Application Value Of Corneal Horizontal Diameter And Lens Thickness In Barrett Universal Ⅱ Intraocular Lens Prediction Formula

Objective:To examine the contribution of lens Thickness(LT)and white-to-white(WTW),which also known as corneal horizontal parameters(CHD),to the prediction of intraocular lens(IOL)refraction by using Barrett Universal Ⅱ(BUII)formula.The study was divided into two parts(1)Preoperative: Theoretical differences in predicted diopters compared with calculations without neglecting parameters when LT and(or)WTW were calculated.(2)Postoperatively: the influence of BUII formula omitting those optional biometry parameters on the prediction of postoperative intraocular lens accuracy.Methods:Prospective clinical study.The following data were retrieved for 279 eyes of 196 patients undergoing phacoemulsification surgery in May 2020 to December 2020 in cataract section of Shanxi Eye hospital.The Tomey OA-2000,a non-contact optical biological measuring instrument,measured biological parameters of every patient.According to the measured AL results,the patients were divided into three groups: 1,AL<22mm(15 eyes),2,22≤AL<26mm(219 eyes),and 3,AL≥26mm(45 eyes).And uses BUII formula and input all the known parameters to guide patients implanted Bausch&Lomb MX60 intraocular lens,in determining the implanted IOL degree,are calculated respectively(1)ignore LT + WTW(2)ignore WTW(3)ignore LT(4)no ignored parameters of four cases,IOL diopter corresponding prediction in turn to(1)(4),(2)(4),(3)(4)to predict diopter difference between groups(NE)and between groups predict diopter AE(prediction)correlation of absolute value of difference analysis,correlation analysis and grouped by AL.Follow-up to 1 month after surgery,the actual refractive status of the patients was reexamined.The difference between the actual refractive value(NE)and the absolute value of the difference(AE)between the actual refractive value(SE)and the theoretical prediction of the 4 prediction methods was calculated.The correlation between the change of axial length and AE was compared,and the prediction accuracy of the 4 prediction methods was compared as a whole and in groups.SPSS software 25.0 was used for data analysis of all statistical results.Results:1Theoretical comparison:Overall,the predicted MAE of each group was less than 0.1d.In the OWL group,the predicted MNE(0.07)and predicted MAE(0.08)were the largest,and the difference was statistically significant compared with each group.There was no statistically significant difference in MAE between the OW group(0.04)and the OL group(0.04).The predicted maximum values of NE were-0.27,0.41 in OWL group,-0.24,0.21 in OW group,and-0.19,0.27 in OL group.The predicted frequency and frequency distribution of AE≥0.25 D were 5(1.79%)in OWL group,4(1.43%)in OL group,and 0(0%)in OW group.The prediction performance of the normal axial subgroup(22≤AL<26mm)was consistent with the general trend,and the difference between the three groups was statistically significant.In the OWL group,the predicted MNE(0.08)and predicted MAE(0.09)were the largest.In the short-axis subgroup(AL<22mm),there was no statistical difference in the predicted MAE among the three groups.The maximum values of NE were-0.27,0.24 in the OWL group,-0.24,0.06 in the OW group,and-0.12,0.25 in the OL group.In the long axis subgroup(AL≥26mm),the predicted AE was less than 0.25 D,and there was no statistical difference in the predicted MAE(0.02)among the three groups.The maximum predicted NE(D)was-0.09,0.17 in the OWL group,-0.01,0.05 in the OW group,and-0.09,0.13 in the OL group.Using the same prediction method(OWL/OW/OL),the long axis subgroup had the lowest predicted MAE(0.02)among all subgroups,while there was no statistical difference in the predicted MAE between the short axis subgroup and the normal axis subgroup.2.Actual comparison:In general,(1)MNE of the four groups was different from each other by Friedman test and pairwise comparison,and the difference was statistically significant;There was no statistical difference in MAE among the four groups,which was about 0.23 D.(2)The similarity between the real SE and the predicted SE of the four groups was compared by using Wilcoxon signed rank sum test.The refractive prediction error NE of the OWL group was statistically significant(z=-2.537,P<0.05),while the real SE of the OW,OL and NO group was not statistically different from the predicted SE.(3)NE maximum value(D):-1.25,1.50 in OWL group,-1.12,1.40 in OW group,-1.12,1.50 in OL group,-1.06,1.41 in NO group.The extreme values of NE appeared in the OWL group-1.25,1.50.(4)Cochran Q test showed that there was no statistical difference in the distribution of AE cumulative frequency between groups within the range of ±0.25 D,±0.50 D,±1.00 D and >1.00 D.About 50% AE≤0.25 D,75% AE≤0.50 D,and over 90% AE≤1.00 D.In the same ocular axis subgroup,there was NO statistical difference in MAE among OWL,OW,OL and NO groups,and NO statistical difference in AE cumulative frequency distribution among the four groups.Using the same prediction method,there was no statistical difference in MNE and MAE among the subgroups of short axis,middle axis and long axis Sanya group when compared horizontally.Conclusion:1.The theory shows that when using Buii formula to predict IOL diopter,LT and WTW have little influence on the predicted value,the predicted MAE is less than 0.1D,and the predicted maximum value of NE appears in OWL group-0.27 and 0.41.In patients with long axis,LT and WTW had the least influence on the formula and could not be substituted into the calculation.In patients with normal axis,when only one of LT or WTW was ignored,the predicted value was closer to the theoretical value.2.The actual results show that the theoretical differences can be ignored in the actual prediction.No matter whether LT and WTW were included in BUII calculation or not,the MAE and AE distribution of the four groups had good consistency,and the axial length did not affect the predicted results.The predicted Se of the OWL group was statistically different from the real Se,and the maximum value of NE appeared in the OWL group at-1.25 and 1.50,suggesting that the maximum prediction deviation may occur when the prediction of LT and WTW is ignored in comparison with the extreme conditions of other groups.3.Conclusion: Corneal transverse diameter and lens thickness have limited predictive value in Barrett Universal Ⅱ intraocular lens calculation formula,and can be ignored.If possible,at least one of the terms of corneal transverse diameter or lens thickness can reduce the possibility of extreme refractive prediction errors.