Visual Outcome of the Toric Intraocular Lens in Eyes with Low Corneal Astigmatism

Objective: To evaluate the results of a Toric intraocular lens (IOL) for correction of low preoperative astigmatism in cataract patients. Methods: In this prospective, case series study, 65 eyes (56 cataract patients) were enrolled from January to December 2016 from Eye Hospital, Wenzhou Medical University, all patients were divided into 2 groups: A Toric group (n=33) with implantation of a Toric IOL (Acrysof IQ Toric IOL, Alcon, SN6AT2 and SN6AT3); an IQ group (n=32) with implantation of a non-Toric IOL (Acrysof IQ IOL, Alcon, SN60WF). Uncorrected distance visual acuity (UDVA, LogMAR), best corrected distance visual acuity (CDVA, LogMAR), preoperative corneal astigmatism, residual refractive error, and the axis of the toric IOL were measured. UDVA and CDVA were measured preoperatively and 3 months after surgery. A vector analysis of postoperative residual astigmatism was performed and compared between the groups. Data were statistically analyzed using an independent samples t test and non-parametric rank sum test. Results: The preoperative CDVA was 0.39 in the Toric group and 0.30 in the IQ group. At 3 months after surgery, the UDVA in the Toric group was 0.09, which was significantly better than that in the IQ group (Z=-2.802, P=0.005). The median residual astigmatism in the Toric group was 0.5 D, which was significantly smaller than that in the IQ group (1.00 D, Z=-3.636, P<0.001). Vector analysis showed that the difference in the mean vector J0 between the Toric group and IQ group was 0.11 D (t=1.456, P=0.151), and that of J45 was 0.11 D (t=1.998, P=0.050). Conclusions: Compared with non-Toric IOLs, Toric IOLs (SN6AT2 and SN6AT3) are more efficient for the correction of low corneal astigmatism (≤1.0 D). Key words: phacoemulsification; intraocular lenses; corneal astigmatism; low degree