Abstract:AIM: To compare the accuracy of intraocular lens(IOL)calculation formulas based on different corneal refractive power in calculating IOL diopters of cataract patients with a history of corneal refractive surgery.
METHODS: A prospective clinical study was conducted with a cohort of 32 cataract patients(42 eyes)who had previously undergone myopic laser corneal surgery at Jinan Mingshui Eye Hospital between February 2022 and August 2024. The study employed several IOL calculation formulas, including the Haigis-L formula, the Barrett True K formula based on simulated keratometry(SimK), the Haigis formula based on total keratometry(TK), the Potvin-Hill Pentacam(PVP)formula based on corneal true net power(TNP), and the OCT formula based on net corneal power(NCP). These formulas were used to calculate IOL power and predict postoperative refractive outcomes. At 1 mo postoperatively, subjective refraction was performed, and the prediction error(PE), mean absolute prediction error(MAE), median absolute prediction error(MedAE), and the percentage of prediction errors within the ranges of ±0.25, ±0.50, ±0.75, and ±1.0 D were determined.
RESULTS: The intraclass correlation coefficient for the four types of corneal refractive power was 0.986(P<0.001). There was no significant difference between TNP and NCP(P=0.491), and there were differences between the other two groups(all P<0.001). Statistically significant differences were observed between PE and 0 for the Haigis-L(K)and Haigis(TK)formulas(all P<0.001). In contrast, no statistically significant differences were noted between PE and 0 for the PVP, OCT, and Barrett True K formulas(all P>0.05). The MedAE value of Barrett True K was the smallest 0.32(0.19, 0.71)D among the five formulas, and there was no significant difference in MedAE among the five formulas(P=0.870). The proportion of eyes with PE within ±0.25 and ±1.0 D in Barrett True K formula was 38%(16/42)and 95%(40/42), respectively. The proportion of eyes within ±0.50 D in PVP formula was 71%(30/42); and the proportion of eyes with PE within ±0.75 D in Haigis(TK)formula was 83%(35/42).
CONCLUSION: After corneal refractive surgery, there are differences between different types of corneal refractive power. When calculating IOL, the accuracy of TK combined with Haigis formula is better than that of Haigis-L(K)formula, and Barrett True K formula shows good accuracy.
