OBJECTIVE To compare spherical aberration, visual quality and apparent accommodation between pseudophakic patients with an aberration-free aspheric intraocular lens (IOL) and patients with a spherical IOL. METHODS A prospective study of 130 consecutive cases (132 eyes) was conducted. All cataract patients underwent phacoemulsification were randomized to receive an aberration-free aspheric IOL (Akreos AO, Bausch & Lomb) or a spherical IOL (KS-1, Cannon Staar). Spherical aberration of total eye, best corrected visual acuity (BCVA), near visual acuity (NVA), contrast sensitivity, glare sensitivity and apparent accommodation were measured. Data were analyzed using chi-square test and independent t-test. RESULTS The mean spherical aberration in eyes with a Tecnis IOL [(0.141 +/- 0.070) microm] was significantly lower than that of eyes with a spherical IOL [(0.210 +/- 0.108) microm; t = 4.365, P = 0.000]. In addition, Akreos AO IOL provided a better contrast sensitivity at 2.5 degrees visual angle (30.62 +/- 12.50 vs. 25.92 +/- 7.36; t = 2.606, P = 0.010), and improved glare sensitivity at 4.0 degrees (31.25 +/- 8.65 vs. 26.70 +/- 7.98; t = 3.116, P = 0.002), 2.5 degrees (26.35 +/- 8.72 vs. 22.43 +/- 7.35; t = 2.772, P = 0.006) and 1.6 degrees (12.35 +/- 4.01 vs. 9.82 +/- 4.12; t = 3.553, P = 0.001) visual angles. The difference of BCVA, NVA and apparent accommodation between these two groups was not statistically significant. CONCLUSION The present results demonstrated that an aberration-free aspheric IOL, Akreos AO, may reduce the spherical aberration and improve visual performance of pseudophakic eyes and without negative influence on apparent accommodation as compare to conventional spherical IOL.