Influence of Corneal Spherical Aberration and Intraocular Lens Asphericity on Optical Quality After Cataract Removal

Abstract

Purpose: : To investigate the influence of corneal spherical aberration and intraocular lens (IOL) asphericity on optical quality after cataract removal.

Methods: : We included 119 eyes of 72 cataract patients who were implanted with different spherical and aspheric IOL. 26 eyes received AcrySof SN60AT (Alcon, spherical aberration [SA] = 0.28µm), 21 eyes Sensar AR40e (AMO, SA = 0.1µm), 25 eyes Akreos TL MI60 (Bausch & Lomb, SA = 0µm), 26 eyes AcrySof IQ SN60WF (Alcon, SA = -0.2µm), and 21 eyes Tecnis Z9000 (AMO, SA = -0.27µm), all IOL-SA according to manufacturer’s information. Absolute values of corneal and ocular higher order aberrations were measured, and best-corrected visual Strehl ratio based on the optical transfer function (BCVSOTF) values were computed. All trial-specific measurements (corneal topography, wavefront sensing) were performed 3-6 months after surgery. Linear regression, ANOVA and Tukey HSD test were used to evaluate intergroup differences.

Results: : Incision size (IS) ≥ 3mm caused a significantly higher change of corneal SA (p<0.001) and showed high variance of ocular SA of 0.64±0.23µm (AR40e) and 0.32±0.34µm (Z9000), whereas IS of 1.7 mm and 2.5mm lead to minimally variant ocular SA of 0.24±0.07µm (MI60), 0.03±0.07µm (SN60WF) and 0.53±0.07µm (SN60AT). A significant relationship between ocular SA and BCVSOTF was shown (r²=0.244, p<0.01). Smaller values for ocular SA were associated with higher values for BCVSOTF. BCVSOTF was of interindividual variance in all groups [-1.17±0.28 (IOL-SA = 0.28µm), -1.04±0.16 (IOL-SA = 0.1 µm), -1.02±0.17 (IOL-SA = 0µm), -0.73±0.21 (IOL-SA = -0.2µm), -0.98±0.23 (IOL-SA = -0.27µm)] with significantly better values for BCVSOTF compared to all other groups (p<0.01) for IOL-SA of -0.2 µm.

Conclusions: : Because of variance of surgically induced corneal SA, predictability of resulting ocular SA is limited depending on IS. Up to minimum ocular SA of about 0.0µm, lower residual ocular SA causes better performance in terms of BCVSOTF. A distinct customization based on individual pre-surgical corneal SA is not to be postulated, but an IOL-SA of -0.2µm in addition to an incision size limited to 2.5mm shows best performance.

Clinical Trial: : www.clinicaltrials.gov not found

Keywords: refractive surgery: optical quality • intraocular lens • aberrations