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

To determine whether objective biometry can guide intraocular lens formula selection in post-laser vision correction (LVC) eyes with indeterminate classification of actual LVC type (total keratometry [TK] TK_ave - keratometry [K] K_ave = 0.00 to 0.06), and to compare refractive accuracy among contemporary LVC formula strategies.

A total of 507 post-LVC eyes (inclusive of both myopic [M-LVC] and hyperopic [H-LVC] eyes) with TK_ave - K_ave between 0.00 and 0.06 measured by swept-source optical coherence tomography biometry (IOLMaster 700; Carl Zeiss Meditec AG) were analyzed. Refractive prediction errors were calculated for 22 formulas, including eight H-LVC, eight M-LVC, and six non-LVC formulas. Formula performance was assessed using root mean square error rankings and heteroscedasticity testing for dependent data. The main outcome measure was refractive prediction error and proportion of eyes within ±0.50 diopters (D) of target refraction.

H-LVC formulas demonstrated superior refractive accuracy across all eyes, regardless of reported LVC type. Pearl DGS and Barrett True K No-History (H-LVC) achieved the highest proportion of eyes (approximately two-thirds) within ±0.50 D of target. K-based H-LVC formulas outperformed variants incorporating posterior K or TK. Standard formulas showed intermediate performance, whereas M-LVC formulas ranked lowest. Differences between top-performing formulas were statistically significant.

In post-LVC eyes with TK_ave - K_ave between 0.00 and 0.06, H-LVC formulas provide the most accurate refractive outcomes, independent of reported treatment type. These findings challenge reliance on historical LVC classification for formula selection and support a measurement-driven approach in which biometry-guided formula selection improves outcomes when history is unreliable in ambiguous post-LVC eyes.