The most common clinical refractive eye diseases are as follows: myopia, hyperopia, astigmatism, presbyopia, and refractive error. Astigmatism is a state of refractive error of the eye, caused by the inconsistent curvature of the cornea or lens surface, such as an olive sphere, resulting in two mutually perpendicular meridians with different refractive powers that cannot focus on one point, forming an unclear or overlapping image. Refractive aberrations are the result of unequal refractive power between the two eyes, with a difference of ≥1.50D between spherical lens degrees and ≥1.00D between cylindrical lens degrees, which is called refractive aberration. (For every 1.00D difference in refractive error in both eyes, there is a 2% difference in image size).