Optimal parameters to improve the interface quality of the flap bed in femtosecond laser-assisted laser in situ keratomileusis.
OBJECTIVE
To analyze the interface quality of the anterior stroma after femtosecond laser flap creation using atomic force microscopy.


METHODS
IRCCS Fondazione G.B. Bietti, Rome, Italy.


METHODS
Experimental study.


METHODS
A 110 μm depth flap was created in 20 human corneal tissues using a femtosecond laser platform (Intralase iFS). Tissues were divided into 4 groups of various cutting parameters: pulse energy and spot separation of 0.75 μJ and 6 μm (Group 1), 0.65 μJ and 5 μm (Group 2), 0.55 μJ and 4 μm (Group 3), and 0.45 μJ and 4 μm (Group 4). Four additional tissue sections were cut using a motorized microkeratome (Hansatome). Atomic force microscopy (Autoprobe CP) analysis was performed on the stromal bed of each sample.


RESULTS
The corneal tissues treated with higher pulse energies and wider spot separations (Groups 1 and 2) showed a rougher stromal bed interface (root mean square [RMS] rough = 0.23 μm ± 0.008 (SD) and 0.24 ± 0.009 μm, respectively) than tissues in Groups 3 and 4 (RMS rough = 0.18 ± 0.006 μm and 0.18 ± 0.008 μm, respectively; P<.001, 1-way analysis of variance). The stromal surface quality of tissues treated with pulse energies of 0.55 μJ or lower and 4 μm spot separation compared favorably with that of tissues cut by the microkeratome (RMS rough = 0.17 ± 0.006 μm; P>.05, Tukey).


CONCLUSIONS
The femtosecond stromal interface quality was improved with pulse energy lower and spot separations narrower than those currently used in the clinical setting. The flap interface smoothness created by the femtosecond laser was comparable to that created by the microkeratome.


BACKGROUND
No author has a financial or proprietary interest in any material or method mentioned.
IRCCS Fondazione G.B. Bietti, Rome, Italy. serrao@serraolaser.it
Sebastiano
S
Serrao
Lucio
L
Buratto
Giuseppe
G
Lombardo
Maria P
MP
De Santo
Pietro
P
Ducoli
Marco
M
Lombardo
D000368:Aged; D003319:Corneal Stroma / Q000473:pathology* / Q000601:surgery; D006801:Humans; D020731:Keratomileusis, Laser In Situ; D054018:Lasers, Excimer / Q000627:therapeutic use*; D018625:Microscopy, Atomic Force; D008954:Models, Biological; D013499:Surface Properties; D013524:Surgical Flaps / Q000473:pathology*; D014019:Tissue Donors