Do upper and lower orbital fat have a connection?

This study, using cadavers, was conducted to determine whether there is a true connection between upper and lower orbital fat. A total of 39 orbits of 20 fresh Korean adult cadavers were used. Colored gelatin was injected into the upper or lower peripheral fat (preaponeurotic fat) of each orbit. One week after injection, dissection was continued and connection of the upper and lower orbital fat was examined. No migration of gelatin injected into the upper or to the central fat (intermuscular cone fat) was observed. However, migration of gelatin injected into the upper or lower preaponeurotic fat into the entire episcleral space through the adipose orifice (AO) was observed. The 3 sides of the upper AO consisted of the superior oblique muscle before the trochlea, superior oblique tendon after the trochlea, and sclera. The 3 sides of the lower AO consisted of the inferior oblique muscle, lateral rectus muscle, and fascia between the inferior rectus muscle and lateral rectus muscle. The upper AO was located at the medial one third of the orbital width and superior one fifth of the orbital height. The lower AO was located at the lateral one third of the orbital width and inferior one fifth of the orbital height. The shape of the upper AO was a triangle with a base of 4.3±2.0 mm and a height of 2.3±1.2 mm. The shape of the lower AO was a triangle with a base of 4.5±1.8 mm and a height of 2.7±1.1 mm. We think that surgical obliteration of the AO might prevent migration of preaponeurotic fats. Prevention of migration of preaponeurotic fats will aid in avoidance of baggy lower eyelid or deepening of the supratarsal fold.