The evidence behind under-eye treatment

three things that look alike.

Most tired-looking under-eyes are one of three things, sometimes in combination.

A hollow: the groove running down and out from the inner corner of the eye, where a ligament tethers the skin to the bone of the eye socket. As the cheek loses support with age, the tissue below the groove drops and the groove deepens and catches shadow.

A bag: fat from inside the eye socket pushing forward, because the membrane that holds it in has weakened. A bag sits above a shadow, not in it.

A dark circle: colour rather than shape. Brown pigment, or blue and purple vessels showing through thin skin.

A simple test is overhead light. A hollow casts a shadow below the lid in any overhead light. A bag bulges, with the shadow beneath the bulge. Pigment stays the same colour whatever the light does. In practice many people have more than one, which is why the assessment is most of the work.

filler for the hollow.

Hyaluronic acid filler placed deep, onto the bone beneath the groove, is the most studied treatment for the under-eye hollow. A 2023 meta-analysis in Aesthetic Plastic Surgery pooled 31 reports with 2,556 participants and found it an effective way to correct the tear trough. It also gives the side effects patients should expect: swelling and bruising were each reported in roughly 1 in 5 people.

How long it lasts is less settled than most clinics suggest. The literature commonly reports 6 to 12 months. A 2025 retrospective study in the Journal of Clinical and Aesthetic Dermatology followed 155 patients treated over 16 years and found improvement still measurable at 18 months. It is observational rather than a trial, but it matches what imaging studies suggest: hyaluronic acid in this area can persist longer than it appears to. It is one reason to treat conservatively and review before adding more, rather than topping up on a schedule.

the risks.

The under-eye sits close to the arteries that supply the eye, and the skin is the thinnest on the body. Rare but serious complications of facial filler include vascular occlusion, where filler blocks a blood vessel, and in the most serious reported cases, loss of sight. These are rare, and the risk is reduced by deep placement on bone, small volumes and a cannula rather than a needle, although it cannot be removed entirely. Any clinician injecting the under-eye should hold the agent that dissolves hyaluronic acid filler and be trained in using it urgently.

filler for a bag.

Filler placed under a fat bag can camouflage it in some cases, but more often it adds weight to an area that is already too full, and the result looks heavier and puffier. The published evidence for treating bags with filler is mostly case reports. For true fat prolapse, lower eyelid surgery (blepharoplasty) is the treatment with a long track record, done by an oculoplastic or plastic surgeon.

polynucleotides for thin skin.

Where the problem is the skin itself, thin, crepey and showing the vessels beneath, polynucleotides are the better-evidenced injectable. A randomised split-face trial of 27 people compared them with an uncross-linked hyaluronic acid under the eyes; both sides improved in elasticity and skin tone. A prospective study published in 2026 followed patients for 6 months after polynucleotide treatment for under-eye lines and found sustained improvement on a validated patient questionnaire. The studies are small, but consistent. Polynucleotides improve the skin over a hollow; they don't fill it, and they are often used before or alongside filler.

pigment.

Pigmented dark circles respond to sunscreen, skincare that targets pigment, and in some cases peels or laser, which are dermatology treatments. No injectable changes pigment, which is a common reason for disappointment after under-eye filler elsewhere.

what the evidence adds up to.

For a true hollow, hyaluronic acid filler has good evidence, predictable side effects and a longer duration than often quoted. For thin under-eye skin, polynucleotides have smaller but consistent evidence. For bags, surgery has the evidence and filler mostly doesn't. For pigment, the answer is not an injection at all. Most people who look tired under the eyes have a combination, which is why a common plan uses polynucleotides in the tear troughs whilst considering the surrounding volume replacement needs. Where surgery is the more appropriate option, this will be explained at consultation, and we can refer you onwards.

Under-eye hollows · Tear trough filler · Polynucleotides