Intraoperative OCT vs Scheimpflug and swept-source OCT measurements for anterior eye parameters

Purpose: To compare agreement of anterior segment parameter measurements using an intraoperative optical coherence tomography (iOCT) of a femtosecond laser (LenSx) during interface docking to the eye with preoperative Scheimpflug tomography (Pentacam AXL) and swept-source optical coherence tomography (SS-OCT) (IOLMaster 700). Setting: Department of Ophthalmology, Goethe University, Frankfurt, Germany. Design: Retrospective study. Methods: Anterior segment measurements were performed in mydriasis prior to surgery using Scheimpflug tomography and SS-OCT. Postoperatively, iOCT images were analyzed using a modification of the FIJI image-processing program. Outcome measures included external anterior chamber depth (ACD), central corneal thickness (CCT), and central lens thickness (LT). Results: 95 eyes of 66 patients who underwent planned OCT guided femtosecond laser-assisted lens surgery were included. The ACD measured with the iOCT was −0.011 ± 0.126 mm smaller ( P = .389) than that with the SS-OCT and −0.059 ± 0.185 mm than with the Scheimpflug tomography ( P = .003). The SS-OCT measured a −0.047 ± 0.146 mm smaller ACD than the Scheimpflug tomography ( P = .002). The measurements of CCT using the iOCT and the Scheimpflug tomography (−0.705 ± 20.837 μm, P = .742) and the LT measurements using SS-OCT and iOCT (−0.050 ± 0.089 mm, P < .001) showed no clinically relevant difference. Only the ACD between the iOCT and the Scheimpflug tomography showed a clinically relevant difference. Conclusions: The comparison of the anterior segment parameters of iOCT with SS-OCT showed no clinically relevant differences regarding the ACD and the LT. However, Scheimpflug tomography vs iOCT measured a small clinically relevant difference for ACD. The iOCT showed no clinically relevant differences in anterior segment parameters compared with the SS-OCT. A small clinically relevant difference for ACD was found in comparison with that of a Scheimpflug device.