blindness Archives | The Aesthetic Clinique

New Research Suggests that Not All Cannulas are Safe!

Cannulas, specifically, blunt microcannulas, can be used to administer fillers by advanced injectors. They a favorable over needles because they have a blunt round tip and are flexible, leading to the following advantages:

Less discomfort – one entry point can serve a large area, thus avoiding multiple dermal penetrations which is more uncomfortable.
Less bruising – the rounded/blunt tip tends to bend around blood vessels rather than nick or penetrate them.
More accurate – a recent study shows that the filler is most likely to be deposited in the area of the exit port vs a needle which has been shown to have filler travel up the shaft (back flow)
Safer – cannulas are less likely to give intraluminal vessel injections because of the blunt tip and therefor less possibilities of vascular compromise and blindness.

However, a recent publication by Drs Pavicic, Cotofana et al. has shown that #4 comes into question with certain cannulas. There study consisted of a total of 294 penetrations of the superficial temporal artery in cadavers using 22, 25, and 27 gauge cannulas and needles. The force applied to enter the vessel was measured for each. The cannulas had statistically higher forces needed to enter the vessel for the 22 and 25 gauge cannulas.

Interestingly, there was no difference in the forces when comparing 27g cannulas and needles.

The conclusion was that a 27g cannula was not safer than a 27g needle when used for filler injections. While 27g cannulas can be used, it is up to the injector to realize these are not safer than needles and to take the appropriate safety measures during treatments.

(Article: Plast Reconstr Surg. 2019 Mar;143(3):504e-512e. doi: 10.1097/PRS.0000000000005321)

Why are Blunt Microcannulas the Obvious Choice for Dermal Fillers?

Dermal fillers are becoming increasingly popular worldwide. Contouring of the face, restoring volume loss, enhancing features such as lip plumping can all be obtained with very little downtime. Just 15 years ago, surgery was the only way these enhancements could be performed. There are some minor complications associated with fillers such as pain, bruising, swelling which are fairly common (>70%) and some major risks such as vascular occlusion, blindness, and stroke which are much less common.

The most common method to administer fillers is using the needle which is packaged with the product. While needles are very easy to use, in the author’s opinion, they are more risky and lead to more downtime versus the blunt microcannula technique. Microcannulas were introduced to the United States about 8 years ago from Europe. These were a smaller version of the already widely cannulas which were used for fat transfer. When compared with a needle, cannulas are more flexible, longer, and their tip is more rounded. The following advantages are found with cannulas:

Fewer dermal penetrations – cannulas are introduced through only a small number of pilot holes.
Less discomfort – the dermis contains more pain fibers than the deeper tissues. The injections with cannulas are below the dermis, so discomfort is less.
Less trauma to tissues/less bruising – because of the rounded tip, the cannula is less likely to nick blood vessels leading to less bruising and swelling.
Faster procedure times – With an experienced cannula user, placement of filler is done very quickly and efficiently. (Cheek/tear troughs <5 minutes per side, lips <5 minutes)
Less vascular occlusion risks – While cannulas aren’t 100% safe, the risks of injecting into a blood vessel are less because entering a vessel is more difficult with the rounded tip and flexible shaft. This is true for the larger gauge cannulas such as 22, 23, and 25. Recent studies by Dr. Pavicic and Cotofana have shown the 27g cannulas have the same force needed to enter a vessel as a 27g needle and therefore should not be used.

Galderma recognized the advantages of microcannulas and became the first company to get FDA approval for their use with Restylane Silk in lips in 2017, and for Restylane Lyft for the cheeks in 2018. While less than 10% of providers use cannulas in the US, there is a push by the top injectors to encourage their widespread use.

Dr. Weiner has been using microcannulas since 2012 and is one of the most experienced cannulas injectors in the US. He is one of the leading trainers for Galderma, particularly for their cannula trainings. He is available for private trainings in off label use of fillers – face/body. There are shadowing opportunities as well as week long internships opportunties. For inquires, please email: info@theclinique.net or steve@stevenfweiner.com

How to Minimize Risks of Vascular Occlusion and Blindness During Filler Injections

Dermal fillers improve volume loss or enhance facial features. Their use is increasing at rate of 10% or more per year worldwide. Adverse events are usually minor and consist of bruising, swelling, asymmetries, and nodularity. More significant complications are fortunately rare and include infection, granuloma, skin necrosis, and blindness. This blog will concentrate on techniques to minimize the risks of having a vascular event.

There are 2 ways a blood vessel can become occluded. If an artery is entered and filler is injected within the lumen (Intraluminal), filler will travel down the vessel until it gets lodged. At this point, the filler stops the flow of blood to areas which are dependant on this blood supply. Smaller pieces of the filler can break off and flow into areas far from the initial injection and into the very small arterioles. There are theories that an inflammatory response/cascade exacerbates the injury to the skin and dependent structures. This is Dr. Weiner’s opinion for the etiology of the majority of vascular occlusion cases.

A second way a vessel can occlude is if there is external compression of the vessel by filler. This is plausible in areas of compartmentalization, such as in the nasal tip. If the pressure within the nasal tip exceeds the pressure within an artery, flow will stop. Unfortunately in this area, vascularity is so poor that peripheral flow doesn’t occur. External compression is not a major problem in most areas of the face in Dr. Weiner’s opinion. Most vessels can be ligated during surgery and there is no resultant skin necrosis – proving that peripheral flow can make up for an externally compressed vessel.

The worst cases of vascular occlusion result in blindness. This is the result of a filler embolus that travels through an anastomosis between the external and internal carotid systems. The filler backs up into the central retinal artery which feeds the retina. Blood flow is blocked to the retina and blindness ensues.

In most cases, early recognition of a vascular event can be reversed with hyaluronidase if a hyaluronic acid filler was used. Minimal or no sequelae are seen if action is taken within the first 4-6 hours. Unfortunately, even immediate action for blindness related to a filler complication, has little or no success.

There have been about 100 reported cases of blindness from fillers, with most of the cases coming out of Asia. This is certainly underreported though. The areas of most risk for blindness are injections in: glabella, nose, periocular, and NLF. Fat is the most common filler causing blindness, but all fillers have been implicated. Any area of face is at risk for vascular occlusion/necrosis.

The key to avoiding vascular complications from fillers is implementing safe techniques and knowledge of the vascular anatomy. While there is a paucity of data to support this, Dr. Weiner believes that cannula injections are less risky than needles for a vascular event. Larger cannulas, 25g or larger, are less likely to enter a vessel than a needle. While there have been cases of vascular occlusion with cannulas, to the author’s knowledge, none have been reported with 23g or larger. The smaller the cannula, the closer it becomes to looking like a needle, and therefore the advantages are less. (Please read Dr. Weiner’s blog about cannulas to understand their advantages.)

Techniques for optimizing safety during dermal filler administration:

Know the major vascular structures and their landmarks
Avoid areas you (the injector) are not comfortable with. Particularly the high risk areas: glabella, nose, periocular
Consider using only reversible fillers if there is any concern regarding vascular occlusion or experience
Use cannulas whenever feasible, preferably 25/23g or larger
Avoid boluses, small linear threads are safer
Constantly move tip of cannula/needle. If more filler is needed in a particular area, revisit the area with another pass.
A NEGATIVE ASPIRATION DOESN’T EQUATE TO BEING EXTRAVASCULAR AND CAN GIVE A FALSE SENSE OF SAFETY
Injection onto periosteum is safest but does not guarantee a vascular free injection
Pressure on the supratrochlear vessels during glabellar or nasal injections might limit reflux of filler into the orbital vessels
Retrograde injections are safer than anterograde injections
Dermal injections should be relatively safe
Avoid deep injections in the lips. Stay superficial to the muscles
An injection that is perpendicular to a vessel is purported to be safer than one which is parallel because the time within the vessel should be less if it is entered
Have on hand 6-8 vials of Hylenex
Any unusual bruising, pain or visual change needs immediate evaluation

The bottom line is that complications can occur with dermal fillers, even during a routine procedure. Many measures can be taken to minimize the risks. Choosing an experienced injector will result in safer and better outcomes.

Dr. Steven F. Weiner is the #1 physician trainer for Galderma (Restylane, Silk, Lyft, Sculptra, Defyne, Refyne). He has been using cannulas since 2011 and is one of the most experience injectors in the US.

Cannulas Were Approved by the FDA for Restylane Silk….Finally!

On October 12, 2017, Galderma was notified by the FDA that Restylane Silk was approved to be administered using blunt microcannulas. Galderma deserves a huge “high 5” for stepping out of the box in recognizing the improved patient outcomes and safety benefits of cannulas. No other dermal filler in the US has been approved for use with cannulas, it is a “First for Fillers”. Galderma is researching other areas for cannula use and expect approval in 2018 for another 1 or 2 indications.

What’s the big deal with cannulas?

The traditional method to administer dermal fillers is using a needle. Unfortunately, there are many side effects and risks using needles. These include:

Bruising – sticking a needle into a highly vascular organ, skin, will lead to bruising a majority of the time. This is corroborated by the FDA studies for all the US approved fillers.
Pain – needles require multiple entry points to deposit the filler. Pain fibers are most prevalent in the dermis.
Vascular Occlusion Risk – when a blood vessel is cannulated with a needle and the filler is injected directly into the vessel, occlusion of the vessel occurs. The sequelae of such event can result in skin necrosis, eye injury, or even blindness.

Cannulas have a blunted, rounded tip which is less likely to injure blood vessels than a needle is. When the cannula brushes up against a vessel, it is deflected away, in distinction to a needle which will often pierce the vessel. When a vessel is traumatized, a bruise will occur.

To use cannulas, a small pilot hole using a needle is required. Unfortunately, completely eliminating needles is not possible. However, after that entry is performed, the cannula can be placed through the dermis and into the subcutaneous tissue or deeper fat compartments. The areas below the skin surface are generally less innervated and are more comfortable to place filler.

The most important quality of cannulas is their safety. By design, they are much less likely to result in placement of filler within the lumen of a blood vessel. The rounded tip eludes lumens of blood vessels whereas needles don’t offer that protection. Although vascular occlusion is possible with cannulas, it is much less likely when compared to the risks associated with needles.

Dr. Weiner has been an advocate of injecting dermal fillers with cannulas for the past 6 years, since 2012. He has become one of the most experienced cannula users in the US. He has been chosen by Galderma to use his cannula experience to “Train the Trainers” in the use of cannulas for Restylane Silk in the lips.

Dermal Filler Providers Must Also Be Proficient With Hyaluronidase

The adoption of dermal fillers for age related volume replacement has contributed to the surge in aesthetic patients. As patients become more savvy, it becomes obvious that filler outcomes are dependent primarily on the provider and not the brand of the filler injected. Somewhere between 80-90% of the fillers used are based on Hyaluronic Acid, a naturally occurring substance found throughout the skin, and joints. (It is an interesting side note that the structure of HA is similar throughout all species.) One of the attractive qualities of HA is that there is an “antidote”, an enzyme called hyaluronidase, which can dissolve HA based dermal fillers.

There are several versions of hyaluronidase available in the US. There are animal based products such as Vitrase (ovine based), Hydase (bovine), and Amphadase (bovine). The one product, Hylenex, is actually a recombinant form of the human hyaluronidase. There is some risk of allergic reaction to the animal based products but not Hylenex (author’s preferred choice). The intended use of hyaluronidase is to allow for increased tissue permeability, thereby allowing for greater dispersion and delivery of products injected. It is also used when hyperosmolar fluids extravasate into the skin and in improving uptake of radiopaque solutions in the bladder. The primary reason it is used in aesthetics is to dissolve HA filler.

The reasons to dissolve HA filler are:

Poorly placed filler giving an aesthetically poor result
Where too much filler was placed
Filler that is infected
Filler is forming a granuloma
Filler is causing ischemia/vascular occlusion
Filler is causing visual changes or blindness

The are more and more fillers being introduced to the market each year. Each one has it’s own characteristics and nuances when injecting. There are also, many new injectors entering the industry daily. It is fair to say that the number of poor outcomes and complications is inevitably going to rise. Unfortunately, trainings are not being done for the indications and administration of hyaluronidase. It is beyond comprehension that there are many offices, I dare say, a majority, who either don’t normally have any or adequate doses of hyaluronidase.

It is absolutely imperative that a facility that injects HA fillers stock at least 1000 units of hyaluronidase. Doses of 400 units or more need to be injected in areas of vascular occlusion immediately to achieve optimal outcomes. If no response, additional doses need to be injected. If an ophthalmologic complication occurs, at least 1000 units needs to be injected immediately to have any chance for recovery of vision. Even with doses in the thousands of units, there should be no concern regarding loss of naturally occurring hyaluronic acid as it will replaced by the body’s normal regenerative process over 24-48 hours.

Unfortunately, the majority of providers have little or no experience with hyaluronidase and/or have none available in their facilities. It is beyond comprehension the lack of preparedness for not only reversing poor outcomes, but in resolving medical emergencies. The industry must rise up to educate about complication identification and treatment protocols. Poor outcomes and complications affect the entire aesthetics field and not just the individuals involved.

Filling The Temples Should Be Done With Sculptra…Period.

Temporal volume loss is part of the natural aging process of the face. It is the result primarily of fat pad atrophy, but loss of bone, soft tissue, and muscle also contribute. Losing volume in the temples leads to:

Lowering of the eyelid and eyebrow
Skin laxity in the periorbital and cheek area
Changes to the overall shape of the face

Temporal volume loss changes the shape of the face

Probably the most significant of the above changes is #3. A youthful face is “upside down egg” or “heart” shaped. The upper face is rounded, with the widest part being the upper cheeks. The center of beauty is the eyes, and the youthful face emphasizes this. With the temple wasting associating with the aging face, the overall shape turns more square, and the lower face becomes dominant. Filling the temporal defect can help to re-establish the upper face dominance that is the hallmark of youth and beauty.

There are basically 2 ways to fill the temples. Filler can be placed deep to the temporalis muscle, at the level of the periostium of the bone in the temporal fossa. This type of correction will lift the muscle, fat, and soft tissue “en mass” for a very even appearance. Needles are needed for this technique because the temporal fascia is difficult to pierce with cannulas. This is the preferred method of the author. The second method is placement of the filler just below the dermis, in the subcutaneous tissue. Imperfections caused by uneven placement of the filler will be more visible because the tissue in this area is very thin. Bruising is more likely as well because there are multiple veins in this area. Using blunt cannulas helps to mitigate bruising but not eliminate it.

Risks associated with temporal fillers are similar to placement in all other areas: bleeding, bruising, infection, unevenness, unsatisfactory result, need for more filler, vascular compromise including necrosis AND BLINDNESS. Fortunately, blindness is an extremely rare complication of fillers with somewhere between 100 and 200 cases reported in the literature. The most common “filler” sighted for this complication is fat, but it has occurred with all the fillers. It is the duty of the injecting physician to take all precautions to minimize this catastrophic risk. The etiology of blindness is occlusion of the retinal artery by filler that is obstructing its blood flow. Filler makes it to this area because there are natural occurring anastomoses between the external (face) and the internal carotid (ophthalmic) systems. Techniques to minimize blindness are:

Slow injection of the filler which prevents retrograde flow of filler
Use of large cannulas or needles which makes entry into vessels more difficult. (Using cannulas has been shown to be significantly safer than needles because their blunt tip is less likely to result in an intravascular injection)
Moving the end of the needle or cannula constantly to avoid a bolus injection within a vessel
Aspiration prior to injection to see if there is a flash of blood, indicating a intravascular location

Sculptra is ideally suited for correcting the temple defects. When placed at the level of the periostium (the author’s preferred method), it creates a very long lasting correction (at least 2-3 years) formed by collagen and neo-osteogenesis. More importantly, it is the only filler in which aspiration can be relied upon to produce a flash. Sculptra is nearly the consistency of water and will flash with a red reflux of blood if intravascular. The viscosity of all the other fillers makes this technique an unreliable indicator for testing where the tip of the needle is. That makes Sculptra much safer for use in this area.

For improving temporal volume loss, Sculptra will produce a long acting and natural appearing correction with a safety profile that is superior to all other fillers on the US market.

What is Vascular Occlusion or Vascular Compromise from Dermal Fillers?

Dermal fillers of becoming the fastest growing area of aesthetic enhancements. In general, the procedure of injecting the filler is safe, with very little downtime, and with visible results. However, there is a rare, but extremely significant potential risk, that patient’s, medical staff, and providers need to always be aware of: Vascular Occlusion or Vascular Compromise.

What is Vascular Occlusion or Vascular Compromise? This is caused when the dermal filler is either injected into an artery or around an artery to the point that the blood flow is reduced or completely stopped. The area of skin or other tissues that are supplied by the affected vessel will start to die without the necessary blood supply. Almost always, if this complication occurs, there will be an immediate blanching (paleness, tissue turns white) when the blood flow is interrupted, often in areas far away from the actual injection. Recognition is key to a favorable outcome. If this occurs, the injector must stop immediately and take measures to resolve the problem. Pain is usually associate with vascular occlusion. There have been cases reported that occurred 12-24 hours after being injected but almost always it occurs immediately.

If no treatment is initiated to improve the vascular flow, the skin will start to appear dusky, a bluish tint, with fine reticulations (lace like) to areas WELL BEYOND THE SITE OF INJECTION. This occurs within 24 hours. If still no therapy is done, the skin will start to die, turning black, and sometimes there is an associated infection. At this point, scarring will likely occur and surgery is often needed to remove dead tissue and/or to close the wound.

If there is a recognized vascular event, several steps should be initiated.

Hyaluronidase, an enzyme that dissolves Hyaluronic Acid, should immediately be injected in the area, and into the vessel if possible. Some doctors advocate using hyaluronidase even if the filler is not an HA filler because it will dissolve the naturally occurring hyaluronic acid hopefully improving blood flow.
Massaging the area will help mostly if the filler is externally pushing on the vessel. This might move the filler away from the vessel to re-establish flow.
Blood thinners will allow the blood to flow thru a smaller vessel or to go around a blockage. Aspirin and possibly heparin are recommended by most physicians.
Vasodilators such as nitroglycerin are also recommended by most physicians. There is a question as to whether this might allow the blockage to travel further down the vessel.
For severely vasacular compromised tissue, hyperbaric oxygen treatments are beneficial.

Administering dermal fillers with blunt tip cannulas will minimize the chances of a vascular event. The fact that the ends of the cannulas are rounded, makes it very difficult to enter a vessel, particularly with the larger cannulas. To the author’s knowledge, there have been no reported events of vascular occlusion with cannulas larger than a 27g. There is still the possibility of causing external pressure on vessels, but this seems to be a low risk, and mainly associated with fillers that expand, like the HA fillers.

The areas prone to vascular events are areas of the face that are called “watershed areas”. These are areas where there is poor collateral blood supply. These areas are:

Glabella
Under the eye
Nose and around the nasal ala (nostrils)
Nasolabial folds
Upper lip

The catastrophic complication of blindness from dermal fillers is also a form of vascular occlusion. This is when a bolus of dermal filler is injected into an artery in such a way that it travels back to the vessels supplying the retina. Not only does the injector have to be within an artery, but he/she has to exert a force of injection that overcomes the blood pressure (retrograde flow) in the vessel. This is an extremely rare occurrence but unfortunately is almost universally irreversible.

Prevention is key to avoiding a vascular event with dermal fillers. The safest fillers are the HA fillers which can readily be dissolved with hyaluronidase. Cannulas should be used in all high risk areas in the author’s opinion. If using needles, aspiration to see if the tip is within a vessel should be done before all injections in these areas. Careful counseling of patients and staff is needed to recognize a potential event early to get the best possible outcome.

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