RESUMO
To determine the predictability of flap thickness in laser in situ keratomileusis [Lasik] using the newly introduced disposable plastic head intended to make 130 micron flaps. To identify relationship of obtained flap thickness with different variables like preoperative corneal thickness, spherical equivalent refraction, mean keratometry, age of the patient and size of the microkeratome ring used during the procedure. Prospective non-comparative interventional case series. Sixty four eyes of thirty six patients underwent laser in situ keratomileusis. In all cases Moria M2 microkeratome with single use 130 micron head was used to create the flap. Manufacturer provided nomogram were used for suction ring selection. Laser ablation was performed with Allegretto Wavelight Eye-Q 400 Htz excimer laser. Central flap thickness was calculated by subtraction pachymetry using DGH-500 pachymeter. The obtained flap thickness was correlated with the age of the patient, preoperative pachymetry, spherical equivalent refraction, mean keratometry, and size of the keratometry ring. Mean flap thickness obtained was 130.7 +/- 27.35 micro m [range 69 to 188 micro m]. Flap thickness directly correlated with preoperative pachymetry [p = 0.001]. There was no correlation between flap thickness and age, mean keratometry, spherical equivalent refraction or the suction ring size. The Moria M2 130 micro m single use head gives flaps with wider standard deviation than previously reported. We recommend that the target flap thickness should be set at 160 micro m for residual bed calculation. In patients with calculated residual stromal bed of less than 275 micro m intra-operative pachymetry should be performed