Objective To observe the clinical effects after implantation of an aspherical intraocular lens Acrysof IQ.Design Prospective,randomized concurrent-controlled study.Participants 64 patients(64 eyes)with bilateral senile cataracts.Methods Pa- tients were operated with phacoemulsification and IOL implantation.They were divided randomly into 2 groups according to the table of random number:one group with Aerysof IQ(aspherical IOL)implantation and the other with Acrysof SN60AT(spherical IOL).Thor- ough ophthalmic examinations,including visual acuity,slit lamp examinations,fundoseopy,wavefront aberrometry,contrast sensitivity, were performed 1 week,1 month and 3 months after surgery.Main Outcome Measures Visual acuity,the best corrected visual acuity, spherical aberration(C 12),the root mean square of the total higher-order aberration(RMSh),and contrast sensitivity at 4 kinds of light backgrounds.Results At 1 postoperative month,RMSh(0.30?0.68?m)and C12(0.07,?0.04?m)in aspherical IOL group were signifi- cantly lower than those of the spherical IOL group(0.49?0.14?m,0.36?0.06?m)(P=0.00)with a 6.0 mm aperture.At 3 postoperative months the RMSh(0.30?0.07?m)and C12(0.06?0.06?m)in aspherical IOL group were significantly lower than those of the spherical IOL group(0.47?0.14?m,0.34?0.06?m)(P=0.00)with a 6.0 mm aperture.The asphefieal IOL(Acrysof IQ)provided statistically sig- nificant better contrast sensitivity at all spatial frequencies under mesopic conditions(3 cd/m~2)with and without glare(P