopia, the more pronounced the changes in the fundus, and the greater the likelihood of retinal detachment. Some people even believe that retinal detachment can occur in more than 5% of people with high myopia, which means that the chance of retinal detachment in highly myopic eyes is large. The retina is the innermost layer of the eye wall, which is very thin and has a fine and complex structure. Retinal detachment is a serious eye disease, once it occurs, it is like the detachment of the negative in a camera, objects cannot form an image in the eye, causing serious vision loss, if the detachment is extensive and not treated in time, it can often lead to blindness. Therefore, people with high myopia should have regular eye examinations, visual acuity and optometry, and should not do strenuous sports and heavy physical labor to avoid head injuries. In addition, when choosing an occupation, one should also choose an occupation with indoor work, and it is not suitable to choose an occupation with a lot of sports such as athletes, porters, etc.