RÉSUMÉ
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.
RÉSUMÉ
Objective The difference of the equivalent IOL powers before and after LASIK was calculated by using the Haigis-L formula and Sirius ray-tracing respectively.And study the correlation be-tween the intraocular lens power and the myopic before laser in situ keratomileusis.Methods Ninety-one patients undergoing myopic laser in situ keratomileusis were enrolled, they were divided into 3 groups ac-cording to myopic diopter, group I (-1.00D~-3.00D) 13cases, group II( -3.25D and -6.00D)60 cases, group III(-6.25D~-10.0D)18 cases.The equivalent IOL power before and after LASIK will be calculated using Haigis-L formula and Sirius ray-tracing.The data were analyzed using SPSS20.0.Results 80.2%of the cases calculated using Haigis-L formula were within ±0.50D of the predicted refraction , 94.5%were within ±1.00D, and 100%within ±1.50D.also, within ±0.50D of the predicted refrac-tion 13cases(100%),51cases(85%),9cases(50%) in group I, II, III respectively.74.7% of the eyes calculated using Sirius ray-tracing were within ±0.50D of the predicted refraction , 89.0%were within ± 1.00D, and 100%within ±1.50D.within ±0.50D of the predicted refraction 12cases(92.3%),48cases (80%),8cases(44.4%) in group I, II, III respectively.Conclusions Sirius ray-tracing and Haigis-L formula can calculate IOL power accurately in eyes with prior myopic LASIK, with no need for preoperative data.and there is positive correlation between the intraocular lens power aberration and the myopic diopter before LASIK.