to assess the efficacy and advantages of femtosecond laser enabled keratoplasty ( flek ) over conventional penetrating keratoplasty ( pkp ) in advanced keratoconus . detailed review of literature of published randomized controlled trials of operative techniques in pkp and flek . flek was found to have better outcome in view of better and earlier stabilization uncorrected visual acuity ( ucva ) , best corrected visual acuity ( bcva ) , and better refractive outcomes with low astigmatism as compared with conventional pkp . wound healing also was noticed to be earlier , enabling early suture removal in flek . studies relating to flek have shown better results than conventional pkp , however further studies are needed to assess the safety and intraoperative complications of the procedure . with the use of proprietary software , femtosecond lasers are currently able to create precise corneal incisions in almost any plane while minimally distorting corneal tissue . the flek edges provide a smooth anterior transition between donor and host , which allows for a watertight wound seal . same sized donor and graft improved natural alignment intrinsically and produces less optical distortion that , combined with a watertight seal and less suture tension , results in lesser amount of induced astigmatism . further , there may be a rapid resolution of wound edema in the femtosecond group owing to less tissue manipulation and trauma as compared with conventional trephination . we noticed a similar trend in our study where there was early stabilization of bcva , low astigmatism , and minimal wound edema on the 1 postoperative day with a better ucva as compared to conventional pkp . fibrosis along incisions and suture tracks indicating wound healing , was evident by 3 months in all patients and appeared stronger than typically seen after standard pkp in patients of similar age and diagnoses . in our experience , anterior segment optical coherence tomography ( as - oct ) images taken at 3 months postsurgery showed good fibrosis along the graft host junction [ fig . 4 ] . as - oct image of a patient who has undergone flek at 3 months postop showing good scarring and approximation at the interface busin first described the novel wound configuration described as top hat  for pkp , theoretically providing better resistance against leakage attributable to the self - sealing posterior lip . sutures therefore would not need to be as tight , which might reduce initial suture - induced astigmatism . complete suture removal has been reported as early as the 3 postoperative month , potentially permitting rapid visual rehabilitation as compared with traditional pkp . steinert et al . , recently described a series of patients who underwent flek , a low mean cylindrical refractive error of 1.97 d was achieved in seven patients at 3 months . wound integrity of one patient was maintained even with early suture breakage and complete removal at 3 months . price in his study showed that when the donor and recipient posterior diameters were sized the same , the posterior brim , was observed to buckle with suture placement . however , by the 3 month , all cases exhibited good apposition of posterior donor and recipient tissue with no evidence of posterior buckling . when the donor posterior diameter was undersized relative to the recipient , although the posterior donor tissue was well - opposed to the recipient , a slight gap developed between the posterior rim of the donor and recipient as the wound healed and suture tension relaxed . we would advocate using same diameter of the donor and recipient graft as this has shown to provide good visual as well as biomechanical outcome . long - term benefits of femtosecond laser keratoplasty and cost - to - benefit ratio for patients needing corneal transplantation remain to be determined . potential risks with greater donor manipulation and risks of perforation with hypotony and choroidal hemorrhage during transport from laser suite to the operating room remain theoretical at this point . femtosecond laser reliably trephines donor corneas and recipient beds for pkp , providing good visual outcomes . better optimization of laser parameters for different degrees of corneal opacity and edema would increase ease of surgery and possibly improve outcomes . although both conventional and alternate trephine profiles such as mushroom pattern , top hat , and zigzag configurations seem to provide good results with low astigmatism , further studies with new trephine patterns may better define the advantages associated with femtosecond laser assisted pkp .
purpose : to assess the efficacy and advantages of femtosecond laser enabled keratoplasty ( flek ) over conventional penetrating keratoplasty ( pkp ) in advanced keratoconus.materials and methods : detailed review of literature of published randomized controlled trials of operative techniques in pkp and flek.results:fifteen studies were identified , analyzed , and compared with our outcome . 
 flek was found to have better outcome in view of better and earlier stabilization uncorrected visual acuity ( ucva ) , best corrected visual acuity ( bcva ) , and better refractive outcomes with low astigmatism as compared with conventional pkp . 
 wound healing also was noticed to be earlier , enabling early suture removal in flek.conclusions:studies relating to flek have shown better results than conventional pkp , however further studies are needed to assess the safety and intraoperative complications of the procedure .