Influence of flap thickness on results of laser in situ keratomileusis for myopia.
OBJECTIVE
To study whether flap thickness influences laser in situ keratomileusis (LASIK) results.


METHODS
This comparative, non-randomized, retrospective study comprised 421 LASIK eyes (233 patients) with spherical equivalent refraction between -0.60 and -6.00 diopters (D). Laser in situ keratomileusis was performed with the Moria One manual microkeratome and the Chiron Technolas 217C laser. Depending on the flap thickness, the eyes were divided into three groups (group 1, flap thickness < or =100 microm; group 2, flap thickness > 100 microm and < 130 microm; and group 3, flap thickness > or = 130 pm). For each group uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity, residual spherical equivalent refraction, and keratometric power (D) were measured 1 day, 1 week, 1 month, and 6 months after LASIK. Complications, retreatment, and correlation between flap thickness and preoperative corneal thickness and keratometric power were also analyzed.


RESULTS
One month postoperatively, UCVA was > or = 20/20 in 76% (96 eyes), 56% (79 eyes), and 61% (93 eyes) of eyes in the three group, respectively (P = .015). One month postoperatively, UCVA was > or = 20/25 in 88% (111 eyes), 76% (108 eyes), and 76% (116 eyes) of eyes in the three groups, respectively (P = .015). Complication rate and retreatment rate were not statistically different among the groups. At 6-month follow-up, no statistically significant differences were noted in UCVA between the groups. Significant correlations between flap thickness and preoperative corneal thickness (P < .0001) and between flap thickness and preoperative keratometric power (P < .05) were found.


CONCLUSIONS
Patients with flaps < or = 100 pm had better functional results at 1 month than those with thicker flaps. It may be important to perform LASIK with thin flaps to save corneal tissue in the stromal bed.
Prandi
Barbara
B
Clínica Baviera, Instituto Oftalmológico Europeo, Valencia, Spain. bprandi@clinicabaviera.com
Baviera
Julio
J
Morcillo
Miguel
M
D000293:Adolescent; D000328:Adult; D003319:Corneal Stroma / Q000473:pathology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007431:Intraoperative Complications; D020731:Keratomileusis, Laser In Situ; D008297:Male; D008875:Middle Aged; D009216:Myopia / Q000601:surgery*; D011183:Postoperative Complications; D012086:Reoperation; D012189:Retrospective Studies; D013524:Surgical Flaps / Q000473:pathology*; D016896:Treatment Outcome; D014792:Visual Acuity