Purpose:

Although Femto assisted LASIK is the most common keratorefractive procedures in the world however femto flap parameters including depth, size and side cut angle can be variable between refractive surgeons. We have reviewed 22500 LASIK procedures to compare these parameters for common flap related complications and produce a recommendation

Methods:

This study is retrospective and compares commonly used femto flap parameters for stability and flap related complications across our multiple refractive centres. Most common flap related complications included in this study are Dry eye, DLK (grade 1 to 3), Flap stria (Micro and Macro) as well as traumatic flap displacement All centres were equipped with Femto IntraLase laser and Star 4S IR excimer Laser.They follow unique standard protocol of care and post op follow up and electronic data entry

Results:

We have reviewed 13271 patients with 22525 eyes treated with Femto Intra Last LASIK during the last 8 years. Mean age of 34+/-10 and female to male ratio of48 to 52% .93% myopic vs7 % hyperopic treatments. all used parameters show low complication rate however Long term dry eye (>6months)was significantly higher with flap size of 9.0mm compare to 9.2mm and higher with side of 120' compare to 90' Flap microstria and DLK Gare 1&2 was higher with flap side cut of 120' compare to 9.0 ' Flap microstria and DLK gare 3 was higher with flap 9.0mm compare to 9.2mm no significant differences was noticed between flap thickness of 100 to 110 microns.

Conclusions:

This study reveals low complications for all routine femto flap procedures however the most optimised flap diameter for Femto assisted LASIK procedure was with flap dept of 110 micron, 9.2 mm size and side cut angle of 90 '. Although recommended but other cofactors such as cornea diameter, ablation profile and zone, RSB should be considered.