A 68-year-old man with senile cataract underwent femtosecond laser-assisted cataract surgery (FLACS) in his left eye. Only anterior capsulotomy and lens fragmentation were planned with a femtosecond laser. Docking of the patient interface and anterior capsulotomy were completed without any complications. During the lens fragmentation process, the patient could not resist the temptation to squeeze his eyes shut, which caused excessive pressure from the eyelids. As the procedure proceeded, a bubble was formed at the edge of the patient interface and became increasingly larger. In addition, wrinkles in the conjunctiva were observed. As the lens fragmentation was approaching the final stage, the surgeon was reluctant to release the foot pedal to stop the laser emission. Finally, the patient interface lost adhesion to the cornea. Owing to the high repetition rate of the laser, the laser beam slipped into the corneal layers. Under an operating microscope, a grid-pattern laser beam trace was observed in the peripheral part of the cornea. As posterior capsule rupture occurred during the lens removal process, IOL insertion was no longer a suitable option. Therefore, scleral fixation of the implanted intraocular lens was performed without any unexpected events. One year postoperatively, the laser beam trace in the corneal layers could still be identified by slit-lamp examination. Nonetheless, since the laser beam trace was limited to the peripheral part of the cornea, and there was no damage to the central cornea, the visual acuity was 20/20. FLACS has significant benefits, especially in challenging cases of cataract surgery, and has well-established built-in safeguards for complications. However, this case study indicates the possibility of a suction break during laser emission and the preoperative risk factors. It demonstrates that recognizing the signs of suction break is necessary to avoid misplacement of the laser beam on the corneal layers.