Femtosecond laser FLEx surgery — first experience of application

ABSTRACT Purpose. A comparative estimation of the thickness of corneal flap formed with Moria microkeratome and VisuMax femtosecond laser as well as refraction, visual acuity, changes of contrast sensitivity and higher order aberrations after LASIK and FLEx for myopia and myopic astigmatism correction. Material and methods. Two groups of patients, 70 eyes in each were investigated. In the group 1 the standard LASIK was performed. In the group 2 the FLEx was carried out. Besides standard investigations, in both groups wavefront aberrations were measured before operation and 1 month later in Malacara notation with WASCA aberrometer (Carl Zeiss Meditec, Germany) with a non-medicamentous pupil diameter of 6mm. Flap thickness measurement in the center of the cornea and 1, 2 and 3mm from the center was performed in both groups with the Visante OCT (Carl Zeiss Meditec) in High Resolution Corneal Quad and High Resolution Corneal Single modes. Contrast sensitivity was measured in both groups with CSV-1000 unit (VECTORVISION). Follow-up period was 1 month. Results. Uncorrected visual acuity before surgery in groups 1 and 2 was 0.05±0.07; 0.06±0.02 and made after the operation 0.99±0.05; 0.95±0.09 (p>0.05). Spheric equivalent before surgery in groups 1 and 2 was -4.13±2.08 D; -3.78±1.47 D and after surgery became 0.02±0.16 D; 0.03±0.14 D (p>0.05). Corrected visual acuity before surgery in groups 1 and 2 was 0.98±0.05; 0.99±0.02 and made 0.99±0.07; 0.98±0.04 after surgery (p>0.05). The RMS HO before surgery in groups 1 and 2 was 0.18±0.07 µm, 0.17±0.09 µm and increased after surgery up to 0.37±0.11 µm, 0.29±0.07 µm (p<0.05). Spheric aberration value in groups 1 and 2 before surgery was -0.12±0.19 µm; -0.11±0.15 µm, after surgery it increased negatively in both groups up to -0.53±0.30 µm; -0.24±0.28 µm (p<0.05). Conclusions. 1. Laser femtosecond microkeratome VisuMax allows FLEx without excimer laser. 2. Laser femtosecond microkeratome VisuMax allows a formation of corneal flaps with precisely preset thickness parameters unlike mechanical microkeratome. 3. FLEx provides an improvement of visual acuity up to preoperative best corrected level with restoration of preoperative contrast sensitivity parameters under mesopic conditions at 1 month after the operation