From One Medical Student to Another
The retina is a multi-layered sheet composed of neurons, photoreceptors, and support cells. It is one of the most metabolically active organs in the body, and as a result, it is extremely sensitive to ischemia and nutrient imbalances (Frank 2004). A perfused retina is a happy retina.
The outer one-third of the retina receives its blood supply from the choriocapillaris, a vascular network that lies between the retina and sclera. The inner two-thirds of the retina is supplied by branches of the central retinal artery, which comes from the ophthalmic artery (the first branch off of the internal carotid artery).
The central retinal artery exits out of the optic nerve, and its branches arch temporally both above and below the macula (the sensitive region of the retina responsible for central vision).
Although the exact pathophysiology of diabetic microvascular disease is unknown, hyperglycemia is thought to cause endothelial damage, selective loss of pericytes, and basement membrane thickening, all of which contribute to leaky, incompetent blood vessels