A cadaveric study investigating the anatomy of the medial orbital wall

The purpose of this study is to investigate the applicability of the current surgical guideline, known as ‘24-12-6’ surgical guideline, in the Hispanic and European populations. This guideline is used during numerous orbital surgeries and states that the distance between the anterior lacrimal crest (ALC) to the anterior ethmoidal foramen (AEF) (24 mm), the AEF to the posterior ethmoidal foramen (PEF) (12 mm), and the PEF to the optic canal (OC) (6 mm) follows a Rule of Halves. Previous studies suggest this surgical guideline is not applicable for all ethnicities; however, to our knowledge, no data has been published regarding the accuracy of this guideline pertaining to the Hispanic population. An experimental study was performed on 79 orbits (52 cadavers) donated to the Human Anatomy Program at UT Health San Antonio. The ALC, AEF, posterior ethmoidal foramen, and OC were identified; the orbit was enucleated and all remaining soft tissue removed. The distance between each landmark was recorded using a digital caliper. For all cadavers studied, the distances between the ALC, AEF, posterior ethmoidal foramen, and OC were 24.76 mm, 13.89 mm, and 7.61 mm, respectively. Thus, the ‘24-12-6’ surgical guideline was not applicable to the sample studied. Based on ethnicity data, these relationships were also not true for the European or the Hispanic populations. Therefore, significant anatomical variations exist in the current surgical guideline. Clinicians may need to adjust their methodology during surgical procedures in order to optimize patient care.