PURPOSE: To compare spherical aberration and contrast sensitivity with two different types of aspheric posterior chamber intraocular lenses (PCIOLs): Tecnis Z9000 versus Akreos AO. METHODS: Thirty-four eyes of 34 patients undergoing phacoemulsification for senile cataracts were randomly assigned to implantation of Tecnis Z9000 or Akreos AO PCIOLs. Outcome measures included best-corrected visual acuity (BCVA), spherical aberration (SA) with 4 and 6 mm pupil diameters and contrast sensitivity under photopic and mesopic conditions at spatial frequencies of 1, 2, 5, 10 and 20 cycles per degree (cpd) three months postoperatively. RESULTS: Mean BCVA was 0.08±0.08 logMAR in the Tecnis Z9000 group and 0.11±0.09 logMAR in the Akreos AO group (P=0.33). SA was less with Tecnis than Akreos AO with 4 and 6 mm pupil diameter (0.14±0.10 µm vs 0.28±0.09 µm, P < 0.001 and 0.30±0.18 µm vs 0.33±0.08 µm, P=0.4, respectively). Contrast sensitivity was significantly higher in the Tecnis Z9000 group at 1, 2, 5 and 10 cpd under photopic and at 1, 2 and 10 cpd under mesopic conditions. CONCLUSION: Tecnis Z9000 IOL seems to entail better visual outcomes in terms of spherical aberration and contrast sensitivity as compared to Akreos AO.