Femto-flap Versus SBK Flap,Predictability and Variability
Condition: Refractive Errors; Refractive Surgery
MeSH terms: Refractive Errors
Study type: Interventional

Summary: 
      Laser Insitu keratomileusis (LASIK) has become the most popular procedure for refractive
      error correction. Lasik flap creation is the first and critical step during LASIK surgery
      because of its consensual effect on a residual stromal bed, corneal biomechanics, and hence
      the future risk of ectasia⁴.In the current study, we compared the Visumax FSL flap thickness
      predictability, accuracy, and variability with the flap created by single-use Moria SBK
      microkeratome.
    

Detailed description: 
      Flap creation techniques have evolved from the old manual procedure of mechanical
      microkeratome to the automated one with the use of microkeratome and more recently to
      Femto-laser procedure using a variety of machines.

      Authors have reported that the primary vision nearly the same despite the different methods
      of flap creation in the first 6 months post LASER vision correction. Others have reported
      that a thinner flap is associated with better primary vision and refractive outcomes. SBK
      (Sub Bowman Keratomileusis), is a procedure in which the Lasik flap is thinner, and has the
      advantage of leaving a sufficient stromal bed for safer excimer Laser ablation.

      There are five types of femtosecond Laser that were already approved currently for Lasik flap
      creation.

      The Zeiss (Visumax FSL ) which has been used in the current study uses 1043 nm, a repetition
      rate of 500 kHz, and 220-580 femtoseconds pulse duration. Each laser pulse produces
      micro-photo disruption in the tissue, contiguous few microns sized photo disruptions will
      create a continuous cut in the corneal tissue at precise preset position and depth.

      In the current study, the Visumax flap thickness predictability, accuracy, and variability
      were compared with the flap created by a single-use Moria SBK microkeratome.
    

Intervention name(s): Visumax Femto-flap; Sub Bowman's keratomileusis (SBK)-flap
Intervention type(s): Procedure; Procedure
Intervention description(s): 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.; Under topical anesthesia [Tetracaine eye drop 0.5%] .A-90µm flaps done using Maria one use plus SBK mechanical microkeratome with a nasal located hinge. 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 the 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
.
Allocation: Non-Randomized
Intervention model: Parallel Assignment
Masking: Double (Investigator, Outcomes Assessor)
Primary purpose: Treatment
Keywords: Visumax; femtolasik; Sub Bowman keratomileusis(SBK); LASIK