Assessment of IOL Power Calculation Methods in PARTIAL-Range of Field IOLs and TVO Optimization

Overview

This study evaluated seven modern intraocular lens (IOL) power calculation formulas in two PARTIAL-Range of Field (RoF) extended depth of focus IOL models, Acrysof IQ Vivity and Tecnis Symfony. Additionally, it assessed the efficacy of a novel three variable optimization (TVO) technique for constant optimization, demonstrating improved predictive accuracy across formulas.

Background

PARTIAL-RoF extended depth of focus IOLs aim to enhance intermediate vision without compromising distance acuity, offering advantages over traditional multifocal lenses such as fewer photic phenomena and better contrast sensitivity. Precise refractive outcomes are critical for these lenses, as small deviations can impact visual performance. Accurate IOL power calculation remains challenging due to measurement errors in axial length, anterior chamber depth, and keratometry. The Acrysof IQ Vivity and Tecnis Symfony IOLs utilize distinct optical designs to extend depth of focus, necessitating evaluation of formula accuracy specific to these lenses. The recently proposed TVO method offers a simplified approach to constant optimization but had not been validated in this context prior to this study.

Data Highlights

Key Findings

• Seven modern IOL power calculation formulas were assessed for accuracy in eyes implanted with Acrysof IQ Vivity and Tecnis Symfony PARTIAL-RoF IOLs.
• The Barrett Universal II, Cooke K6, EVO 2.0, Kane, and Pearl DGS formulas demonstrated superior accuracy with higher percentages of eyes within ±0.5 D prediction error.
• The novel three variable optimization (TVO) method effectively optimized lens constants, reducing mean prediction errors close to zero across all formulas.
• Formula Performance Index (FPI) rankings favored Barrett Universal II and Cooke K6, indicating better overall predictive performance.
• Distinct optical designs of the Vivity and Symfony IOLs influence refractive outcomes and formula accuracy, underscoring the need for lens-specific optimization.

Clinical Implications

Clinicians implanting PARTIAL-RoF extended depth of focus IOLs should consider using Barrett Universal II or Cooke K6 formulas for improved refractive predictability. Employing the TVO constant optimization method can further enhance accuracy by simplifying constant adjustments, potentially leading to better visual outcomes. Awareness of the specific optical characteristics of Vivity and Symfony lenses is important when selecting and optimizing IOL power calculation formulas.

Conclusion

This study validates the accuracy of modern IOL power calculation formulas in PARTIAL-RoF extended depth of focus IOLs and supports the use of the TVO method for efficient constant optimization. These findings facilitate improved refractive outcomes in cataract surgery with advanced IOL technologies.

References

1. Buonsanti et al. 2023 -- Three Variable Optimization (TVO) Method for IOL Constant Optimization
2. Hoffer and Savini 2020 -- Methodology for IOL Power Formula Comparison
3. Haigis 2017 -- IOL Formula Performance Index