As diabetic retinopathy advances, what do "cotton wool" spots represent?

Cotton wool spots are indicative of localized ischemic events in the retina, specifically representing nerve fiber layer infarctions. These spots are formed due to the accumulation of axoplasmic material within the nerve fiber layer of the retina as a result of occlusion of pre-capillary arterioles, leading to ischemia. As such, they signal underlying diabetic retinopathy progression, where damage to the retinal nerve fibers occurs due to prolonged high blood sugar levels that can impair blood flow.

In contrast, blood vessel proliferation, venous beading, and retinal hemorrhage represent different processes in the spectrum of diabetic retinopathy. Blood vessel proliferation pertains to the growth of new, often abnormal, blood vessels which can leak and lead to more serious complications. Venous beading refers to changes in the structure of retinal veins that can occur as the condition worsens, and retinal hemorrhages involve bleeding into the retina due to ruptured vessels, which is another manifestation of vascular complications. Understanding cotton wool spots as nerve fiber layer infarctions helps delineate their role in the pathophysiology of diabetic retinopathy and recognize their clinical significance in monitoring eye health in diabetic patients.