3 Anatomic Considerations in the Aesthetic Surgery of the Upper Face
Abstract
Aesthetic management of the upper eyelids and face requires a thorough understanding of differences in anatomy, gender, and race. These differences are important to recognize to understand their clinical implications for surgery and thereby achieve good cosmetic and functional outcomes.
3.1 Introduction
Facial beauty is an evolving concept comprising objective, subjective, and relational aspects, broadly defined by culturally prescribed representations. 1 , 2 Treatment is, therefore, sought to correct underlying structural features that may produce a negative aesthetic impact. 1 The ideals of facial beauty continually change over time. Old beauty standards were determined by anthropometric data, dating back from the canons of facial aesthetics from the Renaissance era. 3 , 4 These, however, no longer represent the current perceptions of facial beauty.
Recent studies have reported that beauty ideals and attractiveness are broadly consistent regardless of race, age, or nationality, 5 , 6 yet slight differences exist in terms of specifically desired shapes and characteristics that are thought to enhance existing ethnic features. 6 ID#b1a591a212_7– 8 Asians were initially perceived to undergo aesthetic surgery to achieve a “Westernized” beauty; however, the new science of beauty emphasizes the optimization of one’s existing features, such as wanting to look like beautiful Asians rather than distinctly “Western.” 7 , 8 In terms of the upper face, the current ideals for the female Asian face include a smooth, convex forehead and large eyes, 6 while Caucasian females who similarly have a relatively large forehead, small jaw, and large eyes are deemed attractive. 9 Wide-set eyes and a lower brow position are also considered attractive features regardless of race. 10 On the contrary, some contend that the current concept of facial beauty depends on dynamic features such as facial expression 1 and facial proportions rather than specific facial traits. 3 , 8
The eyelids and eyebrows are the most important landmarks and distinguishing features of the upper face. 11 As such, these structures are usually the focus of aesthetic surgery. While the proper planning of surgery entails a detailed understanding of anatomy, differences exist according to race and gender. These variations, along with an adequate understanding of patient motivations and expectations, are equally important considerations for the evaluation and aesthetic treatment of the upper face.
3.2 Racial Differences
Racial differences in facial structures are well recognized in that comparative anthropometric studies have been previously done on one or more of the following principal racial groups: Caucasians (Europeans and Native Americans), Africans, and Asians. 12 ID#b1a591a212_13 –ID#b1a591a212_14 ID#b1a591a212_15 ID#b1a591a212_16 17 The greatest variation is seen within the upper third of the face 18 ; in fact, the two most studied facial structures in aesthetic surgery are the eyes and nose, which show the highest degree of interethnic variability. 15
In general, Caucasian groups of Europe and North America share similar facial morphology, while similarities in the morphology of the head, mouth, and ear are observed across all ethnic groups and races. 13 Africans share identical intercanthal distance with Caucasians; however, variable patterns of eye fissure length and biocular width exist across different African ethnic groups.
Asians, on the other hand, are not a homogenous group but rather comprise many varied ethnicities that possess unique facial characteristics. 6 Farkas et al compared anthropometric measurements among different ethnic groups to normal values established on North American Whites. In their study, Indians and Middle Eastern ethnic groups shared similar orbital measurements such as intercanthal distance, eye fissure length, and biocular width with Caucasians. 13 Southeast Asians (Vietnamese, Chinese of Singapore, and Thais), on the other hand, showed both similarities and differences in upper facial morphology relative to Caucasians. Thai and Vietnamese males showed similar intercanthal distance with Caucasians, while larger measurements were observed among Singaporean Chinese of both sexes, Japanese males, and Vietnamese females. Smaller eye fissure lengths were also seen among Singapore Chinese females and Vietnamese males, while wider biocular widths were observed among Japanese of both sexes.
Asians age differently from Western populations. 7 Facial aging proceeds at a slower rate in Asians compared to their age-matched Caucasian counterparts, which is in part likely due to increased amounts of melanin that provides a higher sun protection factor in Asians. Moreover, the presence of dense fat and fibrous connections in Asians also provide a lower tendency for midfacial sagging. 19
Most literature on the anatomy of the eyelids and upper face are focused on Caucasians (North Americans and Europeans) and Asians (Japanese, Koreans, native Chinese, or those of Chinese descent) due to the distinct differences mentioned earlier as well as the presence or absence of an upper eyelid crease. The focus of the following sections will be on these two major racial groups.
3.2.1 Eyelid Skin
Skin thickness varies across different regions of the body, and is influenced by factors such as race, age, and sex. 20 In a comparative study of skin thickness among Asians and Caucasians, the epidermis accounts for 8.3 and 4.1–4.2% of the total skin depth in these races, respectively, while dermal thickness is similar in both races. 20
The upper eyelid has the thinnest skin in the body. 21 In Asians, the thinnest part of the upper eyelid is near the ciliary margin (320 ± 49 µm), followed by the lower tarsal area (703 ± 103 µm) and upper tarsal area (832 ± 203 µm), while the thickest part is just below the eyebrow (1,127 ± 238 µm). 22 The epidermis accounts for 11.2% of the entire skin depth near the ciliary margin compared to only 4.2 to 5.5% at other levels toward the eyebrow. 22 Although no similar study has determined skin thickness at different levels in Caucasian upper eyelids, one study measured skin thickness at different topographic areas of the face. For the upper eyelid, skin thickness was measured on the medial and lateral aspects, with the thinnest part found on the medial eyelid (799 ± 458 µm), followed by the medial canthus (883 ± 592 µm) and the lateral eyelid (1,131 ± 539 µm). 23 It was also found that dermal thickness pattern, and not epidermal thickness, dictates total skin thickness, 23 which is consistent with the finding in Asian eyelids. 22
The skin of the upper eyelid is generally thicker in Asians (521 ± 115.8 µm) 21 than in Caucasians (380 ± 90 µm). 21 , 24 Consequently, too much skin removal during Asian upper eyelid blepharoplasty may result in an overhanging or full appearance of the thicker upper skin on the eyelid crease. 25 Because of this, a sub-brow skin excision is often more suitable in Asians to treat dermatochalasis with thicker upper eyelid skin. By contrast, a forehead lift or suprabrow excision is more suitable in Caucasians, as they have more prominent supraorbital rims with lower set eyebrows and less preaponeurotic fat. 26
3.2.2 Upper Eyelid Crease
The upper eyelid crease is formed by the insertion of the posterior layer of the levator aponeurosis on the anterior aspect of the tarsal plate and subcutaneous tissue (Fig. 3.1 a). 27 ID#b1a591a212_28 – 29 On the other hand, the anterior layer of the levator aponeurosis fuses with the orbital septum. 27 ID#b1a591a212_28 – 29 The Asian upper eyelid has a less apparent crease and more prominent fold that lead to a fuller appearance compared to Caucasians. 27 This distinction is caused by racial differences in the location of preaponeurotic fat and thickness of the submuscular fibroadipose tissue. 27
The junction of the orbital septum and the anterior levator aponeurosis is located above the superior tarsal border in both Asians and Caucasians. 27 , 30 However, preaponeurotic fat or submuscular fibroadipose tissue, which is thicker in Asians, occasionally protrudes inferiorly below the level of the superior tarsal border in Asians. 27 , 30 , 31 This interrupts the superficial fibers of the levator aponeurosis from reaching the subcutaneous tissues, resulting in a less apparent upper eyelid crease (Fig. 3.1 b). 32 , 33 In a study of eyelid structure using electron microscopy, it was observed that fibers from the levator aponeurosis penetrate the orbicularis oculi muscle (OOM) and reach the subcutaneous tissue in double eyelids, while none of the fibers pass through the OOM in nondouble eyelids. 34 Furthermore, the height of the upper eyelid tarsal plate is smaller in Asians than Caucasians, 35 which makes the preaponeurotic fat pad extend further downward.
Eyelid crease formation is also associated with the thickness of the OOM, such that a thinner OOM contributes to the formation of a double eyelid. 30 In a Japanese cadaveric study, the OOM was significantly thinner at the skin crease 10 mm from the upper eyelid margin in double eyelids compared to single eyelids, while there was no difference in thickness 3 to 5 and 15 mm from the upper eyelid margin. 30 Thickness of the skin and subcutaneous tissue, however, were not influential factors for double-eyelid formation in this report. In this regard, the surgical creation of a double eyelid entails forming a connection between the levator aponeurosis, tarsal plate, and subcutaneous tissue, as well as reducing the thickness of the OOM. 30
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