you need to be medically fit before joining ICG, you will not be granted leave for LASIK as it is considered a cosmetic surgery
after lasik it takes a minimum of 3 months for your eyes to get back to the required standards. Can take upto 6 months also.
All depends on your eyes and the type of LASIK performed.
I had undergone LASIK by a Dr in Juhu,Mumbai who was aware about the standards required for LASIK for F16 pilots at USAF and not DGCA/IAF.
All his reports after 3 months were approved by IAM and DGCA and had got FIT in class 1 renewal. Although IAM did their own tests also to verify reports.
Hope this helps
and oh.. at the medical they will treat you as any other Defense candidate form NDA or CDS,, Not the leniency you find ,if go and do your Class I medical 
.... so if you wear Glasses. chances are very slim... and the question of Lasik.Of what I have read in "The Indian Airforce Recruitment add" for pilots, is that at least 12 months should have lapsed post the Surgery without any complications..I, guess this will also apply to the coast guard .since the Medicals are carried out by Doctors of the Indian Aiforce. so doing the Surgery 3 months or so before the medical won't help, then again anything could happen,This is India 
