Intraocular Lens Power Calculations in Posthyperopic Laser Vision Correction Eyes: Comparing Legacy and New No-History Formulas.

PURPOSE: To compare the refractive accuracy of legacy and new postrefractive formulas in eyes with previous hyperopic laser vision correction (H-LVC).

DESIGN

Retrospective cohort study.

SUBJECTS: Total 153 eyes (109 patients) with previous H-LVC that underwent cataract surgery between 2019 and 2023.

METHODS

An SS-OCT biometer was used to obtain biometric measurements, including standard (K), posterior (PK), and total keratometry (TK) values. Refractive prediction errors were calculated and compared for two legacy H-LVC formulas using K values, six new H-LVC formulas using K values, and four new H-LVC formulas using PK or TK values.

MAIN OUTCOME MEASURES: All formulas were ranked by root mean square error (RMSE) and percentage of eyes with prediction errors within ±0.50 D. Heteroscedastic (RMSE) testing was used to evaluate relative formula performance.

RESULTS

When ranked by RMSE, newer formulas ranked higher than legacy formulas, and new formulas with PK/TK values ranked higher than versions without PK/TK values. Using heteroscedastic (RMSE) testing, Barrett True K NH-K was superior to Shammas PHL (P < .001). Shammas-Cooke (Kpost = 0.8977 x K -0.2976 x AL + 11.7149) and K6-TK were superior to their prior H-LVC versions (Shammas-PHL and K6-K, respectively) (P < .05).

CONCLUSIONS

The top-ranking formulas (Barrett True K-TK, K6-TK, and EVO 2.0-PK) were all new H-LVC formulas. Formula performance may variably improve with PK/TK values. When PK/TK values are unavailable, EVO 2.0-K, Barrett True K NH-K, and Pearl DGS may be the most reliable formulas.