Bootstrap Outlier Identification in Clinical Datasets for Lens Power Formula Constant Optimization.
Achim Langenbucher1, Nóra Szentmáry2,3, Alan Cayless4
1Department of Experimental Ophthalmology, Saarland University, Homburg, Saar, Germany.
Current Eye Research
|January 3, 2023
Summary
Bootstrapping with outlier identification using Bootlier plots effectively cleans datasets for optimizing intraocular lens formula constants, improving prediction accuracy.
Area of Science:
- Ophthalmic optics
- Statistical modeling
- Data cleaning techniques
Background:
- Bootstrapping is a statistical method for evaluating model parameter performance.
- Accurate formula constants are crucial for effective intraocular lens (IOL) power calculation.
- Outliers in datasets can significantly skew optimization results.
Purpose of the Study:
- To develop and validate a strategy for identifying and removing outliers from datasets used in optimizing IOL formula constants.
- To enhance the reliability of statistical models used in ophthalmic calculations.
Main Methods:
- A dataset of 888 clinical cases using a specific monofocal aspherical IOL was analyzed.
- Constants for SRKT, Haigis, and Castrop formulas were optimized, and prediction error (PE) was calculated.
- Bootstrapping (NB=1000) generated Bootlier plots to visualize PE distribution and identify outliers via a Bootlier Index, with stepwise removal until the index fell below 0.001.
Main Results:
- Outlier removal improved prediction error metrics across all tested formulas (SRKT, Haigis, Castrop).
- For SRKT, PE metrics improved from -0.0045/0.44415 to -0.0036/0.4028 (mean/SD) after removing 13 outliers.
- Multimodality in Bootlier plots, indicative of outliers, was significantly reduced across all formulas after implementing the outlier removal strategy.
Conclusions:
- The Bootlier plot and Bootlier Index provide a robust method for outlier detection in statistical analyses.
- This bootstrapping-based approach effectively cleans datasets, leading to more reliable optimization of formula constants for IOL power calculation.
- The validated strategy enhances the precision of ophthalmic calculations, benefiting clinical outcomes.
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