The Stretch Test: How Dermatologists Tell Pigment, Blood Vessels, and Shadow Apart Before Treating Dark Circles

Ask ten people with dark circles what causes them and most will say the same things: bad sleep, screens, genetics. All three can play a role, but they play it through completely different mechanisms, and that distinction decides whether a cream, a laser, or a filler has any chance of working. Clinicians sort under eye darkness into three broad categories: pigmented, vascular, and structural. Most people carry a blend, but one type usually dominates, and identifying it is the single most useful step you can take before spending money on anything.

The fastest way to sort them at home is a simple maneuver dermatologists use in clinic, sometimes called the stretch test. Stand in front of a mirror in bright, even light, look straight ahead, and gently pull the skin below your eye downward and slightly outward with one finger. Watch what the dark area does.

If the darkness moves with the skin and stays just as dark, pigment is the likely driver. Melanin sits in the epidermis and upper dermis, so stretching the skin does not change its color. Pigmented circles tend to be brown or gray brown, are more common in medium to deep skin tones, and often extend slightly beyond the eyelid onto the upper cheek. Causes include genetics, chronic rubbing from allergies or eczema, sun exposure, and post inflammatory pigmentation. This is the one category where topical ingredients have a legitimate mechanism: agents such as azelaic acid, vitamin C, kojic acid, and low strength retinoids interfere with melanin production or speed up its turnover. Sunscreen matters here more than any serum, because ultraviolet light directly stimulates the pigment cells you are trying to quiet.

If the darkness fades or lightens when you stretch the skin, the problem is usually vascular. The lower eyelid skin is among the thinnest on the body, often under one millimeter, and it sits directly over a dense network of veins and capillaries. When that skin is thin or pale, deoxygenated blood shows through as a blue, purple, or maroon tint. Stretching thins the tissue over the vessels differently and shifts the appearance. Vascular circles are the type most affected by sleep, allergies, nasal congestion, and dehydration, because all of these change blood pooling and vessel dilation. This is also the category where caffeine containing eye creams have a plausible, if modest, mechanism: caffeine is a mild vasoconstrictor and can temporarily reduce the visible blood volume. The effect is real but short lived, measured in hours, not weeks. Cold compresses work on the same principle. For durable improvement, treatments that thicken the skin, such as retinoids used consistently over months, or vascular targeted lasers performed by a qualified physician, address the actual anatomy.

If the darkness disappears when you look up, tilt your chin toward the ceiling, or shine light from below, you are probably looking at a shadow, not a color. Structural dark circles are caused by a groove called the tear trough, where the eyelid meets the cheek. As we age, fat pads under the eye can bulge forward while the cheek fat descends and midface bone remodels, deepening that groove. Overhead lighting then casts a shadow into it. No cream can treat a shadow, because there is no pigment or blood to act on. This is the one category where injectable fillers or, in selected cases, lower eyelid surgery have a rational basis: they fill or smooth the groove so light no longer catches it. It is also why so many people are frustrated after months of expensive serums. They were treating a lighting problem with chemistry.

A quick note on blends. Many people, especially with age, have a vascular tint sitting inside a structural hollow, or pigment layered over both. In practice that means combination approaches are common, and it also means managing expectations: fixing one component often reveals the other. Someone who fills a tear trough may still see a faint bluish tone afterward, because the thin skin over the vessels was there all along.

Two myths worth retiring. First, dark circles are not primarily a sleep problem for most people. Poor sleep can worsen vascular circles by promoting fluid retention and vessel dilation, but it does not create pigment or bone structure. Someone with genetically pigmented circles will have them after ten hours of sleep. Second, hemorrhoid cream under the eyes is a persistent internet remedy with a shaky foundation. Older formulations contained a vasoconstrictor that has since been removed from many products, and the remaining ingredients can irritate the delicate periorbital skin.

The practical takeaway: spend thirty seconds with a mirror before you spend anything else. Stretch the skin, change the lighting angle, look up. If the darkness moves, think pigment. If it fades, think vessels. If it vanishes with the light, think shadow. Match the treatment to the mechanism, and if the picture is mixed or you are considering injections or lasers, a board certified dermatologist or oculoplastic specialist can confirm the diagnosis before anything touches your face.

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