Under-eye hollowing is a shadow-producing depression caused by thinning of under-eye fat and cheek tissue.
When substantial volume is lost, filling with a dermal filler is often more appropriate; when the skin itself is thin and its texture deteriorates, improving tissue quality with Rejuran I may be more suitable.
However, if pigmented dark circles coexist, volume correction alone has limitations, so identifying the cause comes first (individual variation applies).
➊What is under-eye hollowing?
Under-eye hollowing occurs when fat and surrounding tissue beneath the eyes thin or change position, making boundaries more prominent and shadow-like.
It can occur naturally with age, but may also become prominent relatively early in people with a lean build or repeated sleep deprivation.
Hollowing can make someone look tired or older than their age, so requests for improvement are common in consultation.
This area has some of the thinnest skin on the face, making even small changes noticeable.
Simply adding volume therefore does not resolve every case; the causes need to be distinguished first.
➋How does under-eye hollowing differ from dark circles?
Under-eye hollowing and dark circles can look similar but often have different causes.
Dark circles appear dark because of deposited pigment or visible vessels, while hollowing is closer to a shadow caused by volume loss.
The two commonly coexist and can be difficult to distinguish by appearance alone.
During examination, we gently stretch the skin to see whether the color lightens and change the lighting angle to assess the shape of the shadow.
Because the approach differs entirely between pigment and volume issues, this distinction is the first step in deciding treatment direction.
➌How do filler and Rejuran I differ?
Under-eye filler physically fills the hollow boundary by placing small amounts into areas where volume has been lost.
For thin, sensitive areas such as beneath the eyes, we mainly use formulations that spread softly through tissue, such as Belotero.
Rejuran I, by contrast—a skin booster using repeated injections of salmon-derived ingredients—is closer to gradually improving the skin's own thickness and texture than replenishing volume.
In other words, filler focuses on immediate volume correction, while Rejuran I focuses more on gradually improving the texture and elasticity of thinned skin.
“If volume is the issue, the direction is filler; if thin skin and texture are the issue, it is Rejuran I.”
➍Which suits me: filler or Rejuran I?
With clear volume loss and deep shadows, immediate improvement is often sought through filler.
If volume loss is not substantial but thin skin, fine lines, and deteriorated texture create shadows, tissue improvement with Rejuran I may be more appropriate.
Both may be needed in some cases.
If volume and texture issues coexist, we may consider restoring volume with filler first, then refining the surface with Rejuran I.
| Category | Filler (Belotero) | Rejuran I |
|---|---|---|
| Main purpose | Volume correction | Improvement of skin tissue |
| When effects are noticed | Immediately after treatment | After several sessions |
| Suitable situation | Deep shadows from hollowing | Thin skin with deteriorated texture |
- ✓ Filler: Focus on immediate volume correction
- ✓ Rejuran I: Focus on skin tissue recovery
- ✓ Both may be needed; choose according to the condition
➎How do swelling and duration differ?
Filler and Rejuran I also differ in recovery pattern and duration.
However, both swelling duration and longevity can vary with skin condition, healing capacity, and metabolism.
| Category | Filler (Belotero) | Rejuran I |
|---|---|---|
| Swelling and bruising | Approximately 2–3 days immediately afterward | Temporary raised swelling, tending to settle within several days |
| Duration | About 6 months to 1 year or longer | Improvements build with repeated treatment |
➏How we distinguish treatment choices
If rapid visible improvement is important and volume loss is clearly apparent, I generally discuss filler first.
If the main concerns are thin skin, fine lines, and changes in color rather than volume, Rejuran I may be more helpful.
The under-eye region has many vessels and thin tissue, so formulation and injection volume must be carefully controlled; I do not recommend excessive filling.
More than necessary can instead create unnatural bulging.
Depending on the condition, combining the two may yield a better result. Rather than choosing one in advance, I recommend considering the cause and degree of hollowing, accompanying dark circles, and skin thickness together (individual variation applies).
“Improving under-eye hollowing is not about one procedure being superior; it is about choosing a method suited to the cause and degree of the hollowing.”
QFrequently asked questions
Under bright light, if gently stretching the skin makes the color lighter, pigmented dark circles may be more likely; if the shadow shape remains, hollowing-related shadow may be more likely.
However, the two often coexist, so an accurate assessment is best made in consultation.
Yes. If volume is lost and the skin is thin with poor texture, treatment may combine filler to restore volume first and Rejuran I afterward to improve surface texture.
Whether combination treatment is appropriate depends on the condition and is decided during examination.
Filler may cause swelling or bruising for approximately 2–3 days immediately afterward. With Rejuran I, temporary raised swelling at injection sites tends to subside within several days.
Recovery speed varies between individuals.
Filler often lasts about 6 months to 1 year or longer, depending on the area and amount used. Rejuran I is administered repeatedly at set intervals to improve tissue quality.
Duration can vary considerably with metabolism and routine care.
First, the under-eye area is inspected; if needed, the skin is gently stretched to assess hollowing, pigment, and thickness together.
After assessment and consultation, filler, Rejuran I, or a combination is selected (individual variation applies).
Improving under-eye hollowing is not only about filling; it can also involve creating conditions for tissue to recover in a way suited to the cause.
Under-eye hollowing is a shadow produced by overlapping volume loss and skin thinning; the appropriate choice between filler and Rejuran I depends on the cause.
If you would like an accurate assessment of whether your under-eye concern is volume loss or skin tissue quality, please visit LUNN Clinic for consultation.
Dr. Park Hyungkwon, Board-Certified Dermatologist and Medical Director, LUNN Clinic
In accordance with Article 56 of the Medical Service Act, please note that side effects can occur. Filler may cause swelling, bruising, inflammation, and pigmentation, and rarely vascular occlusion or skin necrosis. Skin boosters such as Rejuran I may cause injection marks, temporary papules, or nodules.
Treatment and procedure results may vary according to the individual's condition.
This article is intended to provide medical information.
