Predictability Of Intraocular Lens Power Calculation After Small Incision Lenticule Extraction In Chinese Eyes

Objective:Using Barrett True K formula as the standard of reference,we compare the accuracy of the lens power(IOL)calculation formulas(Clinical history method with HofferQ、Clinical history method with Holladay I、Clinical history method with SRK/T、Double-K、Masket、Modified Masket、Shammas-PL、Haigis-L、Barrett True K no history)in patients after small incision lenticule extraction(SMILE).Methods:In this study,a total of 80 eyes(41 cases)who received SMILE surgery in Xiamen Eye Center rom May 2020 to December 2020 were collected.The optical biometric datas were measured by Lenstar before and 3-month after SMILE.For each formula,The intraocular lens(IOL)power calculation was recorded and keratometry(K)subgroup analysis was performed based on keratometry(K)(K<38D;38 ≤ K ≤ 40D;K>40D).The IOL prediction error(PE),the absolute prediction error(AE),and the percentages of eyes within±0.50 diopter(D)and±1.00 D of the predicted refraction were also calculated.Results:Barrett True K no history performed well in both subgroups,with no significant statistical differences comparing with the standard formula.The AE values in group A,B and C were 0.30 ± 0.22D,0.31±0.20D,and 0.29±0.21D respectively.The percentage of eyes within ±0.50 D of the predicted refraction was 81.48%,78.26%and 83.33%respectively,and the percentage within ±1.0D all reached 100%.In GourpA(K<38D),the Masket formula achieved the smallest absolute prediction error(0.29±0.17 D)and the largest percentage of eyes within±0.50D(85.19%)、±1.0D(100.00%).In Group B(38≤K≤40D),the AE of CHM-Holladay I formula was 0.63±0.36D,and the percentage of PE within±0.5D and±1.0D was 39.13%and 82.61%respectively.In Group C(K>40D),the Double-K formula resulted in a lower AE(0.43±0.38D)and the percentage of prediction error within±0.5D and±1.0D was 66.67%and 90.00%respectively.Conclusion:In this study,Barrett True K no History formula is applicable to any corneal curvature.In addition,we recommend using Masket formula,ChM-Holladay I formula and Double-K formula with patients after SMILE accuracy in group A(K<38D),B(38≤K ≤ 40D)and C(K>40D)respectively.