Is it safe to dye eyelashes before LASIK?

Yes you can dye your lashes after LASIK.  Generally after a 4 hour nap the edge of the flap is sealed and mascara or dye will not get under the flap.  It is important to avoid make-up prior to surgery to avoid contamination or particulate matter floating in the tears to implant under the flap.  With that said, as long as the material does not create an infection, generally the debris is inconsequential.