Biometry-Guided IOL Formula Selection in Post-Laser Vision Correction Eyes

Area of Science:

• Ophthalmology
• Biomedical Engineering

Background:

• Accurate intraocular lens (IOL) power calculation is crucial for refractive outcomes after laser vision correction (LVC).
• Determining the precise LVC type can be challenging in some post-operative eyes, complicating IOL formula selection.

Purpose of the Study:

• To evaluate if objective biometry can guide IOL formula selection in post-LVC eyes with indeterminate LVC classification (TKave - Kave = 0.00 to 0.06).
• To compare the refractive accuracy of various contemporary LVC intraocular lens formula strategies.

Main Methods:

• Analysis of 507 post-LVC eyes (myopic and hyperopic) using swept-source optical coherence tomography biometry.
• Calculation of refractive prediction errors for 22 formulas (8 hyperopic LVC, 8 myopic LVC, 6 non-LVC).
• Assessment of formula performance via root mean square error and heteroscedasticity testing.

Main Results:

• Hyperopic LVC formulas demonstrated superior refractive accuracy across all analyzed eyes.
• Pearl DGS and Barrett True K No-History (hyperopic LVC) formulas achieved the highest proportion of eyes within ±0.50 D of target refraction.
• K-based hyperopic LVC formulas outperformed those using posterior K or total keratometry (TK).

Conclusions:

• Hyperopic LVC formulas provide the most accurate refractive outcomes in post-LVC eyes with indeterminate classification.
• A measurement-driven approach using biometry for formula selection improves outcomes when historical LVC data is unreliable.
• Findings challenge the reliance on historical LVC classification for formula selection in ambiguous cases.