Vector analysis of astigmatic changes after cataract surgery with implantation of a new toric multifocal intraocular lens

Abstract

To analyze the astigmatic changes after cataract surgery with the implantation of a new toric multifocal intraocular lens (IOL) using the Alpins vector method. Vissum-Instituto de Oftalmológico de Alicante, Alicante, Spain. Prospective case series. After cataract surgery with implantation of an AT Lisa 909M toric multifocal IOL, the visual, refractive, corneal topographic, internal astigmatism, defocus curves, and contrast sensitivity outcomes were evaluated over 6 months. Refractive astigmatic changes (target astigmatism [TIA]; surgically induced astigmatism [SIA]; difference vector; magnitude of error; flattening effect; torque) were analyzed using the Alpins vectorial method. The study enrolled 23 eyes (12 patients). Postoperatively, there was a significant reduction in refractive cylinder (P < .01) with an associated visual improvement for near (P = .03) and distance (P=.01). The magnitude of SIA vector was significantly larger than the TIA 3 months postoperatively (P = .03). The mean magnitude of the difference vector was 0.67 diopter (D) ± 0.51 (SD) at 6 months. The mean magnitude of error remained positive and close to zero over the entire follow-up (P ≥ .19). The mean magnitude of torque vector was 0.49 ± 0.54 D at 6 months. Significant positive correlation was found between the magnitude of torque and the difference vector (r ≥ 0.70, P<.01). The new toric IOL restored distance and near visual function with excellent predictability in eyes with moderate to high corneal astigmatism having cataract surgery.