Accuracy Of Intraocular Lens Power Calculation After Small Incision Lenticule Extraction

Objective:To explore the relative factors of intraocular lens?IOL?power calculation with myopia after small incision lenticule extraction?SMILE?and accurately prediction the really IOL power after SMILE through postoperative data.Methods:A Prospective case study.From June 2017 to December 2017,totally 62cases?120 eyes?with myopia accepted SMILE were collected in the refractive surgery center in our hospital.Routine ophthalmology examination was did at preoperation and postoperation 1 month,IOL-Master was used to measure the ocular parameters such as axial length?AL??corneal curvature?K??corneal radius of curvature?R??anterior chamber depth?ACD??white to white?WTW?and the IOL power was calculated by Haigis formula targeting emmetropia with the A-constant was 118.0,and we can obtain?IOL=IOL_{postoperation meas}–IOL_{preoperation meas},we also recorded the corneal central thickness?CCT?by AC-OCT.Then statistical analysis to the data,the paired t test analysis was performed for the IOL power of preoperation and postoeration,the Pearson correlation analysis was used to analyze the relationship between?IOL and its relative factors,multiple linear regression model analysis were used to calculate postoperation really IOL power of SMILE.Results:1.At postoperative 1 month of SMILE,uncorrected distance visual acuity?UDVA?improved significantly compare to preoperation?P=0.000?.2.There was significant statistical increase in IOL power at postoperative 1 month compare with IOL power at preoperation by paired t test?t=53.223,P=0.000?.3.The?IOL power in myopia were correlated with?R??SE??CCT?central lenticule thickness?peripheral lenticule thickness?r=0.938?0.912?0.814?0.814?-0.674,P=0.000?.4.The multiplelinearregressionmodelanalysisrevealedthat Y=X₁+6.096-2.301X₂+0.016X₃?Y was postoperation really IOL power,X₁ was postoperation measure IOL power,X₂ was postoperation R,X₃ was postoperation CCT?,and F=63.826,P=0.000,multiple regression coefficient R=0.722,adjusted R²=0.514.Then we can get the formula IOL_{post really}=IOL_{post meas}+6.096-2.301R_post+0.016CCT_post.So we through postoperative data can accurately prediction the really IOL power after SMILE.5.Highly positive correlation can be find between actual IOL power values and predicted IOL power values.So,our formula have a good effect.Conclusion:1.The IOL power after SMILE was increased compare to preoperation.2.The?IOL power were correlated with?R??SE??CCT?central lenticule thickness?peripheral lenticule thickness.3.Also,we can accurately prediction the really IOL power calculation formula after SMILE through postoperative data,IOL_{post really}=IOL_{post meas}+6.096-2.301R_post+0.016CCT_post,and how many power of IOL should be implanted in cataract patient with previous SMILE can be predicted to achieve good refraction.