Comparison Of Sirius Ray-tracing Method And IOL Master In Calculating The IOL Power After LASIK

Background and PurposeLaser in situ keratomileusis(LASIK) correction myopia and myopic astigmatism has good safety, efficacy and predictability,and was widely used in clinic.As time goes on,the patients who had LASIK surgery before may face cataract.The corneal shape and corneal curvature changed after LASIK.There will be appear IOL calculation error(using conventional formula) when this part cataract patients undergoing cataract extraction combined with intraocular lens(IOL) implantation surgery.It will appears different degree of hyperopia drift and affect the postoperative visual quality after cataract surgery.There were many methods to calculate IOL degree at present.Optical coherent biological measurement instrument(IOL Master) internal software contains Haigis-L formula.Haigis-L formula is designed for corneal refractive surgery patients to calculate IOL power.Clinical studies indicated that Haigis-L formula had good accuracy in calculating IOL power for corneal refractive surgery patients,and it do not need corneal refractive surgery preoperative information.Sirius three-dimensional corneal topography and anterior segment analysis apparatus(CSO, Italy,phoenix software version 3.0)not only is a new generation of corneal topography instrument,but its internal software contains ray-tracing technique to calculate IOL power directly,and do not need refractive surgery information.But the studies on accuracy and predictability of Sirius ray tracing method in calculating IOL power for corneal refractive surgery patients were few.The purpose of this paper is to compare the consistency and predictability between the Sirius Ray-Tracing method and IOL Master in calculating the IOL power after LASIK surgery,and provide objective data for clinic to reasonable calculation the IOL power after LASIK. MethodsIn the prospective clinical study,89 eyes of 89 patients who underwent myopic and myopic astigmatism LASIK surgery were selected according to preoperative SE and divided into two groups,59 eyes for mild and moderate myopia(≤-6.0D),30 eyes for high myopia(>-6.0D).Haigis formula was used to measure the IOL(The types of IOL were Alcon SN60 WF and AMO Tecnis ZA9003)power before LASIK,and Haigis-L formula,Haigis formula were used after LASIK one month by IOL Master.Compare the results with Sirius Ray-tracing method(the next short as Sirius method).The Bland-Altman consistency analysis and paired t test were used to analyze the results. Results Postoperative general conditionAfter one month, 89 cases with 89 eyes were all followed up.All corneal flap were reseted suitable,corneal transparent.89 eyes all meet preoperative best spectacled-corrected visual acuity and uncorrected visual acuity≥0.8.Spherical equivalent was +0.34D~-1.25 D,and average diopter was(-0.45±0.78)D.Corneal curvature was 36.48 ~ 43.21 D,average( 40.39±1.63) D.Axial length was(23.93±0.86)mm. Bland-Altman consistency analysis before and after operation(1) The comparison of Sirius method and Haigis formula in calculating IOL power preoperative:Bland-Altman consistency analysis showed the 95%LoA of mild and moderate myopia group of two type IOL were(-0.78~+0.84)D and(-0.57~+1.21)D,respectively.There were 3.4%,3.4% of the points beyond their respective LoA.The intraclass correlation coefficient(ICC) were 0.976 and 0.945, respectively. The 95%LoA of high myopia group were(-0.83~+0.69)D and(-0.57~+0.93)D, respectively.There were 3.3%,3.3%of the points beyond their respective LoA. The ICC were 0.981 and 0.979,respectively.(2) The comparison of Sirius method and Haigis-L formula postoperative:The 95%LoA of mild and moderate myopia group of two type IOL were(-1.02~+0.58)D and(-1.10~+0.77)D,respectively.There were 0%,1.7%of the points beyond their respective LoA.The ICC were 0.986 and 0.955,respectively.The 95%LoA of high myopia group were(-2.36~+0.80)D and(-1.98~+1.22)D,respectively.There were 6.7%,10%of the points beyond their respective LoA.The ICC were 0.981 and 0.979,respectively.(3) The comparison of Sirius method and Haigis formula postoperative:The 95%LoA of mild and moderate myopia group of two type IOL were(-0.27~+2.59)D and(-0.50~+3.30)D,respectively.There were 5.1% and 5.1% of the points beyond their respective LoA.The ICC were 0.641 and 0.584,respectively. The 95%LoA of high myopia group were(-0.48~+2.78)D and(-0.17~+3.17)D,respectively. There were 10% and 6.7% of the points beyond their respective LoA.The ICC were 0.622 and 0.651,respectively. IOL power comparison before and after operation(1) The IOL power calculation of Sirius method preoperation:The IOL power of mild and moderate myopia group of two type IOL were(16.29±2.51)D and(16.70± 2.58)D,respectively.The IOL power of high myopia group were(14.78±2.94)D and( 15.13±3.03) D,respectively.The IOL power calculation of Haigis formula preoperation:The IOL power of mild and moderate myopia group were(16.26±2.46)D and(16.38±2.52)D,respectively.The IOL power of high myopia group were(14.85±2.87)D and(14.95±2.93)D,respectively.There was no significant statistical difference between Sirius and Haigis formula in calculation IOL power in two groups preoperative.(2) The IOL power calculation of Sirius method postoperation:The IOL power of mild and moderate myopia group were( 23.26±1.19) D and( 23.46±1.30)D,respectively.The IOL power of high myopia group were(23.52±1.64)D and(23.85±1.86)D,respectively. Haigis-L formula postoperation:The IOL power of mild and moderate myopia group were(23.48±1.11)D and(23.39±1.07)D, respectively.The IOL power of high myopia group were( 24.88±1.99) D and(24.93±2.12)D,respectively. Haigis formula postoperation:The IOL power of mild and moderate myopia group were( 22.10±1.05) D and( 22.09±1.02) D, respectively.The IOL power of high myopia group were( 22.87±1.54) D and(22.95±1.58)D,respectively.There was no significant statistical difference between Sirius method and Haigis-L formula in mild and moderate myopia group,but significant statistical difference in high myopia group postoperative.There was significant statistical difference between Sirius and Haigis formula postoperative in two groups. ConclusionThere was better consistency and predictability of Sirius Ray-Tracing method and Haigis formula in unoperative eyes,and better consistency and predictability with Haigis-L formula in mild and moderate myopia after LASIK,but poor consistency and predictability with Haigis-L formula in high myopia after LASIK to calculate the IOL power.