Dr Stephen Humble discusses the aetiology and management of dark circles in skin of colour patients
In aesthetic medicine, dark circles under the eyes are a common concern across all ethnicities, but they may be particularly prominent in the setting of skin of colour due to higher concentrations of melanin.1 Regardless of the Fitzpatrick scale,2 before determining the best way to manage dark circles under the eyes, it is always useful to assess what the specific contributing factors are. Specifically, within the setting of skin of colour (SOC), the universal causes of dark circles must be considered, such as tear trough deformity; however, the approach to treatment may be modified appropriately. For instance, higher baseline concentrations of melanin may significantly accentuate underlying hollowness and hyperpigmentation can cause dark circles even in the absence of tear trough hollowing, especially in SOC.1,3-6
Perhaps the first thing to consider in dark circles is the underlying anatomy around the eye, including the nasojugal fold.1 The orbicularis oculi muscle and the levator palpebrae superioris control the opening and closing of the eyelid.7 The tear trough is a triangular depression below the lower eyelid and within the orbicularis oculi muscle that runs diagonally from the medial canthus to the mid-pupillary line.7,8 It is comprised of a superficial and deep plane and is supported inferiorly by the orbicularis retaining ligament.8,9
The anatomical predisposition to the development of tear trough deformity is not known to be significantly different between differing ethnicities.8,10 However, the overlying skin varies significantly with regards to its thickness and its melanin concentration, and this can magnify the prominence of the tear trough deformity disproportionately.1,4
The angular artery is the most important vascular structure to consider (although there are others) and it emerges below the orbicularis oculi muscle to travel along the inner canthus of the eye, it is accompanied by the angular vein.7,8,11 The potentially catastrophic risk of intravascular injection to vision must be minimised by careful technique, aspiration and arguably the blunt cannula technique.11 The infraorbital nerve emerges from the infraorbital foramen inferior to the orbital rim within the mid-pupillary line.7
Dark circles under the eye area may be evaluated more generally by assessing the depth of the tear trough deformity, the intensity of hyperpigmentation, the severity of the nasal fat pad prolapse and the degree of rhytidosis (or myocutaneous laxity) of the eyelid as well the amount of fluid retention or oedema.7,8
Tear trough deformity may be classified as follows:12,13
Tear trough deformity may be treated effectively with hyaluronic acid (HA) filler particularly well in Class I patients and may be improved in Class II patients, however HA filler will not improve orbicularis oculi hypertrophy, pigmentation, myocutaneous laxity or oedema.7 Patient selection is of vital importance as the most severe cases may not respond well to treatment with HA fillers and more invasive surgical techniques are indicated such as blepharoplasty or fat grafting.5,8,12,14 There are two main approaches for the administration of HA filler to the tear trough area: performance is with either a needle or a cannula.7 There is no proven advantage of one technique over the other for any given skin type, but my personal preference is for the cannula technique due to its better safety profile and less risk of bruising, which may appear particularly dark in SOC patients.
Hyperpigmentation may be more prevalent and more noticeable in patients with SOC due to a number of exogenous and endogenous factors.1,3-6 Naturally, darker skin tones Fitzpatrick2 IV-VI tend not to experience sunburn and as such, especially during childhood, may not have necessarily had a natural prompt to wear SPF.3 Many people with SOC have connections with hot countries and may have spent time living in or visiting regularly, thus increasing their cumulative exposure to UV light, which is one if the principle exogenous causes of hyperpigmentation.4,5,15
Common endogenous factors include atopic dermatitis or eczema, which may be associated with periorbital pruritis. Regular vigorous rubbing of itchy skin around the eyes is associated with microtrauma and inflammation, which in itself may exacerbate pigmentation.1,5,6 The presence of tear trough deformity and/or localised oedema may also combine well with periorbital pigmentation to generate particularly dark circles in SOC.5 There also appears to be an inherent genetic predisposition observed in familial groups which may be autosomal dominant in some cases.5,16,17
The aim of management is to first identify the causative factors and modify them wherever possible (e.g. avoiding sun exposure, using SPF 50 suncream1 and wearing good quality sunglasses) before determining the appropriate treatment plan.
The principle active treatment for infraorbital pigmentation in SOC is topical therapy such as cosmeceutical agents containing tyrosinase inhibitors.1,5,15 Tyrosinase in the enzyme that converts dopa to the pigment melanin and thus is the main target in the treatment of hyperpigmentation.1,5,15 The most effective and well-known tyrosinase inhibitor in this setting is hydroquinone, but treatment typically requires at least three months’ duration due to the length of time the skin cycle takes to complete.5 It is a relatively potent treatment and one or two pea sized amounts may be sufficient for the entire face. Long term use of hydroquinone is contraindicated, and it has the potential to be carcinogenic in animal models with systemic ingestion; however, it is considered safe for topical use on the face in humans for limited periods of time.5 Use around the periorbital area is more contentious as it may be more irritant in the delicate under eye area, although there is a clinical precedent for its careful use in Asian skin.1,18
The principle active treatment for infraorbital pigmentation in SOC is topical therapy containing tyrosinase inhibitors
Other tyrosinase inhibitors include kojic acid, arbutin and azelaic acid, which are less potent than hydroquinone and may potentially be used over longer periods of time in patients that require ongoing treatment to prevent pigmentation returning.5,15 It is of critical importance in the context of SOC for patients to be informed that these treatments may temporarily make the skin more susceptible to the development of new pigmentation during the active treatment phase. I tell my patients it is mandatory that scrupulous SPF 50 protection is used every day during treatment to prevent the development of hyperpigmentation and sun exposure should be minimised.1 This approach also applies to retinoids, which are often used as co-agents in the management of hyperpigmentation due to their ability to accelerate cell turnover within the skin cycle and thus accelerate the lightening effects of tyrosinase inhibition.1,6,15
It is worth noting that the while drugs such as hydroquinone can lighten hyperpigmentation, they do not usually make the skin lighter than the baseline skin tone.19 Antioxidants such as vitamin C, ferulic acid and phloretin are also very useful in the setting hyperpigmentation.6 UV rays penetrate through the layers of the skin and generate free radicals, which in turn can trigger melanogenesis and collagen degradation.
Antioxidants scavenge the free radicals and may therefore treat and prevent the development of future pigmentation.5,6,20 Peptides are involved in protein regulation and synthesis as well as cell proliferation, angiogenesis and melanogenesis. Peptides can improve the appearance of dark circles under the eyes in numerous ways including the stimulation of collagen synthesis and modulation of neurotransmitter release.6
Lower lid blepharoplasty may involve excision of excess skin as well as fat excision and transposition.21-23 A transconjunctival or transcutaneous approach may be used to target the inferior orbital fat pads for their excision, repositioning or augmentation.22,23 This may even be combined with fat grafting for facial rejuvenation.24 Non-surgical options in the setting of SOC include: platelet-rich plasma (PRP), Er:YAG Laser, radiofrequency devices, cautious superficial chemical peels, and topical agents.1,5,15,25-28 Hydroxyapatite has also been proposed as an alternative to HA fillers to treat tear trough deformity,29 although this is not widely popular due to its inflexibility and the perceived associated risks.30 It is worth noting that not all types of chemical peel or laser are suitable for people with SOC due to the increased risk of new-onset hyperpigmentation observed with darker skin tones. Therefore, it’s key that practitioners ensure they have undertaken the correct training/education so they are able to choose the right treatment.
Dark circles may be significantly more prominent in the setting of SOC, and their treatment has similarities and differences in comparison to lighter skin tones. In addition to the individual anatomy of the patient, there are both endogenous and exogenous factors to consider carefully during the diagnostic process, including cumulative sun exposure and genetic predisposition. Appropriate clinical treatment should be individualised and based on the identified causative elements.
Tear trough fillers may be appropriate for loss of volume of the bony orbit, while cosmeceuticals containing tyrosinase inhibitors, retinoids and antioxidants are mainstays of treating dark circles in SOC. Other more invasive options such as surgical blepharoplasty or fat transfer may be appropriate for the most severe cases, typically in the older demographic, but these approaches are perhaps left until after more conservative treatment has been trialled extensively due to the risk benefit profile.
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