Refractive abnormality, or refractive error, refers to the inability of parallel light from the outside world to focus accurately on the retina, including myopia, hyperopia, and astigmatism. The refraction of light from one medium to another occurs and becomes refraction in the optical system of the eye. Parallel light from the outside will be focused on the retina by the refractive system of the normal eye, and then processed by the brain to form a clear image. If the light cannot be focused on the retina, it is anomalous vision, which is also known as refractive error or refractive abnormality. Refractive errors include myopia, hyperopia, astigmatism, etc. Myopia refers to the parallel light from the outside world focusing in front of the retina after passing through the refractive system of the eye, hyperopia refers to the light from the outside world focusing behind the retina, and astigmatism refers to the refractive system’s refractive errors in different directions, so that the light from the outside world can’t form a focal point on the retina. It is recommended that patients with refractive errors should seek timely medical attention to assess their condition and follow the doctor’s instructions.