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Luke Dolezal, Veren Rana, Jason Sokol; A cadaveric study of periocular and orbital surgical anatomy. Invest. Ophthalmol. Vis. Sci. 2018;59(9):331.
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© ARVO (1962-2015); The Authors (2016-present)
This study focuses on the anatomy of multiple periocular and orbital tissues important in oculoplastic surgery including the levator palpebrae superioris (LPS) muscle, the inferior tarsal muscle, and the location of the ethmoid foramina and optic canal. The goal was to determine important anatomic measurements and identify variation useful to understand for common oculoplastic procedures.
Between 46 and 54 specimens of formalin- fixed cadavers were examined in each anatomic group. Upper eyelids were dissected through a supraorbital approach to identify the LPS and measure aponeurosis length and attachment points histologically. Lower eyelids were examined through gross and histologic examination to identify the presence or absence of an inferior tarsal muscle. Medial orbital landmarks were examined by removing orbital contents to reveal the anterior lacrimal crest (ALC), anterior ethmoidal foramen (AEF), posterior ethmoidal foramina (PEF), and optic canal (OC) and measuring the distance between each.
The LPS aponeurosis was found to attach more commonly to the orbital septum (63.8%) than attaching directly to the superior tarsus plate (36.2%). Average levator aponeurosis length was 10.29 mm with a standard deviation of 3.16 mm. Twenty six out of 50 lower eyelids revealed the presence of gross muscle fibers upon examination (52.00%) with confirmation by H&E demonstrating smooth muscle fibers. Gender contingency analysis also revealed that sex did not influence the presence or absence of the inferior tarsal muscle (Chi Square 0.63). Medial wall distances were measured at ALC - AEF: 20.68 mm, AEF - PEF: 14.32 mm, and PEF - OC: 7.59 mm.
The upper eyelid study quantified the length of the LPS aponeuriosis and further described its attachment points within the upper eyelid. The lower eyelid study demonstrated that the inferior tarsal muscle runs horizontally and characterized the frequency of its presence or absence. Measurements of the location of the ethmoid foramina and optic canal location demonstrated variation from the “24-12-6 mm rule” as “21-14-8 mm”, indicating a variation from the rule which is used as a guide for surgeons operating in the medial orbit. Each of these studies adds to the current scientific knowledge of periorbital and orbital anatomy and is important information to aid surgeons operating in these spaces.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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