[Evaluation of residual internal astigmatism after cataract surgery based on intraocular parameters measured by swept-source OCT].

<b>Objective:</b> To explore the influencing factors of intraocular residual astigmatism (RIA) after the implantation of non-toric intraocular lens (IOL), and to analyze the differences in the positional characteristics of the IOL and RIA between the eyes. <b>Methods:</b> This was a retrospective case series study. The data of 122 cataract patients (122 eyes, 67 right eyes and 55 left eyes) in the Eye Hospital of Tianjin Medical University from October 2022 to September 2023 were included. The patients' age was (68.80±8.82) years old, with 57 males and 65 females. All patients underwent phacoemulsification combined with the implantation of non-toric IOL. Swept-source optical coherence tomography (SS-OCT) was used to measure the decentration displacement, tilt vector of the lens and IOL, and anterior segment parameters before and 1 month after the surgery. The main indicators included the magnitude and direction of RIA, the tilt vector and decentration displacement of the IOL. <b>Results:</b> The absolute value of the overall RIA was (0.67±0.39) D. The absolute value of RIA in the left eyes [(0.81±0.43) D] was significantly greater than that in the right eyes [(0.56±0.31) D, <i>P</i><0.001]. The tilt angle of the IOL was 5.00°±1.54°. The tilt angle in the left eyes (5.51°±1.59°) was greater than that in the right eyes (4.58°±1.36°, <i>P</i>=0.001). RIA was positively correlated with the tilt angle of the IOL (<i>r</i>=0.22, <i>P</i>=0.016). Multiple regression showed that for every 1° increase in the tilt angle of the IOL, RIA increased by 0.06 D (<i>β</i>=0.06, <i>P</i>=0.016). The anterior chamber depth (<i>r</i>=-0.24, <i>P</i>=0.008) and axial length (<i>r</i>=-0.38, <i>P</i><0.001) were negatively correlated with the tilt angle of the IOL, and the refractive power of the IOL (<i>r</i>=0.37, <i>P</i><0.001) was positively correlated with the tilt angle. <b>Conclusions:</b> After the implantation of non-toric IOL, RIA is significantly correlated with the tilt angle of the IOL, but not with the decentration distance. IOL tilt is an important factor affecting the postoperative visual quality. Both the tilt angle of the IOL and RIA in the left eyes are significantly greater than those in the right eyes. The eye side may be an important factor affecting the position of the IOL and the postoperative visual quality.