Periocular Fillers and Related Anatomy

Rejuvenation of the periocular area is in high demand among patients who want to look and feel their best. Physicians should understand the complicated anatomy surrounding the eyes before attempting to inject this area with facial fillers, both to understand the aging process and to minimize treatment complications.

Basic Oculoplastic and Orbital Anatomy

The injector should understand the anatomy of the periocular muscles, the orbital osteology, and the secretory and lacrimal system, in addition to the fat, ligaments, and vascular anatomy in this area.¹

The eyes are surrounded by fat compartments that provide glide planes for the motion of the eyelids and globe. There are 2 upper eyelid fat-pads—nasal and central [preaponeurotic])—in the upper lid, leaving room for the lacrimal gland laterally. There are 3 fat compartments—nasal, central, and lateral—in the lower eyelid. The nasal and central compartments are separated by the inferior oblique muscle, which elevates and extorts the eye. The orbital septum holds the fat-pads in place in the orbit. The brow fat-pad is the retro-orbicularis oculi fat-pad (ROOF). There are fat compartments that lie in the subcutaneous space along the entire forehead and in the temple. The suborbicularis oculi fat-pad (SOOF) lies over the malar eminence. Superficial and deep submuscular fat compartments of the face have been described.² Deep fat compartments also have been examined on computed tomography.³

Orbital circulation comes from the internal carotid artery and anastomoses with the supply from the external carotid artery to supply the orbit. The first branch off of the carotid artery is the ophthalmic artery, and the first branch off of the ophthalmic artery is the central retinal artery that enters the optic nerve sheath 1 cm behind the globe to supply the retina. The supraorbital and supratrochlear arteries branch off of the ophthalmic artery and supply the forehead. The supraorbital artery runs through the supraorbital notch (foramen in 8%)¹ and can usually be palpated with one’s finger. There are 15 to 20 short posterior ciliary arteries leading to the choroid, 2 long posterior ciliary arteries to the iris circle, and 7 anterior ciliary arteries to the extraocular muscles. The superior and inferior venous systems drain into the cavernous sinus.⁴

The ligaments are important to signs of facial aging because tissue atrophy occurs along them. The main orbital ligaments are the lateral orbital thickening (known as the LOT) that adheres the eyelids to the lateral orbital rim and the orbitomalar ligament (orbicularis retaining ligament), which is a condensation fibrous tissue that attaches the skin to the inferior orbital rim and orbital septum along the arcus marginalis and defines the superior edge of the SOOF.⁵ The zygomatic ligament not only suspends the zygomaticus major and zygomaticus minor muscles to the malar eminence but there are osseocutaneous attachments that connect the skin over the zygoma’s malar eminence and demarcate the inferior edge of the SOOF.⁶

Periocular Aging

The skin, fat, muscles, and bones change and rotate with aging, and not all orbits age in the same manner. Older patients with dermatochalasis (excess skin fat and muscle) often undergo rejuvenation with blepharoplasty, a brow-lift, and a midface-lift, but many atrophic changes can be improved with facial fillers.^7,8

As adults age, the soft tissue along the ligaments begins to show atrophy, prime signs of aging that are often improved with fillers. Atrophy along the orbitomalar ligament along the infraorbital rim creates a depressed tear trough, which is an early sign of aging. A 3-point grading system reported by Hirmand⁸ describes the severity of progressive hallowing. There also is atrophy along the zygomatic cutaneous ligament that creates the malar hollow. The SOOF appears to be more prominent when these areas above and below show atrophy, which creates the look of an unwanted bag known as a festoon. Additionally, there is atrophy along the superior orbital notch where the ophthalmic branch of the trigeminal nerve (V1) and the supraorbital artery traverse. Soft-tissue atrophy along the supraorbital notch resembles the peak at the top of the letter A, giving the slang term A-frame deformity.

Periocular fat can atrophy, hypertrophy, herniate forward as the septum weakens, or become ptotic. Some patients develop hypertrophy and herniation of the superior and inferior orbital fat-pads, while others develop unwanted atrophy leaving a hollow superior orbit and loss of support to the levator muscle that contributes to eyelid ptosis. The frontalis fat deflates, leaving veins, arteries, and the hypertrophied corrugators unwantedly visible. Loss of subcutaneous fat in the glabella contributes to the formation of frown lines between the brows (also called number 11’s). The ROOF deflates in some patients adding to brow ptosis. Loss of the facial frame occurs when temple fat atrophies.

Skeletal rotation also occurs. Throughout a patient’s life, the skeleton remodels itself via activity of osteoclasts and osteoblasts. Pessa et al^9,10 has described the expansion of the anterior orbital aperture superomedially and inferolaterally as well as maxillary retrusion that results in angular changes of the midface in relation to the orbital rim. Lambros’ algorithm describes the rotational changes of the cranium where the superior orbit protrudes as the maxilla retreats posteriorly.^9-11 The equator of the globe does not change its distance from the ROOF of the orbit, presumably because of its suspension in the orbit by the optic nerve after it passes through the optic canal and trochlea via the superior oblique muscle, but the distance of the inferior equator of the globe to the floor of the orbit increases as the floor of the orbit descends.¹²