Femtosecond laser and microkeratome corneal flaps: comparison of stromal wound healing and inflammation.
OBJECTIVE
To examine early postoperative wound healing in rabbit corneas that had LASIK flaps formed with three different models (15 KHz, 30 KhZ, and 60 KHz) of a femtosecond laser compared with flaps formed with a microkeratome.


METHODS
Thirty-nine rabbit eyes were randomized to receive either no surgery or corneal flaps formed with one of the lasers or the microkeratome. Sixteen eyes also had lamellar cuts with no side cuts with the 30 KHz laser. Animals were sacrificed and corneas processed as frozen sections or fixed for transmission electron microscopy. Frozen sections were evaluated with the TUNEL assay to detect apoptosis, immunocytochemistry for Ki67 to detect cell mitosis, and immunocytochemistry for CD11b to detect mononuclear cells.


RESULTS
Rabbit corneas that had flaps formed with the 15 KHz laser had significantly more stromal cell death, greater stromal cell proliferation, and greater monocyte influx in the central and peripheral comea at 24 hours after surgery than corneas that had flaps formed with the 30 KHz or 60 KHz laser or the microkeratome. Results of the 60 KHz laser and microkeratome were not significantly different for any of the parameters at 24 hours, except for mitotic stromal cells at the flap margin. Transmission electron microscopy revealed that the primary mode of stromal cell death at 24 hours after laser ablation was necrosis.


CONCLUSIONS
Stromal cell necrosis associated with femtosecond laser flap formation likely contributes to greater inflammation after LASIK performed with the femtosecond laser, especially with higher energy levels that result in greater keratocyte cell death.
Netto
Marcelo V
MV
The Cole Eye Institute, Cleveland Clinic, Cleveland, Ohio 44195, USA.
Mohan
Rajiv R
RR
Medeiros
Fabricio W
FW
Dupps
William J
WJ
Sinha
Sunilima
S
Krueger
Ronald R
RR
Stapleton
W Michael
WM
Rayborn
Mary
M
Suto
Chikako
C
Wilson
Steven E
SE
D000818:Animals; D017209:Apoptosis; D039481:CD11b Antigen / Q000378:metabolism; D002452:Cell Count; D003319:Corneal Stroma / Q000378:metabolism / Q000473:pathology*; D005260:Female; D019084:Fluorescent Antibody Technique, Indirect; D020287:In Situ Nick-End Labeling; D007249:Inflammation / Q000378:metabolism / Q000473:pathology; D007634:Keratitis / Q000378:metabolism / Q000473:pathology*; D020731:Keratomileusis, Laser In Situ / Q000379:methods*; D019394:Ki-67 Antigen / Q000378:metabolism; D009336:Necrosis / Q000473:pathology; D011184:Postoperative Period; D011817:Rabbits; D013524:Surgical Flaps / Q000473:pathology*; D014945:Wound Healing
D039481:CD11b Antigen; D019394:Ki-67 Antigen