Cotton wool spots

Overview
Cotton wool spots are an abnormal finding on fundoscopic exam of the retina. They appear as puffy white patches on the retina.

Pathophysiology
They are caused by damage to nerve fibers. The nerve fibers are damaged by swelling in the surface layer of the retina. The cause of this swelling is due to the reduced axonal transport (and hence backlog of intracellular products) within the nerves because of the ischaemia.

Common Causes

 * Diabetes
 * Hypertension

Rare Causes

 * HIV
 * Pancreatitis (Purtscher retinopathy)

Treatment
Treatmen of the underlying disease is the mainstay of therapy. In diabetes, cotton wool spots are one of the hallmarks of pre-proliferative retinopathy.