Accuracy Of Oct- And Scheimpflug-Based Ray Tracing Vs. Conventional Formulas In Iol Power Calculation For Triple-Dmek In Fuchs' Endothelial Dystrophy
Published 2025 - 43rd Congress of the ESCRS
Reference: PP23.18 | Type: Free paper | DOI: 10.82333/spyj-rg84
Authors: Ebba Ghyczy* 1 , Alje van Dam 2 , Evelien Berman - de Jong 3 , Martijn van der Kuip 3 , Sebastien Matamoros 2 , Stevie Tan 1 , Robin Houdt 2
1Department of Ophthalmology,Amsterdam University Medical Centers,Amsterdam,Netherlands, 2Department of Medical Microbiology,Amsterdam University Medical Centers,Amsterdam,Netherlands, 3Department of Pediatrics,Amsterdam University Medical Centers,Amsterdam,Netherlands
Purpose
To evaluate and compare the accuracy of intraocular lens (IOL) power calculation using OCT- and Scheimpflug-based ray tracing versus traditional IOL formulas (SRK/T, Barrett, Haigis, and Hoffer Q) in patients with Fuchs' endothelial dystrophy (FED) undergoing Triple-DMEK surgery.
Setting
Department of Ophthalmology, Ludwig Maximilian University of Munich, Germany.
Methods
The preoperative assessment included both Scheimpflug-based imaging (Pentacam HR®) and AS-OCT (MS-39), along with optical biometry (IOLMaster 700), in patients with FED scheduled for Triple-DMEK surgery. IOL power calculations were performed using both OCT-based and Scheimpflug-based ray tracing, utilizing the MS-39 software and Pentacam OKULIX. Additionally, IOL power was calculated using four traditional formulas (SRK/T, Hoffer Q, Barrett, and Haigis). Postoperative refractive outcomes were analyzed at ≥2 months post-surgery. The predictive error (PE) for the target IOL power was assessed and compared across methods. Furthermore, adjustment factors were examined to account for the commonly observed hyperopic shift after DMEK.
Results
To date, this retrospective study has included 49 eyes from 39 patients with FED who underwent Triple-DMEK surgery, with the anticipated sample size expected to increase to 60 eyes. Preliminary data indicate that ray tracing did not outperform traditional formulas in predicting postoperative refraction after Triple-DMEK. A hyperopic shift was observed postoperatively. Among conventional formulas, SRK/T with a +1.00 D IOL power adjustment yielded the lowest prediction error and the highest refractive predictability. The Barrett, Haigis, and Hoffer Q formulas demonstrated moderate accuracy but were inferior to the adjusted SRK/T.
Conclusions
Ray tracing-based IOL power calculations did not provide superior accuracy compared to traditional formulas in eyes with FED, where preoperative IOL planning is complicated by corneal irregularities. The SRK/T formula, adjusted by +1.00 D, demonstrated the highest accuracy, minimizing hyperopic surprises. These findings suggest that modifying established formulas rather than adopting ray tracing may be the optimal approach for IOL power selection in Triple-DMEK patients.