Hard exudates are refractile, yellowish deposits with sharp margins composed of fat-laden macrophages and serum lipids. Occasionally the lipid deposits form a partial or complete ring (called a circinate ring) around the leaking area of pathology. If the lipid leakage is located near the fovea, a spoke or star-type distribution of the hard exudates may be seen.
Cotton wool spots, or soft “exudates,” are actually microinfarctions of the retinal nerve fiber layer, and appear white with soft or fuzzy edges.
Inflammatory exudates are secondary to retinal or chorioretinal inflammation.
Hard exudation and cotton wool spots are associated with vascular diseases such as diabetes mellitus, hypertension, and collagen vascular diseases but can be seen with papilledema and other intrinsic ocular conditions. Inflammatory exudates are seen in patients with such diseases as sarcoidosis and toxoplasmosis.
Hard Exudates. Collection of yellow lipid deposits with sharp margins are seen. Also seen are dot-blot hemorrhages and copper wiring, which are more typical in diabetes mellitus and hypertension, respectively. (Photo contributor: Jeffrey Goshe, MD.)
Management and Disposition
Routine referral for ophthalmologic and medical workup is appropriate.
Hard exudates that are intraretinal may easily be confused with drusen occurring near Bruch membrane, which separates the retina from the choroid.
Cotton Wool Spots. White lesions with fuzzy margins, seen here approximately one-fifth to one-fourth disk diameter in size. Orientation of cotton wool spots generally follows the curvilinear arrangement of the nerve fiber layer. Intraretinal hemorrhages and intraretinal vascular abnormalities are also present. (Photo contributor: Richard E. Wyszynski, MD.)