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Page 2 of 10 Zein et al. Plast Aesthet Res 2020;7:44 I http://dx.doi.org/10.20517/2347-9264.2020.133

by the FDA in 2004, the number of hyaluronic acid (HA) filler injections performed in the United States has
[1]
steadily risen to nearly 2.7 million procedures per year as of 2018 . As a naturally occurring component of
skin and connective tissue, HA is highly biocompatible and non-immunogenic. HA is a favored choice for
patients with little to no history with injectables as its effects are temporary, lasting between 6 to 24 months
with natural degradation. This process can be accelerated with the use of hyaluronidase providing some
ability to reverse unwanted effects.

While soft tissue fillers and HA in particular are non-incisional and less invasive than other interventions
for facial rejuvenation, they still carry a number of risks when performed without proper precautions.
In the United States, soft tissue filler injections are performed by a wide variety of health care providers,
including but not limited to facial plastic surgeons, dermatologists, oculoplastic surgeons, plastic surgeons
and the nurse practitioners and physician assistants working under their supervision. While such providers
may be fully licensed to perform these procedures, there are considerable differences in training, familiarity
with relevant anatomy, and ability to manage complications. Furthermore, the black market in cosmetic
fillers and ready availability of unlicensed injectors provides a steady source of complications that licensed
[2,3]
providers should be prepared to encounter . Between 2013 and 2017 over 2800 reported adverse events
[4]
occurred in the United States according to FDA databases .
Complications vary and range from the mild, self-resolving ecchymoses to the more persistent irregular
surface contours, festoons, and the bluish hue (Tyndall effect) seen with superficial filler placement. Severe
granulomas have also been seen long after filler injection. The most severe complications are due to filler
[5]
vascular occlusion, which can result in skin necrosis and sometimes irreversible vision loss . This review
focuses on filler-associated complications that are most commonly encountered by ophthalmologists and
oculoplastic surgeons, and addresses various preventative and management strategies.

AVOIDING VASCULAR COMPLICATIONS
A thorough knowledge of the local anatomy, use of safe injection techniques and timely recognition
of symptoms can help minimize the risk of the most severe complications. The face and periorbita are
supplied by a rich network of blood vessels that communicate through complex anastomoses. Iatrogenic
perforation or cannulation of the arterial wall during filler injection can introduce emboli that may cause
vaso-occlusion either up- or downstream of the site of injection .
[6]
Pertinent anatomy
Particularly high-risk zones for vascular complications include the glabella, temporalis fossa, tear trough,
midface, nasolabial grooves, and nasal dorsum owing to the large vessels in these areas [Figure 1] .
[7]
In the glabellar region, the supratrochlear branch of the ophthalmic artery exits along the orbital rim
approximately 2 cm lateral to midline superficial to the corrugator and deep to the orbicularis and frontalis,
before becoming more superficial and entering the subcutaneous plane 2 cm above the orbital rim. The
supraorbital branch of the ophthalmic artery exits along the orbital rim through the supraorbital notch
approximately 3 cm lateral to midline. Similar to the supratrochlear artery, the supraorbital artery courses
deep to the orbicularis and frontalis before entering the subcutaneous plane anywhere from 2 to 6 cm
[8,9]
above the orbital rim .

The temporalis fossa consists of skin, subcutaneous fat, temporoparietal fascia, superficial and deep
temporal fascia surrounding loose areolar tissue, temporalis and periosteum. The frontal branch of the
superficial temporal artery courses within the temporoparietal fascia approximately 2 cm superior and
lateral to the peak of the brow. The middle temporal vein and the temporal branch of the facial nerve also
[10]
course near this region, posing the additional risk of pulmonary embolism and nerve injury . There is
also a connection between the temporal fossa and the orbit. The zygomatico-temporal artery connects the