CPD: Understanding Tear Trough Anatomy

2020

Understanding Tear Trough Anatomy

Dr Eleanor Reid, Miss Lara Watson and Miss Priyanka Chadha explore the anatomy of the tear trough for successful injectable treatments

The tear trough deformity is characterised by a sunken appearance of the eye and a resultant dark shadow cast in the lower eyelid region. It is not exclusively a result of facial ageing and a mild tear trough may be seen in younger patients. It is the deepening of the trough and changes to the surrounding soft tissue architecture that occur with age, which leads to the characteristic features of the tear trough deformity. 1 Patients who request correction of the tear trough deformity often present complaining of dark circles, a fatigued appearance, or aged or an un-aesthetically pleasing groove around the eye. Traditional techniques to address this cosmetic issue previously relied on chemical peels or surgical excision of skin, muscle and fat. 2 More recently the need to restore volume to the orbit as part of an overall rejuvenation strategy has been appreciated, with treatment of the tear trough with hyaluronic acid (HA) dermal fillers gaining huge popularity. It is widely recognised that diagnosis and management of complications that arise from medical aesthetic treatments are an unmet training need. 3 This is particularly true with regards to treatment of the tear trough region, where there is very little safety data supporting treatment modalities regarding potential periocular complications and their management. 3 Although the range of potential complications that arise are similar to other areas in the face, the delicate nature of the eyes means that complications from treatment arise more commonly in this region. 4 Understanding soft tissue and vascular anatomy is essential to rejuvenation of the undereye area.

Definitions and nomenclature The term ‘tear trough’ applies to the medial one-third of the periorbital hollow that extends obliquely from the medial canthus the thin, loose skin of the eyelid where it originates at the lower eyelid inner canthus and extends down to the thicker skin of the cheek. 5 This indentation where the thin eyelid skin above meets the thicker nasal and medial cheek skin below defines the tear trough

2 0

1

0

1

2

3 Palpebral line

Tear trough

Palpebromalar groove

Mediojugal fold

3 deformity. This boundary also delineates the line along which fascia is anchored to the underlying periosteum. 1,6 Lateral to this point, the depression is referred to as the ‘palpebromalar groove’ or ‘lid cheek junction’. 7 In patients who present with both a deep tear trough deformity and also a deep lid cheek junction, these two landmarks form an indentation that is nearly continuous and is visible several millimeters beneath the infraorbital rim. 6 Medially and inferiorly the junction is referred to as the ‘mediojugal fold’ or the ‘mid-cheek groove’ (Figure 1). 7 The pretarsal thin skin within the tear trough is different in texture, colour and quality in comparison to the adjacent thicker skin of the nasal and cheek skin. 1 In comparison to the adjacent thicker nasal and cheek skin which is abundant with subcutaneous fat, the pretarsal skin is notably thinner, with little or no subcutaneous fat, and some individuals suffer from the presence of distinct melanocytic pigmentation. 1,5

Factors that contribute to tear trough deformity Pigmentation, fat pat herniation and rhytidosis all contribute to the formation of the tear trough. The appearance of ‘dark circles’ in some patients presenting for tear trough correction may be emphasised by distinct melanocytic hyperpigmentation. 1 Globally, patients with darker skin types are more notably affected than those with lighter skin types. 5 Due to its transitory nature there is little data regarding the exact prevalence of periorbital hyperpigmentation; however, one Indian study by Sheth et al. suggested that it was most prevalent in the age group of 16-25 year olds. 8 Although hyperpigmentation occurs in both sexes it is reportedly more to the mid-pupillary line, forming a sulcus. The sulcus involves

prevalent in females. 5 Hyperpigmentation arises from damage or overstimulation of the cells that contain melanin, resulting in an overproduction of the pigment. 9

The underlying congenital or acquired aetiology behind this cell damage may be multifactorial, with no one aetiological factor predominating. 5,7 Causes may include excessive ultraviolet light exposure, nevi, hormonal changes, melanoma or dermal melanocytosis. 10 However, clinicians should also be aware that the presence of hyperpigmentation may be an indication of an underlying nutritional deficiency, skin disorders, systemic disease or sleep disturbance. 5 Although dyspigmentation does not contribute to the depth of the tear trough, it can create the illusion of depth and therefore exaggerate the appearance of a tear trough deformity. 2 Prominent venous pooling or thin skin can create a purple discolouration to the skin, accentuating periorbital darkening. 1,7 Patients seeking treatment of the tear trough should be adequately assessed with regards to the presence of pigmentation. For these patients, the limitations of treatment with dermal filler alone should constitute a key aspect of the consultation process and other or additional treatment modalities may be indicated (Figure 2 & 3). 8

Anatomy With regards to anatomy, the infraorbital region is one of the most complex areas of the face. To understand the ageing process and safe treatment of the tear trough deformity it is important to consider the relevant muscles, ligaments, fat pads and vasculature in the tear trough and periorbital region. Muscles and ligaments Cadaveric dissections confirm two distinct planes that contribute to the tear trough and lid cheek junctions; the subcutaneous plane and the deep plane. 6 In the subcutaneous plane, there is no distinction or separation between the tear trough anatomy and that of the adjacent lid cheek junction. 6 Superficially, the tear trough is found to correlate with the junction of the preseptal portion and orbital portion of the orbicularis oculi muscle. 6 Anatomically, the tear trough is at the orbital rim in its most medial portion, with the location of the indentation running along the In this position, the orbicularis Figure 4: The v-shaped deformity that correlates to the lid cheek muscle has a direct attachment to junction the inferior orbital rim, running from

the anterior lacrimal crest to the medial limbus. There is scant subcutaneous tissue between the skin and the muscle in this area. 1 The levator labii superioris originates from the medial orbital rim just below the muscle attachment of the orbital portion of the orbicularis oculi muscle. 1 The gap between Figure 2: Patient displaying with perioribital hyperpigmentation. Figure 3: Patient displaying with notable fat pad prolapse in the tear trough region. these two muscles was previously believed to explain the tear trough. 16 However, a 2009 The development of the tear trough deformity is often associated to be located inferomedial to the deformity, indicating that it does not with the orbital fat herniation superiorly into the lower lid fat contribute to the surface anatomy. 6 As the trough progresses laterally, compartments, accentuating the concavity of the trough. 1 Low lid it falls inferiorly with a maximum distance to the orbital rim in the central fat herniation distracts from the deficiency in the trough, forming an portion. 1 Lateral to the corneoscleral limbus the orbicularis oculi muscle independent problem. Orbital fat prolapse may be identified by the attaches to bone by the orbicularis retaining ligaments in the region of characteristic shape of the orbital fat compartments that can often be the lid cheek junction. 1,7 The orbicularis retaining ligament attaches to visualised through the skin, with a cigar shape formed by the central the underlying zygoma caudal to the arcus marginalis at the orbital rim, fat compartment. 11 Patients presenting with notable fat pad prolapse as opposed to directly to the infraorbital rim. 6 may be a contraindication for treatment with dermal fillers alone. In The fibres of the ligament continue superficially, separating the these patients, surgical correction with lower blepharoplasty may be preseptal and orbital portions of the orbicularis oculi muscle. The indicated (Figure 4). 12 length of the fibres of the retaining ligaments increase to a maximum In addition to fat pad prolapse, the occurrence of rhytidosis of the centrally at the arcuate expansion of the orbital septum, decreasing lower eyelid skin may create the impression of a more severe tear in length laterally until becoming almost negligible, merging with trough deformity. 2 The skin in the periocular region is some of the the lateral orbital thickening in the region of the lateral canthus. 1,7 thinnest found in the body. 13 Unlike all other facial areas, there is The presence of a ligamentous attachment in the lid cheek junction minimal or no subcutaneous fat combined with a dynamic structure defines a differential deep plane to the tear trough. 6 The retaining due to an intimate relationship with the orbicularis muscle. 4,10 With ligaments form a v-shaped deformity that correlates to the lid cheek age, connective elements such as collagen and elastin degenerate, junction (Figure 5). 7 compromising the tone and laxity of the skin. 14 Such degeneration It is theorised by authors that with age the tear trough deformity accentuates the appearance of the tear trough, whereby the becomes exacerbated due to soft tissue atrophy and the attenuation underlying depression is unveiled by the thin pretarsal skin. 7 of the orbital septum, allowing orbital fat to herniate through the lax It is important to note that ageing of the periorbital region does not palpebral orbicularis. 7 The tear trough is a dynamic region; given that occur in isolation. Volume loss of the mid-face is attributed to a loss there is a fixed attachment of the orbicularis oculi muscle to the orbital of anterior projection of the maxilla, and the decent and atrophy of rim and subsequent contraction of this muscle, volume loss is visible the malar fat pads contribute to the deepening of the tear trough earlier and more dramatically than in other facial areas. 1 deformity with increasing age. 15

fibres of the orbicularis oculi muscle. 1 cadaveric study by Haddock et al. has shown it

Due to the hydrophilic nature of HA fillers, it’s reported that ‘under treatment’ is imperative and the temptation to create a ‘perfect’ result during treatment should be avoided

Orbital group

Lacrimal artery

Supraorbital artery

Anterior and posterior ethmoidal artery

Internal palpebral artery

Frontal artery (terminal branch)

Nasal artery (terminal branch)

Ocular group

Long ciliary artery

Short ciliary artery

Anterior ciliary artery

Central retinal artery

Muscular artery

Figure 5: The branches of the ophthalmic artery 20,21

Fat compartments The eyes are surrounded by fat contained within deep and superficial fat compartments that are encased in fibrous sheaths containing small blood vessels. 17 Loss of facial fat begins in the mid 20s and it is theorised that deep fat compartments show more significant signs of atrophy as they are adjacent to the bone and therefore less biologically active. 18 The eye is suspended in the orbit by orbital fat which provides glide planes for motions of the eyelid and the globe. 17 As demonstrated in Figure 6 there is a vast network of vascular

In the upper eyelid, there are two fat pads: the nasal and central (preaponeurotic). In the lower eyelid, there are three fat compartments: nasal, central and lateral. 17 The nasal and central fat pads are separated by the inferior oblique muscle which elevates and extorts the eye. 14 The orbital fat pads are held in place over the orbit by the orbital septum. As the orbital septum becomes weak with age, these infraorbital fat pads can herniate against the lower eyelid. 17 Deep to the orbicularis muscle overlying the periosteum of the malar eminence is the suborbicularis fat pads (SOOF). Gradual gravitational descent of the SOOF plays an essential role in descent of mid-facial soft tissues and subsequently the periorbital region. 18

Vasculature The vascular anatomy of the orbit and ocular vascular anatomy is highly complex. Following the pioneering work of anatomist Franz Meyer in 1887, 19 the vascular anatomy of the orbit and ocular region has been extensively documented in the literature for over a century. Most accounts refer to Meyer’s original work, based on 20 specimens, describing the so-called ‘normal pattern’ of the vasculature. 20 However, a series of detailed systematic studies on a large number of specimens by ophthalmologist Sohan Hayreh in 1962 demonstrated eye. For example, a bolus of filler could track retrograde through the angular artery to then travel anterograde through the ophthalmic

that the orbital vasculature presents with a high degree of individual variation. 20 The ophthalmic artery (OA) is the primary source of blood supply to the orbit; it is the first branch of the internal carotid artery

Superficial and vein

Lacrimal artery and marginal arcade

Supratrochlear and supraorbital vessels Angular artery and vein

Figure 6: Vascular anastomoses surrounding and supplying the orbit

after it arises from the cavernous sinus entering the orbital cavity through the optic foramen (Figure 5). 20,21 However, studies report multiple other variants in the origin of the OA with the most common variant, noted in 3% of individuals, being that the OA arises from the middle meningeal branch of the external carotid artery entering the orbit via the superior orbital fissure. 22-24 The branches of the OA listed in Figure 5 can be divided into those that supply the orbit and surrounding parts, and those that supply the surrounding ocular region, supplying the orbital muscles and the bulb of the eye. 20,21 Only a minor extent of orbital blood supply is derived from the external carotid artery via its infraorbital branches and orbital branch of the middle meningeal artery. 22 Reduced or no perfusion of the ciliary blood supply to the optic nerve head via occlusion of the long and short posterior and anterior ciliary arteries can lead to signs and symptoms of anterior ischaemic optic neuropathy (AION), including loss of vision. 25 anastomoses surrounding and supplying the orbit. Anastomoses between branches of the ICA, particularly the terminal supraorbital and supratrochlear branches of the ophthalmic artery and the ECA, namely the terminal angular artery branch of the facial artery, are well documented in the literature. 26 Similarly, the superficial temporal arteries have been demonstrated to anastomose with the orbit. 26 With

The pretarsal thin skin within the tear trough is different in texture, colour and quality in comparison to the adjacent thicker skin of the nasal and cheek skin

this in mind, occlusion of any of these contributing arteries has the potential to cause potential vision change. 27

The mechanism of visual compromise is understood to involve the incorrect deposition of hyaluronic acid filler into an ECA branch artery, which anastomoses with one of the key ICA vessels supplying the temporal artery

artery resulting in visual loss. 3,4

It is important to note that blindness from facial injections is extremely rare. 28 A meta-analysis review of world literature reported that before 2015, there were only 98 cases of vision change after aesthetic facial injection reported globally. 26 It should be noted that this data refers only to those cases of blindness following HA filler injection that have been reported and does not account for any unreported incidents. Injections in the nasal region are the most common area for fillerrelated visual loss due to the location of the dorsal nasal artery branch of the ophthalmic artery. 27 Although risk of blindness can occur with injection of dermal fillers into any anatomical region of the face, the glabella, nasolabial and forehead/temple region are also deemed to be high risk areas. 27 Despite the uncommon incidence of this complication, due to the

potentially devastating outcome of this adverse event, the risk of visual loss should be discussed during the process of informed consent with the patient before facial injections with dermal filler.

Lymphatics The lymphatic vessels in the periocular region are divided into pretarsal and post-tarsal. Lymphatic drainage of the pretarsal orbicularis oculi muscle and eyelid skin are provided by the pretarsal vessels. The deep plexus post-tarsal vessels provide lymphatic drainage of the conjunctiva, lacrimal glands and tarsal plates. The palpebral lymphatic vessels drain in to two main sites; laterally and medially. The lateral lymphatic drainage group drain in to the deep and superficial parotid nodes providing drainage for the deeps vessels of the lacrimal glands of the conjunctiva and lateral aspects of both eyelids. The medial portion of the upper and lower eyelid and lacrimal sac drain into the submandibular nodes. 29

Practical application In aesthetic medicine, the use of HA fillers dominates the market. These products are favoured for: immediate and natural results, non-immunological and highly biocompatible status, long lasting but non-permanent results, reversibility via enzymatic digestion and incremental administration. 30,31 As mentioned, due to the dynamic nature of the area, scant subcutaneous fat and thin skin, the tear trough is a technically challenging area to rejuvenate. 4 Appropriate technique, product selection and placement can help to avoid some complications. 32 Low viscosity, low elasticity products are favoured in this area for their soft flowing qualities and a homogenous pattern of tissue integrations. 33 Highly cross-linked HA fillers are excellent for deep placement and restoring deeper lines and volume loss, however such products are prone to interfering with lymphatic drainage and may induce swelling. They are therefore inappropriate for use in the tear trough region. 3 Due to the hydrophilic nature of HA fillers, it’s reported that ‘under treatment’ is imperative and temptation to create a ‘perfect’ result during treatment should be avoided. 2 Practitioners should respect to the product’s ability to attract water in the weeks following treatment should be made to avoid the treatment area being overcorrected. 2 Safe needle and cannula techniques can both be applied to treat the tear trough deformity. The consideration that microcannulas, particularly those with a narrower calibre, have the potential to act like needles and penetrate vessels, should be made. 4,3 It is imperative the product is placed on to the periosteal level when using needle techniques and in the suborbicularis plane when implementing the use of a cannula to avoid the Tyndall effect or an irregular contour. 4

Treat with care The tear tough is a technically challenging area to rejuvenate and should only be performed by appropriately qualified and trained medical professionals. Understanding the soft tissue and vascular anatomy of the tear trough region and potential variation is essential to achieving safe rejuvenation of the under-eye area. A holistic approach should be taken to treatment with assessment of the mid-face and surrounding structures. Thorough patient assessment with regards to skin texture, pigmentation and presence of fat pad herniation is essential to achieving satisfactory aesthetic outcome.

Dr Eleanor Reid is an aesthetic practitioner and dental surgeon graduating from Newcastle University. Dr Reid has a background in maxillofacial surgery, hospital and practice-based dentistry and is lead trainer in Newcastle-upon-Tyne for Acquisition Aesthetics, as well as being the director of Paragon Aesthetics. Qual: BDS

Miss Lara Watson is dual-qualified in medicine and dentistry and works as a surgical trainee in oral and maxillofacial surgery. Miss Watson is a faculty member for Galderma and is also a co-founding director of Acquisition Aesthetics. Qual: BM, BMedSci, BSc, MRCS(Eng), BDS(Hons)

Miss Priyanka Chadha currently works as a plastic surgery registrar in London and is co-director of Acquisition Aesthetics training academy. Her academic CV comprises national and international prizes and presentations, as well as higher degrees in surgical education and training. Miss Chadha is a faculty member for Galderma. Qual: MBBS(Lond), BSc(Hons), DPMSA(Lond), MRCS(Eng), MSc(Lond)

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