The present invention relates to the treatment of ischemic diseases, and more particularly, to treatment of diabetic retinopathy and ischemia of the retinal and choroidal tissues. The treatment, which will work in vitrectomized eyes as well as non-vitrectomized eyes, is based on selective and fractional electrolysis of the vitreous humor to produce oxygen and optionally active chlorine while simultaneously controlling pH. Oxygen or active chlorine can suppress or reverse the onset of diabetic retinopathy, other retinovascular diseases, and choroidal neovascularization.