My corneal thickness is 493 microns and my eye power is -8.00 on both eyes. Will lasik help improve my sight?

Based solely on your corneal thickness and prescription, you would not be a good candidate for LASIK.  The amount of tissue that needs to be ablated with the laser to fully correct for your prescription will be too much and will leave your corneas too thin.  

You may be a
candidate for the Visian ICL procedure. Because of your thin cornea it may be
safer to go with the ICL surgery.

you are at the limit for having a normal cornea, which is 500-550therefore after a LASIK of -8  you would be at the limit of safe afterso you might not be able to get enhancedjust get a LASEK it is 10x safer and then you can get enhanced if nec