The aspheric, one-piece design of the Tecnis® ZCB00 intraocular lens provided higher mesopic contrast sensitivity and relatively constant refraction at different pupil sizes compared to the Sensar® AR40e.Comparing the impact on functional vision of the aspheric Tecnis® ZCB00 one-piece lens compared to the spherical Sensar® AR40e three-piece lens.National Eye Hospital, Cairo, Egypt.In this prospective study, we implanted 32 Tecnis ZCB00 (Abbott Medical Optics, Santa Ana, CA) and 30 Sensar AR40e (Pharamacia and Upjohn LLC, North Peapack, NJ) lenses. Twenty-three patients in the ZCB00 group and 13 patients in the AR40e group provided reliable, reproducible data, and were therefore included in the statistical analysis. After 8 weeks, we measured photopic contrast sensitivity (PCS) at 85 cd/m(2) and mesopic contrast sensitivity (MCS) at 5 cd/m(2). Uncorrected and best-corrected visual acuity were measured. Myopic shift was analyzed by comparing the manifest refraction spherical equivalent at 3 days and 8 weeks after surgery in the normal and dilated pupil.The Tecnis ZCB00 group showed significantly better MCS than the Sensar AR40e group at a spatial frequency of six cycles per degree (cpd) (P = 0.037), but not at 3, 12, or 18 cpd (P = 0.299, P = 0.226, and P = 0.396, respectively). There were no significant differences between groups in corrected distance visual acuity (P = 0.175) or PCS at 3, 6, 12, or 18 cpd spatial frequencies (P = 0.440, P = 0.176, P = 0.365, and P = 0.251, respectively). The ZCB00 group showed less myopic shift in normal and dilated pupils between 3 days and 8 weeks after surgery compared to the AR40e group, but this difference was not significant.The Tecnis one-piece ZCB00 provided higher MCS at moderate spatial frequency than the three-piece Sensar AR40e, and was associated with relatively constant refraction at different pupil sizes.