Correlation Between Refractive Error And Ocular Biological Parameters After Cataract Surgery Under Different Formulas

Objective:Compare the accuracy of 8 formulas commonly used in clinic under different eye parameters,and make multiple linear regression analysis between each parameter and postoperative refractive error of each formula and postoperative spherical equivalent,so as to obtain multiple regression equation and accurately calculate intraocular lens power and better serve the clinic.Methods : This study was a retrospective study.A total of 101 cases(144 eyes)with cataract more than 3 months after cataract surgery were collected.IOL master,equivalent spherical lens power measurement,diagnostic refraction,slit lamp microscope and non-mydriatic direct ophthalmoscope examination were improved.122 eyes were included in the comparison of axial length before and after surgery,and 144 eyes were included in the comparison of corneal parameters before and after surgery.116 eyes were included in the comparison of the accuracy of eight formulas including Haigis,Hoffer Q,SRK / T,Holladay I,Kane,Barrett universal II,T2 and EVO under different parameters.116 eyes were included in the multiple linear regression analysis of eye parameters,age,gender and the postoperative refractive error and equivalent spherical power of the above 8 formulas.According to the length of the eye axis,it is divided into short axial group(AL < 22.50mm),medium axial group(22.50 mm ≤AL < 25.50mm)and long axial group(AL ≥ 25.50mm).The changes of axial length before and after operation and the accuracy of intraocular lens formulas were compared.According to the depth of anterior chamber,they were divided into three groups: shallow anterior chamber group(ACD≤3.0 mm),medium anterior chamber group(3.0 mm < ACD≤ 3.5 mm)and deep anterior chamber group(ACD > 3.5 mm),and the accuracy ofintraocular lens formulas were compared.According to the astigmatism types,the patients were divided into three groups:astigmatism with the rule group,atigmatism against the rule group and oblique astigmatism group,to compare the changes of corneal parameters before and after surgery under different astigmatism types and the accuracy of intraocular lens formulas were compared.The factors such as the length of the eye axis,the depth of anterior chamber,the corneal refractive power,the difference of the axial length between the operating eye and the non operating eye,as well as the factors such as age and sex,were analyzed by multiple linear regression analysis with the equivalent spherical lens degree and the error of the refraction after the operation according to the above 8 formulas.Results: After phacoemulsification combined with intraocular lens implantation,the measured axial length is shortened,but the clinical reasons need to be further explored.Cataract surgery with 2.4mm temporal clear corneal incision has no significant effect on corneal parameters,but the type of astigmatism will change.Axial length was negatively correlated with corneal refractive power,but positively correlated with anterior chamber depth.There was no correlation between anterior chamber depth and corneal refractive power.When not grouped according to eye parameters,there was difference in accuracy between EVO formula and SRK/T,Holladay I,Barrett universal II,Kane,T2 formula.Hagigs formula is more accurate in any axial length,corneal refractive power,anterior chamber depth and astigmatism type.There was no significant difference in the accuracy of the 8 formulas in the long axis group,short axis group,shallow anterior chamber group,medium anterior chamber group,deep anterior chamber group,astigmatism with the rule group,astigmatism against the rule group and oblique astigmatism group.The accuracy of EVO formula,SRK/T and Holladay I formula in the middle eye axis group was statistically significant.There was no significant difference in the accuracy of other formulas.Multiple regression analysis showed the following equation:Postoperative spherical equivalent =-0.389 preoperative AL-0.336 preoperative mean K+0.274 preoperative ACD + 6.761(F=3.944,P=0.003).Hoffer Q postoperative refractive error=-4.102+0.221 preoperative AL+ 0.308 preoperative ACD + 0.188 age(F=8.622,P=0.000).SRK/T postoperative refractive error =8.046-0.426 preoperative mean K-0.245 preoperative AL+ 0.220 preoperative ACD(F = 6.351,P = 0.001).Holladay I postoperative refractive error =0.303 preoperative ACD-0.240 preoperative mean K(F=5.449,P=0.001).Kane postoperative refractive error = 3.201-0.206 preoperative mean K(F=5.031,P=0.027).Barrett universal II postoperative refractive error=3.567-0.231 preoperative mean K(F=6.413,P=0.013).T2 formula postoperative refractive error = 4.610-0.342 preoperative mean K+ 0.229 age + 0.294 preoperative ACD(F=4.040,P=0.004).EVO postoperative refractive error = 2.988-0.219 preoperative mean K+ 0.184 age(F= 3.933.P=0.022).Conclusion:(1)The axial length measured after cataract surgery became shorter.(2)2.4mm temporal clear corneal incision can not reduce corneal astigmatism,but the type of astigmatism changes.(3)Except for the accuracy difference between EVO formula and SRK/T,Holladay I,Barrett universal II,Kane,T2 formula,there is no significant difference between the other formulas.(4)The accuracy of the four generation formula was the best when the parameters of lens thickness and white to white were not included.(5)The multivariate regression equations of preoperative axial length,anterior chamber depth,corneal refractive power,age and postoperative equivalent spherical power,and postoperative refractive error of the remaining seven formulas were established except Haigis formula.