The accuracy of VRF intraocular lens power calculation formula in cataract patients after radial keratotomy.

PURPOSE: To investigate the accuracy of the VRF intraocular lens (IOL) power calculation formula in cataract patients after radial keratotomy (RK).

METHODS

This was a retrospective study that reviewed and retrieved the medical history of patients after RK who underwent cataract surgery from April 1, 2021, to December 31, 2024, at Beijing Tongren Hospital. A total of 50 eyes of 27 patients were included. The absolute error (AE, the absolute value of the difference between the actual Spherical Equivalent after cataract surgery and the Equivalent Spherical predicted by the IOL formulas) and the percentage of eyes with AE within 0.5D, 0.75D, 1.0D, and 2.0D were calculated by using three formulas: the VRF formula, the Kane formula and the Barrett True-K No History formula and were compared.

RESULTS

There was a significant difference in AE values between the three formulas (X2 = 33.556, p < 0.001), with the VRF formula having the smallest median AE value (MedAE) of 0.580D, followed by the Kane formula (0.585D), and the Barrett True-K No History formula (0.670D) the largest. Using the VRF formula, the percentages of eyes with AE within 0.5D, 0.75D, 1.0D, and 2.0D were 48%, 66%, 78%, and 94%, respectively, which were equal to or higher than the other two formulas.

CONCLUSION

For this cohort of patients with cataract after RK, the VRF formula was the most accurate, and the Kane formula also demonstrated good accuracy. Both formulas can be tried to be applied to predict IOL power in patients with cataract after RK in future clinical practice.