ABSTRACT
Femtosecond laser-assisted laser in situ keratomileusis(FS-LASIK)and small incision lenticule extraction(SMILE)are the mainstream corneal refractive surgeries at present. Despite efficacy, safety and predictability they have showed in refractive error correction, there are still complications relating to femtosecond laser, such as suction loss and opaque bubble layer(OBL), due to that the production of corneal flap or lenticule is dependent on the femtosecond laser. OBL is a complication that is unique to femtosecond laser surgery and the bubbles are generated from photo-disruptive effect towards corneal tissues which consisted of water vapor and carbon dioxide, and OBL gradually formed when the bubbles are trapped in the stroma. The bubbles can influence the intraoperative manipulation and postoperative visual quality. This review discusses the mechanism, grading, classification, and influencing factors of OBL and its effects on intraoperative manipulations and postoperative recovery, in the hope of providing reference and basis for further clinical studies.