Based on optical quality metrics of human eyes,the counterbalanced relationship between defocus and spherical aberration for wave-front aberration data of preoperative and postoperative myopic eyes is studied.The results show that defocus can not obviously compensate spherical aberration for preoperative patients.But the counterbalanced relationship can be distinctly observed for the postoperative patients,which reveals that the remained defocus can partially ameliorate the influence of the increased higher-order aberrations after corneal refractive surgery on visual performance.For postoperative patients,more than 20% improvement of optical quality can be achieved when the remained defocus ranges from 0.27D to 0.74D.More than 80% of eyes can achieve better visual performance when the remained defocus ranges from 0.3D to 0.75 for a design of vision correction.