Accuracy Of Intraocular Lenspower Calculation And Refractive Error Analysis In Cataract Surgery

ObjectivePhacoemulsification with intraocular lens (IOLs) implantation is now established as the optimal surgical technique to treat most cataracts, In order to obtain the best refractive status, we study the accuracy of refractive error between SRK-T and Haigis formula using A-scan ultrasonography after phacoemulsification and IOL implantation, analysis the source of refractive error, which will help choosing IOL for cataract surgery.MethodsThis study is a retrospective analysis of biometric and refractive data was performed96eyes of87patients who present cataract surgery. Preoperative axial length (AL) and anterior chamber depth (ACD) were measured by A-scan ultrasonography optical biometry, keratometric values (Ks) examined with by keratometer, Patients were divided into3groups based on AL less than22mm (short axial length),22to26mm (moderate axial), and more than26mm (long axial length). The power of the implanted IOL was used to calculate the predicted postoperative spherical equivalence (SE) by the Haigis and SRK/T formulas The predictive accuracy of each formula was analyzed by comparing the different between the actual and predicted postoperative SE (MAE, mean absolute error). Postoperative refraction was examined3days and3months after surgery. We compared the change of refraction between these different times.ResultsIn the study,2eyes occurred posterior capsule opacification,94eyes were studied, In all the groups, there are no statistical difference of AE between SRK-T and Haigis formula calculation.(P>0.05).The medium eye axis using SRK-T formula,the percent of AE less than0.5D and1.0D are42.7%and84%,which is similar with Haigis formula. Patients with short and long eye axis have smaller AE in SRK-T formula calculation. Predict error showed several hyperopia shifts in short axial and long eyes using the SRK-T and Haigis formula. There are no correlation during AE and AL, ACD, K, in SRK-T and Haigis formula calculation,(P>0.05), the AE Haigis formula calculated have linear positive correlation with ACD (R2=0.542, P=0.024). Long-term postoperative SE showed myopia shift comparing to short ones in short axial (P=0.042<0.05), but there was no statistically significant difference in medium and long axial group (P>0.05)ConclusionsThe IOL power calculation using the Haigis and SRK-T formula showed the similar results for postoperative power prediction in all eyes. Haigis formula is suitable for short axial patients, SRK-T more suitable for patients with long axis. AE and ACD were positively correlated in patients with long axial using Haigis formula. The IOL power calculation using the Haigis and SRK-T formula showed hyperopia shift in short and long axial.