Retrobulbar hemorrhage is a rare but serious complication after blepharoplasty, mid-face injury, and treatment of facial bone fractures. The incidence of postoperative retrobulbar hemorrhage is 0.055% with an incidence of associated permanent blindness of 0.005%. A 69-year-old male came to the emergency room with pain on both orbital areas and uncontrolled bleeding after cosmetic lower blepharoplasty performed at a private clinic. He had not been evaluated preoperatively by the private clinic, but we found that he had undergone percutaneous transluminal coronary angioplasty and taken anticoagulants for 10 years. We performed an emergency operation to evacuate the hematoma. However, after surgery, he persistently complained of orbital pain, pressure and diminished visual acuity. Intraocular pressure was increased, and computed tomography demonstrated a retrobulbar hemorrhage with globe displacement. Emergent lateral canthotomy and cantholysis were performed. Intraocular pressure was decreased to 48/30 mm Hg immediately after the operation, falling within the normal range the next day. We recommend three points to minimize loss of vision by retrobulbar hematoma. Firstly, careful preoperative evaluation must be conducted including current medications, underlying diseases and previous history of surgeries. Secondly, cautious postoperative observation is important for the early diagnosis of retrobulbar hematoma. Lastly, immediate treatment is crucial to prevent permanent blindness.