Anatomical Determinants of Postoperative In-the-Bag IOL Position: Introducing a Novel Biometric Index

Area of Science:

• Ophthalmology
• Biomedical Engineering

Background:

• Accurate intraocular lens (IOL) placement is crucial for refractive outcomes after cataract surgery.
• Predicting postoperative IOL position remains challenging, particularly in eyes with atypical biometry.

Purpose of the Study:

• To evaluate a novel preoperative biometric index, the crystalline lens rise to lens thickness ratio (CLR/LT), for predicting in-the-bag IOL position.
• To assess the accuracy of this index in estimating the IOL position proportion coefficient and final IOL position.

Main Methods:

• Retrospective analysis of 322 eyes undergoing cataract surgery with aspheric IOL implantation.
• Preoperative swept-source anterior segment optical coherence tomography for measuring conventional and composite biometric parameters (e.g., CLR/LT).
• Correlation analysis and machine learning models (support vector machine) to predict the IOL position proportion coefficient.

Main Results:

• The CLR/LT ratio showed a strong correlation with the postoperative IOL position proportion coefficient.
• A machine learning model incorporating CLR/LT significantly improved prediction accuracy.
• IOL position prediction using the CLR/LT-derived coefficient demonstrated enhanced precision compared to standard vergence formulas, especially in atypical axial lengths.

Conclusions:

• The CLR/LT ratio is a clinically valuable preoperative predictor of in-the-bag IOL position.
• Utilizing CLR/LT facilitates more personalized IOL power selection and improves refractive accuracy.
• This index is particularly beneficial for eyes with unusual biometric characteristics.