An anatomical structure which results in puffiness of the upper eyelid anda narrow palpebral fissure in the Mongoloid eye

The typical Mongoloid eye differs from the Occidental one in puffiness of t he upper eyelid and narrowness of the palpebral fissure. We surmised that a n anatomical structure might exist in the preaponeurotic fat space, which d etermines the features of the Mongoloid eye. The upper eyelids of 720 Japan ese patients and eight Japanese cadavers were macroscopically investigated, and sagittal slices of the central upper eyelid of one patient and nine ca davers 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 ap oneurosis in almost every upper eyelid. A robust ligamentous structure was observed in 331 patients (46%) with puffier eyelids and a narrower palpebra l fissure, a diaphanous retinaculum in 381 patients (53%) and no transverse ligamentous tissue in eight patients (1%). Histological evaluation demonst rated that this ligament was composed of tight bundles of collagen fibres c ontaining few elastic fibres. Examination of the preaponeurotic fat space i ndicated that the superficial expansion of the levator aponeurosis turned u p around this transverse ligament to become the orbital septum. When the le vator muscle contracts, the deep expansion of the levator aponeurosis retra cts the tarsus, the middle expansion retracts the pretarsal orbicularis ocu li muscle and skin, and the superficial expansion retracts the preaponeurot ic fat against this ligament. This structure thus determines the low positi on of the preaponeurotic fat and restricts the vertical width of the palpeb ral fissure, causing the features of the Mongoloid eye. (C) 2000 The Britis h Association of Plastic Surgeons.