OBJECTIVE To evaluate contrast visual acuity (CVA) after implantation of an aspheric apodized diffractive intraocular lens (IOL) or a spherical apodized diffractive IOL in cataract surgery. METHODS This prospective randomized controlled study with a 12-month follow-up compared the results of cataract surgery with implantation of an aspheric AcrySof ReSTOR SN6AD3 IOL (30 eyes) and a spherical AcrySof ReSTOR SN60D3 IOL (30 eyes). CVA with best distance correction was measured at 4 contrast levels (100%, 25%, 10% and 5%) under 3 levels of chart luminance [250, 85 and 25 candelas per square meter (cd/m(2))] using a multi-functional visual acuity tester (MFVA-100). RESULTS At 12 months after surgery, there were no statistically significant differences in 100% CVA and 25% CVA under 250cd/m(2) (P 100%=0.875 and P 25%=0.057) and 85cd/m(2) (P 100%=0.198 and P 25%=0.193) between the aspheric group and the spherical group. However, the 10% CVA and 5% CVA were significant better in aspheric group than spherical group under 250cd/m(2) (P 10%=0.042 and P 5%=0.007) and 85cd/m(2) (P 10%=0.002 and P 5%=0.039). Under the luminance level of 25cd/m(2), no significant differences was found in the 100% CVA between the 2 group (P 100%=0.245), while aspheric group had better visual acuity in the remaining 3 contracts (P 25%=0.023, P 10%=0.026 and P 5%=0.002, respectively). CONCLUSIONS [corrected] The aspheric AcrySof ReSTOR SN6AD3 IOL provided patients with better low-contrast visual acuity than the spherical AcrySof ReSTOR SN60D3 IOL.