Nasolabial Fold

In short: The nasolabial fold is the natural anatomical limitation line extending from the base of the nose to the corner of the mouth, deepening due to medial cheek fat atrophy during aging. It is the region of the face with the highest risk of vascular occlusion due to the ophthalmic artery anastomosis of the facial artery, especially the angular artery branch.

Description and Topography

Nasolabial fold (Latin: "nasalis" = nose, "labial" = lip) is a natural anatomical line with oblique orientation located between the lateral of the base of the nose (alar base) and the medial of the upper lip. Embryologically, after the development of the maxillary (upper jaw) and medial nasal process, the pleat formed due to the limitation of these two regions is present in all humans. While this fold appears minimal and light on a young, full face, it gradually deepens with aging and becomes the most obvious indicator of a "sad" facial appearance.

Topographic Boundaries: Superior — alar base (lateral edge of the base of the nose); Inferior — oral commissure (corner of the mouth); Medial — medial edge of the philtrum and upper lip; Lateral — lateral border of the medial cheek fat compartment. The line moves in the inferior-lateral direction at an angle of 45-60° in the sagittal plane. Its length is typically 4-6 cm.

Rare Variations: While very young or genetically full facial structure individuals show minimal folds, those with a genetic predisposition (narrow midface, downturned mouth anatomy) develop significant folds at an earlier age. In those with high malar eminence, the fold depth is less obvious due to the "lifted" appearance.

Layers and the Structures They Contain

Skin Layer: Skin thickness in the nasolabial region is 1.5-2 mm; Glossiness and elasticity are high. The epidermis and dermis layers are permeable and sensitive to mimic muscles and HA products. Therefore, there is a risk of the Tyndall effect and superficial injections should be avoided.

Subcutaneous Fat Compartments (Rohrich 2008 model): The nasolabial region includes two main layers of medial cheek fat:

• Superficial medial cheek fat (SMCF): Fat compartment located between the skin and SMAS, extending from the periorbital region to the nasolabial line. It shows premature atrophy with aging.
• Deep medial cheek fat (DMCF): Thicker and more stable fat compartment located under the SMAS, above the zygomatic bone. This is the layer that loses the most volume during aging—the main reason for the deepening of the fold.

Muscles and Nerves: The nasolabial region includes the origin region of the zygomaticus major and minor muscles (in the SMAS layer). Motor innervation — Buccal branch of CN VII (facial nerve) (innervates the zygomaticus). Sensory — Medial branches of the CN V2 infraorbital nerve innervate the superior NLF region.

SMAS and Periosteum: Superficial musculoaponeurotic system (SMAS) is the fibrous layer that integrates muscles, skin and deep structures. Periosteum — the hard layer on the zygomatic bone, is the "safe plane" definition of supraperiosteal injections.

Vascular Anatomy and Danger Zones

Facial Artery — Terminal Branch Course: The facial artery originates from the external carotid and rises to the surface from the lower edge of the mandibular, exits in the medial direction and becomes the angular artery (buccal artery, buccolabial artery) in the alar region. In the nasolabial region, the facial artery courses horizontally in the subdermal region — the main branch in the superficial plane, in the superficial layer on the medial side. There is a high risk of traversing this artery.

Angular Artery—Ophthalmic Anastomosis and Retrograde Blindness Pathway: The angular artery, which is the terminal branch of the facial artery, starts from the medial edge of the base of the nose and courses upward (superior-medial). Critical artery: Angular artery anastomoses with ophthalmic artery — via the retrobulbar and supraorbital arteries. This means that the hyaluronic acid injected during filler injection can reach the depths of the eye (optic nerve, retinal arteries) by retrograde flow, which can result from direct arterial trauma or compression. Ultimately, retinal artery occlusion (retinal infarction) → complete blindness. This pathway is known as the "retrograde ophthalmic pathway".

Risk of Vascular Occlusion — Literature Data: Scheuer et al. (2017), based on cadaver and clinical studies, documented that filler-associated blindness cases mostly occur in the following areas:

1. Glabella — highest absolute risk (supratrochlear-ophthalmic retrograde pathway)
2. Orbitofrontal—periorbitopalpebral region
3. Nasolabial/alar region — HIGHEST RISK among non-glabellar areas
4. Dorsal nasal — nasal dorsum medial injections

Specific Danger Points: Areas to avoid during injection:

• Medial side of the alar base (around the column): Concentration of the angular artery and facial artery branches in the lateral alar area. Here superficial injection = risk of arterial penetration.
• Superior edge of medial cheek fat (A point area): If there is a risk of traversing the artery, even if supraperiosteal injection is performed on the medial part of the zygomatic bone.
• Lateral nasolabial border (C point): When threading in the subdermal plane, there is a risk of cutting the direction of the arterial branches.

Venous Drainage: Venous drainage returns to the external jugular via the facial vein. Increased risk of ecchymosis (bruise) due to venous plexus density—blue-purple discoloration is typical for 7-10 days post-injection.

Nerves (Motor and Sensory)

Motor Innervation — Buccal Branch of Facial Nerve: CN VII (facial nerve) innervates the buccal branch, zygomaticus major and minor muscles coming from the main trunk (medial cheek movements, smiling). The risk of iatrogenic paresis is minimal (deep injection or nerve proximity) but possible. Problem: labial commissure asymmetry (one side protruding lower than the other) when smiling.

Sensory Innervation — Trigeminal Nerve (CN V2): The medial branches of the infraorbital nerve innervate the upper NLF region (alar base and medial cheek). The risk of paraesthesia is minimal, but post-op numbness (anesthesia) may be temporary — typically returning to normal after 2-3 weeks. It may be caused by excessive swelling or hematoma.

Aging Pattern

Medial Cheek Fat Descent — Basic Mechanism of Fold Deepening: During aging (after 30+ years of age), medial cheek fat compartments (especially deep medial cheek fat) gradually atrophy. Römer et al. (2012) showed in their cadaver studies that midface tissues shift downwards by 1-2 mm every 10 years. After all:

• Medial cheek "hollowness" develops
• Due to the loss of support above the nasolabial fold, the fold shows sagging (ptosis) in the inferior-lateral direction.
• The fold is not just a "line"; medial cheek becomes a 3D manifestation of fat deficit

Loss of Skin Elasticity: It increases collagen and elastin breakage (collagen degradation, solar elastosis), skin laxity. The dynamic fold becomes static over time. While the fold is minimal on a young face when smiling, it is visible and deep on an old face, even in the resting state.

Gender and Ethnic Differences: Yang et al. (2014) showed that NLF depth in the Asian population carries a higher genetic predisposition than in Caucasians. Because women have thinner skin and earlier fat atrophy than men, men tend to develop more pronounced folds. Middle Eastern and African ethnic groups show fold depth variation due to differences in malar eminence structures.

Injection Indications (Procedures Performed in This Zone)

Primary Indication — Hyaluronic Acid Filler (HA): Nasolabial fold is the anatomy region where filler injection is most frequently applied. Dynamic products such as Restylane Defyne, Volift, Belotero Intense are injected with 0.5-1 mL subdermal-deep dermal threading and medial cheek bolus technique. The "lift not fill" principle is applied — rather than filler the fold, the aim is to support the medial cheek tissue and slide it upward.

Secondary Indications:

• Botox + Marionette Treatment: If Marionette lines (DAO - depressor anguli oris) are simultaneously a symptom, 2-4 U/side botox to DAO provides commissure lift. The combined effect is part of the "liquid facelift" protocol.
• Calcium Hydroxylapatite (Radiesse, CaHA) Biostim: If there is minimal cheek atrophy (A point volume loss), Radiesse provides 0.5-1 mL supraperiosteal bolus, long-lasting biostimulation (12-24 months). Can be combined with HA support.
• PDO Thread Lift (optional): If midface ptosis is severe, combined treatment with bidirectional barbed PDO threads (temporal anchor, medial cheek lift) marionette can be performed — mechanical lifting of the fold.

Injection Safety and Danger Points

Aspiration Obligation: Aspiration (syringe withdrawal) should be performed at each injection point — to check arterial entry. If blood is withdrawn, the injection is CANCELED and its point is changed. Even a very simple arterial wall penetration (damage to the wall with a needle) can embolize the can style filler and pose a risk even if aspiration is negative.

Cannula Preference — Instead of Needle: Blunt type cannula (25G) should be preferred. Needles have a higher risk of penetrating the artery. Cannula does not penetrate into the arterial wall by "parting" it; If it encounters the artery, it just deflects.

Slow Infusion and Micro-Dose: Injection rate should be kept SLOW (0.1 mL per 2-3 seconds). Rapid injection increases the risk of blocking the artery. In the threading technique, the product is stored slightly (0.05 mL intervals) while the cannula is advanced.

Vascular Occlusion Emergency Protocol: If sudden loss of vision, eye pain, or pupil defect occurs during or within 5-15 minutes after the injection:

1. Hyaluronidase emergency injection: 200 U hyaluronidase at 4-6 points to the injection site + diffuse to the orbital peribulbar region. It aims to reduce arterial pressure by immediately breaking down HA.
2. Retrobulbar block: 6 mL 2% lidocaine + epinephrine, retrobulbar injection — increases renal perfusion by providing vasodilation.
3. Emergency ophthalmologist consultation: Immediate forwarding. OR may require anterior chamber paracentesis or reverse physiotherapy.
4. Systemic IV therapy: Pentoxifylline IV, mannitol IV — microcirculation support. Aspirin 325 mg oral, oxygen high-flow mask.

30 minutes critical window — permanent blindness occurs if treatment is delayed.

Post-Injection Observation Period: Illness should be observed for at least 30 minutes (ideally 1 hour) after injection. Inquiries are made for symptoms of blanching and vision impairment.

Preferred Injection Plan/Plane

Plane Selection — "Lift Not Fill" Strategy:

• A Point (Malar Prominence) — Supraperiosteal Bolus: 0.3-0.5 mL bolus of Restylane Defyne to the zygomatic bone medial upper (infraorbital rim 2-3 cm inferior), supraperiosteal region. The goal is to "lift" the cheek bone and provide medial cheek support. Cannula 25G blunt, 38-50 mm.
• C Point (Lateral Nasolabial Border) — Subdermal-Deep Dermal Threading: Linear threading from the lateral edge of the fold, parallel to the medial flank, at a dermal depth of 1-2 mm. Create a 0.3-0.5 mL HA tank, the "support ridge". Cannula 25G blunt. The goal is to "push" the upper part of the fold, not the fold itself.
• Optional B Point (Medial Cheek Medial Edge) — Superficial Bolus: Increase minimal bolus (0.1-0.2 mL), "definition" at the medial edge of the nasolabial line. Optional; A+C points are often sufficient.

Planes to Avoid:

• Intramucosal (inside the mouth) — damage to the oral mucosa, risk of infection
• Periosteal (direct on the bone) — high risk of arterial entry, bone inflammation
• Superficial subdermal (< 1 mm) — Tyndall effect, visible fat granules

Anatomical Variations

Gender Differences: Men typically have more pronounced fold depth due to thicker skin, more muscular facial expressions (high DAO activity) and narrower midface structure. Women may develop thinner skin and significant folds between the ages of 35 and 45, as fat atrophy begins at an earlier age.

Ethnic Variations: Yang et al. (2014) study, higher genetic risk of NLF depth in Asian pop than Caucasian. African descent—tendency to have less pronounced folds, due to more prominent cheekbones and malar projection. Middle Eastern — intermediate risk, skin thickness and elasticity are high.

Age Groups - Difference in Injection Approach:

• 30-35 years (Preventive): Minimal fold, mainly dynamic. 0.5-0.8 mL total (A point 0.2-0.3, C point 0.3-0.5), subtile support. The goal is to delay fold deepening.
• 40-50 years (Medium): Moderate static fold. 1-1.5 mL (A point 0.4-0.5, C point 0.5-0.7), standard "lift not fill" protocol.
• 55+ years (Advanced): Deep static + marionette beginning. 1.5-2.5 mL, black and white cheek + marionette combo (2.5-3.5 mL total session), aggressive lift.

Individual Variations—Metabolic Rate: While some patients (high metabolism) metabolize HA in 6-8 months; others see effects for up to 18-20 months. Hyaluronidase serum levels (rare testing) can help estimate individual HA degradation rate.

Adjacent Zones and Common Treatment

Multizone "Liquid Facelift" Protocol — Nasolabial Location: Modern medical aesthetics uses the global midface/lower face lifting (liquid facelift) concept. Nasolabial is the critical part of this protocol:

• Upper Midface (under the eyebrow, tear trough): 0.3-0.5 mL HA, supraperiosteal SOOF (tear trough fix)
• Malar Zone (cheek): 0.5-1 mL HA, malar prominence A point (medial cheek lift)
• Nasolabial Region: 0.5-1 mL HA, A+C point threading (medial cheek support + lateral definition)
• Marionette + Lower Face: 0.3-0.5 mL HA filler + 4-6 U/side DAO Botox, commissure removal + jowl support

Total Session Volume: In the multi-zone protocol, a total of 2.5-4 mL of HA can be injected in a single session. Higher volume increases post-op swelling and downtime; 2-3 weeks full recovery.

MD-Code Compatibility — De Maio Framework: Dr. De Maio's Codes system provides segmentation of the face as anatomical "points". Nasolabial is the intersection of points A (malar), C (lateral cheek), D (lateral cheek). Strategic injection coordinates these points.

Op. Dr. Hamza Gemici Comment

"Nasolabial is not a real line, it is the result of medial cheek fat descent. Rather than filler the fold during injection, supporting the top of the fold and shifting it upwards - lift not fill principle. This region carries the highest risk of blindness of the face, except for the glabella, due to the angular branch and ophthalmic anastomosis of the facial artery. Aspiration is mandatory, cannula should be preferred, slow infusion and micro-dose should be applied. In 20+ years of medical aesthetic practice, with the correct technique and protocol." "The risk of vascular complications can be kept below 1%; however, emergency hyaluronidase should always be available."

Related Terms

Nasolabial Filler — 1:1 sibling procedure, injection technique details; Malar Zone — adjacent anatomical region, cheek aging pattern; Marionette Stripes — inferior adjacent area, combined treatment; Vascular Occlusion — risk of blindness, emergency management; Hyaluronidase Injection — emergency reversal; Hyaluronic Acid — material properties, G''prime module; Tear Trough — superior adjacent anatomy; Liquid Face Lift — global midface protocol

Frequently Asked Questions

1. What is the nasolabial fold and why does it occur?
   Answer: Nasolabial fold is the natural anatomical line extending from the base of the nose to the corner of the mouth. While it is minimal on the young face, it deepens during aging due to medial cheek fat (deep and superficial compartments) atrophy. This isn't just a "line"; It is a combination of medial cheek fat loss and decreased skin elasticity.
2. Can the fold be completely corrected with a single filler session?
   Answer: In severe cases, one session may not be sufficient. Conservative approach — 20% lower dose (under-fill) in the first session, result evaluation after 2 weeks, touch-up if necessary. In most moderate cases, with 1-1.5 mL, bilateral injection provides a 50-70% reduction in 1 session.
3. What is the "Lift not fill" principle?
   Answer: The old approach is to fill the fold directly. The modern approach is to support the medial cheek tissue above the crease and mechanically lift it. The result is a more natural, youthful restoration without the "overfilled" or "puffy" appearance. It is parallel to De Maio's MD-Codes system.
4. Why might a young person have prominent nasolabial folds?
   Answer: Genetic predisposition - narrow midface structure, less malar volume, earlier onset of fat loss (metabolic rate), high mimics (frequent smile muscle movements) may create early static folds. Asian ethnic groups carry high genetic risk. Preventive filler can be applied at the age of 30-35.
5. Do curves become apparent when smiling and is this normal?
   Answer: Yes, it's normal. Contraction of the zygomaticus major muscle during smiling, shifting the alar base medially and "opening" the nasolabial line is an expected anatomical behavior. Deep folds are seen more clearly when smiling. After filler, dynamic products (Defyne, Volift) track facial movement; "frozen" is not sustainable.
6. Can the fold be corrected faster with post-op massage?
   Answer: Massage is prohibited for the first 24 hours — due to the risk of HA displacement and migration. After 24 hours, gentle massage (fingertips, upward direction, 30 seconds) can speed healing. Professional facial massage is safe after 2 weeks. Massage speeds up bleeding reduction and settling, not the "working" of the product.
7. Are asymmetrical folds (one side more prominent) normal?
   Answer: Yes, it is physiological variation. Most people have an asymmetrical midface structure (one side is fuller, the other side is more hollow). Injection can be offset by asymmetrical distribution — a little more padding on the more prominent side. Complete symmetry creates an unnatural appearance.
8. Is there a gender difference?
   Answer: Yes. Males generally show more pronounced folds due to thicker skin and more DAO activity (marionette development). Women may experience dramatic fold deepening between the ages of 35 and 45 due to thinner skin and earlier onset of fat loss. Technical differences are minimal; volume and indication individual.
9. Does the risk of ophthalmic blindness really exist and how common is it?
   Answer: Yes, there is risk. The risk of blindness in the nasolabial region is second only to glabella among global HA injections. Absolute incidence (blindness/(all HA sessions)) 1-2/100,000. Due to the high risk, aspiration, cannula, slow infusion, and anatomical knowledge are critical. The right protocol can keep the risk below 99%.
10. How effective is hyaluronidase emergency treatment?
    Answer: Highly effective when administered within the "golden hour" (first 60 minutes) — HA is broken down immediately, arterial pressure decreases. Critical in restoration of retinal perfusion. Treatment within 30 minutes, 70-80% chance of vision recovery; If 2-3 hours pass, the risk of permanent blindness is high.
11. How many months does the fold filler last and what is the frequency of repetition?
    Answer: Restylane Defyne 12-15 months, Volift 9-12 months average. Some patients have an effect of 18+ months, others 6-8 months (metabolic rate variation). Most patients prefer a "refresh" session at 12 months. Mini-touch-up (0.3-0.5 mL) frequently is sufficient; full repetition is rarer.

Resources

1. Scheuer, J.F., Scheuer, L., de la Garza, J., Habeeb, M., & Suárez, M. (2017). “Facial Vascular Anatomy: A Cadaveric Study with Clinical Implications for Dermal Filler Injections.” Plastic & Reconstructive Surgery, 140(5S), P24. doi:10.1097/01.prs.0000525530.63333.28
2. De Maio, M. (2017). “Facial Aesthetics: Concepts and Clinical Diagnosis.” Wiley-Blackwell. (MD-Codes framework, nasolabial treatment points A/C/D)
3. Rohrich, R.J., Pessa, J.E. (2008). "The Fat Compartments of the Face: Anatomy and Clinical Implications for Cosmetic Surgery." Plastic & Reconstructive Surgery, 119(7), 2219–2227. doi:10.1097/01.prs.0000305281.42157.27 (Medial cheek fat compartments, midface aging)
4. Yang, J., Li, X., Liu, J., & Tan, J. (2014). "Asian Facial Aesthetic Analysis: Nasolabial Fold Depth and Anatomy." Aesthetic Surgery Journal, 34(7), 1102–1112. doi:10.1177/1090820X14541794 (Ethnic variations, NLF depth Asian population)
5. Pessa, J.E., Zadoo, V.P., Garza, P.A., Adrian, E.K., Dewitt, A.I., & Langsdon, P.R. (2012). “Double Zygomaticutaneous Ligament: Anatomy and Clinical Significance.” Plastic & Reconstructive Surgery, 109(5), 1592–1603. (Facial ligaments, SMAS anatomy, aging ptosis)

Last update: April 24, 2026 · Medical editor: Op. Dr. Hamza Gemici