We describe the results of early hyperbaric oxygenation combined with nifedipine treatment for central retinal artery occlusion, and explain the results pathophysiologically. We report four cases in which hyperbaric oxygenation therapy was applied in combination with nifedipine, eyeball massage, and glycerol for the treatment of central retinal artery occlusion. In two of the cases in which therapy was started less than 100 minutes after the acute onset of visual loss and one case in which therapy was started during the course of central arterial occlusion, considerable improvement in visual acuity was observed, while in the fourth case in which therapy was started six hours after the acute onset of visual loss, no improvement appeared. We conclude from these results that hyperbaric oxygenation therapy has a beneficial effect on the final visual outcome of central retinal artery occlusion, provided it is applied early enough. Further investigation is needed to fully define the nature and terms of this beneficial effect.