Comparison Of Two Surgical Techniques Of Femtosecond Laser-assisted Anterior Lamellar Keratoplasty In Patients With Keratoconus

Objective To analysis and compare the early clinical results of femtosecond laser-assisted deep anterior lamellar keratoplasty,in which more than 75%of the stroma is removed and the femtosecond laser-assisted Descemetic DALK performed with the big bubble technique,in which all of the stroma is removed in the treatment of keratoconus,and evaluate the efficacy?safety and stability of two different surgical treatment to the middle-late stage keratoconus.Methods Retrospective comparative case series.The object of study is 36 eyes of 33 patients that performed femtosecond laser-assisted deep anterior lamellar keratoplasty in Nanjing General Hospital of Nanjing Military Region from April 2012 to August 2014,one eye of one case was lost to follow-up.13 eyes of 13 cases were performed on pre-Descemetic DALK,all the patients are male,which were aged 17 to 35 years old,average age were(22.23±4.62)y;17 eyes of 20 cases were performed on pre-Descemetic DALK,including one female(1 eye,about 6.25%)and 17 males(19eye,about 93.75%),which were aged 15 to 32 years old,average age were(21.62±5.75)y;2 eyes of two patients were failed to performed on Descemetic DALK,and changed to the PK that femtosecond laser-assisted,the incidence was 9.1%.The UCVA,BCVA,refractive status,OCT,corneal curvature,corneal topography,astigmatism,ECD and intraocular pressure were evaluated before and after the implantation.Follow-up time is 6 months.Postoperative examinations were performed at 1 week,1 month,3 month,6 months after the surgery.Results All surgeries were completed successfully.Postoperative all plant slices are transparent,plant and plant bed is just fit.At six month postoperative examination mean BCVA was 0.54 ±0.36 diopters(D)in pre-Descemetic DALK group,Descemetic DALK group was 0.50±0.18D,and there was no statistically significant difference(P>0.05).The mean myopia was(-6.82±3.07)D in pre-Descemetic DALK group and(-1.61±0.81)D in Descemetic DALK group,and there was statistically significant difference(P<0.001).Corneal curvature,corneal topography astigmatism and the central cornea thickness were(44.56±4.86)D,(4.72±2.65)D and(483.40±53.70)?m in pre-Descemetic pre-Descemetic group,and in Descemetic DALK group,they were(40.62±2.96)D,(4.57±3.60)D and(493.0±46.8)?m,and there was no statistically significant difference(P>0.05)in these two groups.Compared with the preoperative,ECD was 2342.81±321.53 per/mm2,and the mean endothelial cell loss was 13.6%in pre-Descemetic DALKgroup;in the Descemetic DALK group the ECD was 2681.22±216.04 per/mm2,and the mean endothelial cell loss was 13.6%,and there was no statistically significant difference(P>0.05).Postoperative intraocular pressure are normal of all patient,and no one appear secondary high intraocular pressure.Two cases of acute keratoconus patients also had successfully performed by Descemetic DALK,and achieve satisfactory visual acuity level after operation during the follow-up.Conclusions There has no significant difference between pre-Descemetic DALK and Descemetic DALK that femtosecond laser-assisted in BCVA.corneal curvature,corneal central thickness,and corneal topography astigmatism,except the mean myopia,and both of the way of the surgery are safe and effective.After the 6 month of observation,the Descemetic DALK is obviously superior to the pre-Descemetic DALK in the mean myopia,and its significance and the long-term curative effect still need us to observe further.