Oxygen therapy in ophthalmology: a review of the literature and preliminary exploration of its efficacy in treating ocular ischemia
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BACKGROUND: Oxygen therapy has been widely used for a variety of systemic conditions. The ischemic basis of many ocular conditions provides a basis for oxygen’s application in this area as well. REVIEW: Literature was reviewed to evaluate the efficacy of oxygen therapy in treating inner retinal ischemia (diabetic retinopathy, vein occlusions, artery occlusions, and radiation retinopathy), outer retinal ischemia (retinal detachment, macular holes, and macular degeneration), nerve ischemia (ischemic optic neuropathy, diabetic papillopathy, and ischemic third nerve palsy), and ocular ischemia (ocular ischemic syndrome and retinopathy of prematurity). Published studies support the use of oxygen for a range of ocular conditions including diabetic retinopathy, retinal detachments, and macular holes. For other conditions where autoregulation may limit flow during hyperoxia, isocapnic hyperoxia provides a method to circumvent these limitations. METHODS: One radiation retinopathy patient received a three-hour normobaric hyperoxia trial. Oxygen was delivered by an oxygen concentrator through a face mask at a rate of five liters per minute. Early Treatment Diabetic Retinopathy Study (ETDRS) visual acuity, contrast sensitivity, intraocular pressure, and optical coherence tomography testing were obtained immediately preceding and following the trial to determine any changes. RESULTS: The results show slightly improved ETDRS visual acuity and contrast sensitivity score. Retinal edema in the area of greatest thickness showed a decrease of 3.1%, a larger change than would be expected in a healthy, control eye. CONCLUSIONS: The results of the three-hour normobaric hyperoxia trial suggest that oxygen is effective in reducing retinal edema. Visual acuity was not impacted as greatly, but that may be a result of the specific presentation of this radiation retinopathy patient.