Accuracy Of Intraocular Lens Calculation Formulas In Cataract Patients With High Corneal Curvature

Objective:To compare the accuracy of five kinds of intraocular lens calculation formulas(SRK/T,Haigis,Hoffer Q,Holladay and Barrett Universal Ⅱ)for the calculation of IOL in cataract patients with high Corneal Curvature.Methods:This is a retrospective study of cataract phacoemulsification combined with intraocular lens implantation at Shenyang He Eye Hospital from January to June2019 for patients with cataract together with high curvature cornea(corneal curvature≥ 46D).The power of the IOL calculated by the formulas before the operation(The calculation results of SRK/T,Haigis,Hoffer Q,and Holladay formulas were directly from IOL Master and the calculation results of the Barrett Universal Ⅱ formula were got online by the input biological data of IOL Master),and the objective optometry results at 1 month postoperatively were collected.According to the length of the ocular axis,all patients were divided into three groups: short axis eye group(< 22mm),normal axis eye group(22 < al ≤ 24.5mm)and long axis eye group(> 24.5mm).The refractive error between the predicted postoperative refraction and the actual postoperative refraction value and the absolute value of the refractive error(AE)were calculated.The covariance analysis was used for the comparison of five formulas in each group.The correlation between the refractive error value,the absolute value of refractive error and the length of the eye axis from every formula were analyzed by Pearson correlation test respectively.Result:Total 112 eyes of 83 cataract patients with high curvature cornea were collected.The average absolute refractive errors of the SRK / T,Haigis,Hoffer Q,Holladay,and Barrett Universal II formulas in the short axis group were 0.47 D,0.77 D,0.51 D,0.47 D,0.48 D respectively;the average refractive errors were all positive in the five calculation formulas.The biggest error(0.65D)occurred in Haigis formula,and the smallest error(0.01D)occurred in the Holladay formula.The average absoluterefractive errors of the SRK / T,Haigis,Hoffer Q,Holladay,and Barrett Universal Ⅱformulas in the normal axial eye group were 0.46 D,0.51 D,0.45 D,0.41 D,0.41 D respectively;the average refractive errors were positive in SRK / T and Haigis formulas,but negative in the other calculation formulas.The average absolute refractive errors of the SRK / T,Haigis,Hoffer Q,Holladay,and Barrett Universal II formulas in the long axis group were 0.78 D,0.51 D,0.76 D,0.68 D,0.35 D respectively.The mean refractive error was positive in SRK / T formula,but negative in the rest four calculation formulas.The anterior chamber depth was a covariate in the short axis eye group in the covariance analysis of absolute refractive error(p <0.001),and the comparison between Haigis and Holladay’s formula was statistically significant(P =0.044),but not statistical significant in the other formulas comparison.In the normal axial eye group,the anterior chamber depth had no significant correlation in the five calculation formulas(P = 0.521),and there was no significant difference between the five calculation formulas(P = 0.609).In the long axis eye group,the anterior chamber depth had no significant correlation in the five formulas(P = 0.064),the comparison was significant between SRK / T and Barrett Universal Ⅱ formula(P = 0.025),and between Hoffer Q and Barrett Universal Ⅱ formula(P = 0.040)respectively.The Pearson correlation analysis was used on the correlation study between absolute refractive errors of every calculation formula with the axial length,there was no significant correlation in Haigis(P = 0.428)and Barrett Universal Ⅱ formulas(P =0.278),the positive correlation was in SRK / T formula(R = 0.247,P <0.05),Hoffer Q formula(R = 0.388,P <0.05),and Holladay formula(R = 0.412,P <0.05).The correlation between refractive errors of the five formulas with the axial length were studied by Pearson correlation analysis,the refractive errors of the SRK / T,Haigis,Hoffer Q,Holladay,and Barrett Universal Ⅱ formulas were negatively correlated with the axial length(R =-0.215,-0.653,-0.602,-0.407,-0.207,P <0.05).Conclusion:Barrett Universal Ⅱ formula is more accurate than other calculation formulas in predicting the IOL power in the cataract patients with high corneal curvature,that would get the minimal impact by the axial length compared to others.Inthe short axis group,the SRK/T,Holladay,and Barrett Universal Ⅱ formulas are more accurate in the prediction of the intraocular lens.In the normal axis group,all the five formulas are similar in the prediction of the intraocular lens power.In the long axial group,the advantages of Haigis and Barrett Universal Ⅱ formulas are more obvious.Less impact by the axial length was in Barrett Universal Ⅱ formula than others.