Intraoperative Online Pachymetry As A Safety Tool In Laser Flap Based Refractive Surgery

To assess the efficacy and safety of the intraoperative online pachymetry tool for creation of femtolaser created Lasik flaps of uniform thickness 

1000 eyes with moderate myopia/myopic astigmatism (-2 to -7 Sph/ -0.5 to -1.5 cyl ) were operated with ESIRIS Schwind laser linked with the online pachymetry and created Lasik flaps with femtolaser over a period of 10 months from Feb 22 to Nov 23. 

Before the creation of the flap, the online pachymetry tool noted the thickness of the cornea. The flap was created with the femtolaser with a thickness of either 90 micron or 110 micron depending on the preoperative pachymetry. Single surgeon performed all the cases. The flap created thus was lifted and online pachy reading noted. This reading was subtracted from the one noted before flap creation to get accurate flap thickness. Flap was replaced and postopertaive pachymetry was noted. 750 eyes with 110 micron flap and 250 eyes with 90 micron flap. 

Average flap thickness when creating a 90 micron flap was 90 +/-6 micron and with the 110 micron flap it was 110+/- 5 micron. The variation in flap thickness was minimal between two eyes. 

Online pachymetry is a great safety tool for analysis and assessment of flap thickness in femto lasik flaps. It demonstrates the ability of the femto laser in producing lasik flaps of consistent thickness which ensures accurate results and minimises margin of errors like button holing of flap, irregular flaps especially in patients with steep corneas in high astigmatism where a femtolaser is preferred to produce an evenly thick flap.