Accuracy comparison of different formulas in calculating intraocular lens power in cataract patients after corneal refractive surgery

Abstract

AIM: To compare and observe the accuracy of five intraocular lens(IOL)power calculation formulas in patients with cataracts who have previously undergone corneal refractive surgery.METHODS: Prospective case series study. A total of 23 cataract patients(34 eyes)with a history of myopic corneal refractive surgery at Jinan Mingshui Eye Hospital from September 2021 to March 2023 were collected, including 1 eye treated with photorefractive keratectomy(PRK)and 22 patients(33 eyes)treated with laser-assisted in situ keratomileusis(LASIK). Preoperative ocular biometry was performed using the IOL Master 700, while corneal true net refractive power(TNP)was measured via Pentacam analyzer. Anterior segment optical coherence tomography(OCT)was used to assesse net corneal power(NCP), posterior corneal refractive power, and central corneal thickness(CCT). The Shammas, Haigis-L, Potvin-Hill Pentacam, OCT, and Barrett True K formulas were utilized for IOL power calculations, with the optimal power selected accordingly. At 1 mo postoperatively, actual refractive outcomes were determined through subjective refraction, based on objective optometry results. The refractive prediction error(RPE)and refractive absolute error(RAE)of each formula were calculated and compared, and the percentage of eyes with RAE ≤0.5 D and ≤1.0 D was counted.RESULTS: No significant statistical difference was found in the RPE of the five formulas when compared to zero(all P>0.05), nor were there significant differences in RPE and RAE among the formulas(F=0.554, P=0.696; H=4.402, P=0.354). The RAE was within ≤0.5 D for 26 eyes(76%)using the Potvin-Hill Pentacam formula and for 24 eyes(71%)using the Barrett True K formula, with both formulas achieving an RAE within ≤1.0D in 33 eyes(97%).CONCLUSIONS: The Barrett True K and Potvin-Hill Pentacam formulas demonstrated high predictive accuracy for IOL power calculations in post-corneal refractive surgery cataract patients. Given the variability in corneal refractive power among these patients, further research on IOL power calculation is warranted. Clinically, it is advisable to consider a range of formulas for optimal outcomes.

Keywords

• corneal refractive surgery
• intraocular lens power
• myopia
• haigis-l formula
• corneal curvature