Hyaluronic acid fillers

Hyaluronic acid is a molecule found naturally in the skin, joints and eye, with a great capacity to hold water. In aesthetic medicine it is used as an injectable gel to restore lost volume, define features and soften folds. It is the most widely used facial filler in the world.

What it is

It is a polysaccharide that forms part of the matrix supporting the skin. Its amount decreases with age, and the skin loses hydration and volume. Fillers use laboratory-made, cross-linked hyaluronic acid: its chains are bonded together to form a more stable gel, which the body takes months rather than days to reabsorb.

History

It was isolated in 1934 by Karl Meyer and John Palmer from the vitreous humour of cows’ eyes. Its use as a dermal filler developed in the 1990s with the arrival of non-animal gels; the first hyaluronic acid filler was approved in Europe in the mid-1990s and in the United States in 2003. Since then it has almost completely replaced collagen as a facial filler.

Product types

Products differ in concentration, degree of cross-linking, particle size and whether they contain lidocaine (an anaesthetic). Dense, highly cross-linked gels are used in deep planes to add volume and projection (cheekbones, chin, jaw); finer, softer gels are used for superficial lines and lips. The least cross-linked are used to hydrate the skin (skinboosters).

Treatment areas

Lips, tear troughs, cheekbones, chin, jawline, nose (non-surgical rhinoplasty), nasolabial folds, marionette lines, smoker’s lines and frown lines, among others.

Complications

The most common are mild: swelling, bruising and tenderness. Others include nodules, a bluish tint if the product is placed too superficially (Tyndall effect), product migration and infection. The most serious, though uncommon, is vascular occlusion, when the product blocks an artery: it requires immediate treatment and, very rarely, can affect vision. That is why it should be performed by a doctor with in-depth knowledge of the facial blood vessels.

Reversibility and duration

Unlike other fillers, hyaluronic acid is reversible: it can be dissolved with an enzyme, hyaluronidase, in case of a complication or an unwanted result. It usually lasts six to eighteen months, depending on the area and the product.