Comparison of Four Lens Power Formulas for Sutureless Scleral-Fixated Carlevale Lens

To assess the predictability of intraocular lens (IOL) power calculation formulas for sutureless scleral fixation (SSF) of the Carlevale IOL.

A prospective, single-center, interventional case series was conducted to compare predicted refractive outcomes using the SRK/T, Barrett II, Hoffer Q, and Holladay 1 formulas in patients undergoing SSF of the Carlevale IOL. The main outcomes included mean prediction error (PE), median absolute error (MedAE), mean absolute error (MAE), and the percentage of eyes with a PE within ±0.50 and ±1.0 diopters (D).

Sixty-nine eyes of 69 patients were included. Only the Barrett II formula resulted in a systematic myopic error (p=0.014). The PE of SRKT, HofferQ, and Holladay 1 was closer to 0, indicating that the post-operative refractive outcome was nearer to the predicted value than that of Barrett II (p=0.002, p<0.001, p=0.003, respectively). MedAE and MAE ranged from 0.41 to 0.53 D and 0.6 to 0.67 D, respectively, without significant differences between the formulas. The percentages of eyes with PE within ±0.50 and ±1.00 D varied from 47.8 to 56.5% and 79.7 to 87%, respectively, showing no significant differences across the assessed formulas.

The SRK/T, Hoffer Q, and Holladay 1 formulas provide favorable refractive outcomes for the SSF of Carlevale IOL. The Barrett II formula is less accurate and is not recommended due to its systematic myopic refractive error.