Refraction is not myopia, it is an optical phenomenon, when external light enters from one medium to another medium with different refractive index, the light will be deflected at the interface, this phenomenon is called refraction. In the human eye, an external object passing through the eye’s optical system will be deflected and focused above the retina, at which point the object can be seen clearly. If it is not accurately focused above the retina, it is called refractive error. Refractive error is a complex condition that consists of three main areas, including myopia, hyperopia, and astigmatism. In the clinic, doctors usually write myopia as refractive error because myopia is one of the refractive errors, but without a standardized dilated pupil examination, doctors can not confirm whether it belongs to myopia, astigmatism, or farsightedness, so it is usually abbreviated as refractive error.