[Effects of spherical aberration on objective optical quality after microincision cataract surgery]

To assess the impact of spherical aberration (SA) on clinical ocular performance and the objective quality of vision in pseudophakic patients.

Twenty-five consecutive eyes were divided into two groups: 13 eyes received an aspherical AcriSmart 36A intraocular lens (IOL) (Carl Zeiss Meditec, USA) generating a negative SA and 12 eyes received a zero-aberration AcriSmart 46 LC IOL (Carl Zeiss Meditec, USA). Postoperative evaluations were conducted 6 months after 1.8-mm microincision cataract surgery and included wavefront aberration analysis (Wavescan, AMO, USA) and objective quality of vision (Objective Quality Analysis System, Visiometrics, Spain).

Best corrected visual acuity (BCVA) was not different in the two groups (p=0.89). Total spherical aberration was significantly less with the 36A IOL (0.075 +/- 0.05 microm versus 0.20 +/- 0.05 microm; p=0.0002). The 36A IOL induced better objective image quality with an average MTF of 32.7+/-9.6 c/deg versus 23.8+/-8.1 c/deg with the 46LC, p=0.0002. The 36A IOL group had 1 D less depth of focus than the 46LC IOL group: 1.3+/-0.59 and 2.27+/-0.63 D, respectively. For the whole population, the depth of focus appeared to be correlated with SA (r(2)=0.40, p=0.002) and with trefoil (r(2)=0.53, p=0.001).

Aspheric IOLs objectively improved the quality of vision with greater MTF values. Reduction of aberrations may be also be responsible for reduced depth of focus with the 36A IOLs. However, residual trefoil aberrations may be advantageous for depth of focus.