A case of retinal central vein occlusion (CRVO) in a 43-year-old man is presented in which hyperbaric oxygen (HBO2) was used as the only treatment method. CRVO is a relatively common cause of visual loss, with hypertension, diabetes, glaucoma and hypercoagulable conditions identified as risk factors. The patient in this report had none of these risk factors and declined treatments other than hyperbaric oxygen. HBO2 was effective in sustaining the ischemic retina and controlling retinal edema until the retina revascularized and vision stabilized. The initial visual acuity in the left eye was 20/200 (corrected), and after two hyperbaric treatments it was 20/30 (corrected). Following three months of HBO2 treatments the vision stabilized to 20/20 (corrected) in the affected eye. Treatment considerations in using HBO2 as adjunctive therapy for CRVO are early institution of treatment, and continuation of HBO2 until the retinal edema has resolved and vision has stabilized.