Intraocular lens prediction accuracy after corneal refractive surgery using K values from 3 devices

Area of Science:

• Ophthalmology
• Refractive Surgery
• Biomedical Optics

Background:

• Accurate intraocular lens (IOL) power calculation is crucial for visual outcomes after cataract surgery, especially in eyes with prior myopic refractive surgery.
• Standard keratometry (K) methods can be unreliable in these eyes due to altered corneal curvature.

Purpose of the Study:

• To compare the accuracy of various keratometry (K) values and methods for intraocular lens (IOL) power calculation following myopic refractive surgery.
• To identify the most predictable method for IOL power calculation in post-refractive surgery eyes.

Main Methods:

• The study evaluated IOL power calculations using the SRK/T formula with true net power (TNP) and equivalent K (Pentacam), simulated K, total mean power (TMP 2.0 mm), and total optical power (TOP 4.0 mm) (Orbscan II).
• The Haigis-L method with partial coherence interferometry (PCI) corneal radius was also assessed, using PCI axial length for all calculations.
• Diagnostic test evaluation was the study design.

Main Results:

• The Haigis-L method, TNP, TMP 2.0 mm, and TOP 4.0 mm demonstrated significantly lower prediction errors compared to equivalent K, simulated K, and PCI K.
• The Haigis-L method achieved the highest percentage of correct refraction predictions within ±0.50 D (64.5%), ±1.00 D (80.6%), and ±2.00 D (100%).

Conclusions:

• The Haigis-L method utilizing PCI measurements is the most predictable for IOL power calculation in eyes that have undergone myopic refractive surgery.
• True net power (TNP) and total mean power (TMP 2.0 mm) are also identified as potentially predictable keratometric values for IOL calculations in this patient group.