Pilot Study on Postoperative Toric Intraocular Lens Alignment

Purpose: Assess the comparative accuracy and reliability of postoperative toric intraocular lens (TIOL) alignment measurement methods: Casia2 and Adobe Photoshop with digital slit lamp images (PS method). Methods: In a study of 41 subjects with 58 eyes postimplantation of TIOL, we independently measured TIOL alignment with Casia2 and PS methods. The intraclass correlation coefficient (ICC[sub.1,1]) was employed to assess the repeatability of the Casia2 method. While ICC[sub.2,1] for absolute agreement and Bland-Altman analysis were utilized to determine the interdevice agreement between the two methods, the regression analysis was conducted to identify any proportional bias. Results: Casia2 demonstrated excellent intradevice repeatability with an ICC[sub.1,1] of 0.998. The absolute agreement between Casia2 and PS was very high with an ICC[sub.2,1] of 0.999. The average discrepancy between the two measurement methods was -0.828°, with a 95% confidence interval (CI) ranging from -1.623° to -0.032°. The 95% limits of agreement (LoA) were between -6.761° and 5.105°, indicating a strong concordance in TIOL alignment measurements. Casia2 was capable of accurately measuring the TIOL axis alignment under conditions of pupil diameters (PDs) of 4mm or greater. Conclusion: Casia2 and PS demonstrated significant concordance in measuring postoperative TIOL alignment, with Casia2 offering a more straightforward and accessible alternative, particularly beneficial for patients with suboptimal pupil dilation.