Here we report a case of a 29-year-old myopic female who underwent femtosecond laser-assisted in situ keratomileusis (LASIK) and, on the first postoperative day slit-lamp examination revealed a dense, white, granular reaction with the presence of some blood droplets (stage I diffuse lamellar keratitis [DLK]) in her left eye, specifically localized into the femtosecond LASIK flap tunnel (not extended to the flap interface). The patient received intensive treatment with topical corticosteroids and 5 days later the granular reaction had completely resolved. A new site of DLK, ie, the flap tunnel, in femtosecond-assisted LASIK is presented. DLK into the flap tunnel could be managed with corticosteroids if detected early, without affecting the flap interface.