Upper blepharoplasty with bony anatomical landmarks to avoid injury to trochlea and superior oblique muscle tendon with fat resection

The trochlea and superior oblique muscle tendon separate the medial and central fat compartments in the upper lid. The purpose of this study was to determine anatomical landmarks to predict the location of and avoid injuring the trochlea and superior oblique muscle tendon with orbital fat resection during upper blepharoplasty. The trochlea and superior oblique muscle tendon were identified in 14 cadaver heads. Bony anatomical landmarks were identified to predict the oblique vector along which the trochlea and superior oblique tendon lie. The trochlea was measured in millimeters from the palpable superior orbital foramen. The oblique course of the superior oblique muscle tendon was measured from its medial location in the lateral direction in millimeters from the frontozygomatic Suture. These measurements were obtained with 4.0-power loupe magnification. The trochlea was identified 10.0 +/- 0.9 min inferior to the palpable superior orbital foramen. The superior oblique muscle tendon coursed laterally along an oblique vector to within I min of the frontozygomatic Suture for all 14 dissections. The vertical vector of the superior orbital foramen was measured 15.9 +/- 1.1 min lateral to the medial canthus. The width of the bony orbit measured 42.2 +/- 1.6 mm. In two dissections, the superior orbital foramen could not be palpated, and the latter measurements were used to predict the superior orbital foramen. This anatomical study showed that when performing orbital fat resection with upper blepharoplasty, the trochlea and superior oblique muscle tendon can be identified and avoided with the above-described bony landmarks.