Effect of tilt and decentration of spherical and aspheric intraocular lens on visual quality

Abstract

Objective To study tilt and decentration of spherical and aspheric IOL implantation after phacoemulsification surgery and effect on higher-order aberrations （HOAs） and visual quality. Methods It was a prospective clinical study. A total of 60 eyes （50 patients） were divided into 2 groups randomly, of 30 eyes in each group, one group with Sensar AR40e （AMO）, one group with Tecnis ZA9003 （AMO）. Three to four months after surgery, higher-order aberrations （HOAs） and modulation transfer function （MTF） at six spatial frequencies （5, 10, 15, 20, 25, 30 cpd） were measured in 5.0mm pupil size. Tilt and decentration of the IOLs were measured using Scheimpflug photography. The tilt and decentration, HOAs and subtracted lower order aberration MTF （MTF（HOA）） were compared. The effect of tilt and decentration on HOAs and visual quality was assessed using multiple regression analysis. Results The mean optic tilt was （2.99± 0.94）° for AR40e group and （2.98± 1.15）° for the ZA9003 group. The mean optic decentration was （0.30± 0.13）mm, （0.31± 0.14）mm,respectively. No significant differences in IOL tilt or decentration were found （Z= -0.044, -0.525, P =0.965,0.600, Mann-Whitney U test）. The total 4th order spherical aberration in AR40e group was larger than it was in ZA9003 group and the differences were statistically significant （t = -10.386, P =0.000）. In 5.0mm pupil size,MTF （HOA） at all spatial frequencies in ZA9003 group were larger than they were in AR40e group and the differences were statistically significant （P 〈0.05）. Tilt and decentration did not significantly affect HOAs and MTF （HOA） with either IOL. Conclusions When IOL tilt and decentration are within normal limits, hey do not compromise the correction of spherical aberration by the aspheric IOL and the amounts of tilt and decentration of both IOLs are not large enough to cause deterioration of visual quality. Key words: IOL; Tilt; Decentration; Aberration; MTF