An anatomical structure which results in puffiness of the upper eyelid and a narrow palpehral fissure in the Mongoloid eye

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1 British Journal of Plastic Surgery (2000), 53, The British Association of Plastic Surgeons DOI: /bjps BRITISH JOURNAL OF ~ PLASTIC SURGERY An anatomical structure which results in puffiness of the upper eyelid and a narrow palpehral fissure in the Mongoloid eye S. Yuzuriha, K. Matsuo and H. Kushima Department of Plastic and Reconstructive Surgery, Shinshu University School of Medicine, Matsumoto, Japan SUMMARY. The typical Mongoloid eye differs from the Occidental one in puffiness of the upper eyelid and narrowness of the palpebral fissure. We surmised that an anatomical structure might exist in the preaponeurotic fat space, which determines the features of the Mongoloid eye. The upper eyelids of 720 Japanese patients and eight Japanese cadavers were macroscopically investigated, and sagittal slices of the central upper eyelid of one patient and nine cadavers were microscopically analysed. Another, lower-positioned transverse ligament different from the higher-positioned Whitnall's one was identified just above the fusional line between the orbital septum and the levator aponeurosis in almost every upper eyelid. A robust ligamentous structure was observed in 331 patients (46%) with puffier eyelids and a narrower palpebral fissure, a diaphanous retinaculum in 381 patients (53%) and no transverse ligamentous tissue in eight patients (1%). Histological evaluation demonstrated that this ligament was composed of tight bundles of collagen fibres containing few elastic fibres. Examination of the preaponeurotic fat space indicated that the superficial expansion of the levator aponeurosis turned up around this transverse ligament to become the orbital septum. When the levator muscle contracts, the deep expansion of the levator aponeurosis retracts the tarsus, the middle expansion retracts the pretarsal orbicularis oculi muscle and skin, and the superficial expansion retracts the preaponeurotic fat against this ligament. This structure thus determines the low position of the preaponeurotic fat and restricts the vertical width of the palpebral fissure, causing the features of the Mongoloid eye The British Association of Plastic Surgeons Keywords: Mongoloid eye, puffiness of the upper eyelid, narrowness of the palpebral fissure, another transverse ligament, Whitnall's ligament. The adult Mongoloid eye is characterised by puffiness of the upper eyelid and a narrow palpebral fissure, whereas the Occidental eye is characterised by the sunken upper eyelid and a wide palpebral fissure. 1-7 However, some Mongoloid adult eyes show the sunken upper eyelid and a wide palpebral fissure, whereas some Occidental ones show puffiness and a narrow palpebral fissure. This puffiness is generally believed to be due to low-positioned preaponeurotic fat. 1 The preaponeurotic fat space is anteriorly bound by the orbital septum and posteriorly by the levator aponeurosis and muscle. The aetiology of a narrow palpebral fissure is not well established. We surmised that an anatomic structure might exist in the preaponeurotic fat space, which determines the position of the preaponeurotic fat and restricts the vertical width of the palpebral fissure. This study aimed to identify this anatomical structure through careful investigation of the upper eyelids of Japanese patients and cadavers. Materials and methods Observation of patients' upper eyelids The preaponeurotic fat space was investigated in 720 Japanese patients, including 131 patients with pronounced epicanthal folds, 195 patients with dermatochalasis and Presented at the 5th Research Council Meeting of the Japan Society of Plastic and Reconstructive Surgery, Nagasaki, Japan on 18 October patients with aponeurotic blepharoptosis. The average age was 41.5 years (range years) with 116 being male and 604 female. We always incise the orbital septum horizontally to open the preaponeurotic fat space, which allows us to manipulate the levator aponeurosis and the preaponeurotic fat. During surgical manipulation, ligamentous tissues different from Whitnall's ligament in the preaponeurotic space were photographically recorded. When such ligamentous tissues were found, they were excised except for Whitnall's ligament. Preoperative and post-operative photographs were compared to confirm the effect of excision. Informed consent for this study was obtained in writing from all patients. Observation of cadavers' upper eyelids The three-dimensional distribution of the ligamentous tissue in the preaponeurotic fat space was investigated in detail in two female and six male Japanese cadavers. Their average age was 75.5 years (range years). Histology Ten specimens of the central upper eyelid from another ten Japanese subjects were obtained for microscopic investigation. One specimen was harvested from an 84-year-old woman with extensive squamous cell carcinoma of the lower and upper eyelids, and nine specimens were obtained from three female and six male cadavers whose 466

2 A n a n a t o m i c a l structure in the M o n g o l o i d e y e, '~'~': ~ "~i~ ' A H i::!~ ~84184 i?i 84 G Figure 1--Varieties of shapes of the upper eyelid and the lower-positioned transverse ligamentous tissue. (A, B) A puffy eyelid with a narrow palpebral fissure has a robust ligamentous structure. The asterisk (*) indicates the orbital septum, which is horizontally incised and turned down. (C, D) Drooping of the lateral two-thirds of the upper eyelid corresponds to distribution of the lower-positioned transverse ligament. (E, F) A diaphanous retinaculum is fine and in close contact with either the levator aponeurosis or the orbital septum and may easily be overlooked. 'W' indicates the higher-positioned Whitnall's ligament. (G, H) A sunken eyelid with a wide palpebral fissure has no transverse ligamentous tissue.

3 468 British Journal o f Plastic Surgery C Figure 2--Effect of excision of the lower-positioned transverse ligament in two patients. (A, B) Preoperative primary and upward gazing in an 18-year-old woman depicts a puffiness of the upper eyelid and a narrow palpebral fissure. Retraction of the upper eyelid during upward gazing is restricted compared with that during primary gazing. In addition to excision of the lower-positioned transverse ligament, strip excision of skin, orbicularis muscle, orbicularis fascia and lateral fat pad, and supratarsal fixation to create the superior palpebral crease were carried out. (C, D) Postoperatively, retraction of the upper eyelid during upward gazing is not restricted. (E, F) Preoperative primary and upward gazing in a 46-year-old woman depicts drooping of the lateral two-thirds of the upper eyelid. Retraction of the upper eyelid during upward gazing is restricted compared with that during primary gazing. In addition to excision of the lower-positioned transverse ligament, strip excision of skin, orbicularis muscle, orbicularis fascia and lateral fat pad, and supratarsal fixation to create the superior palpebral crease were eartied ont. (G, H) Postoperatively, retraction of the upper eyelid during upward gazing is not restricted.

4 An anatomical structure in the Mongoloid eye 469 O B e Figure 3----Gross anatomy of the upper eyelid. (A, B) Photograph and diagram of the right upper eyelid of a 63-year-old female. The central fat pad of the preaponeurotic space has been removed. The arrows indicate the lower-positioned transverse ligament (Tr: trochlea, W: Whitnall's ligament, LG: lacrimal gland, A: levator aponeurosis, MFP: medial fat pad of the preaponeurotic space, S: orbital septum). The arrow in the diagram indicates the lower- positioned transverse ligament. (C, D) Schematic diagrams of a typical Mongoloid upper eyelid in the opened position and sagittal section. The arrow in the orbicularis fascia (OF) indicates the vector which widens the palpebral fissure provided by the occipito-frontalis muscle. Whitnall's ligament is located on the levator muscle, whereas the lower-positioned transverse ligament is located on the levator aponeurosis. The other arrow above the levator aponeurosis indicates the other vector which is provided by the levator muscle. average age was 67.6 years (range years). The specimens were fixed in 10% buffered formalin and routinely processed for paraffin embedding. They were then serially sliced in the sagittal plane (6-8 Ixm thickness) and stained with the Azan and elastica van Gieson techniques. Results Patients' upper eyelids In 712 of 720 patients, a transverse ligamentous tissue different from Whitnall's ligament was observed at the bottom of the preaponeurotic fat space. A robust ligamentous structure was observed in 331 patients (46%) with puffier eyelids and a narrower palpebral fissure (Fig. 1A, B). A diaphanous retinaculum was observed in 381 patients (53%) (Fig. 1C, D). In some patients, these diaphanous structures were fine and in close contact with either the levator aponeurosis or the septum and could easily be overlooked (Fig. 1E, F). There was no transverse ligamentous tissue in eight patients (1%) with thinner eyelids and a wider palpebral fissure (Fig. 1G, H). After the lowerpositioned transverse ligamentous tissue was excised by surgery, the upper eyelid could be easily retracted by upward gazing, resulting in a wider postoperative palpebral fissure (Fig. 2).

5 470 British Journal o f Plastic Surgery Figure 4--Histological anatomy of the upper eyelid. (A) Light micrograph of the left upper eyelid of a 66-year-old woman (Azan stain; x 2). (S: orbital septum, A: levator aponeurosis, W: Whitnall's ligament, Ta: tarsus, T: lower-positioned transverse ligamentous tissue.) (B) Another light micrograph of the left upper eyelid of a 72-year-old man (Azan stain; x4). (C) The lower-positioned transverse ligamentous tissue shows tight collagen bundles and few elastic fibres (Elastica van Gieson stain; x 40). (D) Whitnall's ligament shows thin collagen bundles and a few elastic fibre nets.

6 An anatomical structure in the Mongoloid eye 471 Cadavers' upper eyelids When the preaponeurotic fat space was opened and the fat was retracted, the transverse ligamentous tissue was easily identified just above the line of fusion between the orbital septum and the levator aponeurosis (Fig. 3A, B). The medial part of the ligamentous tissue ran through the space between the medial and lateral orbital fat pads and was attached to the supero-medial orbital rim. The lateral part was in close contact with the lateral horn and was finally attached to the lateral orbital rim just above the lateral horn. In some cadavers, this transverse ligament adhered to the innominate diaphanous connective tissue around the preaponeurotic fat. Histology Although the preaponeurotic fat space had collapsed due to senile fat atrophy or drainage of the preaponeurotic fat during slicing, the transverse ligamentous tissue above the point of fusion between the aponeurosis and the orbital septum was observed in all 10 specimens (Fig. 4A, B). Histological evaluation of the slices stained with elastica van Gieson demonstrated that these ligamentous tissues were tight bundles of collagen fibres containing few elastic fibres (Fig. 4C). On the other hand, Whitnall's ligaments were composed of thin collagen bundles and a few elastic fibres (Fig. 4D). Discussion Another, lower-positioned transverse ligament different from Whitnall's higher-positioned transverse ligament was identified just above the line of fusion between the orbital septum and the levator aponeurosis (Figs 1, 3 and 4). Whitnall's ligament is generally considered to be a fascial condensation of the levator muscle, providing a fulcrum to translate a posterior into a superior vector of the levator muscle. 8 The lower-positioned transverse ligament may be another fascial condensation of the levator aponeurosis, possibly acting as retinaculum for the levator aponeurosis, because its histological components contain fewer elastic fibres than Whitnall's ligaments. Our examination of the inside of the preaponeurotic fat space indicated that the superficial expansion of the levator aponeurosis tumed up around the lower-positioned transverse ligament to become the orbital septum (Fig. 3B, D). From this anatomical observation, the following functions of the levator muscle can be surmised. When the levator muscle contracts, the deep expansion of the levator aponeurosis retracts the tarsus, the middle expansion retracts the pretarsal orbicularis oculi muscle and skin, and the superficial expansion retracts the preaponeurotic fat against the lower-positioned transverse ligament. This restricts the excursion of the levator muscle, thus keeping the preaponeurotic fat lower-positioned during retraction of the upper eyelid (Fig. 3D). Subsequently, it may keep the entire upper eyelid low-positioned, resulting in narrowness of the palpebral fissure (Figs 1A and 2A). After the lower-positioned transverse ligament was surgically excised, the upper eyelid could be easily retracted (Fig. 2), so that it can be concluded that this tissue makes not only the upper eyelid puffy but also the palpebral fissure narrow. In the Occidental eyelid, a 'white line' has been reported in some patients with acquired blepharoptosis, and this line is located where we have identified the lower-positioned transverse ligament. 9 However, it has been suggested that this line represents the rolled and retracted fibres of the stretched levator aponeurosis. As far as another biological significance of the lower-positioned transverse ligament is concerned, it may help contraction of the occipito-frontalis muscle to lift not only the upper eyelid but also the lateral canthus upward via the orbicularis fascia in conjunction with retraction of the levator muscle (Fig. 3B, D), resulting in lifting of the brows and upward tilting of the lateral canthus (Figs 1A and 2A). Drooping of the lateral two-thirds of the upper eyelid is commonly observed as a characteristic of the ageing face (Figs 1C and 2E). This may be caused by the lower-placed transverse ligament, which is positioned from supero-medially to infero-laterally in the preaponeurotic fat space and stretches the surrounding soft tissues in reaction to movements to maintain a sufficient visual field such as lifting of the eyebrows as well as the compensatory excessive contraction of the levator muscle. The distribution of this ligament corresponds to the shape of the drooping eyelid (Fig. 1C, D). Therefore, the lower-positioned transverse ligament would benefit from surgical intervention for aesthetic and functional reasons. When the lower-positioned transverse ligament is poorly developed and the deep expansion of the levator aponeurosis is disinserted from the tarsus, the compensatory excessive contraction of the levator muscle may retract the preaponeurotic fat too much, resulting in upward displacement of the superior palpebral crease, leading to a sunken upper eyelid. This phenomenon may be observed in most Occidental and some Mongoloid people (Fig. 1G, H). A creaseless eyelid as one of the Mongoloid features is generally thought to be caused by the absence of insertion of the levator aponeurosis into the septum of the orbicularis oculi muscle as well as the lower insertion of the orbital septum into the levator aponeurosis. We believe that most Mongoloid eyelids have a superior palpebral crease. However, when an epicanthal fold and the lower-positioned transverse ligament are pronounced, the drooped skin fold conceals the superior palpebral crease. The orbital septum does not insert into the levator aponeurosis, but the superficial expansion of the levator aponeurosis turns up around the lower-positioned transverse ligament to become the orbital septum. In conclusion, eyes featuring a puffy upper eyelid with a narrow palpebral fissure were found to contain a lower-positioned transverse ligament different from the higher-positioned Whitnall's ligament at the bottom of the preaponeurotic fat space, which determines the characteristic appearance of the Mongoloid eye. Acknowledgement We would like to thank Dr Nobuteru Usuda, Associate Professor in the First Department of Anatomy, Shinshu University School of Medicine, for his histological support.

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