Femto-flap Versus SBK Flap,Predictability and Variability

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.

Inclusion criteria

• Having refractive errors range from -2 to- 6 DS and from -1 to -3.00DC.
• They have stable refraction for at least one year prior to surgery.
• Normal topography by Placido-Scheimpflug (Sirius, Costruzione Strumenti Oftalmici, Florence, Italia) and normal corneal epithelial map by Anterior segment-OCT system (Optovue Inc, Fremont, California, USA)

Exclusion criteria

• Patient with suspicious topography and or corneal epithelial map.
• Patient with corneal pachymetry below 500µm.
• Patients who have a history of previous ocular surgery or trauma.
• Patient with a current or previous history of herpes simplex or herpes zoster.
• Patient with severe dry eye, diabetes, thyrotoxicosis, and connective tissue diseases.
• Patient with Combined ocular diseases like retinal dystrophy or glaucoma.
• Patient with a history of contact lenses use was meant to stop the use of soft contact lenses for at least 2 weeks or hard type for at least 4 weeks before topography and other investigations were done.
• Patient who refrains from the required follow-up visits; have been excluded from the study.

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