To determine if aspheric intraocular lens (IOL) implantation produces the same degree of postoperative ocular aberration and contrast sensitivity as spherical IOL implantation. In this randomized prospective comparative study, 60 eyes of 30 cataract surgery patients were randomly assigned to receive a spherical IOL (Rayner 620H) in one eye and an aspheric IOL (Rayner 920H) in the contralateral eye. All patients were examined at 1 month postoperatively. Primary outcomes of contrast sensitivity and ocular wavefront higher order aberrations (HOAs) were assessed. Aspheric IOLs (median total HOAs 0.26 root mean square [RMS]; range 0.13-0.82 RMS) produced significantly lower total HOAs than spherical IOLs (median total HOAs 0.34 RMS; range 0.18-1.08 RMS; p<0.05). Contrast sensitivity was significantly better with aspheric IOLs (median contrast sensitivity 1.8 log units; range 1.35-1.8 log units) than with spherical IOLs (median contrast sensitivity 1.65 log units; range 1.35-1.8 log units; p<0.05). When compared with a structurally (platform and material) similar spherical IOL (Rayner 620H), aspheric IOLs (Rayner 920H) appear to significantly reduce HOAs and yield better levels of contrast sensitivity under photopic conditions.