In contrast, for a LASEK, you would again start with a corneal thickness of 500, but only subtract 100 microns for the ablation, BECAUSE THERE IS NO FLAP. This would leave fully 400 microns of untouched corneal tissue after a LASEK for the same prescription--or 150 microns above the 250 safe limit--or Kleiman Evangelista Lasik Eye Center the amount of extra tissue preserved in LASIK (which was 50 microns in the above example.
If a  microkeratome is used, a ring will be placed on your eye and very high pressures will be applied to create suction to the cornea. Your vision will dim while the suction ring is on and you may feel the pressure and experience some discomfort during this part of the procedure.