Refractive Accuracy of Intraocular Lens Power Calculation Formulas in Nonagenarians: A Retrospective Study

To compare the refractive predictive accuracy of three intraocular lens (IOL) power calculation formulas (SRK/T, Barrett Universal II, and Haigis) in patients aged 90 years and older.

This retrospective observational study included 62 eyes of 62 patients aged ≥90 years who underwent cataract surgery between April 2021 and March 2023. All procedures were performed by a single surgeon using a single IOL model (HOYA XY1). Preoperative biometry was performed using the IOL Master 700. The accuracy of each formula was evaluated by comparing the predicted spherical equivalent to the manifest refraction at 3 months postoperatively. The primary outcome was the mean absolute error (MAE) and root mean square absolute error (RMSAE), with secondary outcomes including the percentage of eyes within ±0.5 D and ±1.0 D of the predicted refraction.

The mean age of the patients was 92.2 ± 2.0 years. The MAE was 0.504 ± 0.363 D for SRK/T, 0.441 ± 0.339 D for Barrett Universal II, and 0.503 ± 0.388 D for Haigis. The RMSAE was 0.607 ± 0.552 D for SRK/T, 0.532 ± 0.463 D for Barrett Universal II, and 0.565 ± 0.496 D for Haigis. No statistically significant difference in MAE and RMSAE was found among the three formulas (p = 0.12, p = 0.54). The proportion of eyes within ±0.5 D of the predicted refraction was highest for the Barrett Universal II formula at 64.5%. Multivariate logistic regression analysis found no biometric parameters to be significant predictors of achieving a refractive error within ±0.5 D.

In patients aged ≥90 years, the SRK/T, Barrett Universal II, and Haigis formulas demonstrated comparable refractive accuracy. In this demographic, overall refractive outcomes may be more influenced by the reliability of biometric measurements and the minimization of intraoperative risks than by the choice of formula.