 Proposed procedure, including risks, benefits, and alternatives were discussed with all subjects, and all participants signed of informed consent form. Patients had only mild to moderate PCO were enrolled in this study to reduce obstacles to measurements. Participants who had false-negative acuity predictions because of diffuse PCO, poor pupillary dilation, poor patient posture at the slit-lamp examination, poor patient cooperation, senility, illiteracy, communication problems, nystagmus, tremor, and fatigue were excluded in this study. 