Accuracy of 12 Intraocular Lens Power Formulas After Corneal Myopic Refractive Surgery.

Area of Science:

• Ophthalmology
• Refractive Surgery
• Biomedical Engineering

Background:

• Accurate intraocular lens (IOL) power calculation is crucial for successful cataract surgery outcomes.
• Previous myopic laser refractive surgery (LRS) alters corneal geometry, complicating standard IOL power calculations.
• Newer generation online IOL formulas aim to improve refractive predictability in post-LRS eyes.

Purpose of the Study:

• To evaluate the predictive accuracy of modern online IOL power formulas in eyes previously treated with myopic LRS.
• To assess the impact of corneal asphericity on the refractive prediction error of these IOL formulas.

Main Methods:

• Retrospective analysis of 78 eyes from 52 patients who underwent cataract surgery after LASIK or PRK.
• Comparison of refractive prediction errors from 12 online IOL power formulas, including 8 with post-LRS specific versions.
• Calculation of Mean Absolute Error (MAE) and percentage of eyes within specific refractive error tolerances (±0.25 D to ±1.50 D).

Main Results:

• Significant differences in MAE were observed among the 12 formulas (P < .001).
• Formulas with post-LRS versions showed lower MAEs (0.62–0.94 D) compared to those without (1.07–1.84 D).
• The EVO formula yielded the lowest MAE (0.60 D), followed closely by the Barrett True-K formula.

Conclusions:

• The EVO and Barrett True-K formulas demonstrate reliable performance in eyes with prior myopic LRS.
• Utilizing IOL formulas with post-LRS versions and accurate keratometric inputs is recommended.
• These advanced formulas offer improved refractive predictability for cataract surgery in post-myopic LRS patients.