A novel open-source calculator for lens tilt and decentration using swept-source AS-OCT: Assessment of interrater agreement and reproducibility

Purpose: To introduce an open-source calculator for quantifying lens tilt and decentration using swept-source anterior segment optical coherence tomography (SS-AS-OCT) images, and to evaluate its reproducibility and independence from evaluator experience. Setting: Department of Ophthalmology, Hospital of the Brothers of St. John of God, Vienna, Austria. Design: Prospective interrater agreement study. Methods: Patients scheduled for cataract surgery were screened for eligibility. Inclusion required age ≥21 years, written informed consent, and adequate fixation. Exclusion criteria included physical immobility or other limitations preventing imaging, prior pseudophakia in the fellow eye, contraindications to pharmacologic mydriasis, or tremor. Imaging was performed under pharmacologically induced mydriasis using SS-AS-OCT. Lens tilt and decentration were independently assessed by a novice (medical student) and an expert (ophthalmologist) using a self-developed open-source calculator. Results: A total of 175 eyes from 88 patients, including 30 men (34%) and 58 women (66%) with a mean age of 72 years (range: 30-91), were included. According to expert measurements, lens tilt averaged 5.65°, with a consistent inferotemporal orientation (5.06° temporal, 1.81° inferior). Decentration averaged 146 µm and was primarily directed temporally (79.51 µm), with only a minor inferior component (2.93 µm). The intraclass correlation coefficient (ICC) was 0.972 (95% CI: 0.962-0.979) for tilt, and 0.914 (95% CI: 0.886-0.935) for decentration, reflecting excellent agreement between raters. Conclusions: The evaluated open-source calculator enables accurate and reproducible measurement of lens tilt and decentration using SS-AS-OCT images. In this study, interrater agreement was excellent for both parameters, with ICC values above 0.9 and no evidence of systematic measurement bias.