Development and Validation of a New Formula for Intraocular Lens Power Calculation in Patients With Myopic Corneal...

Area of Science:

• Ophthalmology
• Refractive Surgery
• Cataract Surgery

Background:

• Cataract surgery requires precise intraocular lens (IOL) power calculation.
• Previous myopic refractive surgery (MRS) complicates IOL power calculation due to altered corneal curvature.
• Existing formulas often show significant prediction errors in these eyes.

Purpose of the Study:

• To develop and validate a novel IOL power calculation formula specifically for cataract patients with a history of MRS.
• To compare the accuracy of the new formula against established methods.

Main Methods:

• Development of the LISA MRS formula using a linear regression model to correlate anterior and posterior corneal radii in MRS patients.
• Validation of the formula in a separate cohort of cataract patients with prior MRS.
• Comparison of prediction errors (arithmetic and absolute) with existing formulas like Barrett True K, EVO, Haigis-L, and Hoffer QST.

Main Results:

• The LISA MRS formula demonstrated superior performance compared to existing formulas, achieving the highest formula performance index (FPI).
• LISA MRS-PRC and EVO-PRC had the lowest median absolute prediction error (0.47 D).
• The formula showed particular accuracy in eyes with axial lengths (AL) ≥ 28 mm, and incorporating posterior corneal radius (PRC) significantly improved accuracy for multiple formulas.

Conclusions:

• The developed LISA MRS formula offers accurate IOL power calculation for cataract patients post-MRS.
• The formula is especially reliable for eyes with longer axial lengths (AL ≥ 28 mm).
• Utilizing posterior corneal radius (PRC) data is recommended to enhance calculation accuracy whenever available.