The Stretch Test: How to Tell If Your Dark Circles Are Pigment, Blood Vessels, or Shadow

Walk into any pharmacy and you will find a wall of eye creams promising to erase dark circles. What the packaging rarely mentions is that "dark circles" is not one condition. Clinicians generally sort them into three categories: pigmented, vascular, and structural. Each has a different mechanism, and each responds to different interventions. A brightening cream built for excess melanin will do nothing for a shadow cast by a hollow tear trough, and no amount of concealer strategy changes the underlying biology. The good news is that you can get a reasonable working answer at home, using two simple maneuvers dermatologists rely on during consultations.

The stretch test. Stand in front of a mirror in daylight or under a bright neutral light. Gently pull the skin under one eye downward and slightly outward with a clean fingertip, then watch what happens to the color. If the darkness fades or disappears when the skin is stretched, the discoloration is likely structural: a shadow created by the contour of the area rather than by anything in the skin itself. Stretching flattens the groove between the lower eyelid and the cheek, called the tear trough, and the shadow vanishes with it. If the darkness stays put and moves with the skin, something in the skin is producing the color, which points toward pigment or blood vessels.

The glass test. To separate those last two, press a clear glass slide, or in a pinch the flat side of a clear phone screen protector, lightly against the area. This is a version of what clinicians call diascopy. Pressure temporarily pushes blood out of the small vessels under the skin. If the darkness lightens noticeably under pressure and returns when you release, the cause is likely vascular: dilated or congested veins and capillaries showing through thin eyelid skin, which is often the thinnest skin on the body at roughly half a millimeter. If the color barely changes under pressure, melanin is the more likely culprit, since pigment sits in the skin itself and cannot be compressed away.

Color offers a second clue, though it is less reliable than the maneuvers. Vascular circles tend to look blue, purple, or reddish, and they often worsen with poor sleep, allergies, nasal congestion, or alcohol, all of which affect blood flow and fluid retention around the orbit. Pigmented circles tend to look brown or tan, follow the shape of the eyelid rather than the tear trough, and frequently appear on both the upper and lower lids. They are more common in people with medium to deep skin tones and often run in families, a pattern sometimes called periorbital hyperpigmentation. Structural shadows shift with lighting: they look dramatic under overhead light and can nearly disappear when light hits the face straight on, which is why they seem worse in bathroom mirrors than in selfies taken near a window.

Why does the distinction matter? Because the effective interventions barely overlap. Pigmented circles respond to the same logic as other hyperpigmentation: daily sunscreen to stop further melanin production, plus ingredients such as azelaic acid, vitamin C, retinoids in eye-appropriate concentrations, or, under medical supervision, prescription lighteners. Rubbing the eyes, a habit common in people with allergies and eczema, drives pigment production through chronic friction, so treating itch is part of treating color. Vascular circles improve when you address the plumbing: managing allergies and nasal congestion, sleeping with the head slightly elevated to reduce overnight pooling, using a cold compress in the morning, and applying caffeine-containing products, which constrict superficial vessels temporarily. Retinoids can help here too, but indirectly, by thickening skin over time so vessels show through less. Structural shadows are the hardest to treat topically, because no cream changes bone or fat position. Options discussed with qualified medical providers include hyaluronic acid filler placed in the tear trough to soften the groove, or, in select cases, surgical repositioning of under-eye fat. Filler in this area carries real risks, including vascular complications, and requires an experienced injector, so it is a decision to make carefully, not a casual add-on.

One honest caveat: many people have a mixed picture, such as a mild tear trough plus vascular show-through, and aging tends to add the structural component over time as fat pads shift and skin thins. The self-exam gives you a starting hypothesis, not a diagnosis. If circles appeared suddenly, affect one side only, or come with swelling, pain, or vision changes, see a physician, since thyroid disease, dermatitis, and other medical conditions can present around the eyes. But for the common, stubborn, gradual kind, two minutes with a mirror can save you months of buying products aimed at a problem you do not have.

Related reading: The Stretch Test: How Clinicians Tell Pigment, Vessels, and Shadow Apart Before Treating Dark Circles.