1.Accuracy comparison of different formulas in calculating intraocular lens power in cataract patients after corneal refractive surgery
Kaifang WANG ; Mingchao QIAO ; Songsong QIAO ; Kejiao ZHAO ; Xiaoming WANG
International Eye Science 2024;24(7):1143-1146
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.
2.Comparison of the accuracy of intraocular lens calculation formulas based on different types of corneal refractive power
Kaifang WANG ; Songsong QIAO ; Kejiao ZHAO ; Mingchao QIAO ; Xiaoming WANG
International Eye Science 2025;25(7):1172-1176
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.
3.Early visual quality and stereopsis after implantation of trifocal intraocular lenses
Kaifang WANG ; Kejiao ZHAO ; Chuanjing GAO ; Mingchao QIAO ; Juanjuan ZHENG ; Songsong QIAO ; Xiaoming WANG
International Eye Science 2025;25(4):656-660
AIM:To investigate the visual quality and stereopsis after the implantation of PanOptix trifocal intraocular lens(TFNT00).METHODS: A prospective clinical study was conducted. A total of 36 cataract patients(50 eyes)who underwent phacoemulsification combined with TFNT00 implantation in Jinan Mingshui Eye Hospital from November 2022 to April 2024 were selected. They were followed up until 3 mo after the operation. The uncorrected distance visual acuity(UCDVA), uncorrected intermediate visual acuity(UCIVA), uncorrected near visual acuity(UCNVA), objective scatter index(OSI), modulation transfer function cut off(MTF-cut-off), Strehl ratio(SR)and 100%, 20%, 9% contrast visual acuity(CVA)were observed. The binoptometer was used to collect the patients' far and near stereopsis acuities. The defocus curve was drawn after the operation; the Chinese version of the VF-14 Visual Function Index Scale was used to evaluate the visual quality and satisfaction after the operation.RESULTS: There were statistically significant differences in the UCDVA, UCIVA and UCNVA of the patients at different time after the operation(all P<0.05). The transition of the defocus curve was gentle between +0.5--3.0 D after the operation. The OSI value at 3 mo postoperatively after the operation was significantly lower than that before the operation(P<0.01), and the MTF-cut-off, SR, 100% CVA, 20% CVA and 9% CVA were significantly improved than those before operation(all P<0.01). The far and near stereopsis acuities of 34 patients were abnormal before the operation. The far stereopsis acuities of the patients who underwent bilateral eye surgeries were all normal after the operation, and the near stereopsis acuity of 12 patients was normal. Among the patients who underwent unilateral eye surgeries, the far stereopsis acuities of 13 patients were normal, and the near stereopsis acuities of 11 patients were normal. The far and near stereopsis acuities of the patients who underwent bilateral eye surgeries were significantly better than those patients who underwent unilateral eye surgeries.CONCLUSION: The PanOptix trifocal intraocular lens can provide patients with good full-range visual acuity. The stereopsis of the patients with bilateral implants is better than that of the patients with unilateral implants. The overall visual quality and satisfaction of the patients after the operation are relatively high.