Contrast Sensitivity after Refractive Lens Exchange with A Multifocal Diffractive Aspheric Intraocular Lens

Purpose: To evaluate distance and near contrast sensitivity (CS) under photopic and mesopic conditions before and after refractive lens exchange (RLE) and implantation of the aspheric AcrySof ReSTOR (SN6AD3 model) intraocular lens (IOL) Methods: Sixty eyes of 30 consecutive patients after RLE underwent bilateral implantation with the aspheric AcrySof ReSTOR IOL. The patients sample was divided into myopic [n=15, mean spherical equivalent (SE) -6.87± 2.03 diopters (D)] and hyperopic (n=15, mean SE +4.52±1.14 D) groups. Monocular uncorrected visual acuity at distance and near (UCVA and UCNVA, respectively) and monocular best corrected visual acuity at distance and near (BCVA and BCNVA, respectively) were measured before and 6 months postoperatively. Monocular CS function was measured with the Stereo Optical FACT CS chart at distance and near, at three different luminance levels (85, 5 and 2.5 cd/m2) before and after RLE. Postimplantation results at 6 months were compared with those found before surgery. Results: Our results revealed that patients in both groups obtained good UCVA and BCVA after RLE at distance and near vision in relation to presurgery values. The safety and efficacy indexes were 1.06 and 0.87 for the myopic group and 1.02 and 0.86 for the hyperopic group at distance vision. At near vision, the safety and efficacy indexes were 1.24 and 1.16 for the myopic group and 1.15 and 1.13 for the hyperopic group. No statistically significant differences were found between the values of CS pre and post-RLE at distance and near, at any lighting condition and spatial frequency (P>0.002). Conclusion: RLE with aspheric AcrySof ReSTOR IOL in myopic and hyperopic population provided good visual function and yield good distance and near CS under photopic and mesopic conditions. Although mesopic CS is reduced at distance and near in relation to photopic CS, the performance is comparable to that obtained prior to surgery with the natural lens and better than published results of the spherical AcrySof ReSTOR model.