VRF-G, a New Intraocular Lens Power Calculation Formula: A 13-Formulas Comparison Study

Area of Science:

• Ophthalmology
• Biomedical Engineering
• Optics

Background:

• Accurate prediction of postoperative refractive error is crucial for successful cataract surgery outcomes.
• Existing intraocular lens (IOL) power formulas vary in their predictive accuracy, particularly in eyes with atypical axial lengths.
• The development of novel IOL power formulas aims to enhance refractive predictability and minimize refractive surprises.

Purpose of the Study:

• To evaluate the accuracy of a new intraocular lens (IOL) power formula, VRF-G, against twelve established formulas.
• To compare the performance of these formulas in predicting refractive outcomes following cataract surgery.

Main Methods:

• A retrospective analysis of 828 patients undergoing cataract surgery with a specific IOL model (SN60WF) was conducted.
• Refraction prediction error for each formula was calculated using optimized constants.
• Subgroup analysis was performed based on axial length (short, medium, long); key metrics included mean absolute error (MAE) and median absolute error (MedAE).

Main Results:

• Significant differences in absolute errors were observed among the formulas (p<0.001).
• The Kane formula exhibited the lowest MAE, while VRF-G and EVO 2.0 showed the lowest MedAE.
• Kane, EVO 2.0, and VRF-G demonstrated the highest accuracy across all axial length subgroups, with VRF-G achieving the highest percentage of eyes within ±0.50D (79.5%).

Conclusions:

• Newer generation IOL power formulas, including Kane, EVO 2.0, and VRF-G, offer improved refractive predictability.
• These formulas show potential for reducing refractive variance, particularly in eyes with extreme axial lengths.
• Kane, EVO 2.0, and VRF-G are promising candidates for achieving better refractive outcomes in cataract surgery.