Analysis Of The Clinical Learning Curve Of Femtosecond Small Incision Lenticule Extraction For Myopia And Myopic Astigmatism In The Early Stage

Objective:To evaluate the safety,efficacy,predictability,stability and complications and operation time of femtosecond laser comeal small incision lenticule extraction(SMILE)for the correction of myopia and myopic astigmatism operative by analyzing the learning curve of the operation.Methods:In this retrospective study.200 cases(390 eyes)of myopia and myopic astigmatism were selected by SMILE surgery in initial stage,the first 100 patients(195eyes)in group A,patients in 100 cases(195 eyes)for the B group.All patients took measurements of uncorrected visual acuity(UCVA),best corrected visual acuity(BCVA),refractive power and intraocular pressure,slit-lamp microscopy,and corneal topography preoperatively and at 1 day,1 week,1 month,3months,6 months and more postoperatively.The t test was used to compare the diopters and morphological parameters at each time point postoperatively and preoperatively and the basic characteristics preoperatively and the diopters and operation time.Linear regression analysis was used to compare the difference between the expected corrected SE and the actual corrected SE.Results:The two group of spherical equivalent about the difference of 1d was statistically significant(P<0.05).No significant differenee was found between the two groups of the postoperative Cylindrical diopter.After 6 months and more follow-up postoperatively,A group of 95.59% patients with UCVA ?0.8,B group of 94.92% patients with UCVA?0.8.A and B two groups had relatively stable refraction after operation,and B group had smaller fluctuation.Intraoperative complications,3 eyes(1.54%)suffered from the suction loss in A group,2 eyes(1.03%)suffered from the suction loss in B group.55 eyes(28.21%)developed opaque bubble layer in A group,43 eyes(22.05%)developed opaque bubble layer in B group.Postoperative complications,The first day afteroperation,13 eyes(6.67%)included mild diffuse lamellar keratitis(DLK)in A group,39eyes(20%)included mild diffuse lamellar keratitis in B group.After 6 months and more follow-up postoperatively,5 eyes(2.56%)under correction in A group,3 eyes(1.54%)under correction in B group;4eyes(2.05%)refractive regression in A group,4eyes(2.05%)Refractive regression in B group.The duration of docking was63.74±101.19and37.01±544.80 seconds for group Aand group B,(P<0.05).The duration of lenticule extraction was255.12±158.75and183.86±64.36 seconds for group A and group B,respectively(P<0.05).Conclusions:With the increase in the number and experience of surgery,SMILE has improved in postoperative visual acuity,incidence of complications,shortening the operation time.Clinical operation learning curve exists in SMILE.