Other Retinal Vascular Diseases

Retina has the highest metabolic activity in the human body and consumes a much higher amount of oxygen and nutrients per weight than any other organ. Its oxygen consumption is several folds greater than that of the central nervous system. The main reason for high oxygen demand is to fuel ionic pumps that continuously move positively charged electrolytes out of photoreceptors in the dark. This high oxygen demand gives rise to two separate vascular networks: retinal and choroidal. The presumed reason for such a privileged oxygen supply is the evolutionary need of vision for survival. Retina is highly sensitive to systemic vascular events that block the supply of oxygen and other nutrients, despite the fact that it has approximately 100 times more photoreceptors than are required for seeing. Thus, systemic vasculopathies that may alter retinal blood flow, such as hypertension, atherosclerosis, and diabetes, almost always constitute a risk for retinal dysfunction.