Can I do LASIK ? My cornea thickness is 493-503 micron

The short answer is, it depends. It depends on how strong your prescription is, whether you are nearsighted or farsighted, how regularly shaped your cornea is, your family history of corneal anomalies, and how much risk you are willing to take. Assuming that you are nearsighted, when we perform your LASIK surgery we remove tissue in the center of the cornea in order to correct your prescription. We also create a flap which effectively thins the cornea more. If we thin the cornea to much the concern is that it can bulge similar to if you were to thin one area of a car tire. If the cornea becomes to irregular from the bulging then it could blur your vision even to the point that it may not be completely correctable with contacts or glasses and in a worse case need further surgery including corneal transplantation. An alternative to LASIK which effectively thins the cornea less is PRK (Photorefractive Keratectomy). Your surgeon may discuss PRK or another alternative to LASIK in your situation.   

It is not safe to have LASIK in high prescriptions or where the cornea is too thin. Risk of ectasia (cornea thinning and becoming unstable) is higher when correcting > 6 degrees or in corneas thin than 500 microns.In this particular case I would suggest ICL (implantable contact lens) provided you meet the criteria of this procedure.