A 43-year-old man developed acute corneal hydrops after laser in situ keratomileusis (LASIK). A persistently fluid-filled interface between the corneal flap and stroma (without flap dehiscence or wound leakage) did not respond to the conservative treatment. To avoid keratoplasty, the subflap fluid was drained by an air injection into the anterior chamber; the surgery also included suturing of the corneal flap and stroma. The corrected distance visual acuity improved rapidly after resolution of the fluid-filled interface and corneal stromal edema, and no leakage was observed. Thus, a minimally invasive surgery to drain the subflap fluid by an air injection was effective for treating a persistently fluid-filled interface in a case of acute corneal hydrops after LASIK.