The lines under your eyes can be one of several distinct things: fine wrinkles from aging and sun exposure, a natural groove called a tear trough, or a specific crease known as a Dennie-Morgan fold that’s linked to allergies and eczema. Identifying which type you have helps explain why they’re there and what, if anything, you can do about them.
Why Under-Eye Skin Shows Lines So Easily
The skin around your eyes is the thinnest on your entire face. Ultrasound measurements show the dermis (the structural layer of skin) around the eyelid is only about 0.6 mm thick in women and 0.67 mm in men. Compare that to your forehead, where the dermis is roughly 0.86 to 1.17 mm thick, or your cheekbone area at 0.87 to 1.14 mm. The under-eye area has nearly half the thickness of these neighboring regions.
That thinness means the skin has less collagen, less elastin, and less of the natural cushioning that keeps other parts of your face smooth. Every time you squint, smile, or rub your eyes, the muscles underneath fold that ultra-thin skin. Over time, those temporary creases become permanent lines. Sun exposure, smoking, and genetics all speed up the process by breaking down what little structural support the skin has.
Fine Lines and Wrinkles From Aging
The most common lines under the eyes are simply wrinkles. They start as faint creases that appear when you smile or squint and gradually become visible even when your face is at rest. This happens because your body produces less collagen and hyaluronic acid (a molecule that holds moisture in skin) as you age. The combination of thinner skin, less hydration, and years of repeated muscle movement creates the crinkling texture many people notice in their late 20s or 30s.
These lines typically fan outward from the corner of the eye (crow’s feet) and run horizontally beneath the lower lid. They tend to look worse when you’re dehydrated, sleep-deprived, or spending a lot of time in the sun without protection. Unlike some of the other under-eye lines described below, aging-related wrinkles are progressive: they deepen over years rather than appearing suddenly.
Tear Troughs: The Hollow Groove
A tear trough is a groove that runs from the inner corner of your eye diagonally downward along the side of your nose. It’s not a wrinkle in the traditional sense. It’s a structural shadow created by the way fat pads, muscle, and bone are arranged beneath your skin. Everyone has some degree of tear trough anatomy, but it becomes more noticeable when the fat pads around the eye shift or shrink with age, a process sometimes called fat pseudo-herniation.
If the lines you see look more like a shadow or valley than a crinkle in the skin, you’re likely seeing your tear trough. These are particularly visible in people with lighter skin, less facial fat, or a naturally deep-set bone structure. They can appear as early as your 20s and have more to do with your facial anatomy than with skin damage.
Dennie-Morgan Folds: The Allergy Connection
If you notice one or two distinct horizontal creases running across the skin just below your lower eyelid, you may have what’s called a Dennie-Morgan fold. These look different from fine wrinkles. They’re defined, symmetrical lines that often appear in childhood and don’t change much with facial expressions.
Dennie-Morgan folds are strongly associated with atopic dermatitis (eczema). In one study evaluating 210 people with an existing eczema diagnosis, 84% had these folds. A pediatric study in India found them in nearly 72% of children with eczema, making them the single most common minor sign of the condition. The folds develop because chronic inflammation and swelling in the lower eyelid skin causes the tissue to crease permanently.
These folds aren’t exclusive to people with eczema, though. A study of children in London found that 25% of white children and 49% of Black children had Dennie-Morgan folds even without an eczema diagnosis, suggesting that skin thickness and pigmentation patterns play a role too. Still, if you have these creases along with dry, itchy skin elsewhere on your body, they may be a clue that eczema or an allergic condition is involved. Eczema affects 15 to 20% of children, and up to 30% of those children also have food allergies, so recognizing these folds can sometimes prompt useful testing.
How to Tell Which Lines You Have
A quick way to distinguish between these types: smile broadly and then relax your face. If the lines appear with the smile and soften when you relax, they’re dynamic wrinkles caused by muscle movement. If they’re visible all the time regardless of expression, they’re either static wrinkles (from accumulated skin damage), tear troughs (structural hollows), or Dennie-Morgan folds.
Tear troughs run diagonally from the inner eye toward the cheek and look like a shadow or indentation. Dennie-Morgan folds run horizontally across the lower lid and look like a defined crease, almost like a second eyelid line. Fine wrinkles tend to appear as multiple small, irregular lines that may fan outward or crisscross beneath the eye.
Skincare Options That Actually Help
For aging-related wrinkles, retinoids are the most studied topical option. A clinical trial of 26 participants using a retinoid eye cream nightly for 12 weeks found a 33% improvement in the appearance of lines and wrinkles, a 37% improvement in skin texture, and a 41% reduction in under-eye darkness. Adding a peptide-rich eye cream in the morning provided additional benefits for texture and puffiness. Importantly, these products were well-tolerated with no irritation, which matters given how sensitive the under-eye area is.
Products containing growth factors, which are proteins that stimulate your skin to produce more collagen, have also shown measurable results in the under-eye area. One study found a 28% improvement in skin texture and a 14% improvement in periorbital wrinkles after six weeks of twice-daily use. Copper peptides work through a similar mechanism, encouraging the skin to rebuild its structural support from within.
Sunscreen is non-negotiable for preventing further damage. UV exposure is the single biggest accelerator of collagen loss in the periorbital area, and the thin skin there is especially vulnerable. A broad-spectrum SPF applied daily does more to prevent new lines than most treatment products do to fix existing ones.
When Lines Are Structural, Not Skin-Deep
If your concern is a tear trough or deep hollow, topical products won’t make a significant difference because the issue isn’t at the skin surface. Tear troughs are caused by volume loss beneath the skin, where fat pads have thinned or shifted. Dermal fillers placed along the trough can restore that lost volume and soften the shadow, though results are temporary and typically last 6 to 12 months.
For Dennie-Morgan folds related to eczema, managing the underlying inflammation is the most effective approach. When eczema flares are controlled and the chronic swelling in the eyelid skin resolves, the folds often become less pronounced, particularly in children whose skin still has significant elasticity. In adults with longstanding folds, the crease may be permanently set into the skin even after eczema is managed.