Hyaluronic acid (HA) is a cross-linked gel placed in an emptied fat compartment or a chosen groove. Its advantage is reversibility: hyaluronidase can dissolve HA. Its disadvantage is ischaemia if the wrong plane meets a vessel lumen. This article is not written to frighten; it translates the vascular emphasis on our filler page into patient language.
What the gel corrects — and what it does not
Facial ageing changes bone, ligaments, deep fat and skin together. High-G′ gels are chosen for near-bone projection; low-G′ gels for spread control in superficial grooves and lips. They do not carry descended SMAS upward. Meaningful ptosis is a facelift or neck-lift problem, not a millilitre problem.
High-risk corridors
Arterial anatomy varies, yet some regions are statistically more dangerous:
- Glabella (supratrochlear / supraorbital)
- Nasal dorsum and tip (dorsal nasal, angular)
- Temple (superficial temporal artery)
- Lips (labial arcade)
‘A cannula solves everything’ is false in these zones. A cannula may lower the chance of entering a lumen; it does not zero it. Aspiration is not safety by itself. Real safety is anatomy, slow injection, small aliquots, stopping for symptoms, and hyaluronidase on the tray.
How is occlusion recognised?
Disproportionate pain, blanching, livedo, or delayed capillary refill during or right after treatment is a warning. Visual loss or a field defect is an emergency. ‘Wait and massage’ is not appropriate here. A hyaluronidase protocol should be written in advance.
Delayed nodules may appear weeks to months later; biofilm, product and immune history are examined. Tyndall is the bluish scatter of superficial HA, often discussed in the tear trough.
Why under-eye and nose are not ‘for everyone’
At the lid–cheek junction, malar bags and thin skin raise Tyndall and chronic oedema. Many patients are blepharoplasty or midface-support candidates, not tear-trough gel candidates.
The nose is a high-risk corridor because of the angular and dorsal nasal arteries. It is considered for selected dorsal irregularity, with explicit risk discussion. It is not an alternative to structural rhinoplasty.
Ask in consultation
- Whether the gel is HA and whether the brand is licensed
- Whether hyaluronidase is present in clinic
- Whether the plan is staged or a one-session ‘full face’
- If a surgical indication exists, why filler is proposed first
Permanent silicone and unknown products sit outside this protocol. Prior filler history should not be hidden.
In short
Filler is a proportion tool when measured HA sits in the right compartment. Vascular occlusion is rare, manageable and serious. Safety is anatomy before advertised millilitres.
