Abstract
Purpose: :
To compare differences in higher order aberrations (HOA) and surgical induced astigmatism (SIA) between coaxial micro-phacoemulsification (Co-MICS) and small-incision cataract surgery (SICS) in eyes implanted with AcrySof IQ aspheric intraocular lenses (IOLs).
Methods: :
77 eyes of 51 patients were included in this prospective study. 46 eyes underwent Co-MICS (2.2 mm incision) and 31 eyes SICS (3.0 mm incision). After phacoemulsification through a temporal clear cornea incision all eyes received an AcrySof IQ (SN 60 WF) posterior chamber lens. Preoperatively, 1 day, 2 and 4 weeks after surgery uncorrected visual acuity (UCVA) and best spectacle corrected visual acuity (BSCVA) were determined and corneal topography using Orbscan II and refractometry ( Canon RK-F1) were performed to calculate SIA. Furthermore, all eyes underwent wavefront analysis using the Z-View aberrometer originally designed for determination of wavefront corrected spectacle lenses. SIA was determined using the subtraction method. Statistical comparison between the 2 groups was performed using Student's t-test or Wilcoxon test for non parametric data.
Results: :
There was no statistically significant difference in age, sex, mean preoperative BSCVA and other preoperative ocular characteristics between both groups. 4 weeks after surgery SIA was statistically significantly higher In the SICS group than in the Co-MICS group (1.14 +/- 0.685 diopters versus 0.820 +/-0.504 diopters, p<0.005) 4 weeks after surgery. Consequently, 34.5 % of eyes in the Co-MICS group achieved a UCVA of 20/20 or better versus 15.8 % in the SICS group 4 months postoperatively (p<0.05). Spherical aberrations statistically significantly decreased both in the Co-MICS group from 0.119 +/-0.084 (mean +/- SD) preoperatively to 0.043 +/-0.035 (mean +/- SD) postoperatively (p=0.009) and in the SICS group from 0.172 +/-0.114 (mean +/- SD) preoperatively to 0.056 +/-0.053 (mean +/- SD) postoperatively (p=0.018). Although there was a minimal reduction in coma and trefoil in both groups postoperatively, no statistically significant differences pre-and 4 weeks postoperatively could be detected between the two groups.
Conclusions: :
The results of the present study clearly show that SIA was statistically significantly lower in the Co-MICS group than in the SICS group resulting in better UCVA at least up to 4 weeks after surgery. Furthermore, spherical aberrations were significantly reduced in both groups due to the aspherical optic of the AcrySof IQ posterior chamber lens.
Keywords: astigmatism • aberrations • intraocular lens