I have dark circles under my eyes that I'm told can be caused by sinus problems, which I have. Is there anything that actually works to get rid of these dark circles? I have not been able to find an effective treatment for my sinusitis.

J.R.

Dark circles are also called "allergic shiners" due to the fact that they commonly occur in people with allergic rhinitis. "Shiner," in this context, means "black eye." There is a bruised appearance that makes the owner of said shiner appear tired and abused. In a sense, the afflicted individual is tired and abused: She is "beaten up" by her longstanding nasal allergies and/or sinus infections.

Allergic shiners look a bit like bruises, but bruises are different. In a bruise, a few capillaries have been disrupted to the point that blood leaks out into the tissues. This blood cannot return to the circulation. The red blood cells eventually die and "spill their contents," some of which is heme, the pigment that gives blood its red color. Heme is slowly broken down into other compounds, and is eventually completely cleared from the tissues. These other compounds are also pigments; this accounts for the many colors of a bruise.

In an allergic shiner, we are dealing with an altogether different problem: venous congestion. Remember that there are two circulatory systems for blood: The high-pressure arterial system (oxygen-rich blood pumped out from the heart) and the low-pressure venous system (oxygen-depleted blood returning to the heart). Arterial blood is bright red because when heme binds oxygen, the pigment takes on a bright red color. As heme sheds its oxygen, the structure of the pigment changes in subtle ways, leading to a much darker red color. Veins beneath the skin look blue because the light reflected by these dark red vessels is altered by the overlying skin.

Venous circulation is low-pressure; venous blood returns to the heart by fairly passive mechanisms (in contrast to the active function of the heart, which pumps blood at a much higher pressure through the arterial circulation). It doesn't take much to impede the venous circulation. In people with chronic nasal or sinus inflammation, venous blood circulating through tiny vessels in facial skin may have a hard time reaching the larger veins. If you can imagine the swollen tissues of the nasal cavity/sinuses acting as millions of separate tourniquets on these tiny venous channels, you will have a fairly accurate idea of what's going on.

Thus, due to sinus/nasal inflammation, venous blood in the facial vessels is impeded in its return to the heart. This is venous congestion -- "congestion" in the same sense as "traffic congestion." When the small vessels in skin become congested with venous blood, the skin takes on a dusky or bluish hue ... thus producing allergic shiners.

There's no known treatment for allergic shiners. Aggressive treatment of the underlying condition is clearly helpful, but successful treatment does not always cause the shiners to vanish. Unfortunately, the only sure-fire solution to the problem is the artful use of cosmetics.