The purpose of this study was to evaluate the structural and functional effects of systemic oxygen therapy and enalapril in patients with diabetic macular ischemia (DMI). This randomized clinical trial consisted of 105 eyes with DMI divided into three groups. Group I received systemic oxygen by face mask at a flow rate of 10 L/min; Group II received 5 mg enalapril daily; and Group III received placebo tablets for 3 months. Best-corrected visual acuity (BCVA), central macular thickness (CMT) measured by optical coherence tomography (OCT), extent of foveal avascular zone (FAZ) on fluorescein angiograms, and electroretinograms (ERG) were obtained at baseline and after 3 and 6 months. Overall, 102 patients completed the study. Baseline characteristics were not significantly different among groups. Significant improvement in BCVA and decrease in CMT and FAZ occurred at months 3 and 6 in oxygen group compared to deterioration in enalapril and control groups (All P values <0.001). ERG parameters were significantly better in oxygen group compared to enalapril group at months 3 and 6 and better than those in control group at month 3. Normobaric oxygen therapy for 3 months in DMI decreased CMT and FAZ and improved BCVA and ERG parameters. Enalapril did not show any favorable effect.
Keywords: Diabetic macular ischemia; Enalapril; Ischemic maculopathy; Oxygen therapy.