A Comparative Study On The Consistency Of Lenstar LS900 And ITrace Measuring Kapppa Angle And Angle Of Cataract Patients Before Surgery

Objective :To compare the consistency of angle Kappa and angle Alpha measured by Lenstar Ls900 and i Trace before age-related cataract surgery.Methods :From December 2017 to June 2018,55 patients(59 eyes)with age-related cataract were collected from ophthalmology department of the Fourth Affiliated Hospital of Chinese Medical University,Before the operation,the pupil centered axis of sight eccentric distance(angle Kappa)and the iris centered axis of sight eccentric distance(angle Alpha)were measured by Lenstar Ls900 and i Trace wavefront aberrometer respectively.Firstly,The x-axis and y-axis coordinates are decomposed in the iris plane,and then the axis of sight eccentric distance is calculated by trigonometric function.Finally,The x-axis,y-axis,pupil diameter,corneal horizontal diameter and axis of sight eccentric distance are compared respectively.The paired t-test was used to compare the data measured by the two instruments.Bland-altman ananlysis was used for consistency compatrson.Results :The mean angle kappa measured by Lenstar LS900 was(0.270 ? 0.128)mm,the mean angle Alpha was(0.349 ? 0.128)mm,the mean pupil diameter was(4.101 ? 0.773)mm,the mean corneal horizontal diameter(white to white,WTW)was(10.848 ? 0.467)mm,The mean value of X-axis of angle kappa is(0.0157 ? 0.225)mm,that of Y-axis of angle Kappa is(0.105 ? 0.185)mm,and that of X-axis of angle Alpha is(0.01 ? 0.353)mm.The mean value of Y-axis of angle Alpha is(0.0415 ? 0.195)mm the mean angle Kappa measured by i Trace was(0.296 ? 0.131)mm,the mean angle Alpha was(0.338 ? 0.121)mm,and the mean pupil diameter was(10.848 ? 0.467)mm.(4.103 ? 0.797)mm,mean corneal horizontal diameter(white to white,WTW)was(10.837 ? 0.475)mm,The mean value of X axis of angle Kappa is 0.0218 ? 0.233 mm,that of Y axis of angle Kappa is(0.0906 ? 0.172)mm,that of angle Alpha is(0.0062 ? 0.345)mm and that of Y axis of angle Alpha is(0.0294 ? 0.112)mm.There was no significant difference between the two instruments(p> 0.05).Bland Altman analysis shows that the test results of the two instruments are in good consistency.Conclusion :Lenstar Ls900 and i Trace have good consistency in measuring the angle Alpha and angle Kappa in patients with age-related cataract before operation,which can provide some reference for the selection of refractive intraocular lens.