MRI findings of the upper eyelid and their relationship with single- and double-eyelid formation.

Before the invention of magnetic resonance imaging (MRI), it was impossible to observe an architectural deformation of the eyelid because of its movement. The authors observed MRI films of 15 eyelids in both closed and opened positions and obtained new information on the architecture of the upper eyelid and also the mechanism of single and double eyelids, and sunken eye formation. (1) Orbital fat is transposed when the lid moves. If the fat can not return into the orbit when the lid opens, it droops and interferes with the fold formation of the lid. (2) The thickness of the eyelid skin is associated with double-eyelid formation. The skin fold is observed at the junction between thick skin with subcutaneous fat and thin skin without it. (3) We could not confirm Doxanas and Anderson's assertion that septal insertion was lower in Orientals. However, we observed pretarsally drooped or herniated orbital fat in many slit-eye Orientals. (4) There are three angles at the tarso-levato-aponeurotic line: one at the junction with transverse ligament, one at the point of septal insertion, and another at the aponeurotic terminal on the tarsus.