Comparison Of Four Intraocular Lens Power Calculation Formulas With And Without Optimizing Axial Length In Eyes With An Axial Length Greater Than 26.0mm

Objective:To evaluate and compare the accuracy of SRK/T、Haigs、Hoffer Q、Holladay1and their optimized formulas for calculating the intraocular lens(IOL) power for eyes with axial lengths greater than 26.00 mm by IOL Master.Methods:Prospective clinical study.To analyze the data of the 122 eyes,who were all high myopic eyes(with IOL Master axial length greater than 26.0mm) with cataract and accepted the phacoemulsification and fold-able lens implantation surgery.The intraocular lens(IOL) power was determined by SRK/T、Haigis、Hoffer Q、Holladay1and their optimized formulas,respectively.Postoperactive refractive errors about one month after surgery were measured with phoropter and compared with the predicted postoperative power.Result:In 71 of 122 eyes,the IOL was more than 6.0 diopter(D)(Group A)and in 51 eyes was 6.0D or less(Group B).In group A the mean axial length was 27.45 mm,and it was 30.64 mm in group B.In group A,the MNEs of the SRK/T、Haigis、Hoffer Q and Holladay1 formulas were(-0.05±0.57)D 、(0.13±0.58)D 、(0.39±0.61)D and(0.40±0.60)D respectively.When used the optimized formulas,the numerical value of the Haigis、Hoffer Q and Holladay1 formulas tended to negative.The MAEs of the SRK/T 、 Haigis 、 Hoffer Q 、 Holladay1 and their optimized formulas were(0.38±0.43)D 、(0.41±0.43)D 、(0.55±0.48)D 、(0.55±0.47)D 、(0.57±0.54)D 、(0.67±0.53)D 、(0.56±0.52)D and(0.51±0.51)D respectively.The MAEs were significantly lower in SRK/T and Haigis formulas than Hoffer Q and Holladay1formulas(χ2=11.74,P=0.008).The MAEs were calculated by the SRK/T and Haigis formulas compared with their optimized formulas(Z=-3.521,P=0.008;Z=-3.728,P=0.00).In group B,the MNEs of the SRK/T、Haigis、Hoffer Q and Holladay1 formulas were(0.75±0.77)D、(0.57±0.53)D、(1.32±0.62)D and(1.06±0.52)D respectively,which were all hyperopic.When used the optimized formulas,the numerical value of all the formulas tended to negative.The MAEs of the SRK/T、Haigis、Hoffer Q、Holladay1 and their optimized formulas were(0.83±0.68)D、(0.63±0.45)D、(1.32±0.62)D、(1.06±0.52)D、(0.61±0.42)D、(0.52±0.36)D、(0.48±0.34)D and(0.53±0.39)D, respectively.The MAEs were calculated by the SRK/T、Hoffer Q and Holladay1 formulas compared with their optimized formulas((Z=-2.081,P=0.037;Z=-5.444,P=0.00;Z=-4.003,P=0.00)).The MAEs were significantly lowest in Hoffer Q optimized formula(F=1.075,P=0.361).Conclusions:When selecting IOLs for more than 6.0D,chosing the SRK/T formula.And for IOLs 6.0D or less,the method of optimizing axial length could reduce prediction error and the percentage of long eyes with hyperopic outcome significantly.