Supplemental Oxygen Improves Diabetic Macular Edema: A Pilot Study

Abstract

Abstract: : Purpose: Diabetic macular edema (DME) is the most common cause of moderate visual disability in working age Americans. The pathogenesis of DME is poorly understood. In this study, we sought to examine the effect of retinal hypoxia in the development and maintenance of DME. Methods: Five patients with chronic DME despite at least 1 focal laser photocoagulation treatment (9 eyes) received 4 liters/minute of inspired oxygen by nasal cannula for 3 months. Best corrected visual acuity (VA) and retinal thickness, assessed by optical coherence tomography (OCT), were measured at baseline, during 3 months of oxygen treatment, and 3 months after stopping oxygen. Results: After three months of oxygen therapy, 9 of 9 eyes with DME at baseline had reduction in thickness of the center of the macula. Foveal thickness above the normal range was reduced by an average of 43.5 % (range 14–100%), excess foveolar thickness was reduced by an average of 42.1% (range 13–100%), and excess macular volume was reduced by an average of 54% (range 35–100%). Statistical analyses suggested that these changes were unlikely to be due to chance (p= 0.0077 by Wilcoxon signed–rank test). Three eyes showed improvement in VA by at least 2 lines, one by slightly less than 2 lines, and 5 eyes showed no change. Three months after discontinuation of oxygen, 5 of the 9 eyes showed increased thickening of the macula compared to when oxygen was discontinued. Conclusions: Supplemental inspired oxygen may decrease macular thickness due to DME, suggesting that retinal hypoxia is involved in the development and maintenance of DME.

Keywords: clinical (human) or epidemiologic studies: treatment/prevention assessment/controlled clinical trials • diabetic retinopathy • hypoxia