Objective: To investigate whether there are some differences in the accuracy of Acrysof Toric intraocular lens (IOL) implantation and the ability to correct astigmatism between 2 types of clear corneal incisions used in phacoemulsification: the on-axis (i.e on the steeper corneal meridian) and the temporal clear corneal incision (OCCI and TCCI, respectively).
Methods: In this prospective study, thirty-nine eyes with cataract and mild to moderate corneal astigmatism (1.00 - 2.26 diopters on corneal curvature) were recruited and divided into OCCI group (20 eyes) and TCCI group (19 eyes) respectively. All of these patients underwent phacoemulsification and an Acrysof Toric IOL implantation (single surgeon, 3.2 mm incision). Main outcome measurements included uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA), corneal curvature, surgically induced astigmatism (SIA), deviation of lens axis (LAD), index of corrected astigmatism (CAI) and accuracy of astigmatism correction (ACA) at 3 months postoperatively.
Results: At 3 months postoperatively, simple algebraic difference showed a mean increase in the astigmatism magnitude of (0.28 + or - 0.27) D in the TCCI group and a mean reduction in the astigmatism magnitude of (0.31 + or - 0.26) D in the OCCI group (t = 5.756, F = 0.000). The average LAD was 0 degrees + or - 0 degrees in the OCCI group and 2.22 degrees + or - 2.99 degrees in the TCCI group(t = 3.860, P = 0.000). The average CAI were 1.04 + or - 0.27 and 0.59 + or - 0.44 respectively (t = 3.187, P = 0.004). The ACA were 0.838 and 0.484 respectively (Z = 1.970, P = 0.049).
Conclusions: Compared with the TCCI, the OCCI could correct some corneal astigmatism and reduce IAD induced by the SIA shift. As a result, the OCCI could improve the accuracy of Acrysof Toric lens implantation and the ability to correct astigmatism.