Evaluation Of The Accuracy Of Different Intraocular Lens Calculation Formulas In Predicting The Refractive Power Of Anti-VECF Treatment Eyes

Objective:To evaluate the accuracy of SRK/T,Haigis and Barrett Universal II formulas for intraocular lens refraction in anti-VEGF eyes and the timing of cataract surgery.Methods:Prospective case study.34 eyes of 31 cataract patients with anti-vascular endothelial growth factor(VEGF)treated with phacoemulsification and intraocular lens implantation in the affiliated Hospital of Guizhou Medical University from February 2019 to December 2020 were collected.Corneal curvature(K),anterior chamber depth(ACD)and axial length(AL)were measured by IOL Master 500 before operation.The expected diopter of the type of IOL used was selected by using the SRK/T and Haigis IOL formulas built in IOL Master 500,and the expected diopter of the IOL with Barrett Universal II formula was calculated online.The visual acuity before and 3 months after operation,the postoperative diopter predicted by SRK/T,Haigis and Barrett Universal II formula and the actual postoperative diopter were recorded.The absolute value of the difference between the actual postoperative diopter and the expected postoperative diopter was recorded as the absolute diopter error(ME).The main result was the difference in mean absolute prediction error(MAE)between the formulas.The median and maximum absolute prediction errors(Med AE and Max AE),and the percentage of postoperative refractive error distribution and the proportion of postoperative refractive drift were evaluated.Comparison completed anti-VEGF treatment eyes in 6 months with 6 months after cataract surgery on re-anti-VEGF treatment.Wilcoxon rank sum test was used to compare the difference between preoperative visual acuity and postoperative visual acuity,Fried Man test was used to compare the percentage of MAE and absolute refractive error of the three formulas,and Wilcoxon rank sum test was used to analyze the pairwise comparison.The Fisher exact probability method was used to analyze the refractive drift of the three formulas after operation.Results:1.The uncorrected visual acuity was less than 0.1 in 14 eyes,0.1 to 0.3 in 14 eyes,>0.3 in 6 eyes,3 months after the operation and preoperative visual acuity was<0.1 in 22 eyes,and 0.1 to 0.3 in 12 eyes,The difference was statistically significant(Z=-3.880,P=0.001);2.The formulas were ranked by the MAE as follows: Barrett Universal II(0.259D),SRK/T(0.329D)and Haigis(0.422D),The differences in absolute errors with the formulas were significant(M=6.652,P=0.036).Comparing the formulas in pairs,the MAE value of the Barrett Universal Ⅱ formula was significantly lower than the Haigis formula(Z=-2.759,P=0.006);3.There was no statistical difference in the type of refractive drift calculated by the three formulas(P=0.065);the ratio of ME calculated by the three formulas was not statistically different(P=0.053);4.Of the 5 eyes with submacular CNV who underwent cataract surgery within 6 months after the completion of anti-VEGF treatment,2 eyes needed anti-VEGF treatment again,accounting for 40%;of the 19 eyes who underwent cataract surgery > 6 months,1eyes needed anti-VEGF treatment again,accounting for5.3%.Conclusions:1.Phacoemulsification combined with intraocular lens implantation can improve the visual acuity of anti-VEGF treated eyes.2.Comparing the accuracy of SRK/T,Haigis,and Barrett Universal II formulas in predicting intraocular lens power in anti-VEGF treatment eyes,the accuracy of Barrett Universal II formula is better than the other two calculation formulas.3.Suggested that eyes with submacular CNV undergo cataract surgery at least more than 6 months after the completion of anti-VEGF treatment.Cataract surgery can be performed first for patients with severe cataract opacity.