Abstract
Purpose: :
The goal of the study was to investigate spherical aberration (SA) profile of various intraocular lenses (IOLs) and its impact on effective IOL power.
Methods: :
An optical bench system equipped with a high resolution Shack-Hartmann wavefront sensor was used to measure the aberration of different IOLs placed in a wet cell: 2 spherical IOLs (AcrySof (SA60AT, Alcon), Sensar (AR40e, Abbott Medical Optics)), 2 aspheric IOLs (AcrySof IQ (SN60WF, Alcon), Tecnis (ZA9003, Abbott Medical Optics)), and an aberration-free IOL (Akreos AO (MI60, Bausch & Lomb)). For each IOL platform, lenses with different powers (12-28D) were measured to examine the relationship between SA and IOL power. Effective IOL power, defined as power required to optimize retinal image quality from defocus and SA interaction was calculated.
Results: :
For 20-diopter (D) SA60AT, AR40e, SN60WF, ZA9003, and MI60, SA was 0.182, 0.045, -0.230, -0.261, and 0.001 um, respectively, at 5 mm aperture. When aperture changed from 5 to 3 mm, SA for each IOL was 0.022, 0.007, -0.020, -0.022, and 0.001 um, respectively. At 5 mm aperture, SA60AT showed IOL power-dependent increase of SA (R²= 0.843). SN60WF showed a tendency of negative-shift dependent on IOL power (R²= 0.700). In other IOLs, SA was not dependent on IOL power.Effective IOL power was greater than measured IOL power in SA60AT. When measured IOL powere changed from 12 to 28D, additional defocus increased by 0.36D according to increase of postitive SA. Effective power of SN60WF, on the contrary, was smaller than measured value. Difference of additional defocus between 12 and 28D was 0.19D.
Conclusions: :
Significant amounts of positive and negative SA for a larger pupil were found in SN60AT and aspheric IOLs, respectively although SA became negligible for aperture smaller than 3 mm. Only SN60AT and SN60WF showed an increase in SA with increasing IOL power, which resulted in changes in effective power when considering defocus-SA interaction. These findings suggest that SA of IOL and cornea should be taken into account for enhancing the accuracy of IOL power calculation.
Keywords: intraocular lens