Ray Tracing versus Thin-Lens Formulas for IOL Power Calculation Using Swept-Source Optical Coherence Tomography
Reza Ghaffari1,2, Parisa Abdi1, Alireza Moghaddasi1
1Eye Research Center, Department of Cornea, Farabi Eye Hospital, Tehran University of Medical Sciences, Tehran, Iran.
Journal of Ophthalmic & Vision Research
|June 29, 2022
Summary
The ray tracing method using Okulix software and swept-source optical coherence tomography (SS-OCT) biometry offers accurate intraocular lens (IOL) power calculations. This method demonstrates comparable or superior precision to traditional formulas across various axial lengths.
Area of Science:
- Ophthalmology
- Biomedical Optics
- Computational Optics
Background:
- Accurate intraocular lens (IOL) power calculation is crucial for achieving desired refractive outcomes after cataract surgery.
- Traditional thin-lens formulas have limitations in predicting refractive error, especially in eyes with atypical biometric parameters.
- Advancements in optical coherence tomography and ray tracing software offer potential improvements in IOL power calculation accuracy.
Purpose of the Study:
- To evaluate the accuracy of the ray tracing method using Okulix software for IOL power calculation.
- To compare the performance of ray tracing with standard thin-lens formulas (SRK/T, Hoffer Q, Holladay 1, Haigis) using swept-source optical coherence tomography (SS-OCT) biometry data.
- To assess the accuracy across different axial length ranges.
Main Methods:
- A total of 188 eyes from 180 patients were analyzed.
- Biometric data were acquired using an OA2000 SS-OCT biometer.
- Postoperative refraction was predicted using thin-lens formulas and the Okulix ray tracing software.
- Prediction error and absolute prediction error were calculated to compare accuracy.
Main Results:
- The ray tracing method demonstrated the lowest mean absolute error (0.56) and standard deviation (0.55).
- A higher proportion of patients (87.43%) achieved predicted refraction within 1 diopter using ray tracing.
- Ray tracing showed comparable or superior accuracy to traditional formulas, particularly in the normal axial length range (22-24 mm).
- Okulix and Haigis formulas exhibited the least variability in prediction error across different axial lengths.
Conclusions:
- The ray tracing method with Okulix software and SS-OCT biometry provides accurate IOL power calculations.
- This approach performs comparably to established third-generation and Haigis formulas.
- Ray tracing offers potential for enhanced accuracy in normal axial lengths and consistent results across diverse axial lengths.
