The Accuracy And The Effect Factors Of Intraocular Lens Diopter Calculation In Cataract Patients With Short Axial Length

Objective: To compare and analyze the IOL diopter predictive accuracy of 7different intraocular lens calculation formulas(EVO,Kane,Barrett Universal Ⅱ,SRK/T,Hoffer Q,Holladay Ⅰ,Haigis)in short-axial length cataract patients with different corneal curvature and anterior chamber depth,and to analyze the relevant influence factors contributing to the refractive prediction error of each intraocular lens calculation formula.Methods: This is a retrospective case analysis study.A total of 125 patients diagnosed as "age-related cataract" with ocular axial length(AL)less than 22 mm were collected who were treated in Shenyang He’s Eye Hospital from November 2020 to December 2021,one eye per person,125 eyes in total.All the recruited patients who underwent standard cataract phacoemulsification surgery combined with intraocular lens implantation(HOYA PY-60AD),without any surgical complications,and were observed for at least 1 month after operation.The preoperative biological parameters such as ocular axial length,corneal curvature,anterior chamber depth,central corneal thickness,and horizontal diameter of cornea were collected by optical biological measuring equipment,to calculate the intraocular lens power of each formula,and the predicted value was obtained by combining the actual implantation intraocular lens power and the equivalent spherical lens converted from the postoperative refraction results,and then to calculate the predicted refractive error,and the mean error(ME),mean absolute error(MAE),median absolute error(Med AE)and the proportion distribution of prediction error of each formula in different ranges(± 0.25 D,± 0.50 D,± 0.75 D,± 1.00 D).Divided them into 3groups: low flat corneal curvature group(Km ≤ 45.5D),medium high corneal curvature group(45.5<Km<47)and steep corneal curvature group(Km ≥ 47D);Divided them into3 groups according to the preoperative anterior chamber depth,very shallow anterior chamber group(ACD ≤ 2.09mm),shallow anterior chamber group(2.09mm<ACD<2.58mm)and normal and deep anterior chamber group(ACD ≥2.58mm),and then compare the prediction accuracy of 7 different intraocular lens calculation formulas.Multiple linear regression analysis was used to analyze the correlation between the postoperative predictive error of each formula and the factors such as ocular axis length,average corneal curvature,preoperative anterior chamber depth,central corneal thickness,horizontal diameter of cornea,degree of intraocular lens implantation,age and sex of patients.Results: According to the total data,there are significant statistical differences in the absolute prediction error of 7 formulas(χ~2= 49.934,P<0.001),there is statistical difference between the absolute prediction error of Barrett Universal Ⅱ formula and the other six formulas(P<0.05).The minimum value of MAE was 0.26D(Barrett Universal Ⅱ),the second one was 0.37D(Kane),The minimum value of Med AE was 0.17D(Barrett Universal Ⅱ),the second one was 0.26D(SRK/T).The proportion distribution of prediction error of Barrett Universal Ⅱ formula is all the highest(64.80%,92.80%,94.40%,96.00%)in different ranges.There were significant statistical differences in the proportion distribution of each formula within the range of ± 0.25 D and ± 0.5D.In different corneal curvature groups,there was no statistical difference in the absolute prediction error and the proportion distribution of prediction error of each formula in the low flat corneal curvature group(P>0.05);There was all significant statistical difference in the absolute prediction error of each formula in the medium-high and steep corneal curvature groups(χ~2= 34.375,P<0.001;χ~2= 34.804,P<0.001).The MAE(0.23 D,0.30D)and Med AE(0.14 D,0.20D)of Barrett Universal Ⅱ formula in the medium-high and steep corneal curvature group were all the smallest,followed by SRK/T formula.The proportion distribution of prediction error of Barrett Universal Ⅱ formula in the range of ± 0.25 D,± 0.50 D,± 0.75 D and ± 1.00 D is the highest,and there is no significant statistical difference between most formulas.In different anterior chamber depth groups,there were significant statistical differences in the absolute prediction error of each formula in all subgroups(very shallow group χ~2= 22.863,P=0.001;shallow group χ~2= 25.568,P<0.001;normal and deep group χ~2= 13.647,P<0.05.The MAE(0.35D;0.20D;0.30D)and Med AE(0.27D;0.15 D,0.16D)of Barrett Universal Ⅱ formula were all the smallest in each subgroup.In all subgroups,the proportion distribution of prediction error of Barrett Universal Ⅱ formula in the range of ± 0.25 D,± 0.5D,± 0.75 D and ± 1.0D is all the highest,and there was no significant statistical difference between most formulas.Multiple linear regression analysis was carried out between the refractive prediction error of each formula and the related factors such as the ocular biometric parameters,the degree of intraocular lens implantation,and the age and sex of the patient and other factors.According to the coefficient of regression analysis,to establish the relevant equation.It was found that the ocular axial length was positively correlated with KANE formula,Hoffer Q formula,Holladay Ⅰ formula,and Barrett Universal Ⅱ formula;the average corneal curvature was positively correlated with Kane formula,SRK/T formula,Haigis formula,Hoffer Q formula,Holladay Ⅰ formula and Barrett Universal Ⅱ formula;the horizontal diameter of cornea is positively correlated with EVO formula;the central corneal thickness is positively correlated with Haigis formula;the degree of implanted intraocular lens is positively correlated with Kane formula,Hoffer Q formula and Barrett Universal Ⅱ formula,and the age is positively correlated with Kane formula,SRK/T formula,Haigis formula,Hoffer Q formula,Holladay Ⅰ formula.Conclusion: As a new generation of IOL calculation formula,the Barrett Universal Ⅱ formula is superior to the traditional convergence and dispersion formula in predictive accuracy of IOL refractive power in the short ocular axial population with different corneal refractive power and different anterior chamber depth,and is even more accurate than some new formulas(Kane,EVO).Especially when the corneal refractive power and anterior chamber depth are in the special measurement range,the Barrett Universal Ⅱ formula shows certain advantages,which can be used as preferred choice.Among them,the ocular axial length and corneal curvature and the degree of intraocular lens implantation are closely correlated with the prediction accuracy of Barrett Universal Ⅱ formula.