The easiest way to measure myopia is to dilate the pupils, that is, to use eye drops, commonly used compound tropicamide eye drops. The eye drops paralyze the ciliary muscle inside the eyeball, causing the pupil to dilate, which results in a more accurate measurement. True myopia is caused by the lengthening of the eyeball, after dilating the pupil, the eye still exists, while pseudomyopia is caused by the eye’s own regulation, after dilating the pupil to remove this part of the regulation, there will be no degree. If there is true myopia after dilating the pupils, glasses are necessary because they are less likely to cause myopia to deepen. If there is no myopia after dilating the pupils, it means that the myopia was pseudomyopia before dilating the pupils, in this case, you do not need to wear glasses, and pay attention to the habits of eye use.