Fifty eyes of fifty patients with age range 20-38 years, with myopic astigmatism refractive errors, ranged from -2 to- 6 DS and from -1 to -3.00DC, with stable refraction for at least one year before the surgery, normal corneal topography, anterior and posterior segments examinations. Refractive surgery was planned for both eyes and they chose the Visumax Femto-LASIK after a complete explanation of all the possible complications, costs, and differences. The right eye of each patient was taken for analysis, LASIK flap thickness was measured six months after the procedures using the anterior segment OCT, at seven points (one central and 3 points at each side of the horizontal meridian). The three nasal points were located (1mm, 2mm, 3mm respectively) from the center, and the remaining three temporal points located again ( 1mm, 2mm, 3mm) from the center.

Fifty eyes of fifty patients with age range 20-38 years, with myopic astigmatism refractive errors, ranged from -2 to- 6 DS and from -1 to -3.00DC, with stable refraction for at least one year before the surgery, normal corneal topography, anterior and posterior segments examinations. They chose LASIK with mechanical SBK microkeratome surgical approach to be their refractive surgery for both eyes after all the possible complications, costs and differences had been explained clearly. The right eye of each patient was taken for analysis, LASIK flap thickness was measured six months after the procedures using the anterior segment OCT, at seven points (one central and 3 points at each side of the horizontal meridian). The three nasal points were located (1mm, 2mm, 3mm respectively) from the center, and the remaining three temporal points located again ( 1mm, 2mm, 3mm) from the center.

Under topical anesthesia [Tetracaine eye drop 0.5%]. A-90 µm thick flap was done by using Visumax femtosecond laser. The flap hinge was set to be nasally placed. A nasal-hinge flap with 90 µm thickness, 8.8 mm flap diameter, and 90º side cut angles were created with 500 kHz Visumax FSL, 160 nJ energy [Carl Zeiss, Meditec, Germany]. The sphero- cylindrical refractive corrections with optical zone 6.5 mm and ablation zone 8.0 mm were done by excimer laser operating system [Carl Zeiss, Meditec, MEL 90, Germany]. Automatic iris registration and pupil-tracking system were activated before photoablation. The patient's eyes were examined postoperatively on a slit-lamp biomicroscope and all treatments that were given for home use have been explained in terms of frequency of instillation, possible side effects, and benefits before discharging them on the same day.

Follow up visits were scheduled clearly on printed patients' discharging cards.

The lasik flap thickness in the right eye in both groups were measured six months after the procedures using non touch method by anterior segment OCT without instillation of topical anaesthesia, at seven points in each eye (one central and 3 points at each sides of horizontal meridian).The three nasal points were located (1mm, 2mm, 3mm respectively) from the center and remaining three temporal points located again ( 1mm, 2mm, 3mm) from the center. Data from both groups were comparing to evaluate predictability and variability of the flap thickness.