Comparison Of Outcomes Of Femtosecond Laser-Assisted And Manual Trephine Deep Anterior Lamellar Keratoplasty In Treating Keratoconus

Objective:To compare the clinical outcomes of femtosecond laser-assisted(FSL)and manual trephine(MT)Pocketing Air-Visco Expanding Detachment Technique for Performing Deep Anterior Lamellar Keratoplasty(PAVED-DALK)in treating keratoconus.Method:This was a retrospective case-control study.In the management of keratoconus,a cohort of 14 eyes that underwent FSL PAVED-DALK between March 2017 and November 2017 was compared with 23 eyes that underwent MT PAVED-DALK between June 2015 and March 2017.Intraoperative and postoperative complications between two groups were compared.Patients were followed at 3 month,6 months,9 months and 1 year for uncorrected visual acuity(UCVA),best corrected visual acuity(BCVA),spherical equivalent(SE),intraocular pressure(IOP),mean keratometry(Km),total corneal astigmatism at a zone of 3 mm diameter from the corneal apex(TA3mm),corneal total higher-order aberration for 3 and 6 mm corneal diameters(HOA3mm,HOA6mm),corneal asymmetry index(ISV,IHA,IVA,IHD),corneal total densitometry between 6 to 10 mm corneal diameters(CD6-10mm),thinnest corneal thickness(TCT)and endothelial cell density(ECD),as well as the OCT images.Two independent sample t test,rank-sum test,Chi-squared test were used for analyzing various parameters between the two groups.To compare the parameters of preoperative and postoperative follow-up time points,repetitive measurement deviation analysis was performed.The significance level was set to P<0.05.Results:(1)There was no statistical difference in gender,age,UCVA,BCVA,SE,IOP,ocular axis,TCT,ECD,Km,TA3mm,HOA3mm,and HOA6mm of preoperative between two groups.(2)The incidence of intraoperative and postoperative complications was low in both groups and there was no statistical difference.The main intraoperative complication was mainly Descemet membrane microperforation,and no case was converted to PKP.Postoperative complications included double anterior and high intraocular pressure,and were all improved after treatment.(3)Compared with preoperative data,the UCVA,BCVA,SE,Km,and TCT were significantly improved in both groups,and the differences were statistically significant.(4)The time of suture removal in FSL group was significantly earlier than MT group.After the time of suture removal,the UCVA,HOA6mm,CD6-10mm,IHA,IVA,IHD in the FSL group were significantly better than that in the MT group.Further study found that UCVA was significantly positively correlated with CD6-10mm(r=0.340),HOA6mm(r=0.424),and IVA(r=0.442).(5)The OCT images of two groups at postoperative one year shown that the Descemet membrane was well attached to the graft,the graft-host junction was smooth.But the opacity degree,opacity area and opacity length of graft-host junction in FSL group were much smaller than that in MT group.(6)The UCVA,HOA6mm of FSL group were significantly better than that in MT group in the postoperative follow-up.At 3 and 6 months follow-up,the BCVA,SE,HOA3mm were better in the FSL group compared with the MT group.In terms of TA3mm,Km,TCT and ECD in the postoperative follow-up,there were no statistically significant difference between the two groups.Conclusion:Femtosecond laser-assisted PAVED-DALK and manual trephine PAVED-DALK have certain safety and efficacy in the treatment of keratoconus.Compared with manual trephine PAVED-DALK,femtosecond laser assist PAVED-DALK has earlier suture removal,better uncorrected visual acuity,better optical quality,better corneal regularity,faster corneal incision healing.