Vision loss

A 42-year-old man presented with acute, painless visual loss and visual field loss in his left eye. The patient travelled to Tibet before the onset of symptoms when he took 1 day to ascend to the high altitude by car. He spent 1 week at a high altitude before descending back, which took him 1 day by car. The complaints began at a low altitude after the end of his journey. The patient had type II diabetes, which was controlled by insulin for 10 years. According to the severity of DR from the patient's description, the left eye was slightly worse than the right eye.