Comparison of digital image-guided and smartphone-based toric intraocular lens axis marking systems

Purpose: To compare digital image-guided and smartphone-based toric intraocular lens (IOL) axis marking systems. Methods: This is a retrospective study where subjects who have undergone toric IOL implantation between June 2024 and December 2024 were included. These subjects had undergone IOL axis marking procedure using I toric Patwardhan (I toric), precision toric guidance system (PTGS) and Verion Reference Unit (Verion) to mark reference point preoperatively with an intention to confirm and know their agreement with Verion, which was used intraoperatively. Subjects with corneal Astigmatism >0.75 D, measured using IOL master 700, were included. Angular deviation of smartphone-based instruments was noted and compared with the Verion angular deviation. Results: Eighty-five eyes of 72 patients were included in the analysis. The mean ± standard deviation (SD) age of the patients was 62.17 ± 11.07 years. The mean ± SD absolute angular deviation of PTGS and I toric from verion was 2.67° ± 1.79° and 3.05° ± 2.06°, respectively. The mean ± SD absolute angular deviation difference between the two phones based on the app was 1.76° ± 2.12°. The Bland–Altman plot demonstrated good agreement between the PTGS and I toric App axis marking. Conclusion: PTGS and I toric have shown minimum angular deviation compared to Verion. These apps can be considered as an adjunct to manual toric IOL axis marking in small setups where access to exorbitant and sophisticated toric axis marking instruments is limited.