Assessing Postoperative Toric Intraocular Lens Rotation: A Comparative Analysis

Purpose: To investigate the accuracy of three distinct postoperative toric intraocular lens (TIOL) rotational stability measurement methods. Setting: Department of Ophthalmology and Optometry, Medical University of Vienna, Austria. Design: Single-center, prospective, interventional clinical trial. Methods: 128 eyes of 81 patients with age-related cataract received a hydrophobic acrylic TIOL Clareon CNW0T3-9. To evaluate rotational stability, three distinct assessment methods were used: ( Rotix ) comparing the TIOL axis at the end of surgery (EoS) to 1 week (1w) and 6 months (6m) postoperatively using reference vessels at the sclera, ( Slit-lamp ) comparing the intended axis (IA) with the axis at 1w and 6m using slit-lamp photography using the horizontal axis as a reference and ( Casia ) comparing the IA with the axis at 1w and 6m using the axis determination tool of a swept-source anterior segment optical coherence tomographer (Casia 2). Results: Mean absolute rotation from EoS/IA to 6m differed significantly among Rotix (1.33± 1.99° [0.01;19.80]), Casia (2.88± 2.64° [0.00; 19.00]), and Slit-lamp (4.38± 3.38° [0.02;19.38]), as indicated by Friedman's test (X 2 =71.852, p<0.001). Bland-Altman coefficients (CoR) of repeatability indicated the closest agreement of results between Casia and Rotix , with a CoR of ±3.95°, followed by Slit-lamp and Casia (±6.82°), and lastly, between the Slit-lamp and Rotix (±7.19°). Conclusion: When assessing true TIOL rotational stability, it is imperative to use fixed anatomical landmarks as reference and establish a baseline at the end of surgery. When assessing TIOL rotation along the horizontal axis, considering cyclorotation of the eye is crucial and must not be underestimated.