Rejuran I (Rejuran eye) in Singapore:
polynucleotide for the under-eye, and how it differs from tear trough filler

What is Rejuran I, and why is it different from Rejuran Healer?

Rejuran I is the periorbital preparation in the Rejuran range. The material is the same polynucleotide, long chains of nucleotides purified from salmon DNA, filtered and sterilised so that what is injected is the polymer and not genetic information. What differs is viscosity. The lower-eyelid skin is among the thinnest on the body, and a mid-viscosity gel placed there sits visibly for longer and is more likely to leave a lump; Rejuran I is formulated thinner so that it spreads in that fragile dermis.

The intention is the same as for Rejuran Healer on the rest of the face: a signal to the dermis to repair rather than a material that holds a shape. Polynucleotides influence fibroblast activity and matrix turnover and signal through adenosine A2A receptor pathways; recent prospective work on periorbital lines describes gradual change in fine lines and skin texture over the months after injection, and a 2026 review comparing hyaluronic acid fillers with polynucleotides for the under-eye frames them as answers to different problems rather than rivals.

Rejuran I vs tear trough filler: which under-eye problem does each address?

The under-eye is where the most money is wasted on the wrong treatment, because four different problems look alike in the mirror. Rejuran I addresses one of them.

Tear trough filler is covered in the owner guide to under-eye filler in Singapore, and the three types of dark circle, with the stretch test and light test used to tell them apart, on the dark eye circle treatment page. Many under-eyes have two findings at once, and then the plan is two decisions, not one syringe.

“Under the eye I treat the finding, not the request. If the problem is a shadow from a hollow, a polynucleotide will not touch it; if the problem is crepey skin, more filler will make it worse. Telling the two apart is the whole consultation.”

Dr Sin YongOn Rejuran I polynucleotide injection for the under-eye

Who does Rejuran I suit?

The person Rejuran I is planned for has under-eye skin that creases finely when they smile and stays lined at rest, looks crepey in side-light, or has thinned enough that a blue-violet tint shows through, and whose rim is not markedly hollow. It is often the right first step in a younger face with early lines, in a face that has been told it needs filler but has little hollow on examination, and in skin that has already had tear trough filler and now needs the skin over it supported rather than more volume beneath.

It is not a filler alternative for someone whose complaint is a shadow. And it is not for everyone:

• Fish allergy is asked about directly, because the material is fish-derived.
• Pregnancy and breastfeeding: treatment is deferred.
• Active infection, eczema or dermatitis of the eyelid skin: settled first.
• Blood-thinning medication and a bleeding tendency are discussed, since bruising is more likely here.
• Anyone with a true bag or a marked hollow is told what will and will not change, and is referred where surgery is the honest answer.

What Rejuran I cannot do for eye bags and hollows

An eye bag is a bulge of orbital fat that has pushed forward past a weakened septum, or sometimes fluid pooled over the cheekbone. A polynucleotide signals the dermis above the bag to repair; it does nothing to the fat behind it, and the bag will look the same once the papules have settled. The causes of eye bags are set out on their own page, and eye bag removal describes when a surgical opinion is the right next step.

A hollow is the opposite problem: missing support between the lid and the cheek, casting a shadow that deepens under overhead light. Rejuran I adds no volume, so a hollow is unchanged by it. Where the hollow is real and the skin is thick enough to cover a small volume, soft hyaluronic acid placed deep on the bone is the treatment, and Dr Sin Yong images any earlier filler with ultrasound before adding any, because the tear trough is the least forgiving area on the face for over-filling. Where filler is already the cause of puffiness, the first step is dissolving, not adding, as explained under tear trough refinement.

What a Rejuran I visit involves

Examination comes first. Dr Sin Yong looks at the under-eye in frontal and overhead light, stretches the skin gently to see whether the colour moves with it, and checks for a bag by asking the person to look up. If filler has been placed before, it is imaged with ultrasound. The decision that follows is whether the problem is skin, structure, pigment or fat, and whether a polynucleotide has a part in it at all.

Topical anaesthetic is applied. The thinner preparation is then placed in the dermis of the lower lid and the upper cheek junction as a series of very small, closely spaced intradermal deposits by fine needle, staying superficial and away from the orbital rim vessels. Each point raises a tiny papule. Because the eyelid skin is thin, the papules and any bruising are more visible here than elsewhere on the face, and a cool compress is applied before leaving. Dr Sin Yong performs the injections personally after in-person assessment; the plan and any intervals are set at review.

Aftercare after Rejuran I

For the first evening, avoid make-up over the treated skin, rubbing the eyes, heat, alcohol and vigorous exercise; sleeping with the head slightly raised limits swelling. The papules flatten as the material is taken up and bruising, if it appears, fades on its own; concealer can be used once the skin is intact. Sun protection is resumed as soon as the skin allows, because the under-eye pigments readily after any inflammation. The general guidance for injected boosters is on the skin booster aftercare page.

Not for waiting: a change in vision or eye pain, call 995 now; pale, dusky or mottled skin, or pain that is getting worse, urgent assessment by the doctor who injected you, or at A&E, now; spreading redness or warmth, or swelling that does not subside, a doctor the same day (A&E if no doctor can see you today); a lump that persists once the papules are gone, have it scanned. Nodules are uncommon but more visible here than elsewhere, which is why the thinner preparation and a superficial, small-volume technique are used.