Fillers 101: Foundations for success

Take-home message: The foundations for success in using fillers during oculofacial surgery include understanding the characteristics of these products, which influences outcomes, and learning techniques to avoid and treat complications.

By Nancy Groves; Reviewed by Julie A. Woodward, MD

Injectable fillers are growing in popularity, with an increase in use of neurotoxins and fillers of 20% or more reported in 2015. To achieve success with these fillers, it’s essential to understand their characteristics, interactions, and risks, said Julie A. Woodward, MD, associate professor of ophthalmology and dermatology, and chief, oculofacial surgery, Duke University School of Medicine.

The American Society for Aesthetic Plastic Surgery claims that use of neurotoxins grew 19.9% and fillers 26.6% in 2015, and as their use becomes more widespread one of the most important characteristics to understand about fillers is the G prime or stiffness, Dr. Woodward said.

“All of these fillers have different characteristics, and it makes them behave differently in the tissue,” she said, citing a 2013 study by Sundaram and Casuto that analyzed the G prime of a series of fillers. “What they found was that certain fillers are very, very stiff, which gives them certain characteristics which are good for lifting cheekbones, and other fillers are very soft, which makes them good for fine lines in the perioral or periocular areas.”

Having a bit of background on how fillers are produced is also helpful. All but one of the hyaluronic acid fillers are crosslinked with a chemical called BDDE (1,4-butanediol diglycidyl ether). If the filler goes through a sieving technology, as do products in the NASHA family (Restylane, Restylane Lyft, Restylane Silk by Galderma), it’s called a biphasic filler, and the tissue will conform around the filler. These products are well suited to structure and lifting. Monophonic fillers include technologies including Hylacross (Juvederm Ultra and UltraPlus by Allerga), Vycross (Voluma, Vollure, Volbella by Allergan)  and Cohesive Polydensified Matrix (Belotero by Merz Aesthetics). These technologies have various levels of tissue integration. The newest technology is the XpressHAn (Restylane Refyne, Restyland Defyne)  technology that results in fillers with increased flexibility to move naturally with facial expression.

More than a dozen fillers have received FDA approval since the first in 2003, but they cannot be compared directly, because their clinic trials were different, Dr. Woodward said. One difference is that fillers are classified as medical devices, which require a one-point improvement on a four-point scale, while neurotoxins are considered drugs, requiring a two-point improvement. The scales used may vary from company to company.

In addition, the amount of filler used in the clinical trial varies considerably. For example, more than 2 cc of filler was used in the lips in one FDA trial.

“You have to look at these things when you judge how you’re going to use them because you’re probably not going to put that much in your patients in your clinical practice,” she said.        

The G prime also varies tremendously among products, depending on which rheometer was used in testing, the barometric pressure, and the temperature.

Another important rheologic characteristic is cohesivity, or how much a filler sticks to itself.

“Fillers that stick to themselves more counterintuitively spread through the tissue better, so the ones that are the least cohesive are the ones that set up shop a little bit more in their own personal space,” Dr. Woodward said.

Another variable characteristic to consider is hydrophilicity. While this characteristic has not been well studied, a general rule is to avoid using certain more hydrophilic fillers in the infraorbital hollows.

Surgeons also should understand interactions between hyaluronidase and various HA-based fillers, which can ultimately affect the cosmetic results of facial correction. A study by Rao et al, of which Woodward was a coauthor, found that of four fillers tested, Restylane was easiest to dissipate with hyaluronidase.

“If you order filler, you should definitely have hyaluronidase in your office,” she said.

Dr. Woodward also cautioned that any experienced surgeon will eventually experience complications, referring to a 2015 study by Beleznay et al on avoiding and treating blindness from fillers. Blindness may occur when filler is inadvertently injected into an artery then flows retrograde into the ophthalmic artery and back into the central retinal artery into the eye. Highest risk arteries are the dorso-nasal, supratrochlear, supraorbital, and angular.

The paper described 98 cases of blindness resulting from inadvertent arterial injection.

“Even the nasolabial folds, which is the most common FDA-approved area, can track up into the orbital circulation,” she said. “Most of these cases happen in Asia, but there are cases in the United States, so be aware of your anatomy and your depth.”

A study at Duke University to determine the minimum amount of filler necessary to potentiate visual loss from this complication found that the average volume of the supratrochlear artery was less than one-tenth cc. Although the term “small aliquots” is often used as a guideline for the amount of filler that can safely be injected, based on the study’s findings Dr. Woodward recommended using aliquots of 0.03 cc.

“If you have the needle in someplace, move it around before you inject your next one-third of one-tenth,” she recommended.

She also advised thinking of your patients as if they had an anatomical diagram overlaid on their face helping you identify particular danger zones such as the supratrochlear, dorsonasal, angular, and infraorbital. Also be mindful of variations in anatomical patterns.

“Only about 40% of patients have a facial artery that extends up into the orbital circulation. In other cases the lower face can be separate, but it is possible that these things can connect,” Dr. Woodward said.

Julie A. Woodward, MD

E: woodw005@mc.duke.edu

This article is based on Dr. Woodward’s Oculofacial Plastic Surgery Subspecialty Day presentation during the American Academy of Ophthalmology 2016 annual meeting.

Dr. Woodward is a consultant for Allergan, Galderma, Lutronic, Merz, Valeant, and Skin Ceuticals.